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Distribución Potencial de Dendroctonus rhizophagus (Coleoptera: Scolytinae) en la Sierra Madre Occidental y su Aplicación para la Generación de un Modelo de Riesgo para el Municipio de Casas Grandes, Chihuahua. T E S I S QUE COMO UNO DE LOS REQUISITOS PARA OBTENER EL GRADO DE DOCTOR EN CIENCIAS QUIMICOBIOLÓGICAS P R E S E N T A M. C. MARÍA GUADALUPE MENDOZA CORREA MÉXICO, D. F., ENERO del 2011 Instituto Politécnico Nacional Escuela Nacional de Ciencias Biológicas Sección de Estudios de Posgrado e Investigación María Guadalupe Mendoza Correa El presente trabajo se realizó en el Laboratorio de Variación Biológica y Evolución del Departamento de Zoología de la Escuela Nacional de Ciencias Biológicas del Instituto Politécnico Nacional, bajo la dirección del Dr. Gerardo Zúñiga Bermúdez y la codirección del Dr. Héctor Omar Mejía Guerrero. María Guadalupe Mendoza Correa La presente investigación formó parte del proyecto “Biología, ecología y manejo de poblaciones de Dendroctonus rhizophagus Thomas y Bright (Coleoptera, Curculionidae: Scolytinae) en el estado de Chihuahua”, CONAFOR, CLAVE 69539. El sustentante fue becario del Consejo Nacional de Ciencia y Tecnología (CONACYT) de Enero del 2007 a Diciembre del 2010 y del Programa Nacional de Formación de Investigadores (PIFI) del Instituto Politécnico Nacional, de Enero de 2007 a Junio de 2010. María Guadalupe Mendoza Correa DEDICATORIAS Dedico esta investigación con todo mi amor, admiración y respeto: A mi esposo: Marco Antonio Por seguir apoyándome en TODOS mis proyectos, Por ser papá y mamá durante mis ausencias, Por ser un padre amoroso y ejemplar, Por ser tan pasional, comprensivo y paciente, Por seguir siendo el mejor esposo, amigo y amante Por tus valores, creencias, defectos y virtudes Por ser mi complemento y mí premio mayor Por amarme tanto… ¡¡¡TE ADMIRO Y TE AMO!!!! A mis hijos: Marquito y Nayeli: Por su comprensión, apoyo, alegría y paciencia, Por ser tan responsables y buenos estudiantes, Por darme la tranquilidad necesaria durante mis ausencias, Por darme tanta felicidad, Por su ánimo para continuar hasta el final, Por ser mi motivación y mi mayor logro en la vida….¡¡¡LOS AMO!!! María Guadalupe Mendoza Correa AGRADECIMIENTOS A mis Padres Ines y José Guadalupe Gracias por su amor, apoyo y comprensión, los cuales me han permitido culminar una meta más, Gracias por quererme tanto, no sólo a mí sino a mi esposo e hijos, ¡¡¡Dios me escogió a los mejores padres!!! A mis hermanos Jorge, Miguel, Agustin, Ramón e Ignacio y mis ″hermanas” Lety, Lola, Moni, Ale y Rosalía Gracias también por apoyarme tanto para culminar esta nueva meta, Por su gran ánimo, por su cariño y por siempre estar a mi lado cuando los hemos necesitado, porque donde hay amor, la distancia no importa… Y si volviera a nacer y tuviera que elegir a mi familia ¡¡¡Sin dudarlo los escogería a ustedes otra vez!!! Al Dr. Gerardo Zúñiga Gracias por un logro más juntos, Gracias por la oportunidad, el apoyo, la tolerancia y el respeto, Porque aunque a veces ha sido difícil el trabajo conjunto, Al final siempre prevalece la comprensión, la admiración y sobre todo el cariño mutuo… ¡¡¡Gracias!!! María Guadalupe Mendoza Correa A mis sinodales: Dr. Guillermo, Dr. Fabián, Dr. Cesar, Dr. Omar y Dr. Fernando Gracias por su apoyo, sus revisiones y sus acertados comentarios para la mejora de este escrito. Al M. en C. Daniel Núñez López Gracias por todo tu apoyo, tu paciencia y sobre todo tus enseñanzas, las cuales fueron fundamentales para desarrollar esta investigación, en verdad te admiro por tu profesionalismo… Al Ing. José Luis Aguilar Vitela, Ing. Sergio Quiñones y Biol. Antonio Olivo Gracias por su colaboración en la colecta de los datos, Por todo su apoyo incondicional, su generosidad y su alegría, Gracias por esos bellos paisajes que no olvidaré, y los agradables momentos que pasamos juntos, con todo mi cariño, admiración y respeto… María Guadalupe Mendoza Correa A todos los compañeros del laboratorio de Variación Biológica y Evolución A Ericka, Claudia, Rosita, Fernanda, Paquito, Enrico, Javier, Gabriel, Vero Torres, Belinda, Faviel, Verito, Kim, Karina, Mariana, Karina Martínez, Alba y Berenice: Gracias por su amistad, alegría, apoyo y comprensión, Por haberme aceptado como compañera y hacer más agradable la estancia en el laboratorio, Los voy a extrañar…. Al CONACYT y PIFI Gracias por el apoyo logístico recibido y por la confianza depositada en mi persona. María Guadalupe Mendoza Correa ÍNDICE Páginas Índice de Figuras I Índice de Tablas II Introducción General IV Justificación VIII Objetivos IX Capitulo I: Factores que influyen la distribución geográfica de Dendroctonus rhizophagus (Coleoptera: Curculionidae: Scolytinae) en la Sierra Madre Occidental, México 1 Abstract 3 Resumen 4 Introduction 5 Materials and Methods 8 Results 12 Discussion 15 Acknowledgments 19 References Cited 20 Tables 27 Figure Legends 35 Figures 36 María Guadalupe Mendoza Correa Capitulo II: Determinación de áreas de susceptibilidad y riesgo de presencia de Dendroctonus rhizophagus (Coleoptera: Curculionidae: Scolytinae) en los bosques de pino del municipio de Casas Grandes, Chihuahua. 39 Abstract 41 Resumen 42 Introduction 43 Materials and Methods 46 Results 51 Discussion 54 Acknowledgments58 References Cited 59 Tables 66 Figure Legends 77 Figures 78 Conclusiones Generales 82 Referencias Generales 84 María Guadalupe Mendoza Correa I ÍNDICE DE FIGURAS Páginas CAPITULO I Fig. 1. Potential distribution of D. rhizophagus in the Sierra Madre Occidental, México modeled with BIOCLIM 36 Fig. 2. Habitat suitability (HS) for D. rhizophagus in the Sierra Madre Occidental, México modeled with ENFA. 37 Fig. 3. Potential distribution of D. rhizophagus in the Sierra Madre Occidental, México modeled with MaxEnt 38 CAPITULO II Fig. 1. Location of Casas Grandes municipality, Chihuahua, and map of the potential distribution of pine forests (García-Nájera 2009) 78 Fig. 2. Potential distribution of D.rhizophagus in Casas Grandes municipality, modeled with MaxEnt 79 Fig. 3 Susceptibility’s model of pine forests of Casas Grandes municipality, Chihuahua 80 Fig. 4. Risk Model of presence of D. rhizophagus in pine forests of Casas Grandes municipality, Chihuahua 81 María Guadalupe Mendoza Correa II ÍNDICE DE TABLAS Páginas CAPITULO I Table 1. Collection records and reference sources of D. rhizophagus 27 Table 2. Bioclimatic profile of D. rhizophagus for each location (obtained using BIOCLIM) 28 Table 3. Percentage of incidence of D. rhizophagus on host Pinus species in the Sierra Madre Occidental, México 30 Table 4. Principal component analysis of BIOCLIM climatic variables 31 Table 5. Percentage of variation explained by ecogeographic variables for D. rhizophagus using ENFA 33 Table 6. Percentage of estimated contribution for environmental variables using MaxEnt 34 CAPITULO II Table 1. Ecogeographic (topographic, climatic and biotic) variables regarded as predictor variables in MaxEnt analysis 66 Table 2. Regression coefficients used to generate models of temperature and precipitation variables for Casas Grandes municipality, Chihuahua 67 Table 3. Suitability values for each alternative of the precipitation criterion, and their corresponding byte values 68 Table 4. Suitability values for each alternative of the temperature criterion, and María Guadalupe Mendoza Correa III their corresponding byte values 69 Table 5. Suitability values for each alternative of the topographic and biotic criteria, and their corresponding byte values 70 Table 6. Measurement scale for assignment of value judgments, defined by Saaty (1980) 71 Table 7. Percent contribution by each ecogeographic variable as estimated by MaxEnt 72 Table 8. Pairwise comparison matrix of precipitation variables and the weight assigned to each variable 73 Table 9. Pairwise comparison matrix of temperature variables and the weight assigned to each variable 74 Table 10. Pairwise comparison matrix of topographic variables and the weight assigned to each variable 75 Table 11. Pairwise comparison matrix of the criteria taken into account in order to obtain the susceptibility map and the weight assigned to each criterion 76 María Guadalupe Mendoza Correa IV INTRODUCCIÓN GENERAL Los escarabajos conocidos como descortezadores (Coleoptera: Curculionidae: Scolytinae) destacan como uno de los grupos de insectos que mayor impacto tienen en los bosques de coníferas. De manera particular, las especies del género Dendroctonus Erichson son consideradas como uno de los agentes destructivos más importantes en condiciones epidémicas de los bosques de los géneros Pinus (L), Picea (A. Dietr.), Pseudotsugae (Carr.) y Larix (Mill.). El género tiene una distribución Holartica y está integrado por 19 especies, 17 de las cuales se distribuyen en Norteamérica y 2 en Europa y Asia. En México están presentes 12 especies y entre las más agresivas destacan D. mexicanus, D. adjunctus, D. frontalis y D. rhizophagus. Las especies de este género, al igual que muchos otras, son componentes naturales del bosque, su función ecológica es la de coadyuvar a la regeneración y restauración natural de los bosques (Salinas et al. 2010) al matar árboles enfermos, dañados o debilitados por diversos factores (Wood 1982). Sin embargo, cuando las condiciones de equilibrio de los bosques son alteradas por factores naturales o por actividades antropogénicas, sus poblaciones pueden convertirse en plagas (Raffa et al. 2005) ocasionando pérdidas económicas importantes a la industria forestal (Wood 1982). Dado que los descortezadores del género Dendroctonus son la principal causa de mortalidad de las coníferas de Norteamérica (Raffa y Berryman 1987), históricamente se han venido aplicando métodos agresivos de control como son: el derribo y abandono de los árboles; el derribo, descortezado y arropado, y la inyección de químicos a los árboles plagados, entre otros. En Canadá y Norteamérica el conocimiento preciso del sistema de comunicación química de las especies más agresivas del género, ha permitido el uso exitoso de compuestos químicos (semioquimicos) sintéticos que alteran su conducta, al funcionar como mezclas de agregación o María Guadalupe Mendoza Correa V antiagregación. Desafortunadamente, los semioquímicos para las especies mexicanas no son conocidos, lo que ha dado lugar al traslado y aplicación de estos compuestos generados en otras latitudes (Sánchez-Martínez 2007), sin embargo, su uso no ha producido resultados satisfactorios. Debido a la falta de información relacionada con la biología y ecología de las especies de descortezadoresmexicanos, es fundamental generar información básica de manera consistente que contribuya en la resolución de los problemas específicos relacionados con estos insectos y que por consiguiente derive en un mejor manejo de los bosques. El estudio de la distribución geográfica de los organismos es crucial para disciplinas como la biogeografía, evolución, conservación y manejo de especies (Anderson et al. 2003). Desde el siglo pasado se ha hecho mucho hincapié en la importancia del reconocimiento y construcción de los patrones de distribución geográfica de las especies y de la relación de éstos con factores climáticos y geográficos (Brown 1984). Asimismo, se ha señalado que al igual que el ambiente, las interacciones bióticas limitan o favorecen la abundancia de las especies y por consiguiente regulan indirectamente su distribución geográfica (Lomolino et al. 2006). Los estudios de distribución geográfica de las especies se han realizado tradicionalmente a partir de la información (localidad y altitud) que acompaña a los ejemplares depositados en las colecciones científicas y en los museos (MacDonald 2003). A partir de esta información se han generado mapas en los cuales la distribución de los taxa se representa simplemente como un conjunto de puntos, y en donde cada punto es una localidad de colecta, de tal modo que al unir los puntos de la periferia, se circunscribe un área que corresponde a su distribución geográfica (Rapoport 1982). En la actualidad una visión más moderna en este tipo de estudios, busca integrar esta información básica con datos climáticos, biológicos y topográficos, con la finalidad de tener un conocimiento más integral de las áreas de distribución de los taxa y comprender mejor cuales son las variables que limitan o favorecen su expansión (Gaston 2003). María Guadalupe Mendoza Correa VI El desarrollo de modelos predictivos ayuda a estimar la distribución potencial de las especies mediante el uso de técnicas estadísticas y probabilísticas, las cuales correlacionan los datos de presencia y/o ausencia con un conjunto de variables ambientales (Guisan y Zimmermann 2000, Pearson y Dawson 2003). Asimismo, estos modelos permiten describir las condiciones bioclimáticas donde están presentes las especies, así como identificar que variables están determinando su presencia. Dichos modelos han ganado importancia como una herramienta de investigación en temas de conservación, nicho ecológico de las especies, patrones espaciales de la biodiversidad, efecto del cambio climático sobre la distribución de las especies y amenaza potencial de plagas o especies invasivas (Casinello et al. 2006, Ungerer et al. 1999). Por otra parte, la integración de las variables ecogeográficas con la presencia real de un agente que potencialmente puede afectar o dañar un recurso en un área geográfica determinada, permite explorar el grado de susceptibilidad o riesgo que ese agente puede tener sobre el recurso. En el caso de los descortezadores, la inclusión de esta información ligada al manejo del bosque, conduce al desarrollo de estrategias preventivas en aquellas zonas boscosas que son susceptibles a la presencia de estos insectos (Mason et al. 1985, Bentz et al. 1993, Llanderal, 1995). Uno de las estrategias preventivas son los sistemas de valoración de susceptibilidad o modelos de riesgo, entendiendo por “riesgo” la probabilidad de que en un sitio particular ocurra un ataque epidémico en un tiempo determinado (Nelson et al. 2006) y por “susceptibilidad” la probabilidad de que un sitio sea infestado debido a sus características inherentes que lo hacen disponible a la presencia de las poblaciones de estos insectos (Shore y Safranyik 1992). Los modelos de susceptibilidad y riesgo han sido desarrollados y aplicados principalmente en Estados Unidos y Canadá (Lorio 1981), ya que en estos países existe un amplio conocimiento de las condiciones de los huéspedes, así como de la biología, ecología y dinámica poblacional de los descortezadores (McGregor 1986). En México, sin embargo, la aplicación de estos modelos ha María Guadalupe Mendoza Correa VII sido escasa aplicándose solo a dos especies del género: D. mexicanus y D. frontalis (Espinosa y Muñoz 1988, Llanderal 1995, Iñiguez 1999). Dendroctonus rhizophagus Thomas y Bright es una especie endémica de la Sierra Madre Occidental en los estados de Sonora, Chihuahua, Durango y Sinaloa, que presenta un comportamiento atípico dentro del género ya que no realiza ataques masivos y solo parasita árboles < 3 m en áreas de regeneración natural y plantaciones de once especies de pinos de importancia forestal, entre las que destacan Pinus engelmannii Carr., Pinus durangensis Martinez, Pinus leiophylla Schlecht y Cham. y Pinus arizonica Engelm. (Cibrian et al. 1995; Salinas-Moreno et al. 2004; Sánchez-Martínez y Wagner 2009). Los daños producidos por esta especie en las dos últimas décadas ascienden alrededor de 12,500 plántulas por año en toda su área de distribución. Una de las zonas afectadas del estado de Chihuahua, es el municipio de Casas Grandes, el cual posee extensas áreas de bosques de pino de importancia forestal en sus regiones sureñas y occidentales. María Guadalupe Mendoza Correa VIII JUSTIFICACIÓN D. rhizophagus es un descortezador endémico de la Sierra Madre Occidental, el cual presenta un comportamiento de ataque diferente, al parasitar únicamente a los renuevos de varias especies de pinos. Dado su comportamiento, este descortezador es considerado dentro de las especies “agresivas” de México (Sánchez-Martínez et al 2007). A pesar de la importancia de D. rhizophagus como una de las principales plagas forestales del país, y en particular del estado de Chihuahua, es muy poco el conocimiento que se tiene acerca de su distribución geográfica, biología y ecología (Estrada-Murrieta 1983, Salinas-Moreno et al. 2004; Sánchez-Martínez y Wagner 2009), el cual es básico para la aplicación en métodos de control directo o preventivo. Esta situación hace que dicha especie sea un ejemplo ideal para la aplicación de los modelajes predictivos de distribución, con la finalidad de generar este conocimiento básico a partir de datos de presencia del insecto, el cual pueda ser útil para obtener modelos de susceptibilidad y riesgo de los bosques de pino a una escala local, que pudieran contribuir a un mejor control de esta plaga. En este contexto, en el primer capítulo de este trabajo se analiza la distribución geográfica potencial de D. rhizophagus a lo largo de la Sierra Madre Occidental mediante varios modelos predictivos de distribución, con la finalidad de describir las condiciones bioclimáticas donde puede estar presente el insecto, así como identificar las variables que determinan su presencia en esta provincia morfotectónica. En el segundo capítulo se generan modelos de susceptibilidad y riesgo para el municipio de Casas Grandes, Chihuahua por medio de técnicas de toma de decisión multicriterio (TDMC) y Sistemas de información Geográfica (SIG), a partir de la información bioclimática y la importancia relativa de las variables eco-geográficas. María Guadalupe Mendoza Correa IX OBJETIVOS OBJETIVO GENERAL: Conocer la distribución geográfica potencial de D. rhizophagus en la Sierra Madre Occidental, para generar modelos de susceptibilidad y riesgo de presencia de este descortezador en el Municipio de Casas Grandes, Chihuahua. OBJETIVOS PARTICULARES: 1) Modelar la distribución geográfica potencial de D. rhizophagus en la Provincia Morfotectónica de la Sierra Madre Occidental usando modelos predictivos de distribución. 2) Describir las condiciones bioclimáticas donde se presenta este descortezador. 3) Identificar cuales variables determinan la presencia de D. rhizophagus en la Sierra Madre Occidental. 4) Modelar la distribucióngeográfica potencial de D. rhizophagus en el Municipio de Casas Grandes, Chihuahua mediante un modelo predictivo de distribución. 5) Describir las condiciones bioclimáticas donde se presenta este insecto en el Municipio de Casas Grandes, Chihuahua. 6) Ponderar y evaluar las variables ecogeográficas que están relacionadas con la presencia de este descortezador mediante técnicas de Evaluación Multicriterio para obtener un modelo de susceptibilidad en el Municipio de Casas Grandes, Chihuahua. 7) Obtener un modelo de riesgo para el municipio de Casas Grandes, en base a las áreas susceptibles y a la proximidad de poblaciones de D. rhizophagus. María Guadalupe Mendoza Correa 1 CAPITULO I Factores que influyen la distribución geográfica de Dendroctonus rhizophagus (Coleoptera: Curculionidae: Scolytinae) en la Sierra Madre Occidental, México Los datos de este estudio son parte del trabajo aceptado para su publicación en la revista Environmental Entomology María Guadalupe Mendoza Correa 2 Mendoza et al.: Factors influencing the geographical distribution of Dendroctonus rhizophagus Environmental Entomology ESA Population Ecology Factors influencing the Geographical Distribution of Dendroctonus rhizophagus (Coleoptera: Curculionidae: Scolytinae) in the Sierra Madre Occidental, México Ma. Guadalupe Mendoza 1 , Yolanda Salinas-Moreno 1 , Antonio Olivo-Martínez 2 and Gerardo Zúñiga 1 1 Laboratorio de Variación Biológica y Evolución. Escuela Nacional de Ciencias Biológicas-IPN. Departamento de Zoología. Carpio y Plan de Ayala s/n, Col. Santo Tomás, C. P. 11340 México City, México. 2 Sanidad Forestal, Comisión Nacional Forestal, Sección VI del Noroeste, Chihuahua México. Avenida Universidad piso 1. No. 3705. C. P. 31170, Colonia Magisterial. María Guadalupe Mendoza Correa 3 ABSTRACT The bark beetle, Dendroctonus rhizophagus Thomas & Bright, is endemic to the Sierra Madre Occidental (SMOC) in México. This bark beetle is a major pest of the seedlings and young saplings of several pine species that are of prime importance to the nation’s forest industry. Despite the significance of this bark beetle as a pest, its biology, ecology and distribution are poorly known. Three predictive modeling approaches were used as a first approximation to identify bioclimatic variables related to the presence of D. rhizophagus in the SMOC and to obtain maps of its potential distribution within the SMOC, which is a morphotectonic province. Our results suggest that the bark beetle could have an almost continuous distribution throughout the major mountain ranges of the SMOC. This beetle has a relatively narrow ecological niche with respect to some temperature and precipitation variables and inhabits areas with climatic conditions that are unique from those usually prevalent in the SMOC. However, the bark beetle has a broad ecological niche with respect to the number of hosts that it attacks. At the macro- scale level, the D. rhizophagus distribution occurs within the wider distribution of its main hosts. The limit of the geographical distribution of this bark beetle coincides with the maximum temperature isotherms. Our results imply a preference for temperate habitats, which leads to the hypothesis that even minor changes in climate may have significant effects on its distribution and abundance. KEYWORDS: Bark beetles, Dendroctonus rhizophagus, geographical distribution, predictive models María Guadalupe Mendoza Correa 4 RESUMEN El descortezador, Dendroctonus rhizophagus Thomas & Bright, es una especie endémica de la Sierra Madre Occidental (SMOC) en México, que coloniza plántulas y árboles jóvenes (< 3 m) de varias especies de pinos de importancia económica para la industria forestal de México. A pesar de la importancia de este escarabajo como plaga, su biología, ecología y distribución son poco conocidas. En este estudio se realizaron tres aproximaciones de modelaje predictivo para identificar variables bioclimáticas relacionadas con la presencia de D. rhizophagus en la SMOC y para obtener mapas de su distribución potencial. Los resultados sugieren que el descortezador puede distribuirse de manera casi continua a lo largo de la SMOC, que su nicho ecológico es relativamente estrecho con respecto a algunas variables de temperatura y precipitación y que habita en zonas con condiciones climáticas particulares que no son las que prevalecen en la SMOC. Sin embargo, esta especie tiene un amplio nicho ecológico con respecto al número de huéspedes que parasita. A nivel de macro-escala la distribución de D. rhizophagus está contenida dentro de la distribución más amplia de sus huéspedes principales y el límite de su distribución geográfica coincide con las isotermas de temperatura máxima. Por último, los resultados indican una preferencia por hábitats templados, lo cual permite hipotetizar que aún cambios menores en el clima pueden tener un efecto significativo sobre su abundancia y distribución geográfica. María Guadalupe Mendoza Correa 5 Both environment and population ecology processes limit the abundance and geographic distribution of species (Brown 1984, Thomas et al. 2001, Lomolino et al. 2006). Traditionally, distribution studies have used only basic information (location and elevation) associated with specimens from museums and scientific collections (MacDonald 2003). Integrating this basic information with additional data on climate, biology and topography is essential to fully understand the distributional ranges of species, the potential for distributions to change, and the variables that limit or favor range expansion or contraction (Gaston 2003). The use of geographic information systems (GIS) and the development of a broad spectrum of spatial modeling approaches, including bioclimatic analysis (BIOCLIM) (Nix 1986), Ecological Niche Factor Analysis (ENFA) (Hirzel et al. 2002), and Maximum Entropy (MaxEnt) (Phillips et al. 2004), have made possible the integration of diverse data on biology, climate and topography. This has led to the development of more reliable distribution maps and the modeling of species responses to different past and future climatic conditions. BIOCLIM, in particular, has been used to predict the climate domain and potential species response to climate change at the meso-scale level (e.g., Mackey and Lindenmayer 2001, Ganeshaiah et al. 2003, Jiménez-Valverde et al. 2007). ENFA and MaxEnt have been used to characterize ecological niches and to determine suitable areas for species conservation and natural resource management (e.g., Braunisch and Suchant 2007, Titeux et al. 2007, Sattler et al. 2007, Kumar and Stohlgren 2009). Frequent use of these tools has shown their usefulness and reliability in analyzing the potential distribution of species that have a relatively wide distribution range and whose biology and ecology are poorly known (Pearson and Dawson 2003, Beaumont et al. 2005). Bark and ambrosia beetles (Coleoptera: Curculionidae: Scolytinae) are important natural components of forest ecosystems. The infestation of weakened mature trees promotes the presence of different successional stages and demographic structures within the forest. María Guadalupe Mendoza Correa 6 Nevertheless, these insects are a worldwide problem for the forest industry and in public parks and natural reserves because of the extensive tree mortality they cause under outbreak conditions and as vectors of diseases that reduce tree vigor (Wood 1982). Moreover, some bark beetles are important invaders that represent a significant threat to the health of forests (Brockerhoff et al. 2006). Specifically, bark beetles of the genus Dendroctonus Erichson have a wide geographic distribution inNorth and Central America. They have caused significant economic losses and irreversible ecological changes in Mexican forests (Cibrián et al. 1995). The development of Dendroctonus species usually takes place on mature trees (> 15 years) of the genera Larix Mill., Picea A. Dietrich Pinus L. and Pseudotsuga Carr. (Wood 1982). The advanced age classes of these trees constitute an adequate resource for bark beetle nourishment and reproduction. The sole exception to this is Dendroctonus rhizophagus Thomas and Bright, a species that is endemic to the Sierra Madre Occidental (SMOC) mountain range in northwestern México. Dendroctonus rhizophagus colonizes and kills the seedlings and young saplings (< 10 years) of various pine species, especially Apache pine (Pinus engelmannii Carr.), Durango pine (Pinus durangensis Martinez), Chihuahua pine (Pinus leiophylla Schlecht and Cham.) and Arizona pine (Pinus arizonica Engelm.) (Cibrián et al. 1995, Salinas-Moreno et al. 2004, Sánchez-Martínez and Wagner 2009). This unique bark beetle is a major threat to regeneration in pine forests throughout its distribution in México (Sánchez-Martínez and Wagner 2009). Although D. rhizophagus infests a significant number of seedlings and young saplings every year, its biology, ecology and geographic distribution are poorly known (Estrada-Murrieta 1983, Salinas-Moreno et al. 2004, Sánchez-Martínez and Wagner 2009). Thus, analyzing its geographic distribution is essential to identify the environmental variables associated with its presence in northwestern México and to evaluate its potential threats in other geographical areas of México. Furthermore, if we assume that ongoing climate change could affect the frequency and intensity María Guadalupe Mendoza Correa 7 of bark beetle outbreaks and the geographic distribution of these insects and their hosts (Logan and Powell 2001, Kurz et al. 2008, Waring et al. 2009), there is a possibility that D. rhizophagus could migrate north into forests of the southwestern United States and cause widespread tree mortality in these large contiguous forest. Thus, the purpose of this study is to model the potential distribution of D. rhizophagus in the Sierra Madre Occidental of northwestern México using BIOCLIM, ENFA and MaxEnt to describe the bioclimatic conditions where it occurs and to identify variables that determine its presence. María Guadalupe Mendoza Correa 8 Materials and Methods Biological Data. Collection records (museum specimens) for D. rhizophagus were obtained from the major entomological collections in México and from technical reports of the Comisión Nacional Forestal (CONAFOR) and the Secretaría de Medio Ambiente y Recursos Naturales (SEMARNAT) for the states of Chihuahua, Durango, Sonora and Sinaloa (Table 1). In addition, we included records gathered in the course of several field studies conducted from 2000 to 2008. While some areas of the SMOC morphotectonic province have been little explored, these records represent a reliable sample of the geographical distribution of Dendroctonus rhizophagus. A morphotectonic province is a zone having distinctive enough geomorphic and geologic/tectonic features to differentiate it from neighboring zones (Ferrusquía-Villafranca 1998). A preliminary database of 669 records was assembled to determine the altitudinal range where D. rhizophagus has been found most frequently and the frequency of its incidence (IP) on different hosts. The IP is a measure of the degree of occurrence of the bark beetle on its host plants (Salinas-Moreno et al. 2004). All location records were georeferenced on 1:50,000 topographic maps obtained from the INEGI. For the potential distribution analysis, 412 records were eliminated from the database, because they differed only minimally in geographic coordinates and elevation. Thus, the spatial modeling database was composed of 257 presence- only records. Similarly, a database of the principal hosts of D. rhizophagus was assembled from specimens stored in the national herbariums of México and online records from the webpage of the Comisión Nacional para el Conocimiento y uso de la de Biodiversidad (CONABIO). The final database included 294 presence-only records of 11 pine species. These records were georeferenced on 1:50,000 INEGI topographic maps. María Guadalupe Mendoza Correa 9 Study Area. The morphotectonic province of the Sierra Madre Occidental (SMOC) is located between 20º 30' and 31º 20' N and between 102º 20' and 109º 40' W. It covers 289,000 km² and runs northwest to southeast. Elevations in this mountain chain range from 200 m to slightly above 3,000 m. The climate is temperate, and the vegetation type is primarily pine forest and, to a lesser extent, oak and pine-oak forest. The mean annual precipitation ranges from 400 to 1,600 mm (Rzedowsky 1978, Ferrusquía-Villafranca 1998). Potential geographic distribution of D. rhizophagus using BIOCLIM. A bioclimatic profile of D. rhizophagus was obtained from BIOCLIM in the DIVA-GIS v.5.2 software package (Hijmans et al. 2002) using 19 default temperature and precipitation variables included in BIOCLIM (Table 2). This profile describes the environment where the bark beetle has been recorded, and it is used to identify other sites where the species may reside. The suitability limits of the species are characterized by the mean, standard deviation, minimum and maximum tolerance and percentiles of each variable to a resolution of 2.5 arc minutes. A principal component analysis (PCA) of these climatic variables was performed with STATISTICS v.7.0 (StatSoft® Inc) to assess the relative contribution of each variable to the bioclimatic profile of the species. In addition, histograms were developed to determine the probabilistic distribution of these climatic variables. Variables that follow a normal distribution or a skewed distribution exert greater influences on the bioclimatic profile (Beaumont et al. 2005). Thus, those variables without a clearly defined distribution or a normal distribution with a truncated histogram were eliminated. Subsequently, grid cells that included the bioclimatic profile of D. rhizophagus were identified using BIOCLIM. Grid cells were grouped into four categories: null (areas outside the 0-100 percentile limits), low (areas within the 0-2.5 percentile limits), moderate to high (areas within 2.5-10 percentile limits) and very high to excellent (areas María Guadalupe Mendoza Correa 10 within the10-100 percentile limits). The scatter of cells associated with these categories represents the potential distribution of the species. Potential geographic distribution of D. rhizophagus using ENFA. Maps showing the major climatic variables (determined by PCA), minimum annual temperature, maximum annual temperature and elevation were plotted with DIVA-GIS v.5.2. Additionally, BIOCLIM was used to draw a map of the potential distribution of the hosts of D. rhizophagus in order to incorporate this variable into the analysis. All maps were imported into ArcView v.3.2 (Environmental Systems Research Institute, 1999) and were transformed to the Idrisi format. Subsequent analyses were conducted with the Ecological Niche Factor Analysis (ENFA) algorithm available in BIOMAPPER v.3.2 (Hirzel et al. 2006a). ENFA conducts a PCA of ecogeographic variables and generates a series of internally uncorrelated factors that are used to plot potential habitat or habitat suitability (HS) maps. Only significant factors were considered for the HS map. Biologically significant factors included marginality and tolerance. Marginality is defined as the difference between the optimum environment for the species and the global mean of environmental variables for the study area. Tolerance indicates the degree of specialization of the species in relation to the range of availableenvironments (Hirzel et al. 2002, 2004). A habitat suitability score (0-100) was derived for each grid cell by comparing its marginality and specialization coefficients with the median of each factor estimated for the study area. Specialization coefficients are defined as the ratio of the ecological variance in mean habitat to that observed for the focal species (Hirzel et al. 2002). HS scores were normalized into four categories: null to low (0-25), moderate (26-50), high (51- 75) and very high to excellent (76-100). The robustness and predictive ability of the HS model were evaluated in BIOMAPPER by a jackknife-type cross-validation using k = 4 partitions of the records of the species based on María Guadalupe Mendoza Correa 11 Huberty’s rule, which is a heuristic method (“rule of thumb”) that determines the ratio of calibration and validation points (Fielding and Bell 1997). Three of the generated partitions were used to calibrate the HS map, and the fourth was used to evaluate the outcome. The process was replicated four times, and each group was used to validate the model for each replicate using Boyce’s continuous index. This index measures the relationship between the expected and observed values for different HS scores (Hirzel et al. 2006b). A value near 1 indicates congruence between the expected and observed values. Potential geographic distribution of D. rhizophagus using MaxEnt. Maps of the major climatic variables obtained from DIVA-GIS v.5.2, determined with the aid of PCA and histograms, plus maps of minimum annual temperature, maximum annual temperature, elevation and host distribution, were analyzed with MaxEnt v.3.3.1 (Phillips et al. 2004). The MaxEnt algorithm was performed using the default parameters (500 iterations with a convergence threshold of 10 -5 ). During model development, 75% of the localities were used for model training, while 25% of the localities were held back to test the model. Suitable regularization values were included to reduce over-fitting and were selected automatically by the program. The output format was the logistic default option (Phillips and Dudik 2008). The model was evaluated by means of the area under the receiver operating characteristic curve (AUC). AUCs near 0.5 are similar to random predictions, which indicate an inaccurate model; in contrast, values above 0.9 indicate a highly accurate model (Swets 1988, Phillips and Dudik 2008). The resultant map showed the probability (0-1) of species presence. Probability values were normalized into four categories: null to low (0-0.22), moderate (0.23-0.44), high (0.45-0.67) and very high to excellent (0.68-1.0). María Guadalupe Mendoza Correa 12 Results The preferential altitudinal range for D. rhizophagus varied between 2,000 and 2,600 m. The percentage of incidence showed a high frequency of attacks by this beetle on P. engelmannii, P. durangensis, P. arizonica and P. leiophylla (Table 3). Bioclimatic profile of D. rhizophagus. The profile based on 257 locations (Table 2) suggests that this bark beetle may be present in sites supporting the following temperatures: annual mean temperatures of 10-19˚C, maximum temperatures of the warmest month of 21-36˚C, mean temperatures of the driest quarter of 9-19˚C and mean temperatures of the coldest quarter of 3- 14˚C. In terms of precipitation, suitable sites are characterized by annual rainfalls of 305-1,406 mm, wettest-month rainfalls of 79-321 mm, driest-month rainfalls of 2-18 mm, wettest-quarter rainfalls of 197-823 mm and warmest-quarter rainfalls of 170-746 mm. PCA showed that the first three principal components accounted for 86.79% of the total variance (Table 4). Of the 19 variables that were analyzed, 13 had high eigenvalues. However, of these 13 variables, only precipitation variables 12, 13, 14, 16 and 18 and temperature variables 1, 5, 9 and 11 were normally distributed. Temperature variables 2 and 7 had normal but truncated distributions, whereas 3 and 4 did not fit any distribution. These last four variables were not used to generate potential distribution models with BIOCLIM, ENFA or MaxEnt. Potential geographic distribution of D. rhizophagus using BIOCLIM, ENFA and MaxEnt. The potential distribution map obtained from BIOCLIM showed a continuous area of moderate to high climate suitability that encompassed the entire length of the SMOC morphotectonic province, as well as a narrower, continuous area with very high to excellent values (Fig. 1). The ENFA map showed a potential distribution that was similar to the distribution derived by BIOCLIM but it had better definition (Fig. 2). The high and very high to excellent HS areas on the ENFA map appeared as small, discontinuous patches scattered along María Guadalupe Mendoza Correa 13 the entire length of the SMOC morphotectonic province. Areas of moderate suitability occurred in the gaps between these patches. The map generated with MaxEnt (Fig. 3) showed two separate, large areas of very high to excellent probability of occurrence in the northern part of the SMOC and some small, discontinuous areas in its central and southern regions. Moderate and high probability areas were found in almost all the SMOC. The global marginality factor was 2.76, suggesting that D. rhizophagus is present in areas supporting bioclimatic conditions that differ from the average conditions in the SMOC. Global tolerance was 0.17, indicating that this species has a relatively narrow ecological niche. The first three factors explained 93.4% of the total variation (Table 5). The marginality factor (number 1) explained only 4.7%, and the first two tolerance factors (numbers 2 and 3) explained 81.4% and 7.3%, respectively. In terms of the marginality factor (Table 5), D. rhizophagus is essentially linked to the precipitation of the driest month (0.352) and the following temperature variables: annual maximum temperature (-0.316), maximum temperature of the warmest month (-0.340), mean temperature of the coldest quarter (-0.300), annual mean temperature (-0.300) and annual minimum temperature (0.269). Additionally, D. rhizophagus is linked to host distribution (0.304) and elevation (0.276). Tolerance factors indicate that D. rhizophagus is associated with annual mean temperature (-0.707), mean temperature of the coldest quarter (-0.707), annual minimum temperature (0.552) and annual maximum temperature (0.461). Jackknife-type cross-validation and evaluation using Boyce’s continuous index yielded a mean of 0.67 and a standard deviation of 0.32, both of which indicated the model is adequately robust. MaxEnt analysis showed that the presence of D. rhizophagus is associated mainly by annual mean temperature (30.1%), elevation (13.4%), maximum annual temperature (12.8%), precipitation of the warmest quarter (10.5%), precipitation of the driest month (9.8%), maximum María Guadalupe Mendoza Correa 14 temperature of the warmest month (8.1%) and precipitation of the wettest month (5.1%) (Table 6). The AUC of the training data was 0.976 (± 0.006), and the AUC of test points was 0.970 (± 0.006), indicating the model is robust. María Guadalupe Mendoza Correa 15 Discussion The spatial modeling of species distributions combining occurrence data with biotic, climatic and topographic variables can be used to determine the bioclimatic profile of a species and, as a consequence, the potential ranges in which it may reside (Anderson et al. 2003, Beaumont et al. 2005). This information provides an initial explanation for the presence of a species in one area but not in another (Lindenmayer et al. 1991). For herbivorous insects, the host is an extremely important limiting factor in terms of geographical distribution, as insects cannot continue to occur in those places where their host plants are not present (Spellerberg and Sawyer1999, Lomolino et al. 2006). Although various studies suggest that the geographic distribution of bark beetles at the macro- scale level is determined by variables such as host availability, temperature and elevation (e.g., Amman 1973, Lekander et al. 1977, Régnière and Logan 1996), few studies have examined the relative importance of these variables (Ungerer et al. 1999, Carroll et al. 2004). With respect to the host, D. rhizophagus has a narrow diet breadth, because it uses a small number (≤ 40%) of the available pine hosts across its distribution (Kelley and Farrell 1998). However, the results of our study indicate that D. rhizophagus attacks almost all (> 80%) species of pine present in its known distribution which is limited to specific areas within the SMOC, especially P. engelmannii, P. durangensis, P. arizonica and P. leiophylla (Wood 1982, Salinas-Moreno et al. 2010). The major incidence percentages (IPs) on these four pine species do not appear to be related to the abundance of them in the SMOC, as all of the hosts used by this bark beetle are similarly abundant elements in the pine forests of this morphotectonic province (Rzedowsky 1978, Perry 1991, García Arevalo and González Elizondo 2003, Ortega-Rosas et al. 2008). However, the observed IP values could be related to the ecologically heterogeneous or patch distribution that these species have in the SMOC morphotectonic province. For example, while Pinus herrerae María Guadalupe Mendoza Correa 16 and P. leiophylla inhabit slopes and ravines, P. arizonica and P. durangensis grow on plateaus and mesas. On the other hand, our study also suggests that the distribution of D. rhizophagus may not be limited by the geographical distributions of its hosts (Table 6), as there are areas in the SMOC morphotectonic province where hosts are present but where there are no records of the beetles presence. In addition, the geographical distributions of the majority of them (≥ 90%) extend over much of the range of this bark beetle; for example, P. cembroides Zucc., P. herrerae Martínez, P. leiophylla, P. lumholtzii Rob. & Fernald, P. oocarpa Schiede and P. teocote Schiede ex Schltdl. & Cham. are present in other morphotectonic provinces in México, and others such as P. cembroides, P. engelmannii, P. leiophylla, P. ponderosa Dougl. and P. strobiformis Engelm. are located beyond the Mexican border and occur in the southwestern United States (Farjon and Styles 1997). Differences in the geographic distributions of D. rhizophagus and its hosts might be the result of their natural history, where the specific biotic interactions and particular ecological requirements of each of them have played important roles. Based on these results and those derived with ENFA and MaxEnt (Tables 5, 6), which suggest that the host distribution has little weight as a predictor variable, we hypothesize that at the macro-scale level the potential distribution of D. rhizophagus is limited more by environmental variables such as precipitation and temperature than by the availability or distribution of hosts (Lekander et al.1977). In this context, the tolerance and marginality coefficients derived from ENFA suggest that this beetle has a relatively narrow ecological niche with respect to some temperature and precipitation variables, inhabiting areas with climatic conditions that differ from those generally prevalent in the SMOC morphotectonic province. Areas of higher suitability may therefore be smaller and may appear in patches along the SMOC, as predicted by ENFA, compared with those predicted by BIOCLIM. http://es.wikipedia.org/wiki/Dougl. http://en.wikipedia.org/wiki/George_Engelmann María Guadalupe Mendoza Correa 17 The influence of elevation on the distribution of this beetle is not clear: while MaxEnt (Table 6) suggests that this factor is important, ENFA (Table 5) suggests the contrary. The relationship between temperature and elevation could be masking the effect of this factor on the altitudinal distribution of D. rhizophagus. The broad elevation range of this species (1,000-2,800 m), matches with the altitudinal range in which pine and pine-oak communities are found in the SMOC. In addition, the preferential elevation range (2,000-2,600 m) of D. rhizophagus is correlated with the preferential altitudinal range of its main hosts (Farjon and Styles 1997, Lammertink et al. 1997) and represents areas identified by BIOCLIM, ENFA and MaxEnt as high to excellent habitats for this bark beetle. The actual distribution limits of D. rhizophagus into the north and south of the SMOC coincides with the isotherms for maximum temperature occurring between the 30º and 23º N of its distribution range. Specifically, these isotherms are annual temperatures of 20-25ºC and temperatures of the warmest month of 23-30ºC. Other bark beetle studies conducted at the macro- scale level report similar associations with climatic variables. For example, the distribution of the mountain pine beetle, D. ponderosae Hopkins, in western Canada is limited by minimum temperatures, rather than by the availability of its preferred hosts (ponderosa pine, P. ponderosa), despite their wide geographic distribution (Logan and Powell 2001). Therefore, its distribution is limited in areas further north (Yukon and Northwest Territories) and east (Alberta) in Canada (Carroll et al. 2004). Ungerer et al. (1999) reported that the isotherm for minimum annual temperature (-16ºC) limits the dispersal of D. frontalis Zimm. into more northerly areas of the United States. Our study suggests that D. rhizophagus could be potentially distributed over a greater extent of the SMOC morphotectonic province. This will occur as a result of both the use of a wide range of pine hosts present in this province and the presence of numerous areas in the SMOC where María Guadalupe Mendoza Correa 18 optimal conditions of elevation, temperature and humidity exist. Moreover, our results suggest that limits of the D. rhizophagus distribution at the macro-scale level could be related to the maximum temperature isotherms and that optimal temperature ranges where the bark beetle occurs are related to temperate habitats. Finally, its relatively narrow ecological niche with respect to some temperature and precipitation variables and the preference for temperate habitats, lead us to hypothesize that even minor changes in climate may have significant effects on the distribution and abundance of this bark beetle. The apparent absence of this species from potentially suitable habitats within the SMOC morphotectonic province and the wide distribution of its hosts outside this province suggest that variations in temperature and humidity, such as those predicted to take place as a result of climate change (Logan and Powell 2001, Bale et al. 2002), may significantly affect its geographic distribution. A shift in the maximum temperature isotherms may favor D. rhizophagus dispersal into temperate areas or beyond its current high altitudinal limit. More detailed modeling studies are required to determine the effects that climate change may have on the distribution of D. rhizophagus. It would also be important to explore how temperature and humidity variables directly affect the development of the life cycle and population dynamics of this bark beetle, given that our study suggests these variables could also have strong influences at the meso- and micro-scale levels, as has been demonstrated in other Dendroctonus species (Logan and Amman 1986, Bentz et al. 1991, Turchin et al. 1991). María Guadalupe Mendoza Correa 19 Acknowledgments We are grateful to José Luis Benito Rosas Ortiz (SEMARNAT-Sonora, México), Ricardo Adán Peralta Durán and Pedro Hernández Díaz (SEMARNAT-Durango, México), Sergio Quiñonez Barraza (CONAFOR Durango-Sinaloa, México), Oscar de León Lara(CONAFOR- Sonora, México), Marcos Daniel Trujano Thomé and José Luis Aguilar Vitela (Secretaría de Recursos Naturales y Medio Ambiente, Durango, México) and Guillermo Sánchez-Martínez (INIFAP-Aguascalientes, México) for providing us with access to their collection records and for their logistic support, time and availability for consultations. We thank Jorge E. Macías Sámano (Colegio de la Frontera Sur, Chiapas, México), Jane L. Hayes (Pacific Northwest Research Station, USDA Forest Service, LaGrande, Oregon) and three anonymous reviewers for their critical review of the manuscript. The project was funded by Comisión Nacional Forestal (CONAFOR, 69539) and Secretaría de Investigación y Posgrado-IPN (SIP-20090576). This work was part of M.G.M.C’s Ph.D. dissertation. She was a Consejo Nacional de Ciencia y Tecnología (207124) and Programa Institucional de Formación de Investigadores del Instituto Politécnico Nacional (PIFI-IPN) fellow. María Guadalupe Mendoza Correa 20 References Cited Amman, G. D. 1973. Population changes of the mountain pine beetle in relation to elevation. Environ. Entomol. 2: 541-547. Anderson, R. P., D. Lew, and A. T Peterson. 2003. Evaluating predictive models of species’ distributions criteria for selecting optimal models. Ecol. Model. 162: 211-232. Bale, S. J., G. J. Masters, I. D. Hodkinson, C. Awmack, T. M. Bezemer, V. K. Brown, J. Butterfield, A. Buse, J. C. Coulson, J. Farrar, J. E. G. Good, R. Harrington, S. Hartley, T. H. Jones, R. L. Lindroth, M. C. Press, I. Symrnioudis, A. D. Watt, and J. B. Whittaker. 2002. Herbivory in global climate change research: direct effects of rising temperature on insect herbivores. Global Change Biol. 8: 1-16. Beaumont, L. J., L. Hughes, and M. Poulsen. 2005. Predicting species distributions: Use of climatic parameters in BIOCLIM and its impact on predictions of species current and future distributions. Ecol. Model. 186: 250-269. Bentz, B. J., J. A. Logan, and G. D. Amman. 1991. Temperature dependent development of the mountain pine beetle (Coleoptera: Scolytidae) and simulations of its phenology. Can. Entomol. 123: 1083-1094. Braunisch, V., and R. Suchant. 2007. A model for evaluating the “habitat potential” of a landscape for capercaillie Tetrao urogallus: a tool for conservation planning. Wildl. Biol. 13: 21-33. Brown, J. H. 1984. On the relationship between abundance and distribution of species. Am. Nat. 124: 255-279. Brockerhoff, E.G., A. M. Liebhold, and H. Jactel. 2006. The ecology of forest insects invasions and advances in their management. Can. J. For. Res. 36: 263-268. María Guadalupe Mendoza Correa 21 Carroll, A. L., S. W. Taylor, J. Régnière, and L. Safranyik. 2004. Effects of climate change on range expansion by the mountain pine beetle in British Columbia, pp. 223-232. In T. L. Shore, J. E. Brooks and J. E. Stone (eds.), Mountain Pine Beetle Symposium: Challenges and Solutions. 30-31 October 2003, Kelowna, British Columbia, Canada, Natural Resources Canada, Canadian Forest Service, Pacific Forestry Centre, Information Report. BC-X-399, Victoria, BC. Cibrián, T. D., J. T. Méndez M., R. Campos B., H. O. Yates III, and J. Flores L. 1995. Insectos Forestales de México/Forest Insects of Mexico. Universidad Autónoma Chapingo, México. Comisión Nacional para el Conocimiento y Uso de la Biodiversidad (CONABIO). 1997. Provincias Biogeográficas de México. Escala 1:4,000,000. México. Environmental Systems Research Institute. 1999. Arcview-Gis 3.2. Environmental Systems Research Institute, Redlands, California, USA. Estrada-Murrieta, O. 1983. Biología del descortezador del renuevo de pino Dendroctonus rhizophagus T. y B. (Col.: Scolytidae) en la región de la Mesa del Huracán, Chihuahua. Bachelor’s Thesis. Universidad Autónoma Chapingo, México. Farjon, A., and B. Styles. 1997. Flora Neotropica. Monograph 75. Pinus (Pinaceae). Organization for Flora Neotropica. New York Botanical Garden, NY. Ferrusquía-Villafranca, I. 1998. Geología de México: Una Sinopsis, pp. 3-108. In T. P. Ramamoorthy, R. Bye, A. Lot and J. Fa (eds.). Diversidad Biológica de México: Orígenes y Distribución. Instituto de Biología. Universidad Nacional Autónoma de México, México. Fielding, A. H. and J. F. Bell. 1997. A review of methods for the assessment of prediction errors in conservation presence/absence models. Environ. Conserv. 24: 38-49. María Guadalupe Mendoza Correa 22 García Arevalo, A y M. S. González Elizondo. 2003. Pináceas de Durango. 2a. ed. Instituto de Ecología A. C. México. Ganeshaiah, K. N., N. Barve, N. Nath, K. Chandrashekara, M. Swamy, and R. U. Shanker. 2003. Predicting the potential geographical distribution of the sugarcane woolly aphid using GARP and DIVA-GIS. Scientific Correspondence. Current Science 85: 1526-1528. Gaston, J. K. 2003. The structure and dynamics of geographic ranges. Oxford University Press, Oxford, New York. Hijmans, R. J., L. Guarino, C. Bussink, and E. Rojas. 2002. DIVA-GIS, version 5.2. A geographic information system for the analysis of biodiversity data. Manual. International Potato Center, Lima, Peru. Hirzel, A., J. Hausser, D. Chessel, and N. Perrin. 2002. Ecological niche factor analysis: How to compute habitat suitability maps without absence data? Ecology 83: 2027–2036. Hirzel, A., B. Posse, P-A. Oggier, Y. Crettenand, C. Glenz, and R. Arlettaz. 2004. Ecological requirements of reintroduced species and the implications for release policy: the case of the Bearded vulture recolonizing the Alps. J. Appl. Ecol. 41: 1103–1116. Hirzel, A. H., J. Hausser, and N. Perrin. 2006a. Biomapper 3.2. Laboratory for Conservation Biology. Department of Ecology and Evolution. University of Lausanne, Lausanne. http://www.unil.ch/biomapper. Hirzel, A. H., G. Le Lay, V. Helfer, C. Randin, and A. Guisan. 2006b. Evaluating the ability of habitat suitability models to predict species presences. Ecol. Model. 199: 142–152 Jiménez-Valverde, A., V. M. Ortuño, and J. M. Lobo. 2007. Exploring the distribution of Sterocorax Ortuño, 1990 (Coleoptera, Carabidae) species in the Iberian Peninsula. J. Biogeogr. 34: 1426-1438. Kelley, S. T., and B. D. Farrell. 1998. Is specialization a dead end? The phylogeny of host use María Guadalupe Mendoza Correa 23 in Dendroctonus Bark Beetles (Scolytidae). Evolution 52: 1731-1743. Kurz, W. A., C. C. Dymond, G. Stinson, G. J. Rampley, E. T. Neilson, A. L. Carroll, T. Ebata, and L. Safranyik. 2008. Mountain pine beetle and forest carbon feedback to climate change. Nature 452: 987-990. Kumar, S., and T. J. Stohlgren. 2009. Maxent modeling for predicting suitable habitat for threatened and endangered tree Canacomyrica monticola in New Caledonia. J. Ecol. Nat. Environ. 1: 94-98. Lammertink, J. M., J. A. Rojas-Tomé, F. M. Casillas-Orona, y R. L. Otto. 1997. Situación y conservación de los bosques antiguos de pino-encino de la Sierra Madre Occidental y sus aves endémicas. Consejo Internacional para la preservación de las aves, sección Mexicana (CIPAMEX). D. F. México. Lekander, B., B. Bejer-Petersen, B. Kangas, and A. Bakke. 1977. The distribution of bark beetles in the Nordic Countries. Acta Entomol. Fenn. 32: 1-37. Lindenmayer, D. B., H. A. Nix, J. P. McMahon, M. F. Hutchinson, and M. T. Tanton. 1991. The conservation of Leadbeater’s possum, Gymnobelideus leadbeateri (McCoy): a case study of the use of bioclimatic modelling. J. Biogeogr. 18: 371-383. Logan, J. A., and G. D. Amman. 1986. A distribution model for egg development in mountain pine beetle. Can. Entomol. 118: 361-372. Logan, J. A., and J. A. Powell. 2001. Ghost forests, global warming and the mountain pine beetle (Coleptera: Scolytidae). Am. Entomol. 47: 160-172. Lomolino, M. V., B. R. Riddle, and J. H. Brown. 2006. Biogeography. Sinauer Associates Inc., Sunderland, Massachussetts.MacDonald, G. M. 2003. Biogeography, space, time and life. John Wiley & Sons. Inc., United States of America. María Guadalupe Mendoza Correa 24 Mackey, B. G., and D. B. Lindenmayer. 2001. Towards a hierarchical framework for modelling the spatial distribution of animals. J. Biogeogr. 28: 1147-1166. Nix, H. 1986. A biogeographic analysis of Australian elapid snakes, pp. 4-15. In R. Longmore (ed.), Atlas of elapid snakes of Australia. Australian flora and fauna series number 7. Australian Government Publishing Service, Canberra. Ortega-Rosas, C. I., M. C. Peñalba, J. A. López-Sáez, y T. R. Van Devender. 2008. Retrospectiva del Bosque de Pino y Encino de la Sierra Madre Occidental, Sonora, Noroeste de México, Hace 1,000 años. Acta Bot. Mex. 83: 69-92. Pearson, R. G., and T. P. Dawson. 2003. Predicting the impacts of climate change on the distribution of species: are bioclimate envelope models useful? Global Ecol. Biogeogr. 12: 361-371. Perry, J. P. Jr. 1991. The Pines of Mexico and Central America. Timber Press Inc., Portland, Oregon. Phillips, S. J., R. E. Schapire, and M. Dudík. 2004. A maximum entropy approach to species distribution modeling, pp. 655-662. In R. Greinerand and D. Schuurmans (eds.), Proceedings of the Twenty-First International Conference on Machine Learning. 2004. Banff, Canada. ACM Press, NY. Phillips, S. J., and M. Dudík. 2008. Modeling of species distributions with MaxEnt: new extensions and a comprehensive evaluation. Ecography 31: 161-175. Régnière, J., and J. A. Logan. 1996. Landscape-wide projection of temperature-driven processes for seasonal pest management decision support: a generalized approach, pp. 43-56. In T. L. Shore and D. A. MacLean (eds.). Symposium Proceedings: Decision support systems in forest pest management. Entomological Society of Canada, FRDA Report No. 260. Victoria, BC. María Guadalupe Mendoza Correa 25 Rzedowsky, J. 1978. Vegetación de México. Limusa. México. Salinas-Moreno, Y., M. G. Mendoza, M. A. Barrios, R. Cisneros, J. Macías-Sámano, and G. Zúñiga. 2004. Areography of the genus Dendroctonus (Coleoptera: Curculionidae: Scolytinae) in México. J. Biogeogr. 31: 1163-1177. Salinas-Moreno, Y., A. Ager, C. F. Vargas, J. L. Hayes, and G. Zúñiga. 2010. Determining the vulnerability of mexican pine forest to bark beetles of the genus Dendroctonus Erichson (Coleoptera: Curculionidae: Scolytinae). Forest Ecol. Manag. 260: 52-61. Sánchez-Martínez, G., and M. R. Wagner. 2009. Host preference and attack pattern of Dendroctonus rhizophagus (Coleoptera: Curculionidae: Scolytinae): a bark beetle specialist on pine regeneration. Environ. Entomol. 38: 1197-1204. Sattler, T., F. Bontadina, A. H. Hirzel, and R. Arlettaz. 2007. Ecological niche modelling of two cryptic bat species calls for a reassessment of their conservation status. J. Appl. Ecol. 44: 1188-1199. Spellerberg, I. F., and J. W. D. Sawyer. 1999. An introduction to applied biogeography. Cambridge University Press, Cambridge. Swets, J. A. 1988. Measuring the accuracy of diagnostic systems. Science 240: 1285-1293. Thomas, C. D., E. J. Bodsworth, R. J. Wilson, A. D. Simons, Z. G. Davies, M. Musche, and L. Conradt. 2001. Ecological and evolutionary processes at expanding range margins. Nature 411: 577-581. Titeaux, N., M. Dufrêne, J. Radoux, A. H. Hirzel, and P. Defourny. 2007. Fitness-related parameters improve niche-based distribution modelling: the case of the Red-backed Shrike. Biol. Conserv. 138: 207-223. Turchin, P., P. L. Jr. Lorio, A. D. Taylor, and R. F. Billings. 1991. Why do populations of southern pine beetles (Coleoptera: Scolytidae) fluctuate? Environ. Entomol. 20: 401-409. María Guadalupe Mendoza Correa 26 Ungerer, M., M. P. Ayres, and M. J. Lombardero. 1999. Climate and the northern distribution limits of Dendroctonus frontalis Zimmermann (Coleoptera: Scolytidae). J. Biogeogr. 26: 1133-1145. Waring, K.M., D. M. Reboletti, L. A. Mork, M. Li, C.H. Huang, R. W. Hofstetter, A. M. Garcia, P. Z. Fulé, and T. S. Davis. 2009. Modeling the impacts of two bark beetle species under warming climate in the southwestern U.S.A.: ecological and economic consequences. Environ. Manage. 44: 824-835. Wood, S. L. 1982. The bark and ambrosia beetles of North and Central America (Coleoptera: Scolytidae) a taxonomic monograph. Great Basin Nat. Mem. 6: 1-1359. María Guadalupe Mendoza Correa 27 Table 1. Collection records and reference sources of D. rhizophagus Reference Source CODE No. of Records Comisión Forestal Nacional, Chihuahua, México CONAFOR-CHIH 236 Comisión Forestal Nacional, Sonora, México CONAFOR-SON 1 Comisión Forestal Nacional, Sinaloa, México CONAFOR-SIN 2 Secretaria de Medio Ambiente y Recursos Naturales, Durango, México SEMARNAT-DGO 119 Secretaria de Medio Ambiente y Recursos Naturales de Sonora, México SEMARNAT-SON 24 Sanidad Forestal, Secretaría del Medioambiente y Recursos Naturales, México SF-SEMARNAT 4 Secretaría de Recursos Naturales y Medio Ambiente, Durango, México SRNyMA-DGO 31 División de Ciencias Forestales, Universidad Autónoma Chapingo DCF-UACH 15 Instituto de Silvicultura, Universidad Autónoma de Nuevo León. IS-UANL 2 Colección Entomológica, Escuela Nacional de Ciencias Biológicas-IPN ENCB-IPN 14 Lab. de Variación Biológica y Evolución, Escuela Nacional de Ciencias Biológicas-IPN LVBE-ENCB 21 Unidad de Conservación de Ecosistemas Forestales, Madera, Chihuahua UCODEFO-CHIH 142 Canadian National Collection of Insects, Arachnids and Nematodes-Ottawa CNCI-Ottawa 10 Bibliographical data (Various authors) 48 TOTAL 669 María Guadalupe Mendoza Correa 28 Table 2. Bioclimatic profile of D. rhizophagus for each location (obtained using BIOCLIM) No. and Climatic Variable Min. Mean Max. S.D. 5% 10% 50% 90% 95% 1) Annual mean temperature ( ºC) 10.2 12.8 19.2 1.4 11.1 11.3 12.6 14.6 15.5 2) Mean diurnal range (ºC) 12.4 16.7 19.1 1.9 13.1 13.6 17.4 18.4 18.7 3) Isothermality 48.4 57.0 63.2 3.6 50.8 51.7 57.7 61.6 62.9 4) Temperature seasonality 306.9 472.6 671.9 101.3 319.9 337.0 486.1 601.1 605.9 5) Maximum temperature of warmest month (ºC) 21.4 27.5 35.6 2.4 23.2 24.1 27.7 30.3 30.8 6) Minimum temperature of coldest month (ºC) -5.8 -2.1 7.0 2.6 -5.2 -5.0 -2.6 1.5 2.3 7) Temperature annual range 21.0 29.5 35.5 4.2 21.9 22.9 31.1 33.8 34.2 8) Mean temperature of wettest quarter (ºC) 13.9 17.8 25.0 1.6 15.5 15.9 17.6 19.9 20.9 9) Mean temperature of driest quarter (ºC) 9.4 12.1 18.9 1.6 10.2 10.4 11.8 14.0 14.9 10) Mean temperature of warmest quarter (ºC) 14.4 18.4 25.8 1.7 16.0 16.5 18.3 20.6 21.7 11) Mean temperature of coldest quarter (ºC) 3.2 7.0 13.9 2.0 4.0 4.5 6.9 9.2 9.9 12) Annual precipitation (mm) 305.0 814.2 1406.0 195.1 518.0 589.0 802.0 1101.0 1229.0 María Guadalupe Mendoza Correa 29 13) Precipitation of wettest month (mm) 79.0 198.1 321.0 44.6 131.0 152.0 189.0 267.0 278.0 14) Precipitation of driest month (mm) 2.0 10.9 18.0 3.2 6.0 7.0 11.0 15.0 15.0 15) Precipitation seasonality (mm) 78.4 93.8 126.2 9.5 80.0 82.2 93.1 108.7 112.2 16) Precipitation of wettest quarter (mm) 197.0 490.0 823.0 118.5 332.0 363.0 479.0 675.0 710.0 17) Precipitation of driest quarter (mm) 10.0 47.8 71.0 11.5 27.0 33.0 48.0 64.0 67.0 18) Precipitation of warmest quarter (mm) 170.0 440.4 746.0 110.6 276.0 325.0 437.0 614.0 628.0 19) Precipitation of coldest quarter (mm) 22.0 124.0 250.0 41.6 57.0 70.0 120.0 180.0 197.0 María Guadalupe Mendoza Correa 30 Table 3. Incidence (%) of D rhizophagus on Pinus species in the Sierra Madre Occidental, México Pinus species Incidence (%) P. engelmannii P. durangensis P. arizonica P. leiophylla P. teocote P. herrerae P. lumholtzii P. strobiformis P. oocarpa P. cembroidesP. ponderosa Pinus sp Total number of records 35.42 16.60 16.14 8.67 3.59 2.84 1.04 0.75 0.45 0.15 0.15 14.20 669 María Guadalupe Mendoza Correa 31 Table 4. Principal component analysis of BIOCLIM climatic variables in relation to the occurrence of D. rhizophagus Climatic Variables Comp. 1 Eigenvalues Comp. 2 Comp. 3 *1) Annual mean temperature -0.02 0.97 -0.18 2) Mean diurnal range [Mean of monthly (max temp- min temp)] 0.71 -0.15 -0.44 3) Isothermality -0.74 0.28 0.07 4) Temperature seasonality 0.91 -0.23 -0.28 *5) Maximum temperature of warmest month 0.83 0.35 -0.42 6) Minimum temperature of coldest month -0.67 0.66 0.20 7) Temperature annual range 0.89 -0.21 -0.37 8) Mean temperature of wettest quarter 0.66 0.62 -0.41 *9) Mean temperature of driest quarter -0.00 0.83 -0.41 10) Mean temperature of warmest quarter 0.70 0.60 -0.36 *11) Mean temperature of coldest quarter -0.54 0.81 0.02 *12) Annual precipitation -0.94 -0.01 -0.29 *13) Precipitation of wettest month -0.81 0.11 -0.43 *14) Precipitation of driest month -0.27 -0.56 -0.62 15) Precipitation seasonality 0.15 0.62 0.17 *16) Precipitation of wettest quarter -0.92 0.14 -0.24 17) Precipitation of driest quarter -0.62 -0.52 -0.53 *18) Precipitation of warmest quarter -0.88 0.14 -0.28 María Guadalupe Mendoza Correa 32 19) Precipitation of coldest quarter -0.70 -0.30 -0.49 % Explained variance 48.18 25.58 13.03 *Most relevant variables according to histograms analysis María Guadalupe Mendoza Correa 33 Table 5. Percentage of variation explained by ecogeographic variables for D. rhizophagus using ENFA Ecogeographic Variable Factor 1 Marginality (4.7%) Factor 2 Specialization (81.4%) Factor 3 Specialization (7.3%) Annual mean temperature -0.300 -0.707 -0.471 Maximum temperature of warmest month -0.340 0.000 0.000 Mean temperature of driest quarter -0.165 0.000 0.000 Mean temperature of coldest quarter -0.300 -0.707 - 0.511 Annual precipitation 0.249 0.000 0.000 Precipitation of wettest month 0.216 0.000 0.000 Precipitation of driest month 0.352 0.000 0.000 Precipitation of wettest quarter 0.202 0.000 0.000 Precipitation of warmest quarter 0.249 0.000 0.000 Minimum annual temperature -0.269 0.000 0.552 Maximum annual temperature -0.316 0.000 0.461 Elevation 0.276 0.000 0.000 Pines distribution 0.304 0.000 0.000 María Guadalupe Mendoza Correa 34 Table 6. Percentage of estimated contribution for ecogeographic variables using MaxEnt Variable % Contribution Annual mean temperature 30.1 Elevation 13.4 Maximum annual temperature 12.8 Precipitation of warmest quarter 10.5 Precipitation of driest month 9.8 Maximum temperature of warmest month 8.1 Precipitation of wettest month 5.1 Minimum annual temperature 3.2 Pines distribution 2.5 Mean temperature of driest quarter 1.5 Precipitation of wettest quarter 1.2 Mean temperature of coldest quarter 1.1 Annual precipitation 0.6 María Guadalupe Mendoza Correa 35 Figure legends Fig. 1. Potential distribution of D. rhizophagus in the Sierra Madre Occidental, México modeled with BIOCLIM Fig. 2. Habitat suitability (HS) for D. rhizophagus in the Sierra Madre Occidental, México modeled with ENFA. Fig. 3. Potential distribution of D. rhizophagus in the Sierra Madre Occidental, México modeled with MaxEnt. María Guadalupe Mendoza Correa 36 María Guadalupe Mendoza Correa 37 María Guadalupe Mendoza Correa 38 María Guadalupe Mendoza Correa 39 CAPITULO II Determinación de Áreas de Susceptibilidad y Riesgo por la Presencia de Dendroctonus rhizophagus (Coleoptera: Curculionidae, Scolyitinae) en los Bosques de Pino del Municipio de Casas Grandes, Chihuahua María Guadalupe Mendoza Correa 40 Determination of Susceptibility and Risk Areas of Presence of Dendroctonus rhizophagus (Coleoptera: Curculionidae: Scolytinae) in Pine Forest of Casas Grandes, Municipality, Chihuahua Ma. Guadalupe Mendoza 1 , Daniel Núñez-López 2 , Yolanda-Morena 1 and Gerardo Zúñiga 1 1 Laboratorio de Variación Biológica y Evolución. Escuela Nacional de Ciencias Biológicas-IPN. Departamento de Zoología. Carpio y Plan de Ayala s/n, Col. Santo Tomás, C. P. 11340 México City, México. 2 Instituto de Ecología A.C., Centro Regional de Chihuahua. Carretera Chihuahua-Ojinaga, Aldama 32900, Chihuahua. México. María Guadalupe Mendoza Correa 41 ABSTRACT Dendroctonus rhizophagus harms and kills seedlings and young saplings of 11 species of pines in states of NW Mexico, particularly Chihuahua. Susceptibility and risk models for Casas Grandes municipality (Chihuahua) were generated by multi-criteria decision making (MCDM) methods based on the potential distribution of this bark beetle in Casas Grandes and the relative importance of the variables determining its presence in this region. Results suggest that D. rhizophagus is present mainly in the mountainous massifs of W and NW Casas Grandes, influenced mainly by precipitation and temperature variables. The preferred climate ranges are narrower than those reported previously for the Sierra Madre Occidental. The susceptibility model shows a continuous area, stretching from NW Casas Grandes to its S and center, where bioclimatic and topographical conditions are favorable for the presence of D. rhizophagus. The risk model shows a possible dispersal corridor running NW and S in adjacent Madera municipality. The latter model also indicates that the highest risk areas are in NW and W Casas Grandes. Periodical monitoring and evaluation of this area of the state are therefore suggested. KEYWORDS: Dendroctonus rhizophagus, Potential distribution, Prediction models, Susceptibility and risk models. María Guadalupe Mendoza Correa 42 RESUMEN Dendroctonus rhizophagus daña y mata plántulas y brinzales de once especies de pino en los estados del noroeste de México, particularmente en el estado de Chihuahua. Modelos de susceptibilidad y riesgo para el municipio de Casas Grandes, Chihuahua, fueron generados por técnicas de toma de decisión multicriterio (TDMC) a partir de la distribución potencial del insecto en este municipio y de la importancia relativa de las variables que determinan su presencia en esa región. Los resultados sugieren que D. rhizophagus se distribuye principalmente en los macizos montañosos de la región NW y W del municipio, influenciado principalmente por variables de precipitación y temperatura. Los intervalos climáticos preferenciales son más estrechos que los reportados para la Sierra Madre Occidental. El modelo de susceptibilidad señala una zona continua desde el noroeste hacia el sur y centro del municipio, con condiciones bioclimáticas y topográficas favorables para la presencia de D. rhizophagus. El modelo de riesgo muestra un corredor posible de dispersión en dirección NW y S en el municipio colindante de Madera. Asimismo, este modelo presenta a las regiones del NW y W del Municipio de Casas Grandes como las de mayor riesgo, por lo cual se sugiere una evaluación y monitoreo periódico de esta región del Estado. María Guadalupe Mendoza Correa 43 Introduction Bark beetles of the genus Dendroctonus (Curculionidae:Scolytinae) have been intensively studied due to the economic loss they entail in epidemic conditions for the lumber industry and the ecological problems caused by methods used fortheir control (Raffa et al. 2005, Sánchez-Martínez et al. 2007). To reduce the effect and intensity of beetle outbreaks, it has been resorted to preventive forestry practices, which are based on detailed knowledge of forest structure and composition as well as the characterization and modeling of environmental conditions favoring bark beetle population explosion (Lorio 1981). Risk assessment models or hazard evaluation systems are tools that have been developed and used to predict the susceptibility of forests to attack by these insects (Bentz et al. 1993, Shore and Safranyik 1992, Shore et al. 2000). Risk prediction models primarily integrate information on the climate, composition and dasonomic characteristics of forests as well as the biological and ecological attributes of beetles (Safranyik et al. 1978, Amman et al. 1977). Risk models have been developed at the micro- (local), meso- (regional), and macroscale (national) levels by the application of diverse criteria such as: forest manager experience (e.g. Lorio 1978) of forest conditions, statistical analysis of the forest characteristics favoring beetle presence (e.g. Chojnacky et al. 2000, Robertson et al. 2008), and evaluation of these characteristics by multi-criteria decision making (MCDM) methods integrated with geographic information systems (GIS) (e.g. Krist 2006). MCDM methods, such as multi-criteria evaluation (MCE) and analytic hierarchy process (AHP), permit identification, ordering and weighting of the relative importance of diverse climatic, biological and physical factors favoring presence of the risk agent. These María Guadalupe Mendoza Correa 44 methods, integrated with GIS, allow susceptibility or risk assessment maps to be drawn in order to be able to visualize the degree of potential affectation that the risk agent may have in a particular area or region. The first step in developing such maps is identification of the major variables related to the risk agent. This is done by using species distribution models (SDMs) such as BIOCLIM, GARP, and MaxEnt. SDMs enable estimation of the potential distribution of species, define the bioclimatic conditions in which they occur, and identify the variables that determine their presence (Guisan and Zimmermann 2000). The control methods used to restrain the more aggressive species of the genus Dendroctonus in Mexico are characterized by a wide use of treatments such as felling trees and leaving them on site, debarking, or the application of chemical compounds (Sánchez- Martínez et al. 2007) that directly suppress beetle activity during or after outbreaks. These methods are costly, slow in operation, and aggressive due to the loss not only of infested trees, but also of those infested during sanitary actions. In spite of the scarcity of reliable information at the national level on the condition of Mexican forests, existing information at the local and regional levels has allowed susceptibility and risk models to be developed for some of the more aggressive bark beetle species, such as D. mexicanus Hopkins and D. frontalis Zimmermann (e.g. Iñiguez 1999, Llanderal 1995, Espinosa and Muñoz 1988). The bark beetle D. rhizophagus Thomas and Bright harms and kills seedlings and young saplings of 11 species of pine that are commercially valuable in the states of Sonora, Sinaloa, Chihuahua and Durango in northwestern Mexico (Estrada-Murrieta 1983, Cibrián et al. 1995). Chihuahua forests have been significantly affected by this beetle. For example, between 1977 and 1982 control actions were undertaken in over two million seedlings and saplings in ~ 12,000 ha of the Mesa del Huracán (29º 38' N, 108º 14' W) (Estrada-Murrieta 1983). More recent reports indicate that D. rhizophagus affected some 1,200 ha in its María Guadalupe Mendoza Correa 45 distribution range between 2003 and 2008. Furthermore, conservative estimates suggest that the surface area susceptible to attack by this bark beetle covers ~ 1000 km 2 (SEMARNAT 2005). Since D. rhizophagus is an aggressive agent in pine forests of the state of Chihuahua in northwest Mexico, the aim of this study was to generate susceptibility and risk models in Casas Grandes municipality (Chihuahua) through the use of MCDM methods. In this study, the term “risk” is understood to mean the potential damage to a forest caused by exposure to an agent (Kaplan 1977), in this case presence of D. rhizophagus, while “susceptibility” is the probability that the forest will be attacked (Mott 1963), given the set of characteristics favoring presence of this bark beetle (Shore and Safranyik 1992). María Guadalupe Mendoza Correa 46 Materials and Methods Biological data. A total of 102 presence-only records for D. rhizophagus were obtained based on technical reports from the Babícora-Casas Grandes Forest Management Unit in the state of Chihuahua, as well as major entomological collections in México. Study area. Casas Grandes municipality is located between 30º 23' N latitude and 107º 57' W longitude in the northwest part of the state of Chihuahua (Fig. 1). It covers a surface area of 3,719 km 2 ; the climate is semiarid and harsh; and its altitude ranges from 1,430 to 2,600 m.a.s.l. Surface relief in Casas Grandes is divided into the North Central Plateau on the E and the Sierra Madre of Chihuahua on the W. The North Central Plateau includes extensive arid areas with a desert climate, where the vegetation is mainly grassland, brush, and oak forest. The Sierra Madre of Chihuahua has a temperate climate and its vegetation cover comprises mainly pine forest and to a lesser extent oak forest (INEGI 2004). Potential geographic distribution of D. rhizophagus using MaxEnt, and determination of percent contribution by ecogeographic predictor variables. Digital maps of Casas Grandes showing 16 ecogeographic (topographic, climatic and biotic) variables that have been cited as significant for occurrence of D. rhizophagus (Mendoza et al. in review) and other bark beetles (Shore and Safranyik 1992, Wulder et al. 2006) were drawn at a spatial resolution of 25 x 25 m. These variables (Table 1) were regarded as predictor variables in order to obtain a model of the potential distribution of D. rhizophagus using MaxEnt v.3.3.1 (Phillips et al. 2004). Topographic variables. The digital elevation model (DEM) of the study area generated by García-Nájera (2009) was used to derive digital maps of the surface slope, aspect, and solar radiation with the spatial analysis tools provided in ArcGis v.9.2 software (ESRI, María Guadalupe Mendoza Correa 47 Redlands CA). The DEM was obtained from the contour lines in the eight vector topographic charts from INEGI (scale 1:50,000) that comprise the municipality. Climatic variables. Digital maps of the different temperature and precipitation variables were obtained (Table 1) through spatial interpolation using regression functions (Ninyerola et al. 2000). These methods are based on existing correlations between the altitude, latitude and longitude of weather stations, and temperature and precipitation values (Muñoz et al. 2005). Regression coefficients were derived for each of the temperature and precipitation variables under consideration (Table 2) based on mean values obtained from the databases of 96 weather stations in the state of Chihuahua (Medina et al. 2006) as well as nine stations in Sonora (4), Arizona (4) and New Mexico (1) that are closest to Casas Grandes. These databases comprised the years 1961-1990. Digital maps of the different temperature and precipitation variables were derived through map algebra with ArcView v.3.2 software, using the following general regression equation: Temperature or precipitation variable = B0 + B1(map-x) + B2(map-y) + B3(map-z) where map-x, map-y and map-z are independent variablesof digital coverages of longitude, latitude and altitude; and B0, B1, B2 and B3 are regression coefficients obtained for each of the temperature and precipitation variables. Biotic variable. A digital map of the potential distribution of pine forests in Casas Grandes generated by García-Nájera (2009) by means of MCE (Fig. 1) was used. The latter method included topographic variables (elevation, slope, aspect), climatic variables (annual mean precipitation), the normalized difference vegetation index (NDVI) obtained from LandSat TM and SPOT5 satellite images, and soil attributes (texture and physical phase). The map shows values at byte scale, where the highest values (>146) represent pine communities. María Guadalupe Mendoza Correa 48 The model of the potential distribution of D. rhizophagus was obtained by entering in MaxEnt data on presence of the species as well as from the 16 maps of ecogeographic predictor variables. The MaxEnt algorithm was derived using default parameters of 500 iterations with a convergence threshold of 0.00001 and a logistic output format (Phillips and Dudik 2008). During model development, 80% of the localities were used for model training and 20% were held back to test the model. The latter was evaluated by means of the area under the receiver operating characteristic curve (AUC). AUCs close to 0.5 are similar to random predictions and indicate poor model performance, while values > 0.9 suggest high model reliability (Swets 1988, Phillips and Dudik 2008). The resulting map shows the probability (0-1) of presence of the species. Based on analysis of the data entered in MaxEnt, a table was constructed to show the percent contribution of each predictor variable to the final potential distribution model. This percentage was determined by the algorithm through the increase in gain in the model provided by each variable incorporated (Phillips et al. 2004). Susceptibility model. Digital maps of the ecogeographic variables used with MaxEnt were standardized, weighted and analyzed by MCE in order to obtain a model for assessing the susceptibility of pine forests to presence of D. rhizophagus. Standardization of factor maps. The MCE method used was weighted linear combination (WLC) with the use of overlay techniques based on GIS, which require that all factor maps (maps of ecogeographic variables) be standardized or converted into units capable of being subsequently compared (Ceballos-Silva and López-Blanco 2003). The nine different ranges obtained by default with ArcView v.3.2 (e.g. slope 0.001-16.48, 16.49-32.95, etc.) for each alternative (e.g. aspect, slope, elevation, etc.) in the factor maps María Guadalupe Mendoza Correa 49 were therefore assigned to one of five possible suitability values (low, medium-low, medium, medium-high, and high). Classification of the ranges was based on the number of location records for D. rhizophagus in each of them. Each range was then standardized to byte scale (Tables 3, 4 and 5), consisting in 256 byte values, of which 0 is the lowest value and 255 the highest. The 256 byte values were divided into five intervals that represent the different suitability values. Weighting of standardized factor maps. Standardized factor maps were weighted at both the alternative (elevation, slope, etc.) and criterion (topographic, temperature, etc.) levels by analytic hierarchy process (AHP). Weighting of maps was based on the percent contribution of each variable to the model of the potential distribution of the bark beetle. AHP requires using a pairwise comparison matrix (PCM), which simplifies the preferred values among the different alternatives or criteria under analysis (Saaty 1980, Tienwong et al. 2009). The method for constructing the PCM uses a basic scale of values from 1/9 to 9 in order to evaluate preferences between the two criteria or alternatives compared (Table 6). Consistency ratio (CR). There is a potential risk that each weight assigned to each of the alternatives or criteria will be inadequate as a result of incorrect or inconsistent pairwise comparisons. Therefore, to ensure credibility of the relative importance assigned, the CR was estimated. This ratio indicates the probability that values have been randomly assigned. Saaty (1980) suggested that if the CR is < 0.1, consistency is largely acceptable, but if it is > 0.1 then inconsistencies are present and the AHP is unable to produce significant results (Tienwong et al. 2009). Multi-criteria Evaluation (MCE). To obtain the susceptibility model for the pine forest, MCE was carried out through weighted linear combination (WLC) using map algebra and overlay techniques available in ArcView v.3.2. To this end, standardized factor María Guadalupe Mendoza Correa 50 maps of the same criterion were multiplied by their corresponding weight and added according to WLC, using the following equations: Topographic_Map = (Std_Slp*0.5842) + (Std_Elev*0.2725) + (Std_Asp*0.0943) + (Std_Sol-Rad* 0.0490) Precipitation_Map = (Std_An-Pp*0.5028) + (Std_Pp-D-M*0.2602) + (Std_Pp-Wm- Q*0.1344) + (Std_Pp-Wt-M*0.0678) + (Std_Pp-Wt-Q*0.0348) Temperature_Map = (Std_Mn-Tp-D-Q*0.4615) + (Std_An-Max-Tp*0.2515) + (Std_Mx- Tp-Wm-M*0.1330) + (Std_An-Mn-Tp*0.0619) + (Std_Mn-Tp-C-Q*0.0619) + (Std_An- Min-Tp*0.0302). The susceptibility map was obtained by multiplying each criterion by its respective weight, and their sum through the equation: Susceptibility_Map = (Std_Pot-Dist-Pines*0.5579) + (Precipitation_Map*0.2633) + (Temperature_Map*0.1219) + (Topographic_Map*0.0569) Risk assessment model. After the susceptibility map was obtained, a map of georeferenced localities of D. rhizophagus in Casas Grandes and Madera municipalities was overlaid on it in order to establish the potential risk areas of presence of this insect, by generating zones of influence based on probable dispersal distances previously reported for these bark beetles (Atkins 1961, Byers 2000, Sánchez-Martínez verbal comm.), for example, is reported that D. valens can flight distances near to 2 km (Kinn 1986). These zones of influence were defined by 1.5 and 3 km dispersal radius using ArcView v.3.2. María Guadalupe Mendoza Correa 51 Results Potential geographic distribution of D. rhizophagus. The map of the potential geographic distribution of D. rhizophagus (Fig. 2) shows two separate areas of high probability of occurrence (> 0.502). The smaller of the two is in NW Casas Grandes and the other in its W part. Both are surrounded by areas of moderate probability (0.196 - 0.501). The north, east, south, and southeast parts of Casas Grandes are the least suitable areas (< 0.196) for presence of this bark beetle. The AUC of training data was 0.956 and that of test points 0.946, indicating robustness of the model. Determination of percent contribution of ecogeographic predictor variables to the potential distribution model. According to MaxEnt results, the ecogeographic variables contributing the most to the potential distribution model of D. rhizophagus were annual precipitation (42.1%), mean temperature of driest quarter (14.1%), slope (10.0%), precipitation of driest month (9.6%), potential distribution of pines (8.5%), elevation (4.6%) and precipitation of warmest quarter (3.5%) (Table 7). Variables contributing the least were: precipitation of wettest quarter (0.1), solar radiation (0.1) and minimum annual temperature (0.01). Standardization of factor maps. Tables 3, 4 and 5 show the suitability values assigned to each of the alternatives of the different criteria under analysis, and their corresponding byte values. This bark beetle occurs preferentially (>70% of the records) in areas with the following precipitation ranges: annual 541-592 mm, driest month 7.7-9.0 mm, warmest quarter 258-286 mm, wettest month 125-137mm, and wettest quarter 300-330 mm. The preferred temperature ranges are: mean of driest quarter 11.3-13.6 ºC, mean of coldest quarter 4.7-6.2 ºC, maximum of warmest month 28.4-31.4 ºC, maximum annual 20.6-22.2 ºC, mean annual 11.5-13.2 ºC, and minimum annual 2.2-4.1 ºC. In addition, this beetle María Guadalupe Mendoza Correa 52 occurs most frequently at elevations between 1,976 and 2,267 m, on gentle slopes (< 33%) facing NE, E or SE with solar radiation from 1,779,502 to 2,065,497 Wh/m 2 . Determination of weight for each criterion and alternative, and consistency ratio (CR). In analyzing the alternatives of the precipitation criterion with PCM (Table 8), the variable with highest weight was annual precipitation (W=0.5028), followed in importance by precipitation of driest month (W=0.2602), precipitation of warmest quarter (W=0.1344), precipitation of wettest month (W=0.0678) and precipitation of wettest quarter (W=0.0348). The CR was 0.093 (< 0.1) and consistency is therefore acceptable. The following weights were assigned for the temperature criterion (Table 9) in descending order: temperature of driest quarter (W=0.4615), maximum annual temperature (W=0.2515), maximum temperature of warmest month (W=0.1330), mean annual temperature (W=0.0619), temperature of coldest quarter (W=0.0619) and minimum annual temperature (W=0.0302). The CR was 0.067 (< 0.1), indicating that this ratio is within the interval established as acceptable. As regards the PCM of the topographic criterion (Table 10), the variable that was assigned the highest weight was surface slope (W=0.5842), followed in order by elevation (W=0.2725), aspect (W=0.0943), and last of all solar radiation (W=0.0490). The CR was 0.044 (< 0.10), meaning the value judgments assigned were also consistent. Finally, in the AHP of the susceptibility model (Table 11) the criterion assigned the highest weight (W=0.5579) was the potential distribution of pines, followed in descending order by precipitation (W=0.2633), temperature (W=0.1219), and last of all the topographic criterion (W=0.0569). The CR was also acceptable, showing a value of 0.065 (<0.1). Susceptibility model. The susceptibility map of the pine forests in Casas Grandes obtained by MCE (Fig. 3) shows a large continuous area of high susceptibility in the NW, María Guadalupe Mendoza Correa 53 stretching towards the S and going around the W side of a low elevation zone in the central part of the municipality. This high susceptibility area encloses the latter zone on the E up to its middle portion, where it then extends as scattered patches. Additional tiny discontinuous high susceptibility areas are evident in SE Casas Grandes. All these high susceptibility areas extend over mountain terrain that forms part of the Sierra Madre of Chihuahua at elevations over 1,600 m. Risk model. For purposes of this study, all zones of influence of D. rhizophagus as determined by its dispersal radius and located in high susceptibility areas were considered potential risk areas. Thus, the model suggests as potential risk areas, the entire high susceptibility area in NW Casas Grandes that runs southward bordering on the west the region of low elevations in the central part of the municipality (Fig. 4). Also, two additional potential risk areas are evident: one in the SW and a second one that is more isolated from the rest, towards the S on small discontinuous areas of medium-high and high susceptibility. Analysis of the zones of influence of D. rhizophagus located in the adjacent Madera municipality evidences their proximity to the high susceptibility areas in S and SE Casas Grandes. María Guadalupe Mendoza Correa 54 Discussion Predictive modeling of the potential distribution of D. rhizophagus using MaxEnt enabled identification of the major bioclimatic variables and conditions that determine the presence of this species. Results suggest that D. rhizophagus presence is correlated mainly with precipitation and temperature, rather than topographic, variables (Table 7). Our results are consistent with those of other authors, who recognize a link between precipitation and temperature variables and the life cycle development and population dynamics (mortality, reproduction, emergence and dispersal) of bark beetles (Safranyik 1986, Bentz et al. 1991, Régnière and Logan 1996, Logan and Bentz 1999). For example, temperature has been said to determine the type of life cycle in some species, as in D. rufipennis Kirby, which usually displays semivoltine cycles, but may have univoltine cycles when environmental conditions become warmer (Hansen et al. 2001). Also, particular temperature and humidity thresholds have been seen to regulate population dynamics and the different life stages of these insects (Powell et al. 2000). Thus, the optimal temperatures for development of all life stages of D. ponderosae Hopkins have been said to fall between 23 and 25 ºC (Bentz et al. 1991) while its emergence and flight are said to be usually initiated after a threshold temperature of 19º C is reached (Rasmussen 1974). In regard to humidity, Coster et al. (1978), for example, found a significant correlation between this variable and the number of beetles present on trees infested by D. frontalis. Furthermore, humidity has been linked to the emergence of outbreaks, since when humidity is low tree resistance has been found to decrease, making trees more vulnerable to successful attack by bark beetles (Hicks 1980). The lesser relevance of topographic variables for determination of presence of D. rhizophagus may be due to their indirect effect, since variables such as elevation, aspect and slope modify both temperature and precipitation (Furniss and Carolin 1977, Nelson et María Guadalupe Mendoza Correa 55 al. 2007). Thus, temperatures in the microhabitat in which D. ponderosae occurs have been said to vary due to these topographic variables (Bolstad et al. 1997). Likewise, topographic variables are known to be more important in determination of the distribution, composition and structure of plant communities (Guisan and Hofer 2003), indirectly affecting therefore the distribution of insects that parasitize them (Wulder et al. 2006). The higher occurrence of D. rhizophagus on gentle slopes facing NE, E and SE appears in turn to be the result of preference for these conditions by the pine communities in Casas Grandes (García-Najera 2009). Analysis of the ranges of the precipitation and temperature variables at which D. rhizophagus occurs is consistent with reports by Mendoza et al. (in review) for the Sierra Madre Occidental (SMOC). However, the former are much narrower, suggesting that this bark beetle is present in highly specific local conditions relative to those found throughout its geographic distribution range. Not so in the case of elevation, since the presence of this beetle in Casas Grandes was associated with preference for elevations over 1,900 m, which is consistent with the preferred range reported for its entire distribution range (Mendoza et al. in review). Determination of susceptible areas and risk areas in Casas Grandes municipality was based on ranking of the criteria for potential presence of the host as well as of climatic and topographic criteria. The highest weight was assigned to host presence, since hosts are the source of food for the beetle without which it could not become established. However, both the potential distribution model and the susceptibility model evidence the fact that not all areas with pines have suitable conditions for presence of this insect. This suggests that its distribution in Casas Grandes may be limited by environmental variables (precipitation and María Guadalupe Mendoza Correa 56 temperature) more than host presence. This same situation wasalso observed to occur throughout its distribution range (Mendoza et al. in review). The susceptibility model obtained by MCE concurs with the potential distribution model in pointing to mountain areas in W and NW Casas Grandes as those with a higher probability of having the most suitable conditions for D. rhizophagus presence. However, the susceptibility map also indicates as important other areas in S and SE Casas Grandes. These results suggest that the potential distribution model tends to underestimate certain areas with a higher probability of presence of the beetle, perhaps due to a spatial bias in sampling efforts since most location records fall within the W and NW regions of Casas Grandes. Phillips et al. (2009) state that a spatial bias in the sampling of data may impact the quality of the prediction model obtained. As regards high susceptibility areas, it is worth stressing that these run continuously along the mountainous massifs in W and NW Casas Grandes descending southwards to the central part of the municipality and going around a central region with low elevations. Such continuity of the areas of high suitability for presence of this bark beetle is important since they may constitute a corridor favoring dispersal of this beetle along the pine communities of Casas Grandes. Comparison of these areas of high susceptibility to the zones of influence of D. rhizophagus determined on the basis of its dispersal radius permitted the establishment of risk areas. The latter coincide in areas of high susceptibility with land surfaces given over to pine forest exploitation where the dominant species are P. durangensis, P. engelmannii, P. leiophylla and P. arizonica, which are the major hosts of this beetle (Cibrian et al. 1995, Mendoza et al. in review). This allow to suggest that priority be given to the monitoring and management of such risk areas, in view of the potential for populations of this beetle to María Guadalupe Mendoza Correa 57 become established or surge out of control, since felling is carried out continuously in some of these areas and the presence of new seedlings is therefore feasible. It may also be advisable in managing these areas to take into account the type of felling as well as the continuity with which it is practiced, since on this will depend the density and availability of new seedlings and saplings for the insect. Ideally, selective felling practices should be favored. Proximity of the zones of influence of D. rhizophagus in Madera to high susceptibility areas in south Casas Grandes is worth noting, as this may also imply an increased probability of risk in the former region, given that bark beetles do not recognize the boundaries between municipalities. Similarly, these observations suggest the existence of a corridor between the two municipalities. Finally, it is worth stressing that occurrence of this bark beetle in high susceptibility areas does not necessarily imply that it will develop in epidemic conditions, since this will depend on the presence of other factors in these susceptible areas including, among others, high populations of this insect, presence of seedlings of its hosts, presence of competitors or predators, as well as microclimatic conditions. This does not diminish the importance of risk models, which are intended as a helping guide for forest managers and are not meant to reproduce exactly the complex character of nature, but rather to identify and interrelate major or key biological and ecological characteristics in the insect-host system that may be of predictive value (Bentz et al. 1993). María Guadalupe Mendoza Correa 58 Acknowledgments We are grateful to Roberto Nevarez (Unidad de Manejo Forestal de Casas Grandes, Chihuahua) and Antonio Olivo Martínez (SEMARNAT-Chihuahua, México) for providing us with only-presence data of D. rhizophagus and for their time and availability. We also are grateful to Ing. Arturo Cedillo Quiñones (Unidad de Aprovechamiento y Restauración de Recursos Naturales de la SEMARNAT), for his availability to providing us with silvicultural information of the forest management plans from Municipality of Casas Grandes. The Project was funded by Comisión Nacional Forestal (CONAFOR, 69539) and Secretaría de Investigación y Posgrado-IPN (SIP-20090576). This work was part of M. G. M. C’s Ph. D. dissertation. She was a Consejo Nacional de Ciencia y Tecnología (207124) and Programa Institucional de Formación de Investigadores del Instituto Politécnico Nacional (PIFI-IPN) fellow. María Guadalupe Mendoza Correa 59 References Cited Atkins, M. D. 1961. A study of the flight behaviour of the Douglas-fir beetle Dendroctonus pseudotsugae Hopk. (Coleoptera: Scolytidae) III. Flight capacity. Can. Entomol. 93: 467-474. Amman, G. D., M. D. McGregor, D. B. Cahill, and W. H. Klein. 1977. Guidelines for reducing losses of lodgepole pine to the mountain pine beetle in unmanaged stands in the Rocky Mountains. U.S.D.A. For. Serv., Intermountain Forest and Range Experiment Station. Gen. Tech. Rept. INT-36. 19 p. Bentz, B. J., J. A. Logan, and G. D. Amman. 1991. Temperature dependent development of the mountain pine beetle (Coleoptera: Scolytidae) and simulations of its phenology. Can. Entomol. 123: 1083-1094. Bentz, B. J., G. D. Amman, and J. A. Logan. 1993. A critical assessment of risk classification systems for the Mountain Pine Beetle. Forest Ecol. Manag. 61: 349-366. Bolstad, P. V., B. J. Bentz y J. A. Logan. 1997. Modelling micro-habitat temperature for Dendroctonus ponderosae (Coleoptera: Scolytidae). Ecol. Model. 94: 287-297. Byers, J. A. 2000. Wind-aided dispersal of simulated bark beetles flying through forests. Ecol. Model. 125: 231-243. Ceballos-Silva, A. y J. López-Blanco. 2003. Delineation of suitable areas for crops using a Multi-criteria Evaluation approach and land use/cover mapping: a case study in Central México. Agr. Syst. 77: 117-136. María Guadalupe Mendoza Correa 60 Cibrián, T. D., J. T. Méndez M., R. Campos B., H. O. Yates III, and J. Flores L. 1995. Insectos Forestales de México / Forest Insects of Mexico. Universidad Autónoma Chapingo, México. Coster, J. E., T. L. Payne, L. J. Edson, and E. R. Hart. 1978. Influence of weather on mass aggregation of southern pine beetles at attractive host trees. The Southwestern Entomologist. 3: 14-20. Chojnacky, D. C., B. J. Bentz, and J. A. Logan. 2000. Mountain pine beetle attack in ponderosa pine: Comparing methods for rating susceptibility. U.S.D.A. For. Serv., Ogden, UT: Rocky Mountain Research Station. Res. Pap. RMRS-RP-26. 10p. Environmental Systems Research Institute. 1999. Arcview-Gis 3.2. Environmental Systems Research Institute, Redlands, California, USA. Espinosa, C. G. M. y M. A. Muñoz. 1988. Sistema de clasificación de riesgo para Dendroctonus mexicanus en los bosques de la Unidad Forestal de San Rafael, México. Tesis Profesional. Universidad Autónoma Chapingo, México. Estrada-Murrieta, O. 1983. Biología del descortezador del renuevo de pino Dendroctonus rhizophagus T. y B. (Col.: Scolytidae) en la región de la Mesa del Huracán, Chihuahua. Bachelor’s Thesis. Universidad Autónoma Chapingo, México. Furniss, R. L., and V. M. Carolin. 1977. Western Forest Insects. Washington, D. C., USDA Forest Service. Miscellaneous Publication No. 1339. 654 p. García-Nájera, E. A. 2009. Distribución Potencial de las Comunidades de Pinos a Través de un proceso de Evaluación Multicriterio basado en SIG en el Municipio de Casas María Guadalupe Mendoza Correa 61 Grandes, Chihuahua. Tesis de Maestría. Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional. México, D.F. Guisan, A. and U. Hofer. 2003. Predicting reptile distributions at the mesoscale: relation to climate and topography. J. Biogeogr. 30: 1233-1243.Guisan, A. and N. Zimmermann. 2000. Predictive habitat distribution models in ecology. Ecol. Model. 135: 147-186. Hansen, E. M., B. J. Bentz, and D. L. Turner. 2001. Temperature-based model for predicting univoltine brood proportions in spruce beetle (Coleoptera: Scolytidae). Can. Entomol. 133: 827-841. Hicks, R. R. Jr., J. E. Howard, K. G. Watterson, and J. E. Coster. 1980. Rating forest stand susceptibility to southern pine beetle in east Texas. Forest Ecol. Manag. 2: 269- 283. INEGI. 2004. Síntesis de Información Geográfica del Estado de Chihuahua. Instituto Nacional de Estadística Geografía e Informática, México. Iñiguez, H. G. 1999. Sistemas de Clasificación de riesgo para Dendroctonus frontalis y D. mexicanus en el Manzano, en Villa de Santiago, Nuevo León, México. Tesis de Maestria. Universidad Autónoma de Nuevo León. 84p. Kaplan, S. 1997. The Words of Risk Analysis. Risk Analysis. 17: 407-417. Kinn, D. N. 1986. Studies on the Flight Capabilities of Dendroctonus frontalis and Ips calligraphus: Preliminary Findings Using Tethered Beetles. U.S.D.A. For. Serv., Res. Pap. SO-324, 3 p. South. For. Exp. Stn., New Orleans, La. Krist, F. J. 2006. A Multi-Criteria framework for producing local, regional and national insect and disease risk maps. Advances in threat assessment and their application to forest and rangeland management. July 18-20. Boulder, Colorado. María Guadalupe Mendoza Correa 62 Logan, J.A. and B. J. Bentz. 1999. Model analysis of mountain pine beetle (Coleoptera: Scolytidae) seasonality. Environ. Entomol. 28: 924–934. Lorio, P. L. Jr. 1978. Developing stand risk classes for the southern pine beetle. U.S.D.A. For. Serv., South. For. Exp. Stn. New Orleans. LA. Res. Pap. SO-144. 9 p. Lorio, L. P. Jr. 1981. Rating stands for susceptibility to Southern Pine Beetle. Chapter 8. In: The Southern Pine Beetle, by Thatcher, C. R., Searcy, L. J., Coster, E. J. Y Hertel, D. G. U.S.D.A. Expanded Southern pine beetle. Research and applications program. Forest Service Science and Education Administration. Tech. Bull. No. 1631. 153-163. Llanderal, O. T. 1995. Sistema de Clasificación de Susceptibilidad para Dendroctonus frontalis Zimm. en el Estado de México. Tesis Profesional. Universidad Autónoma Chapingo, México. Medina, G. G., P. G. Díaz, M. M. Berzoza, S. M. M. Silva y G. A. D. Baez. 2006. Estadísticas Climatológicas Básicas del Estado de Chihuahua (Periodo 1961-2003). Centro de Investigación Regional Norte Centro. Dirección de Coordinación y Vinculación Estatal en Chihuahua. INIFAP. Libro Técnico No. 1. 235p. Mendoza, G., Y. Salinas-Moreno, A. Olivo-Martínez y G. Zúñiga. Factors influencing the Geographical Distribution of Dendroctonus rhizophagus (Coleoptera: Curculionidae: Scolytinae) in the Sierra Madre Occidental, México. Environ. Entomol. In Review. Mott, D.G. 1963. The Forest and the Spruce Budworm in the Dynamics of Epidemic spruce Budworm Populations. R.F. Morris ed. Mem. Entomol. Soc. Can. 31:189-202. Muñoz, R. C. A., E. J. Treviño, J. Verástegui, J. Jiménez y O. A. Aguirre. 2005. Desarrollo de un Modelo Espacial para la evaluación del Peligro de incendios Forestales en la Sierra Madre Oriental de México. Invest. Geogr. 56: 101-117. María Guadalupe Mendoza Correa 63 Nelson, T. A., B. Boots, M. A. Wulder and A. L. Carroll. 2007. Environmental characteristics of mountain pine beetle infestation hot spots. BC J. Ecosys. Manage. 8: 91-108. Ninyerola, M., X. Pons, and J. Roure. 2000. Climatological modeling. A methodological approach of climatological modeling of temperature and precipitation through GIS techniques. http://www.creaf.uab.es/MIRAMON/publicat/papers/lisboa98/climodel.htm (Fecha de consulta: 18 de Mayo del 2007). Phillips, S. J., R. E. Schapire, and M. Dudík. 2004. A maximum entropy approach to species distribution modeling, pp 655-662. In R. Greinerand and D. Schurmans (eds.), Proceedings of the Twenty-First International Conference on Machine Learning. 2004. Banff, Canada. ACM Press, NY. Phillips, S. J., and M. Dudík. 2008. Modeling of species distributions with MaxEnt: new extensions and a comprehensive evaluation. Ecography 31: 161-175. Phillips, S. J., M. Dudík, J. Elith, C. H. Graham, A. Lehmann, J. Leathwick, and S. Ferrier. 2009. Sample Selection bias and presence-only distribution models: implications for background and pseudo-absence data. Ecol. Appl. 19: 181-197. Powell, J., B. P. Kennedy, B. White, J. Bentz, J. A. Logan and D. Roberts. 2000. Mathematical elements of attack risk analysis for Mountain Pine Beetles. J. Theor. Biol. 204: 601-620. Raffa, K.F., B.H. Aukema, N. Erbilgin, D.K. Klepzing, K.F.Wallin. 2005. Interactions among conifer terpenoids and bark beetles across multiple levels of scale: an http://www.creaf.uab.es/MIRAMON/publicat/papers/lisboa98/climodel.htm María Guadalupe Mendoza Correa 64 attempt to understand links between population patterns and physiological processes. Rec. Adv. Phytochem. 39: 79–118. Rasmussen, L. A. 1974. Flight and attack behavior of mountain pine beetles in lodgepole pine of Northern Utah and Southern Idaho. USDA Forest Service. Intermountain Forest and Range Experiment Station. Research Note, INT-180. Régnière, J. and J. A. Logan. 1996. Landscape-wide projection of temperature-driven processes for seasonal pest management decision support: a generalized approach, pp 43-56. In T. L. Shore and D. A. MacLean (eds.). Symposium Proceedings: Decision support systems in forest pest management. Entomological Society of Canada, FRDA Report No. 260. Victoria, BC. Robertson, C., M. A. Wulder, T. A. Nelson, and J. C. White. 2008. Risk rating for mountain pine beetle infestation of lodgepole pine forests over large areas with ordinal regression modeling. Forest Ecol. Manag. 256: 900-912. Saaty, T. L. 1980. The Analytic Hierarchy Process, MacGraw-Hill, New York. Safranyik, L. 1978. Effects of climate and weather on mountain pine beetle populations. pp. 77-86. .In: A. A. Berryman, G. D. Amman and R. W. Stark (eds.). Theory and Practice of Mountain Pine Beetle Management in Lodgepole Pine Forest. University of Idaho, Moscow. Safranyik, L. 1986. Effect of climatic factors on development, survival and life cycle of the MPB. pp. 14-24. In: Proceedings of the mountain pine beetle symposium: April 16, 17 18, 1985. P. Hall and T. F. Maher (eds.). Smithers, B. C. British Columbia Ministry of Forests, Prince Rupert Region, Smithers, B. C. Pest Management Report Number 7. María Guadalupe Mendoza Correa 65 Sánchez-Martínez, G., L. M. Torres-Espinosa, I. Vázquez-Collazo, E. González-Gaona, y R. Narváez-Flores. 2007. Monitoreo y Manejo de Insectos Descortezadores. INIFAP. Centro de Investigación Regional Norte Centro. Campo Experimental Pabellón. Libro Técnico No. 4. 107 p. SEMARNAT. 2005. Aprovechamiento de los recursos forestales pesqueros y de la vida Silvestre. México. Shore, T. L. y L. Safranyik. 1992. Susceptibility and risk rating systems for the mountain pine beetle in lodgepole pine stands. Inf. Rep. BC-X336, Pacific and Yukon Region. Forestry Canada, Pacific Forestry Centre, Victoria, B. C., 12 pp. Shore, T. L., L. Safranyik and J. P. Lemieux. 2000. Susceptibility of lodgepole pine stands to the mountain pine beetle: testing of a rating system. Can. J. For. Res. 30: 44-49. Swets, J. A. 1988. Measuring the accuracy of diagnostic systems. Science 240: 1285-1293. Tienwong, K., S. Dasananda, and Ch. Navanugraha. 2009. Integration of land evaluation and the analytical hierarchical process methods for energy crops in Kanchanaburi, Tahiland. Sci. Asia 35: 170-177. Wulder, M. A., J. C. White, C. C. Dyamond, T. Nelson, B. Boots, and T. L. Shore. 2006. Calculating risk of mountain pine beetle attack: comparison of distance-and density- based estimates of beetle pressure. J. Environ. Inf. 8:1-18. María Guadalupe Mendoza Correa 66 Table 1. Ecogeographic (topographic, climatic and biotic) variables regarded as predictor variables in MaxEnt analysis Ecogeogreaphic Variables Key Topographic 1) Elevation (m.a.s.l) Elev 2) Slope (%) Slp 3) Aspect Asp 4) Solar Radiation (WH/m²) Sol-Rad Climatic 5) Annual Precipitation (mm) An-Pp 6) Precipitation of wettest month (mm) Pp-Wt-M 7) Precipitation of driest month (mm) Pp-D-M 8) Precipitation of wettest quarter (mm) Pp-Wt-Q 9) Precipitation of warmest quarter (mm) Pp-Wm-Q 10) Annual maximum temperature ( ºC) An-Max-Tp 11) Annual mean temperature (ºC) An-Mn-Tp 12) Annual minimum temperature (ºC) An-Min-Tp 13) Mean temperature of driest quarter (ºC) Mn-Tp-D-Q 14) Mean temperature of coldest quarter (ºC) Mn-Tp-C-Q 15) Maximum temperature of warmest month (ºC) Mx-Tp-Wm-M Biotic 16) Potential distribution of Pines (Bytes) Pot-Dist-Pines María Guadalupe Mendoza Correa 67 Tabla 2. . Regression coefficients used to generate models of temperature and precipitation variables for Casas Grandes municipality, Chihuahua Regression Coefficients Variables B0 B1 B2 B3 An-Pp 4811.78943676 -0.0009906486 -0.0009054882 0.09136841 Pp-Wt-M 1105.37880770 -0.0002187836 -0.0002112725 0.02070681 Pp-D-M 35.30690517 -0.0000115821 -0.0000048834 0.00275391 Pp-Wt-Q 2540.64633851 -0.0004437705 -0.0005102990 0.06037525 Pp-Wm-Q 2414.00920504 -0.0004226468 -0.0004876615 0.05000667 An-Max-Tp 36.10514593 0.0000025423 -0.0000016608 -0.00593993 An-Mn-Tp 29.56201031 0.0000016611 -0.0000018158 -0.00631206 An-Min-Tp 22.71528438 0.0000013909 -0.0000020566 -0.00683407 Mn-Tp-D-Q 31.26635547 -0.0000077283 0.0000008181 -0.00530769 Mn-Tp-C-Q 38.09394556 -0.0000014466 -0.0000057050 -0.00533746 Mx-Tp-Wm-Q 33.11896571 0.0000023654 0.0000021388 -0.00678242 María Guadalupe Mendoza Correa 68 Table 3. Suitability values for each alternative of the precipitation criterion, and their corresponding byte values Suitability Values Ranges of Byte Ranges of Pp-D-M Byte Value Ranges of Byte Ranges of Pp-Wt-M Byte Value Ranges of Pp-Wt-Q Byte Value Pp-Wm-Q Value An-Pp Value LOW 191.6-205.0 25 5.7-6.1 25 388.7-414.1 15 90.1-95.9 10 224.1-239.2 10 LOW 205.1-218.4 50 6.2-6.6 50 414.2-439.6 30 96.0-101.7 20 239.3-254.4 20 LOW 439.7-465.0 45 101.8-107.5 30 254.5-269.6 30 LOW 107.6-113.3 40 269.7-284.8 40 LOW 113.4-119.2 50 345.6-360.7 50 MEDIUM-LOW 218.5-231.8 75 6.7-7.1 75 465.1-490.5 65 136.7-142.4 75 284.9-299.9 75 MEDIUM-LOW 231.9-245.3 100 9.6-10.0 100 592.4-617.8 80 MEDIUM-LOW 490.6-515.9 100 MEDIUM 245.4-258.7 115 7.2-7.6 125 516-541.4 125 119.3-125.0 125 330.4-345.5 125 MEDIUM 299.1-312.4 130 9.1-9.5 150 MEDIUM 285.7-299.0 145 MEDIUM-HIGH 258.8-272.1 175 7.7-8.0 175 566.9-592.3 175 130.9-136.6 175 300.0-315.1 175 MEDIUM-HIGH HIGH 272.2-285.6 250 8.6-9.0 230 541.5-566.8 250 125.1-130.8 250 315.2-330.3 250 HIGH 8.1-8.5 250 María Guadalupe Mendoza Correa 69 Table 4. Suitability values for each alternative of the temperature criterion, and their corresponding byte values Suitability Values Ranges of Byte Ranges of Mn-Tp-C-Q Valor Byte Ranges of Byte Ranges of An-Max-Tp Byte Value Ranges of Byte Ranges of An-Min-Tp Byte Mn-Tp-D-Q Value Mx-Tp-Wm-Q Value An-Mn-Tp Value Value LOW 15.3-16.0 25 2.3-3.1 15 33.5-34.4 15 24.9-25.7 15 16.0-16.9 15 7.1-8.1 15 LOW 8.8-9.6 50 8.6-9.3 30 32.5-33.4 30 17.9-18.8 30 8.6-9.5 30 -0.7-0.2 30 LOW 7.7-8.5 45 25.3-26.3 45 24.1-24.8 45 15.1-15.9 45 6.2-7.0 45 LOW LOW MEDIUM-LOW 14.5-15.2 75 3.2-3.8 75 26.4-27.3 75 18.9-19.7 75 9.6-10.5 75 0.2-1.1 75 MEDIUM-LOW 9.7-10.4 100 MEDIUM-LOW MEDIUM 13.7-14.4 125 7.0-7.6 1155 31.5-32.4 125 22.3-23.1 115 10.6-11.4 115 1.2-2.1 115 MEDIUM 10.5-11.2 150 3.9-4.6 130 27.4-28.3 150 23.2-24.0 130 14.2-15.0 130 5.2-6.1 130 MEDIUM 6.3-6.9 145 19.8-20.5 145 13.3-14.1 145 4.2-5.1 145 MEDIUM-HIGH 12.9-13.6 175 4.7-5.4 200 30.4-31.4 175 20.6-21.4 200 11.5-12.3 200 2.2-3.1 200 MEDIUM-HIGH 11.3-12.0 200 HIGH 12.1-12.8 250 5.5-6.2 250 28.4-29.3 225 21.5-22.2 250 12.4-13.2 250 3.2-4.1 250 HIGH 29.4-30.3 250 María Guadalupe Mendoza Correa 70 Table 5. Suitability values for each alternative of the topographic and biotic criteria, and their corresponding byte values Suitability Ranges of Slope Byte Value Ranges of Aspect Byte Value Ranges of Elevation Byte Value Ranges of Byte Value Pot-Dist-Pines Byte Value Values Solar Radiation LOW 131.82-148.28 10 292.5-337.5 50 1393-1538 15 778516-921514 10 26.19-48.56 10 LOW 115.34-131.81 20 1539-1684 30 921515-1064512 20 48.57-70.93 20 LOW 98.87-115.33 30 2559-2704 45 1064513-1207510 30 70.94-93.30 30 LOW 82.39-98.86 50 1207511-1350508 40 93.31-115.67 40 LOW 1350509-1493505 50 115.68-138.04 50 MEDIUM-LOW 65.91-82.38 75 247.5-292.5 75 2413-2558 75 1493506-1636503 75 MEDIUM-LOW 0-22.5 100 138.05-160.41 100 MEDIUM-LOW 337.5-360 100 MEDIUM 157.5-202.5 130 1685-1830 115 1636504-1779501 125 MEDIUM 49.44-65.90 125 202.5-247.5 145 2268-2412 130 160.42-182.78 150 MEDIUM 32.96-49.43 150 1831-1975 145 MEDIUM-HIGH 16.49-32.95 175 67.5-112.5 175 2122-2267 200 1922500-2065497 175 MEDIUM-HIGH 112.5-157.5 200 182.79-205.15 200 HIGH 0.001-16.48 250 1976-2121 250 205.16-227.52 250 HIGH 22.5-67.5 250 1779502-1922499 250 María Guadalupe Mendoza Correa 71 Table 6. Measurement scale for assignment of value judgments, defined by Saaty (1980) 1/9 1/7 1/5 1/3 1 3 5 7 9 Extremely Very Strongly Strongly Moderately Equal Moderately Strongly Very Strongly Extremely Less Important More Important María Guadalupe Mendoza Correa 72 Table 7. Percent contribution by each ecogeographic variable as estimated by MaxEnt Ecogeographic Variables Percentage of Contribution An-Pp 42.1 Mn-Tp-D-Q 14.1 Slp 10.0 Pp-D-M 9.6 Pot-Dist-Pines 8.5 Elev 4.6 Pp-Wm-Q 3.5 An-Max-Tp 2.8 Mx-Tp-Wm-M 1.8 Asp 1.1 Pp-Wt-M 0.7 An-Mn-Tp 0.6 Mn-Tp-C-Q 0.4 Pp-Wt-Q 0.1 Sol-Rad 0.1 An-Min-Tp 0.01 María Guadalupe Mendoza Correa 73 Table 8. Pairwise comparison matrix of precipitation variables and the weight assigned to each variable An-Pp Pp-D-M Pp-Wm-Q Pp-Wt-M Pp-Wt-Q Weight (W) An-Pp 1 3 5 7 9 0.5028 Pp-D-M 1/3 1 3 5 7 0.2602 Pp-Wm-Q 1/5 1/3 1 3 5 0.1344 Pp-Wt-M 1/7 1/5 1/3 1 3 0.0678 Pp-Wt-Q 1/9 1/7 1/5 1/3 1 0.0348 María Guadalupe Mendoza Correa 74 Table 9. Pairwise comparison matrix of temperature variables and the weight assigned to each variable Mn-Tp-D-Q An-Max-Tp Mx-Tp-Wm-M An-Mn-Tp Mn-Tp-C-Q An-Min-Tp Weight (W) Mn-Tp-D-Q 1 3 5 7 7 9 0.4615 An-Max-Tp 1/3 1 3 5 5 7 0.2515 Mx-Tp-Wm-M 1/5 1/3 1 3 3 5 0.1330 An-Mn-Tp 1/7 1/5 1/3 1 1 3 0.0619 Mn-Tp-C-Q 1/7 1/5 1/3 1 1 3 0.0619 An-Min-Tp 1/9 1/7 1/5 1/3 1/3 1 0.0302 María Guadalupe Mendoza Correa 75 Table 10. Pairwise comparison matrix of topographic variables and the weight assigned to each variable Slope Aspect Elevation Sol-Rad Weight (W) Slope 1 7 3 9 0.5842 Aspect 1/7 1 1/5 3 0.0943 Elevation 1/3 5 1 5 0.2725 Sol-Rad 1/9 1/3 1/5 1 0.0490 María Guadalupe Mendoza Correa 76 Table 11. Pairwise comparison matrix of the criteria taken into account in order to obtain the susceptibility map and the weight assigned to each criterion Pot-Dist-Pines Precipitation Temperature Topography Weight (W) Pot-Dist-Pines 1 3 5 7 0.5579Precipitation 1/3 1 3 5 0.2633 Temperature 1/5 1/3 1 3 0.1219 Topography 1/7 1/5 1/3 1 0.0569 María Guadalupe Mendoza Correa 77 Figure legends Fig. 1. Location of Casas Grandes municipality, Chihuahua, and map of the potential distribution of pine forests (García-Nájera 2009). Fig. 2. Potential distribution of D.rhizophagus in Casas Grandes municipality, modeled with MaxEnt. Fig. 3. Susceptibility’s model of pine forests in Casas Grandes municipality, Chihuahua. Fig 4. Risk Model of presence of D. rhizophagus in pine forests of Casas Grandes municipality, Chihuahua. María Guadalupe Mendoza Correa 78 María Guadalupe Mendoza Correa 79 María Guadalupe Mendoza Correa 80 María Guadalupe Mendoza Correa 81 María Guadalupe Mendoza Correa 82 CONCLUSIONES GENERALES 1.- El modelaje espacial de distribución de especies combinando datos de presencia, con variables bióticas, climáticas y topográficas puede ser usado para determinar la distribución potencial de las especies a diferentes niveles, desde locales hasta regionales o nacionales. En este estudio fue posible determinar la distribución potencial de D. rhizophagus tanto a nivel de Municipio (Casas Grandes), como regional (Sierra Madre Occidental). 2.- Estas técnicas de modelaje permiten conocer cuales variables influyen mas en determinar la presencia de la especie en un sitio determinado. 3.- El modelaje predictivo fue una herramienta útil para generar el perfil bioclimático de D. rhizophagus a lo largo de toda su área de distribución. 4.- La incorporación de datos digitales, SIG y técnicas de EMC son una alternativa para modelar la susceptibilidad y el riesgo de los bosques de pino a agentes de riesgo como D. rhizophagus. 5.- D. rhizophagus es un descortezador endémico de la SMOC, el cual se distribuye de manera casi continua a lo largo de esta provincia morfotectónica, 6.- D. rhizophagus presenta un nicho ecológico relativamente estrecho con respecto a algunas variables de temperatura y precipitación, habitando condiciones climáticas particulares que no son las que prevalecen en la SMOC, teniendo una preferencia por hábitats templados. María Guadalupe Mendoza Correa 83 7.- D. rhizophagus presenta un nicho ecológico amplio con respecto al número de huéspedes que parasita (once especies); sin embargo su límite de distribución no parece estar determinado por la presencia de sus húespedes. 8.- A nivel de la SMOC, el límite de la distribución geográfica de D. rhizophagus coincide con las isotermas de temperatura máxima. 9.- A nivel de Casas Grandes, D. rhizophagus se distribuye principalmente en los macizos montañosos de la región NW y W del municipio,influenciado principalmente por variables de precipitación y temperatura. 10.- Los rangos climáticos preferenciales en los que se presenta D. rhizophagus en Casas Grandes, son más estrechos que los reportados para toda su área de distribución en la SMOC. 11.- En Casas Grandes, se presenta una zona continua de alta susceptibilidad que abarca desde el noroeste hacia el sur y centro del municipio, la cual presenta condiciones bioclimáticas y topográficas favorables para la presencia de D. rhizophagus. 12.- El modelo de riesgo señala a las regiones del NW y W de Casas Grandes como las de mayor riesgo a la presencia de D. rhizophagus, por lo que se sugiere una evaluación y monitoreo continuo de estas zonas. María Guadalupe Mendoza Correa 84 REFERENCIAS GENERALES Amman, G. D. 1973. Population changes of the mountain pine beetle in relation to elevation. Environ. Entomol. 2: 541-547. Amman, G. D., M. D. McGregor, D. B. Cahill, and W. H. Klein. 1977. Guidelines for reducing losses of lodgepole pine to the mountain pine beetle in unmanaged stands in the Rocky Mountains. U.S.D.A. For. Serv., Intermountain Forest and Range Experiment Station. Gen. Tech. Rept. INT-36. 19 p. Anderson, R. P., D. Lew, and A. T Peterson. 2003. Evaluating predictive models of species’distributions criteria for selecting optimal models. Ecol. Model. 162: 211-232. Atkins, M. D. 1961. A study of the flight behaviour of the Douglas-fir beetle Dendroctonus pseudotsugae Hopk. (Coleoptera: Scolytidae) III. Flight capacity. Can. Entomol. 93: 467-474. Bale, S. J., G. J. Masters, I. D. Hodkinson, C. Awmack, T. M. Bezemer, V. K. Brown, J. Butterfield, A. Buse, J. C. Coulson, J. Farrar, J. E. G. Good, R. Harrington, S. Hartley, T. H. Jones, R. L. Lindroth, M. C. Press, I. Symrnioudis, A. D. Watt, and J. B. Whittaker. 2002. Herbivory in global climate change research: direct effects of rising temperature on insect herbivores. Global Change Biol. 8: 1-16. Bentz, B. J., J. A. Logan, and G. D. Amman. 1991. Temperature dependent development of the mountain pine beetle (Coleoptera: Scolytidae) and simulations of its phenology. Can. Entomol. 123: 1083-1094. Bentz, B. J., G. D. Amman, and J. A. Logan. 1993. A critical assessment of risk classification systems for the Mountain Pine Beetle. Forest Ecol. Manag. 61: 349-366. María Guadalupe Mendoza Correa 85 Beaumont, L. J., L. Hughes, and M. Poulsen. 2005. Predicting species distributions: Use of climatic parameters in BIOCLIM and its impact on predictions of species current and future distributions. Ecol. Model. 186: 250-269. Braunisch, V., and R. Suchant. 2007. A model for evaluating the “habitat potential” of a landscape for capercaillie Tetrao urogallus: a tool for conservation planning. Wildl. Biol. 13: 21-33. Brown, J. H. 1984. On the relationship between abundance and distribution of species. Am. Nat.124: 255-279. Brockerhoff, E.G., A. M. Liebhold, and H. Jactel. 2006. The ecology of forest insects invasions and advances in their management. Can. J. For. Res. 36: 263-268. Byers, J. A. 2000. Wind-aided dispersal of simulated bark beetles flying through forests. Ecol. Model. 125: 231-243. Carroll, A. L., S. W. Taylor, J. Régnière, and L. Safranyik. 2004. Effects of climate change on range expansion by the mountain pine beetle in British Columbia, pp. 223- 232. In T. L. Shore, J. E. Brooks and J. E. Stone (eds.), Mountain Pine Beetle Symposium: Challenges and Solutions. 30-31 October 2003, Kelowna, British Columbia, Canada, Natural Resources Canada, Canadian Forest Service, Pacific Forestry Centre, Information Report. BC-X-399, Victoria, BC. Ceballos-Silva, A. y J. López-Blanco. 2003. Delineation of suitable areas for crops using a Multi-criteria Evaluation approach and land use/cover mapping: a case study in Central México. Agricultural Systems 77: 117-136. Cibrián, T. D., J. T. Méndez M., R. Campos B., H. O. Yates III, and J. Flores L. 1995. María Guadalupe Mendoza Correa 86 Insectos Forestales de México/Forest Insects of Mexico. Universidad Autónoma Chapingo, México. Comisión Nacional para el Conocimiento y Uso de la Biodiversidad (CONABIO). 1997. Provincias Biogeográficas de México. Escala 1:4,000,000. México. Chojnacky, D. C., B. J. Bentz, and J. A. Logan. 2000. Mountain pine beetle attack in ponderosa pine: Comparing methods for rating susceptibility. U.S.D.A. For. Serv., Ogden, UT: Rocky Mountain Research Station. Res. Pap. RMRS-RP-26. 10p. Environmental Systems Research Institute. 1999. Arcview-Gis 3.2. Environmental Systems Research Institute, Redlands, California, USA. Estrada-Murrieta, O. 1983. Biología del descortezador del renuevo de pino Dendroctonus rhizophagus T. y B. (Col.: Scolytidae) en la región de la Mesa del Huracán, Chihuahua. Bachelor’s Thesis. Universidad Autónoma Chapingo, México. Espinosa, C. G. M. y M. A. Muñoz. 1988. Sistema de clasificación de riesgo para Dendroctonus mexicanus en los bosques de la Unidad Forestal de San Rafael, México. Tesis Profesional. Universidad AutónomaChapingo, México. Farjon, A., and B. Styles. 1997. Flora Neotropica. Monograph 75. Pinus (Pinaceae). Organization for Flora Neotropica. New York Botanical Garden, NY. Ferrusquía-Villafranca, I. 1998. Geología de México: Una Sinopsis, pp. 3-108. In T. P. Ramamoorthy, R. Bye, A. Lot and J. Fa (eds.). Diversidad Biológica de México: Orígenes y Distribución. Instituto de Biología. Universidad Nacional Autónoma de México, México. Fielding, A. H. and J. F. Bell. 1997. A review of methods for the assessment of prediction errors in conservation presence/absence models. Environ. Conserv. 24: 38-49. María Guadalupe Mendoza Correa 87 Furniss, R. L., and V. M. Carolin. 1977. Western Forest Insects. Washington, D. C. USDA Forest Service. Miscellaneous Publication No. 1339. 654 p. García Arevalo, A y M. S. González Elizondo. 2003. Pináceas de Durango. 2a. ed. Instituto de Ecología A. C. México. Ganeshaiah, K. N., N. Barve, N. Nath, K. Chandrashekara, M. Swamy, and R. U. Shanker. 2003. Predicting the potential geographical distribution of the sugarcane woolly aphid using GARP and DIVA-GIS. Scientific Correspondence. Current Science 85: 1526-1528. García-Nájera, E. A. 2009. Distribución Potencial de las Comunidades de Pinos a Través de un proceso de Evaluación Multicriterio basado en SIG en el Municipio de Casas Grandes, Chihuahua. Tesis de Maestría. Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional. México, D.F. Gaston, J. K. 2003. The structure and dynamics of geographic ranges. Oxford University Press, Oxford, New York. Guisan, A. and N. Zimmermann. 2000. Predictive habitat distribution models in ecology. Ecol. Model. 135: 147-186. Hicks, R. R. Jr., J. E. Howard, K. G. Watterson, and J. E. Coster. 1980. Rating forest stand susceptibility to southern pine beetle in east Texas. Forest Ecol. Manag. 2: 269- 283. Hijmans, R. J., L. Guarino, C. Bussink, and E. Rojas. 2002. DIVA-GIS, version 5.2. A geographic information system for the analysis of biodiversity data. Manual. International Potato Center, Lima, Peru. Hirzel, A., J. Hausser, D. Chessel, and N. Perrin. 2002. Ecological niche factor analysis: How to compute habitat suitability maps without absence data? Ecology 83: 2027–2036. María Guadalupe Mendoza Correa 88 Hirzel, A., B. Posse, P-A. Oggier, Y. Crettenand, C. Glenz, and R. Arlettaz. 2004. Ecological requirements of reintroduced species and the implications for release policy: the case of the Bearded vulture recolonizing the Alps. J. Appl. Ecol. 41: 1103–1116. Hirzel, A. H., J. Hausser, and N. Perrin. 2006a. Biomapper 3.2. Laboratory for Conservation Biology. Department of Ecology and Evolution. University of Lausanne, Lausanne. http://www.unil.ch/biomapper. Hirzel, A. H., G. Le Lay, V. Helfer, C. Randin, and A. Guisan. 2006b. Evaluating the ability of habitat suitability models to predict species presences. Ecol. Model. 199: 142– 152 INEGI. 2004. Síntesis de Información Geográfica del Estado de Chihuahua. Instituto Nacional de Estadística Geografía e Informática, México. Iñiguez, H. G. 1999. Sistemas de Clasificación de riesgo para Dendroctonus frontalis y D. mexicanus en el Manzano, en Villa de Santiago, Nuevo León, México. Tesis de Maestria. Universidad Autónoma de Nuevo León. 84p. Jiménez-Valverde, A., V. M. Ortuño, and J. M. Lobo. 2007. Exploring the distribution of Sterocorax Ortuño, 1990 (Coleoptera, Carabidae) species in the Iberian Peninsula. J. Biogeogr. 34: 1426-1438. Kaplan, S. 1997. The Words of Risk Analysis. Risk Analysis. 17: 407-417. Kelley, S. T., and B. D. Farrell. 1998. Is specialization a dead end? The phylogeny of host use in Dendroctonus Bark Beetles (Scolytidae). Evolution 52: 1731-1743. Kinn, D. N. 1986. Studies on the Flight Capabilities of Dendroctonus frontalis and Ips calligraphus: Preliminary Findings Using Tethered Beetles. U.S.D.A. For. Serv.South, For. Exp. Stn., New Orleans, LA. Res. Pap. SO-324. 3 p María Guadalupe Mendoza Correa 89 Krist, F. J. 2006. A Multi-Criteria framework for producing local, regional and national insecte and disease risk maps. Advances in threat assessment and their application to forest and rangeland management. July 18-20. Boulder, Colorado. Kurz, W. A., C. C. Dymond, G. Stinson, G. J. Rampley, E. T. Neilson, A. L. Carroll, T. Ebata, and L. Safranyik. 2008. Mountain pine beetle and forest carbon feedback to climate change. Nature 452: 987-990. Kumar, S., and T. J. Stohlgren. 2009. Maxent modeling for predicting suitable habitat for threatened and endangered tree Canacomyrica monticola in New Caledonia. J. Ecol. Nat. Environ. 1: 94-98. Lammertink, J. M., J. A. Rojas-Tomé, F. M. Casillas-Orona, y R. L. Otto. 1997. Situación y conservación de los bosques antiguos de pino-encino de la Sierra Madre Occidental y sus aves endémicas. Consejo Internacional para la preservación de las aves, sección Mexicana (CIPAMEX). D. F. México. Lekander, B., B. Bejer-Petersen, B. Kangas, and A. Bakke. 1977. The distribution of bark beetles in the Nordic Countries. Acta Entomol. Fenn. 32: 1-37. Lindenmayer, D. B., H. A. Nix, J. P. McMahon, M. F. Hutchinson, and M. T. Tanton. 1991. The conservation of Leadbeater’s possum, Gymnobelideus leadbeateri (McCoy): a case study of the use of bioclimatic modelling. J. Biogeogr. 18: 371-383. Logan, J. A., and G. D. Amman. 1986. A distribution model for egg development in mountain pine beetle. Can. Entomol. 118: 361-372. Logan, J.A. and B. J. Bentz. 1999. Model analysis of mountain pine beetle (Coleoptera: Scolytidae) seasonality. Environ. Entomol. 28: 924–934. María Guadalupe Mendoza Correa 90 Logan, J. A., and J. A. Powell. 2001. Ghost forests, global warming and the mountain pine beetle (Coleptera: Scolytidae). Am. Entomol. 47: 160-172. Lomolino, M. V., B. R. Riddle, and J. H. Brown. 2006. Biogeography. Sinauer Associates Inc., Sunderland, Massachussetts. Lorio, P. L. Jr. 1978. Developing stand risk classes for the southern pine beetle. U.S.D.A. For. Serv., South. For. Exp. Stn. New Orleans. LA. Res. Pap. SO-144. 9 p. Lorio, L. P. Jr. 1981. Rating stands for susceptibility to Southern Pine Beetle. Chapter 8. In: The Southern Pine Beetle, by Thatcher, C. R., Searcy, L. J., Coster, E. J. Y Hertel, D. G. USDA Expanded Southern pine beetle. Research and applications program. Forest Service Science and Education Administration. Tech. Bull. No. 1631. 153-163. Llanderal, O. T. 1995. Sistema de Clasificación de Susceptibilidad para Dendroctonus frontalis Zimm. en el Estado de México. Tesis Profesional. Universidad Autónoma Chapingo, México. MacDonald, G. M. 2003. Biogeography, space, time and life. John Wiley & Sons. Inc., United States of America. McGregor, M. D. 1986. Stand hazard and risk rating for mountain pine beetle susceptibility and losses. In: Proceedings of the mountain pine beetle symposium: April 16, 17, 18, 1985. P. M. Hall and T. F. Maher (ed.) Smithers, B. C. British Columbia Ministry of Forests, Prince Rupert Region, Smithers, B. C. Pest Management Report Number 7. Pp. 87-101. Mackey, B. G., and D. B. Lindenmayer. 2001. Towards a hierarchical framework for modeling the spatial distribution of animals. J. Biogeogr. 28: 1147-1166. María Guadalupe Mendoza Correa 91 Mason, G. N., L. P. Jr. Lorio. R. P. Belanger y W. A. Nettleton. 1985. Rating the susceptibility of stands to southern pine beetle attack. Integrated Pest Management Handbook, USDA Forest Service. Agriculture Handbook. Nm. 65. 31 p Medina, G. G., P. G. Díaz, M. M. Berzoza, S. M. M. Silva y G. A. D. Baez. 2006. Estadísticas Climatológicas Básicas del Estado de Chihuahua (Periodo 1961-2003). Centro de Investigación Regional Norte Centro. Dirección de Coordinación y Vinculación Estatal en Chihuahua. INIFAP. Libro Técnico No. 1. 235p. Mendoza, G., Y. Salinas-Moreno,A. Olivo-Martínez y G. Zúñiga. Factors influencing the Geographical Distribution of Dendroctonus rhizophagus (Coleoptera: Curculionidae: Scolytinae) in the Sierra Madre Occidental, México. Environ. Entomol. In Review. Mott, D.G. 1963. The Forest and the Spruce Budworm in the Dynamics of Epidemic spruce Budworm Populations. R.F. Morris ed. Mem. Entomol. Soc. Can. 31:189-202. Muñoz, R. C. A., E. J. Treviño, J. Verástegui, J. Jiménez y O. A. Aguirre. 2005. Desarrollo de un Modelo Espacial para la evaluación del Peligro de incendios Forestales en la Sierra Madre Oriental de México. Investigaciones Geográficas 56: 101-117. Nelson, W. A., A. Potapov, M. A. Lewis,, A. E. Hundsdörfer and F. He. 2006. The balance of complexity in mechanistic modeling: Risk analysis in the mountain pine beetle. Natural Resources Canada, Canadian Forest Service, Pacific Forestry Centre. Mountain Pine Beetle Initiative. Working Paper 2006-03. Nelson, T. A., B. Boots, M. A. Wulder and A. L. Carroll. 2007. Environmental characteristics of mountain pine beetle infestation hot spots. BC Journal of Ecosystems and Management. 8: 91-108. María Guadalupe Mendoza Correa 92 Ninyerola, M., X. Pons, and J. Roure. 2000. Climatological modeling. A methodological approach of climatological modeling of temperature and precipitation through GIS techniques. http://www.creaf.uab.es/MIRAMON/publicat/papers/lisboa98/climodel.htm (Fecha de consulta: 18 de Mayo del 2007). Nix, H. 1986. A biogeographic analysis of Australian elapid snakes, pp. 4-15. In R. Longmore (ed.), Atlas of elapid snakes of Australia. Australian flora and fauna series number 7. Australian Government Publishing Service, Canberra. Ortega-Rosas, C. I., M. C. Peñalba, J. A. López-Sáez, y T. R. Van Devender. 2008. Retrospectiva del Bosque de Pino y Encino de la Sierra Madre Occidental, Sonora, Noroeste de México, Hace 1,000 años. Acta Bot. Mex. 83: 69-92. Pearson, R. G., and T. P. Dawson. 2003. Predicting the impacts of climate change on the distribution of species: are bioclimate envelope models useful? Global Ecol. Biogeogr. 12: 361-371. Perry, J. P. Jr. 1991. The Pines of Mexico and Central America. Timber Press Inc., Portland, Oregon. Phillips, S. J., R. E. Schapire, and M. Dudík. 2004. A maximum entropy approach to species distribution modeling, pp. 655-662. In R. Greinerand and D. Schuurmans (eds.), Proceedings of the Twenty-First International Conference on Machine Learning. 2004. Banff, Canada. ACM Press, NY. Phillips, S. J., R. P. Anderson, and R. E. Schapire. 2006. Maximum entropy modeling of species geographic distributions. Ecol. Model. 190: 231-259. Phillips, S. J., and M. Dudík. 2008. Modeling of species distributions with MaxEnt: new extensions and a comprehensive evaluation. Ecography 31: 161-175. http://www.creaf.uab.es/MIRAMON/publicat/papers/lisboa98/climodel.htm María Guadalupe Mendoza Correa 93 Phillips, S. J., M. Dudík, J. Elith, C. H. Graham, A. Lehmann, J. Leathwick, and S. Ferrier. 2009. Sample Selection bias and presence-only distribution models: implications for background and pseudo-absence data. Ecological Applications 19: 181- 197. Powell, J., B. P. Kennedy, B. White, J. Bentz, J. A. Logan and D. Roberts. 2000. Mathematical elements of attack risk analysis for Mountain Pine Beetles. J. Theor. Biol. 204: 601-620. Raffa, K. F. and A. A. Berryman. 1987. Interacting Selective Pressures in Conifer-Bark Beetle Systems. A basis for Reciprocal Adaptations?. The American Naturalist. 129: 234-262. Raffa,K. F., B. H. Aukema, N. Erbilgin, D. K. Klepzing, K. F. Wallin. 2005. Interactions among conifer terpenoids and bark beetles across multiple levels of scale: an attempt to understand links between populations patterns and physiological processes. Rec. Adv.Phytochem. 39: 79-118. Rapoport, E. H. 1982. Areografía. Estrategias geográficas de las especies. Fondo de Cultura Económica. México, 214 pp. Régnière, J., and J. A. Logan. 1996. Landscape-wide projection of temperature-driven processes for seasonal pest management decision support: a generalized approach, pp. 43-56. In T. L. Shore and D. A. MacLean (eds.). Symposium Proceedings: Decision support systems in forest pest management. Entomological Society of Canada, FRDA Report No. 260. Victoria, BC. María Guadalupe Mendoza Correa 94 Robertson, C., M. A. Wulder, T. A. Nelson, and J. C. White. 2008. Risk rating for mountain pine beetle infestation of lodgepole pine forests over large areas with ordinal regression modeling. Forest Ecol. Manag. 256: 900-912. Rzedowsky, J. 1978. Vegetación de México. Limusa. México. Saaty, T. L. 1980. The Analytic Hierarchy Process, MacGraw-Hill, New York. Safranyik, L. 1978. Effects of climate and weather on mountain pine beetle populations. pp. 77-86. .In: A. A. Berryman, G. D. Amman and R. W. Stark (eds.). Theory and Practice of Mountain Pine Beetle Management in Lodgepole Pine Forest. University of Idaho, Moscow. Safranyik, L. 1986. Effect of climatic factors on development, survival and life cycle of the MPB. pp. 14-24. In: Proceedings of the mountain pine beetle symposium: April 16, 17 18, 1985. P. Hall and T. F. Maher (eds.). Smithers, B. C. British Columbia Ministry of Forests, Prince Rupert Region, Smithers, B. C. Pest Management Report Number 7. Salinas-Moreno, Y., M. G. Mendoza, M. A. Barrios, R. Cisneros, J. Macías-Sámano, and G. Zúñiga. 2004. Areography of the genus Dendroctonus (Coleoptera: Curculionidae: Scolytinae) in México. J. Biogeogr. 31: 1163-1177. Salinas-Moreno, Y., A. Ager, C. F. Vargas, J. L. Hayes, and G. Zúñiga. 2010. Determining the vulnerability of mexican pine forest to bark beetles of the genus Dendroctonus Erichson (Coleoptera: Curculionidae: Scolytinae). Forest Ecol. Manag. 260: 52-61. Sánchez-Martínez, G., L. M. Torres-Espinosa, I. Vázquez-Collazo, E. González- Gaona, y R. Narváez-Flores. 2007. Monitoreo y Manejo de Insectos Descortezadores. María Guadalupe Mendoza Correa 95 INIFAP. Centro de Investigación Regional Norte Centro. Campo Experimental Pabellón. Libro Técnico No. 4. 107 p. Sánchez-Martínez, G., and M. R. Wagner. 2009. Host preference and attack pattern of Dendroctonus rhizophagus (Coleoptera: Curculionidae: Scolytinae): a bark beetle specialist on pine regeneration. Environ. Entomol. 38: 1197-1204. Sattler, T., F. Bontadina, A. H. Hirzel, and R. Arlettaz. 2007. Ecological niche modelling of two cryptic bat species calls for a reassessment of their conservation status. J. Appl. Ecol. 44: 1188-1199. SEMARNAT. 2005. Aprovechamiento de los recursos forestales pesqueros y de la vida Silvestre. México. Shore, T. L. y L. Safranyik. 1992. Susceptibility and risk rating systems for the mountain pine beetle in lodgepole pine stands. Inf. Rep. BC-X336, Pacific and Yukon Region. Forestry Canada, Pacific Forestry Centre, Victoria, B. C., 12 pp. Shore, T. L., L. Safranyik and J. P. Lemieux. 2000. Susceptibility of lodgepole pine stands to the mountain pine beetle: testing of a rating system. Can. J. For. Res. 30: 44- 49. Spellerberg, I. F., and J. W. D. Sawyer. 1999. An introduction to applied biogeography. Cambridge University Press, Cambridge. Swets, J. A. 1988. Measuring the accuracy of diagnostic systems. Science 240: 1285-1293. Thomas, C. D., E. J. Bodsworth, R. J. Wilson, A. D. Simons, Z. G. Davies, M. Musche, and L. Conradt. 2001. Ecological and evolutionary processes at expanding range margins. Nature 411: 577-581. María Guadalupe Mendoza Correa 96 Tienwong, K., S. Dasananda, and Ch. Navanugraha. 2009. Integration of land evaluation and the analytical hierarchical process methods for energy crops in Kanchanaburi, Tahiland. Science Asia 35: 170-177. Titeaux, N., M. Dufrêne, J. Radoux, A. H. Hirzel, and P. Defourny. 2007. Fitness- related parameters improve niche-baseddistribution modelling: the case of the Red- backed Shrike. Biol. Conserv. 138: 207-223. Turchin, P., P. L. Jr. Lorio, A. D. Taylor, and R. F. Billings. 1991. Why do populations of southern pine beetles (Coleoptera: Scolytidae) fluctuate? Environ. Entomol. 20: 401- 409. Ungerer, M., M. P. Ayres, and M. J. Lombardero. 1999. Climate and the northern distribution limits of Dendroctonus frontalis Zimmermann (Coleoptera: Scolytidae). J. Biogeogr. 26: 1133-1145. Waring, K.M., D. M. Reboletti, L. A. Mork, M. Li, C.H. Huang, R. W. Hofstetter, A. M. Garcia, P. Z. Fulé, and T. S. Davis. 2009. Modeling the impacts of two bark beetle species under warming climate in the southwestern U.S.A.: ecological and economic consequences. Environ. Manage. 44: 824-835. Wood, S. L. 1982. The bark and ambrosia beetles of North and Central America (Coleoptera: Scolytidae) a taxonomic monograph. Great Basin Nat. Mem. 6: 1-1359. Wulder, M. A., J. C. White, C. C. Dyamond, T. Nelson, B. Boots, and T. L. Shore. 2006. Calculating risk of mountain pine beetle attack: comparison of distance-and density-based estimates of beetle pressure. Journal of Environmental Informatics 8: 1- 18.