1982 (Chapter 4) KEMP Fisiology of Ticks Tick Attachment and Feeding = Role of the Mouthparts, Feeding Apparatus, Salivary Gland Secretions

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C H A P T E R 4 
Tick Attachment and Feeding: Role of the 
Mouthparts, Feeding Apparatus, Salivary Gland 
Secretions and the Host Response 
D. H. KEMP 
CSIRO, Division of Animal Health, Long Packet Laboratories, Indooroopilly, (Queensland, Australia 
and 
B. F. S T O N E and K. C. B I N N I N G T O N 
Division of Entomology, Long Packet Laboratories, Indooroopilly, Queensland, Australia 
C O N T E N T S 
4.1. Introduction 119 
4.2. Structure of the Mouthparts and Feeding Apparatus 124 
4.3. The Granular Salivary Cells 132 
4.3.1. Structure and Histochemistry of Granular Salivary Cells 132 
4.3.2. Changes in Granular Salivary Cells During Feeding 137 
4.4. The Process of Attachment, Feeding, and Salivation 138 
4.4.1. Attachment and the Formation, Composition, and Function of the 
Attachment Cement 138 
4.4.2. Mechanism of Feeding and Salivation 142 
4.5. Development of the Feeding Lesion 146 
4.5.1. Role of the Mouthparts, Saliva and Host Reactions in Development of 
the Feeding Lesion 146 
4.5.2. Changes in the Lesion During Tick Feeding 151 
4.5.3. Composition of Ingested Fluid 151 
4.6. Regulation of Ingestion in vivo and in vitro 152 
4.6.1. Changing in Feeding Patterns During Development on the Host 152 
4.6.2. Feeding Stimuli, Deterrents, and Growth Requirements 154 
4.7. Toxic Oral Secretions and their Effects 160 
Acknowledgements 162 
References 162 
4 . 1 . I N T R O D U C T I O N 
A t t a c h m e n t a n d feeding of t icks h a s often b e e n s t ud i ed on ly in pa s s ing , 
whi le t he m a i n objec t ive of t he r e s e a r c h p r o g r a m m e h a s b e e n c o n c e r n e d w i t h 
d i sease t r a n s m i s s i o n , tick pa r a ly s i s , hos t i m m u n i t y , o r tick con t ro l . I n e v i t a b l y , 
the p i c t u r e is f r a g m e n t e d , a n d o n e a i m of this c h a p t e r is to a s s imi l a t e 
119 
120 D. H. Kemp, B. F. Stone and K. C. Binnington 
i n fo rma t ion from d ive r se sources . T h e reviews by A r t h u r (1965, 1970) , a n d 
especia l ly t he o n e by B a l a s h o v (1968, Eng l i sh t r a n s l a t i o n 1972) , a r e v a l u a b l e , 
b u t s ince t h e n in te res t in tick feeding h a s b e e n s t i m u l a t e d by e x p e r i m e n t s 
in severa l subd i sc ip l ines i n c l u d i n g those of G a l u n a n d K i n d l e r (1968a) on 
feeding s t imul i , G r e g s o n (1969) on e lect r ica l r e c o r d i n g of feeding a n d sal-
iva t ion , H o w e l l (1966) a n d T a t c h e l l (1967) on sa l ivary g l a n d funct ion , a n d 
those of T a t c h e l l a n d M o o r h o u s e (1968, 1970) on fo rma t ion of t he t ick feeding 
lesion. M u c h of t he i m p e t u s for those m o r e r ecen t s tud ies h a s c o m e from 
d e v e l o p m e n t s in t he field of insec t phys io logy . 
A préc i s of tick d e v e l o p m e n t on t he hos t is g iven he re , to w h i c h the l a t e r 
de ta i l s of feeding a n d sa l iva t ion c a n be r e l a t ed . T h e sensory p rocesses w h i c h 
lead to a t t r a c t i o n of t icks to the i r hos t , o r i e n t a t i o n , a n d p r o b i n g on the skin , 
a r e d i scussed in t h e p r e v i o u s c h a p t e r ( W a l a d d e & Rice ) . M a n y ticks a r e 
h igh ly select ive in the i r choice of si te before p e n e t r a t i n g the hos t skin w i t h 
the i r che l icera l d ig i t s (Fig. 4 .1 ) . A t t a c h m e n t is s ecu red by l a rge t ee th on the 
h y p o s t o m e a n d this c a n be s t r e n g t h e n e d by secre t ion of a n a t t a c h m e n t 
FlG. 4.1. Boophilus microplus: anterior view of the mouthparts. (Redrawn from Waladde and 
Rice, 1977) 
T
ick 
A
ttachm
ent 
a
n
d
 F
eeding 
1
2
1
 Inset. Pharyngeal valve 
FlG. 4.2. Reconstruction of the feeding apparatus of a Boophilus microplus female. Each line on 
the cuticle of the dorsal surface represents one 10-μιτι section and shows the angle of sectioning, 
ch., chelicera; o.c.s., outer cheliceral sheath; p.v., pharyngeal valve; o.m., oval membraneous 
window; p.o., pharyngeal orifice; 1., labrum; hyp., hypostome; f.c, feeding channel; m.b., 
membrane over hypostomal gutter; oes., oesophagus; sal., salivarium; m.d.sal., salivarium 
dilator muscles; ph., pharynx; sch.p., subcheliceral plate; s.d., salivary duct; l.r., lateral sclero-
tized rod; m.d.ph., pharynx dilator muscles; g.s., "globular structure"; m.c.ph., pharynx closing 
muscles; d.t., dorsal tooth; m.d.v., pharyngeal valve dilator muscles. 
122 D. H. Kemp, B. F. Stone and K. C. Binnington 
FlG. 4.3. Diagrammatic representation of the development of an ixodid tick (esp. Boophilus 
microplus) on the host. 
Tick Attachment and Feeding 123 
FlG. 4.4. The relationship between cement production, salivary gland development, and the 
changes occurring in the host skin (esp. B. microplus) (Adapted from Binnington, 1978). 
124 D. H. Kemp, B. F. Stone and K. C. Binnington 
cernent . F e e d i n g of a r g a s i d t icks (Ba la shov , 1972) is usua l ly c o m p l e t e d w i th in 
a n h o u r , d u r i n g w h i c h t i m e to ta l t ick w e i g h t inc reases u p to 12 t imes . I n the 
cou r se of a d u l t life t he feeding p rocess m a y be r e p e a t e d severa l t imes w i t h 
e a c h b lood m e a l followed by a b o u t of egg lay ing . D i s t ens ion of p r e f o r m e d 
cut ic le is sufficient to a c c o m m o d a t e t he inc reased b o d y size, whi le c o n c e n -
t r a t i o n of t h e m e a l is affected pos t - feed ing by the excre t ion of w a t e r a n d ions 
from coxal o r g a n s . I x o d i d t icks feed for longer pe r i o d s , a n d t h e r a t e of feeding 
is s low for t h e first few d a y s on the hos t (except i m m a t u r e Haemaphysalis 
inermis). D iges t ion of hos t t i ssues d u r i n g this ear ly p h a s e of e n g o r g e m e n t 
p e r m i t s t h e d e v e l o p m e n t of r e p r o d u c t i v e t i ssues , sa l iva ry g l a n d s , a n d o t h e r 
o r g a n s , b u t , in p a r t i c u l a r , g r o w t h of t he cut ic le to a l low for b o d y e x p a n s i o n 
d u r i n g t h e final p h a s e of r a p i d e n g o r g e m e n t (Lees , 1952) (Fig . 4 .3 ) . T h e 
we igh t of female ixod id t icks m a y inc rease 1 0 0 - 2 0 0 t imes d u r i n g feeding, 
b u t t h e q u a n t i t y of m a t e r i a l inges ted is m u c h g r e a t e r as c o n c e n t r a t i o n of t he 
b lood m e a l p r o c e e d s d u r i n g feeding by r e t u r n of excess w a t e r to t he hos t v ia 
spec ia l ized sa l iva ry g l a n d cells ( K a u f m a n & Phi l l ips , 1973; a n d C h a p t e r 7) . 
H o s t t i ssues a n d fluid a r e sucked in by a p h a r y n g e a l p u m p wi th its 
a s soc ia t ed va lve , a n d p a s s t h r o u g h the o e s o p h a g u s to t h e m i d g u t w h i c h 
a c c o m m o d a t e s t h e b lood m e a l in m u l t i p l e sac- l ike d ive r t i cu l ae . F e e d i n g is 
p r o m o t e d b y sec re t ions from the sa l ivary g l a n d s w h i c h pas s o u t t h r o u g h the 
sa l iva ry d u c t s a n d in to t he hos t v ia t h e s a m e c h a n n e l t h r o u g h w h i c h food 
is inges ted (Figs . 4 .2 , 4 .3 a n d 4 .4) . T h e ac t ive sa l ivary ag en t s m a y p r e v e n t 
b lood c lo t t ing , d iges t hos t t i ssues , a n d , b y the i r a n t i g e n i c a n d o t h e r p r o p e r t i e s , 
set in m o t i o n hos t r e sponses w h i c h a r e n o r m a l l y d e t r i m e n t a l to t he tick, b u t 
m a y in s o m e cases ass is t t ick feeding. Sa l iva ry secre t ions m a y a lso i n t r o d u c e 
p a t h o g e n i c d i sease a g e n t s to t he hos t o r they m a y be toxic, l e ad ing to hos t 
pa ra ly s i s a n d d e a t h . A p a r t f rom a few n o t a b l e excep t ions, the n e u r a l a n d 
h o r m o n a l p rocesses , w h i c h in i t i a te feeding a n d i n t e g r a t e feeding a n d sa l iva-
t ion w i t h tick d e v e l o p m e n t , a r e u n k n o w n . 
4.2 . S T R U C T U R E O F T H E M O U T H P A R T S AND F E E D I N G A P P A R A T U S 
T h e m o u t h p a r t s a n d feeding a p p a r a t u s a r e a n i m p o r t a n t p o i n t of e x c h a n g e 
b e t w e e n t h e tick a n d its hos t a n d , as such , h a v e b e e n d e s c r i b e d f requen t ly . 
De ta i l s c a n b e found in t he w o r k of A r t h u r (1957) , G r e g s o n (1960a) , S o n e n -
sh ine a n d G r e g s o n (1970) , K e m p a n d T a t c h e l l (1971) , B a l a s h o v (1972) , a n d 
m a n y ear l ie r p a p e r s to w h i c h these a u t h o r s refer. T h e heavi ly sc lero t ized 
cut ic le of t h e t ick 's c a p i t u l u m a n d m o u t h p a r t s m a k e s sec t ion ing difficult, b u t 
good resu l t s h a v e b e e n o b t a i n e d u s i n g the m e t h o d s de sc r ibed by A r t h u r 
( 1957) , G r e g s o n ( 1960a) , a n d B i n n i n g t o n ( 1970). Be t t e r resu l t s a r e o b t a i n a b l e 
n o w from s e m i - t h i n sec t ions of m e t h a c r y l a t e e m b e d d e d m a t e r i a l ( W e b e r , 
1972; B i n n i n g t o n , 1978) . T h e c leares t syn thes i s of t he s t r u c t u r e a n d funct ion 
of tick m o u t h p a r t s a n d feeding a p p a r a t u s w a s g iven b y G r e g s o n ( 1 9 6 0 a ) , 
Tick Attachment and Feeding 125 
b u t t h e feeding a p p a r a t u s is p a r t i c u l a r l y c o m p l e x , a n d con t rove r sy still exists 
over h o w it o p e r a t e s . 
Chelicerae T h e che l i ce rae a r e r igid sc le ro t ized c u t i c u l a r t u b e s , e ach p r o v i d e d 
wi th a c u t t i n g d ig i t c o m p o s e d of a n i n t e r n a l a n d ex t e rna l a r t ic le w i t h r e c u r v e d 
tee th (Figs . 4 . 1 , 4 .2 ) . S p e c u l a t i o n o n the poss ib le funct ion of the po re s found 
on t h e i n t e r n a l a r t i c le of b o t h a r g a s i d a n d ixodid ticks ( R o b i n s o n & D a v i d s o n , 
1913; G r e g s o n , 1960a) h a s b e e n p a r t l y reso lved by the r ecen t d i scovery of 
the i r s enso ry r e c e p t o r role in Boophilus microplus ( W a l a d d e & Rice , 1977; a n d 
p rev ious c h a p t e r ) . T h e p u r p o s e of t h e l a rge p i t ( C h a p t e r 3 , Fig . 3.29) a t t he 
b a s e of t h e i n n e r a r t ic le is still u n k n o w n ( W a l a d d e & Rice , 1977) , a l t h o u g h 
it m a y b e t he o p e n i n g of a che l icera l g l a n d (Ba l a shov , 1972). W h e n no t in 
use , t h e s t r u c t u r e s on t he d ig i t s a r e p r o t e c t e d by a c u t i c u l a r h o o d a n d 
m e m b r a n o u s folds (Fig . 4.1 ) . T h e d ig i t s a r e p r o v i d e d w i th flexor a n d ex t enso r 
musc l e s w h i c h p a s s to t h e d i s t e n d e d b a s e of t he chel icera l shafts (Fig . 4 .2 ) . 
I n a rga s id t icks t he d ig i t s a r e h e a v i e r a n d the i r m u s c u l a t u r e m o r e ex tens ive , 
a poss ib le a d a p t a t i o n for m o r e r a p i d p e n e t r a t i o n a n d feeding (Ba la shov , 
1972). H o s t skin is p e n e t r a t e d by the c u t t i n g ac t ion of t he d ig i t s , b u t a d e e p e r 
lesion m a y be fo rmed as t h e d ig i t s a r e i n se r t ed by a fo rward m o v e m e n t of 
the w h o l e che l i ce ra . R o t a t i o n of t h e che l i ce rae is no t poss ib le ( R o b i n s o n & 
D a v i d s o n , 1913) , b u t p r o t r u s i o n of t he che l i ce rae m a y be effected by a n 
inc rease in i n t e r n a l b o d y p r e s s u r e a n d r e g u l a t e d by the a n t a g o n i s t i c ac t ion 
of t h e che l icera l r e t r a c t o r m u s c l e s (Fig . 4.2) ( R o b i n s o n & D a v i d s o n , 1913; 
A r t h u r , 1946) . As G r e g s o n (1960a) n o t e d , howeve r , th is m u s t be a de l ica te ly 
ad jus t ed b a l a n c e s ince i n t e r n a l p r e s s u r e m a y c h a n g e w i th b o d y m u s c l e 
c o n t r a c t i o n , u p t a k e of b lood , e tc . C h e l i c e r a l ex t ru s ion m a y be l imi ted as well 
by t h e ex t en t to w h i c h t h e che l icera l s h e a t h s c a n unfold o r by a p p o s i t i o n of 
t he d i s t e n d e d b a s e of t he che l i ce rae a g a i n s t t he c a p i t u l u m . I n t he b a s e of t h e 
che l i ce rae t h e r e is a m e m b r a n o u s c u t i c u l a r w i n d o w (Fig . 4.2) w h i c h m a y 
a l low t h e che l i ce rae to b e n d ( A r t h u r , 1960) . T h e o u t e r che l icera l s h e a t h a lso 
he lps to s ecu re t ick a t t a c h m e n t by m e a n s of sma l l den t i c les w h i c h b e c o m e 
e m b e d d e d in t h e c e m e n t cone (Fig . 4 .2 ) . T h e s e den t i c les a r e l ack ing in a d u l t 
a r g a s i d t icks ( R o b i n s o n & D a v i d s o n , 1913; B e r t r a m , 1939) a n d in Ixodes 
holocyclus ( u n p u b l i s h e d d a t a ) w h i c h d o n o t secre te c e m e n t . T h e o u t e r s h e a t h 
a lso he lps to seal t h e feeding c h a n n e l by a l a p p e t o r r idge a p p l i e d to t he 
edges of t h e h y p o s t o m e a n d a long t o n g u e - a n d - g r o o v e b e t w e e n t h e s h e a t h s 
( G r e g s o n , 1960a; G u i r g i s , 1971) . 
Hypostome, Buccal Canal, Labrum, Salivarium, and Salivary Ducts T h e ex t e rna l 
surface of t h e h y p o s t o m e h a s l a rge r e c u r v e d t ee th w h i c h e n g a g e in t he 
a t t a c h m e n t c e m e n t o r in hos t t i ssues . T h e i n n e r surface of t h e h y p o s t o m e 
forms t h e floor of t h e b u c c a l c a n a l o r feeding c h a n n e l w h i c h is roofed by the 
chel icera l s h e a t h s . T h e floor is a V - s h a p e d or r o u n d e d g u t t e r covered by a 
th in m e m b r a n e w h i c h m a y h a v e s o m e role in feeding (Fig . 4 .2 ) . 
T h e b u c c a l c a n a l is a c o m m o n d u c t for t he i n t a k e of hos t t i ssue fluids a n d 
126 D. H. Kemp, B. F. Stone and K. C. Binnington 
for the o u t p u t of tick sa l iva . S e p a r a t i o n of these fluids occu r s a t t h e p h a r y n g e a l 
orifice; sa l iva ry secre t ions flow o u t from the d o r s a l s a l i v a r i u m a n d hos t 
m a t e r i a l s a r e sucked in t h r o u g h the ven t r a l l y d i r ec t ed p h a r y n g e a l orifice 
(Fig. 4 .2 ) . I t is t h o u g h t t h a t t he sa l iva of a rga s id t icks is exc luded from the 
p h a r y n x by the ac t i on of a m e m b r a n o u s flap-like l a b r u m w h i c h covers t h e 
p h a r y n g e a l orifice ( R o b i n s o n & D a v i d s o n , 1913; Sen , 1935). T h e l a b r u m is 
s u p p o r t e d by a c u t i c u l a r rod a n d its in te r ior , p r e s u m a b l y fluid filled, is 
c o n t i n u o u s w i t h sac- l ike pocke t s w h i c h pro jec t b a c k w a r d s b e t w e e n t h e wal l s 
of t he p h a r y n x a n d s a l i v a r i u m . De ta i l s of these s t r u c t u r e s c a n be found in 
p a p e r s b y B e r t r a m (1939) , S o n e n s h i n e a n d G r e g s o n (1970) , a n d G u i r g i s 
(1971) . T h e l a b r u m of ixod id t icks is sho r t (Gregson , 1960a; K e m p & 
T a t c h e l l , 1971) , a n d it is unl ike ly t h a t it cou ld exc lude sa l iva from the feeding 
c h a n n e l o r ac t as a va lve (Fig . 4 .2 ) . T h e role of t h e l a b r u m in Ixodes species 
is no t c lear . I t is i n t e r m e d i a t e in size in / . ricinus ( A r t h u r , 1946) b u t ve ry 
sho r t in / . holocyclus ( u n p u b l i s h e d d a t a ) . 
I n t e r m s of func t ion , t he s a l i v a r i u m , w h i c h lies a b o v e the p h a r y n x , h a s 
b e e n va r ious ly d e s c r i b e d as a sal iva ry va lve , a reservoi r o r a p u m p ( G r e g s o n , 
1960a; B a l a s h o v , 1972) . I n s o m e cases , the s t rong ly sc lerot ized wal ls a n d 
lack of a p p r o p r i a t e m u s c u l a t u r e p r e c l u d e a n y of these funct ions (Gu i rg i s , 
1971). P r e s e n t ev idence for s a l i v a r i u m funct ion c o m e s solely from its s t r u c t u r e 
(Figs . 4.2 a n d 4 .5 ) . " F l e x i b l e " c u t i c u l a r j u n c t i o n s m a y a l low the fioor of t he 
s a l i v a r i u m to be l owered by c o n t r a c t i o n of musc l e s , w h i c h a r e a lso a t t a c h e d 
to t he a l ae , o r wing- l ike c u t i c u l a r ex tens ions ly ing be low the s a l i v a r i u m 
(Fig. 4 .2 ) . A l a e a r e a b s e n t in a rga s id t icks a n d Ixodes species ( B e r t r a m , 
1939; A r t h u r , 1946, 1951); in these t icks musc le s from the floor of t he sal i-
v a r i u m p a s s i n s t e a d to t he th ick cu t i cu l a r roof of t he p h a r y n g e a l va lve 
(Fig . 4 .5 ) . 
P a i r e d sa l iva ry d u c t s e n t e r t he s a l i v a r i u m a t its pos te r io r e n d . A t th is 
po in t , r idges in t he roof of t he s a l i v a r i u m m a y i m p i n g e on the floor a n d block 
the flow of sa l iva un t i l t h e floor is lowered ( G r e g s o n , 1960a) (Fig. 4 .2 ) . T h e 
sa l iva ry d u c t s h a v e a n i n n e r c u t i c u l a r l in ing w i t h sc lerot ized sp i ra l th ick-
en ings . T h e u l t r a s t r u c t u r e of t he d u c t s h a s b e e n d e s c r i b e d by M e g a w (1976) . 
The Pharyngeal Valve, Pharynx, and Oesophagus T h e s e s t r u c t u r e s a r e re la t ive ly 
s imp le in a r g a s i d t icks , w h e r e the b u c c a l c a n a l is fo rmed in to a t r i a n g u l a r 
t u b e a t t he p h a r y n g e a l orifice. T h i s sho r t p r e - p h a r y n g e a l reg ion passes 
ven t r a l l y to t h e p h a r y n x w h i c h h a s a cross-sect ion s h a p e d like a t r ip le Y. A 
series of powerful d i l a t o r musc l e s a r e inse r t ed o n the wal ls of t h e p h a r y n x 
from t h e orifice (or j u s t in front of it) to its pos t e r io r end , whi le c i r cu la r 
c los ing m u s c l e s lie b e t w e e n t h e d i l a t o r musc le s on t he p h a r y n x itself ( B e r t r a m , 
1939; S o n e n s h i n e & G r e g s o n , 1970). 
T h e tongue- l ike l a b r u m of a r g a s i d t icks is a b s e n t in t he ixodid t icks w h i c h 
h a v e b e e n s t u d i e d . I n these ixodid t icks, t he funct ion of t he p h a r y n g e a l va lve 
is t a k e n over by t h e t r i a n g u l a r t u b e b e t w e e n the orifice a n d the p h a r y n x 
Tick Attachment and Feeding 127 
FlG. 4.5. Transverse section of the capitulum of Ixodes holocyclus cf, showing the salivarium 
dilator muscles (m.d.sal.) attached to the roof of the pharyngeal valve, ch., chelicera; ph., 
pharynx. (Scale = 50 μpiι). 
FlG. 4.6. Transverse section of the capitulum of Ixodes holocyclus Cf, showing "teeth" (g.o. grinding 
organ) in the walls of the pharyngeal valve (p.v., pharyngeal valve). (Same scale as Fig. 4.5). 
p r o p e r . T h e c o m p l e x s t r u c t u r e of th is t u b e is re la t ively un i fo rm in species 
of Dermacentor ( A r t h u r , 1960; G r e g s o n , 1960a) , Rhipicephalus (Ti l l , 1961; 
A r t h u r , 1962) , Hyalomma ( B a l a s h o v , 1972) , a n d Boophilus ( K e m p & T a t c h e l l , 
1971) . De t a i l s of t h e s t r u c t u r e c a n b e found in these p a p e r s , a n d the n a t u r e 
of t he cut ic le of t h e va lve is d i scussed la te r . T h e c u t i c u l a r wal ls of t he va lve 
a r e d o u b l e l aye red a n d j u s t in front of t he p h a r y n x , the o u t e r l ayer forms 
L - s h a p e d s t r u t s w h i c h a p p e a r to force t h e i n n e r wal ls t oge the r aga in s t a solid 
V - s h a p e d t o o t h w h i c h pro jec t s i n to the l u m e n from the roof of t he va lve 
(Fig. 4 .2 ) . T h e cu t i cu l a r , wing- l ike a l ae s p r e a d o u t from the roof of t he va lve . 
T h e r e a r e a lso sc le ro t ized c u t i c u l a r r o d s in t he wal ls of the va lve , a n d these 
b e a r sma l l t ee th p ro j ec t ing in to t h e l u m e n . I n / . holocyclus these t ee th h a v e 
the a p p e a r a n c e of s h a r p r idges a n d they a r e a p p o s e d by s h a r p r idges in t he 
V - s h a p e d t o o t h in t h e roof (Fig . 4 .6 ) . T h i s is t he " g r i n d i n g o r g a n " d e s c r i b e d 
by A r t h u r (1951) . 
O n e o t h e r f ea tu re of t h e va lve is t he " g l o b u l a r , non-sc le ro t i zed s t r u c t u r e " 
(Fig. 4 .2 ) , w h i c h m a y a c t u a l l y func t ion as a p r i m a r y va lve ( G r e g s o n , 1960a) 
o r flexible j u n c t i o n b e t w e e n the sc le ro t ized p h a r y n g e a l va lve a n d the p h a r y n x 
(Ba la shov , 1972; K e m p & T a t c h e l l , 1971) . T h i s non-sc le ro t i zed s t r u c t u r e is 
a b s e n t in t h e Ixodes species s t u d i e d by A r t h u r (1946, 1951) a n d in / . holocyclus 
( u n p u b l i s h e d d a t a ) . 
P r e s e n t i n t e r p r e t a t i o n of t he o p e r a t i o n a l m e c h a n i c s of t he p h a r y n g e a l va lve 
is still specu la t i ve . D i l a t o r m u s c l e s a r e a t t a c h e d a l o n g the wal ls of t he va lve 
128 D. H. Kemp, B. F. Stone and K. C. Binnington 
a n d p a r t i c u l a r l y to t h e sc lerot ized r o d s . M o v e m e n t of t he V - s h a p e d d o r s a l 
t oo th i n to a n d o u t of t h e l u m e n is t h o u g h t to b e ac t i va t ed b y musc l e s w h i c h 
ra i se a n d lower t h e wing- l ike a l a e ( G r e g s o n , 1960a; B a l a s h o v , 1972) . M u s c l e s 
for l ower ing the a l a e a r e a b s e n t in B. microplus ( K e m p & T a t c h e l l , 1971) 
(Fig . 4 .2 ) , a n d a n a l t e r n a t i v e e x p l a n a t i o n of t h e va lve m e c h a n i c s is g iven in 
§4.2 . 
B e h i n d t h e va lve , t he p h a r y n x of ixodid ticks h a s a d o u b l e Y - s h a p e d 
( X) c ross -sec t ion (Fig . 4 .2 ) . By c o n t r a s t , t h e t r ip le Y - s h a p e d cross-sec t ion 
of t h e p h a r y n x in Ixodes hexagonus a n d / . ricinus ( A r t h u r , 1946, 1951) a n d 
females of / . holocyclus ( u n p u b l i s h e d d a t a ) , is s imi la r to t he p h a r y n g e a l 
s t r u c t u r e found in a r g a s i d t icks . I n t he m e t a s t r i a t e t icks, d i l a t o r m u s c l e s p a s s 
from the l a t e r a l a n d v e n t r a l wal ls of t he p h a r y n x to t h e bas i s cap i tu l i . A few 
d o r s a l d i l a t o r s a t t he a n t e r i o r e n d of the p h a r y n x a r e a t t a c h e d to t he 
subche l i ce r a l p l a t e (Fig . 4 .2 ) . P h a r y n g e a l cons t r i c to r musc le s a l t e r n a t e w i t h 
d i l a t o r m u s c l e s , whi le ne rves to b o t h sets of musc le s o r ig ina t e f rom t h e 
s t o m o d e a l p o n s ( B i n n i n g t o n & T a t c h e l l , 1973; O b e n c h a i n , 1974; O b e n c h a i n 
& Ol ive r , 1976) . 
T h e o e s o p h a g u s , l ink ing the p h a r y n x a n d m i d g u t , passes t h r o u g h the 
cen t r a l g a n g l i o n . I t u sua l ly h a s a n i n n e r c u t i c u l a r l in ing , a l t h o u g h th is w a s 
no t o b s e r v e d in Ornithodoros kelleyi ( S o n e n s h i n e & G r e g s o n , 1970). A n o u t e r 
m u s c u l a r l aye r h a s b e e n d e s c r i b e d in different species as a th ick c i r cu la r 
l ayer of m u s c l e w i t h s c a t t e r e d l o n g i t u d i n a l fibres (Gu i rg i s , 1971), o r as a 
vest igia l l aye r of t h e p h a r y n g e a l cons t r i c to r musc l e s ( G r e g s o n , 1960a) , o r 
the l aye r m a y be a b s e n t ( K e m p& T a t c h e l l , 1971). 
T h e o e s o p h a g u s t e r m i n a t e s a t t he e n t r a n c e to t h e m i d g u t in a p l u g of cells 
o r p r o v e n t r i c u l a r fold, w h o s e s t r u c t u r e a n d funct ion h a v e been given a va r i e ty 
of i n t e r p r e t a t i o n s . C o n s t r i c t o r musc l e s , w h e n p r e s e n t , sugges t a p r o v e n t r i -
c u l a r va lve ( S o n e n s h i n e & G r e g s o n , 1970) o r t he p l u g of cells m a y ac t as 
a w e a k va lve (Ti l l , 1961; G r e g s o n , 1960a) . U l t r a s t r u c t u r a l o b s e r v a t i o n s 
a r e n e e d e d to clarify t he s t r u c t u r e of t he o e s o p h a g u s a n d p r o v e n t r i c u l a r 
fold. 
The Cuticule of the Feeding Apparatus T h e use of M a s s o n ' s t r i c h r o m e s t a in 
a l lows t h r e e types of cut ic le to be d i s t i ngu i shed in sec t ions of t he feeding 
a p p a r a t u s of B: microplus. S t r u c t u r e s w h i c h a r e r igid , s u c h as t h e che l icera l 
shafts o r t h e subche l i ce ra l p l a t e , d o no t t ake u p s t a in . T h e cut ic le is p i g m e n t e d 
a n d resis ts t he ac t ion of cold c o n c e n t r a t e d h y d r o c h l o r i c ac id ( K e m p & 
T a t c h e l l , 1971) . U l t r a s t r u c t u r a l o b s e r v a t i o n s on the chel icera l cut ic le of B. 
microplus s h o w t h a t it is a b o u t 5.5 μpiι th ick w i th n u m e r o u s p o r e c a n a l s a n d 
242an ind i s t inc t l a m e l l a r s u b s t r u c t u r e (Fig. 4 .7 ) . I t h a s a ve ry th in ep icu t ic le , 
p r o b a b l y c o m p o s e d on ly of cu t i cu l in . I m m e d i a t e l y b e n e a t h t he ep icu t ic le , 
t he exocut ic le h a s a d i s t inc t microf ibr i l la r s u b s t r u c t u r e w h i c h b e c o m e s less 
d i s t inc t p r o x i m a l l y (Fig . 4 .8 ) . 
F lex ib le s t r u c t u r e s , s u c h as t he p h a r y n x , p h a r y n g e a l va lve , a n d s a l i v a r i u m 
Tick Attachment and Feeding 129 
FlG. 4.7. Ultrastructure of the chelicera (ch.) of a Boophilus microplus female showing the lamellar 
substructure of the cuticle and the pore canals (p.c.) and cheliceral sheath (s.) (Transverse 
section, uranyl acetate and lead citrate; scale = 20 μιη). 
FlG. 4.8. (Inset of Fig. 4.7.) Ultrastructure of the chelicera (ch.) of a B. microplus female, showing 
the epicuticle (ep.) and exocuticle with microfibrils (mf.) distally. (Transverse section; 
scale = 2.0 μpiι). 
130 D. H. Kemp, B. F. Stone and K. C. Binnington 
floor, all s t a in r ed w i t h ac id fuchsin . T h e p h a r y n g e a l cut ic le is a b o u t 3.5 μηι 
th ick a n d is c o m p o s e d of a n ep icut ic le a n d a n u n d e r l y i n g p rocu t i c l e 2.5 μιτι 
th ick (Fig . 4.9) c o n t a i n i n g microf ibr i ls w h i c h a r e o r i e n t a t e d m o r e or less 
p e r p e n d i c u l a r to t h e long axis of the p h a r y n x (Fig . 4.10) (Fi lshie , p e r s . 
c o m m . ) . A l t h o u g h u n p i g m e n t e d , th is cut ic le is r e s i s t an t to cold c o n c e n t r a t e d 
h y d r o c h l o r i c ac id . T h i s sugges t s t h a t s o m e form of s t ab i l i za t ion h a s o c c u r r e d . 
T h e u l t r a s t r u c t u r e of t he p h a r y n g e a l cut ic le , howeve r , is un l ike t h a t of e i the r 
the sc lero t ized o r non-sc le ro t i zed cut ic le of t he b o d y wal l . T h e s ignif icance 
of i ts s t r u c t u r e in r e l a t ion to its funct ion is u n k n o w n , b u t t h e p a r t i c u l a r 
o r i e n t a t i o n of microf ibr i ls m a y be r e l a t ed to m e c h a n i c a l p r o p e r t i e s r e q u i r e d 
of t he p h a r y n x as it c h a n g e s s h a p e r a p i d l y d u r i n g feeding. 
S o m e sma l l sec t ions of t he cut ic le of t he feeding a p p a r a t u s s t a in l ight ly 
w i th t h e an i l i ne b l u e c o m p o n e n t of M a s s o n ' s t r i c h r o m e s ta in , for e x a m p l e , 
t he so-cal led " g l o b u l a r s t r u c t u r e " (Fig. 4 .2 ) . A l t h o u g h B a l a s h o v (1972) 
sugges ted th is s t r u c t u r e m a y be c o m p o s e d of resi l in, it does no t fluoresce 
b r igh t ly in u l t r av io le t l ight w h e n m o u n t e d in buffer a t p H 12 a n d v iewed 
t h r o u g h a 420 μηι in te r fe rence filter ( u n p u b l i s h e d d a t a ) . T h e resi l in of t he 
tsetse fly c iba r i a l p u m p is a l m o s t comple t e ly l ucen t in e lec t ron m i c r o g r a p h s 
(Rice , 1970) b u t t h e " g l o b u l a r s t r u c t u r e " of B. microplus h a s a loose fibrous 
s t r u c t u r e w i t h a m o r e i r r e g u l a r fibre o r i e n t a t i o n t h a n obse rved in t h e p h a -
ryngea l cu t ic le (Fi lsh ie , pe r s . c o m m . ) . 
4 .3 . T H E G R A N U L A R SALIVARY CELLS 
T h e cells of t h e tick sa l iva ry g l a n d s c a n be b r o a d l y classified i n t o those 
w h i c h secre te t he sa l iva ry d u c t s , n o n - g r a n u l a r cells w h i c h form a c i n u s I , 
g r a n u l a r cells, a n d in te r s t i t i a l ep i the l ia l cells. T h e ep i the l ia l cells w e r e first 
d e s c r i b e d in Dermacentor variabilis w h e r e they inc rease m a r k e d l y in size d u r i n g 
e n g o r g e m e n t . T h i s cell t y p e is cha rac t e r i s t i c of ixodid ticks a n d the cells a r e 
often cal led " w a t e r ce l l s" ( M e r e d i t h & K a u f m a n , 1973; M e g a w , 1976). M o r e 
recen t ly , ep i the l i a l cells h a v e a lso b e e n found in a n a rga s id tick Ar gas arboreus 
( R o s h d y & C o o n s , 1975) . T h e s t r u c t u r e a n d funct ion of t he cells fo rming 
a c i n u s I a n d w a t e r cells a r e d i scussed in C h a p t e r s 2 a n d 7. T h e s t r u c t u r e 
a n d funct ion of t he g r a n u l a r cells a r e of m o r e d i rec t i m p o r t a n c e to a n 
u n d e r s t a n d i n g of tick feeding b e c a u s e they v a r y in the i r d ivers i ty a n d p r o p e r -
ties a c c o r d i n g to species , i n s t a r , sex, a n d the s t age of feeding. 
4.3 .1 . Structure and Histochemistry of Granular Salivary Cells 
E a r l y s tud ie s on va r ious a r g a s i d species e s t ab l i shed t h a t the i r sa l iva ry 
g l a n d s c o n t a i n e d o n e g r a n u l a r a c i n u s , t ype I I , w i th u p to t h r ee types o r 
s tages of cell ( C h r i s t o p h e r s , 1906; R o b i n s o n . & D a v i d s o n , 1914; T r u e , 1932; 
V i t z t h u m , 1943) . C h i n e r y (1973a, 1974) de sc r ibed the h i s t o c h e m i s t r y of t he 
Tick Attachment and Feeding 131 
FlG. 4.9. Ultrastructure of the pharynx of a Boophilus microplus female showing the epicuticle 
(ep.) and underlying procuticle. (Longitudinal section; scale = 20 μpiι). 
FlG. 4.10. (Inset of Fig. 4.9.) Ultrastructure of the pharynx, higher magnification than Fig. 4.9, 
showing microfibrils cut in cross-section. (Longitudinal section; scale = 2.0 μpiι). 
132 D. H. Kemp, B. F. Stone and K. C. Binnington 
sa l ivary g l a n d of Argas persicus a n d c o n c l u d e d t h a t a c inus I I c o n t a i n e d t w o 
cell t ypes . S m a l l cells ( type a) s i t ua t ed close to t he d u c t of t he a c i n u s , 
c o n t a i n e d g r a n u l e s w h i c h s t a ined posi t ively for bas ic p ro t e ins b u t nega t ive ly 
for c a r b o h y d r a t e s . T h e g r a n u l e s of t he o the r , m o r e n u m e r o u s cell t ype i, 
w e r e pos i t ive for t h e bas i c p r o t e i n s b u t a lso c o n t a i n e d a g lycopro te in a n d 
w e r e m e t a c h r o m a t i c . I t w a s c o n c l u d e d t h a t n o ac id m u c o p o l y s a c c h a r i d e s 
w e r e p r e s e n t b u t t h a t t he g lyco-p ro te in c o m p o n e n t m a y be s u l p h a t e d a n dcou ld r e p r e s e n t a p r e c u r s o r of t he a n t i - c o a g u l a n t p rev ious ly d e m o n s t r a t e d 
in A. persicus ( N u t t a l l & S t r i ck l and , 1908; R o b i n s o n & D a v i d s o n , 1914) . 
R o s h d y (1972) d e s c r i b e d t h r e e cell types in a c i n u s I I of A. persicus b y 
s u b d i v i d i n g t h e t ype i of C h i n e r y (1973a , 1974) in to cell types b a n d c. Cel l 
t ype b w a s weak ly pos i t ive in h i s t o c h e m i c a l tests for c a r b o h y d r a t e , w h e r e a s 
t ype c w a s s t rong ly pos i t ive . T y p e c a lso s t a ined m e t a c h r o m a t i c a l l y w i t h 
to lu id ine b l u e . G u i r g i s (1971) a lso di f ferent ia ted t h ree cell types in t h e 
sa l ivary g l a n d s of A. arboreus w i t h h is to logica l s t a ins . T h r e e different cell 
types a p p e a r to b e p r e s e n t in Ornithodorus tholozani (Ba la shov , 1972) a n d 0. 
kelleyi ( S o n e n s h i n e & G r e g s o n , 1970) , a l t h o u g h these a u t h o r s r e i t e r a t e t he 
a s se r t ion of R o b i n s o n a n d D a v i d s o n (1914) t h a t these a r e different deve l -
o p m e n t a l s t ages of o n e cell t ype . 
T a b l e 4.1 s u m m a r i z e s s tud ies on t he h is to logy of ixodid sa l ivary g l a n d s . 
A p a r t f rom o n e r e p o r t for / . ricinus (Ba la shov , 1965), t he sa l ivary g l a n d of 
female ixod ids is gene ra l l y t h o u g h t to c o n t a i n t w o types of g r a n u l a r ac in i , 
I I a n d I I I , w i t h a t h i r d a c i n u s , t ype I V , s o m e t i m e s p r e s e n t in m a l e s . T h e 
c o m p l e x i t y of t he sa l iva ry g l a n d s of ixodid t icks a n d the c h a n g e s w h i c h o c c u r 
in t h e g l a n d s d u r i n g feeding h a v e n o d o u b t c o n t r i b u t e d to t he a p p a r e n t 
m o r p h o l o g i c a l d i s c r e p a n c i e s w h i c h exist in t he l i t e r a tu r e ( B i n n i n g t o n , 1978) . 
R e c e n t findings h a v e s h o w n t h a t t he r e a r e seven different g r a n u l a r cell t ypes 
in m a l e D. variabilis ( C o o n s & R o s h d y , 1973) , n i n e types in female B. microplus, 
t en types in m a l e B. microplus ( B i n n i n g t o n , 1978), a n d n ine types in female 
Rhipicephalus appendiculatus ( B i n n i n g t o n , Y o u n g & O b e n c h a i n , in p r e p -
a r a t i o n ) . T h i s sugges t s t h a t t h e n u m b e r of different g r a n u l a r cell types h a s 
b e e n u n d e r e s t i m a t e d , p a r t i c u l a r l y for those ixod ids w h i c h secre te c e m e n t . 
T h e first u l t r a s t r u c t u r a l s tud ies of tick sa l ivary g l a n d s w e r e by D z h a f a r o v 
(1965a , b) a n d B a l a s h o v a n d D z h a f a r o v (1966) . T h e y found t h a t t he g l a n d s 
of Ornithodoros moubata a n d Hyalomma asiaticum c o n t a i n e d ex tens ive r o u g h 
e n d o p l a s m i c r e t i c u l u m a n d v a r i o u s types of sec re to ry g r a n u l e s w h i c h they 
cons ide r ed to r e p r e s e n t s tages in t he fo rma t ion of m a t u r e g r a n u l e s . I n a n 
u l t r a s t r u c t u r a l s t u d y of t h e sa l ivary g l a n d s of A arboreus, R o s h d y a n d C o o n s 
(1975) conf i rmed t h e p r e s e n c e of t h r ee g r a n u l a r cell types (Gu i rg i s , 1971) 
a n d d e m o n s t r a t e d , for t h e first t ime in a n a r g a s i d , ep i the l ia l cells w i t h fea tu res 
c h a r a c t e r i s t i c of fluid sec re t ing cells. T h e sa l ivary g l a n d s oïA. arboreus differed 
from those of ixod id t icks in n o t h a v i n g a p r o m i n e n t c u t i c u l a r va lve s e p a r a t i n g 
t he l u m e n of a c i n u s I I f rom the l o b u l a r d u c t b u t they d id h a v e a s m a l l 
Tick Attachment and Feeding 133 
ep i the l i a l fold w h i c h w a s t h o u g h t to ac t as a va lve . Argas arboreus h a d n o 
g r a n u l a r cells w i t h s u b - u n i t f o r m a t i o n s like those found in cell types a a n d 
d of ixod ids ( D z h a f a r o v , 1965a, b ; B a l a s h o v & D z h a f a r o v , 1966; K i r k l a n d , 
1971; C o o n s & R o s h d y , 1973; M e r e d i t h & K a u f m a n , 1973; M e g a w , 1976). 
K i r k l a n d (1971) s t u d i e d t h e n o n - g r a n u l a r a c i n u s I of sa l ivary g l a n d s in 
n y m p h a l Haemaphysalis leporispalustris. H i s resu l t s for g r a n u l a r cells a p p e a r 
to b e b a s e d o n insufficient m a t e r i a l s ince h e found only o n e g r a n u l a r a c i n u s 
c o m p o s e d of t h r e e cell t ypes . T h e p r e s e n c e of s u c h a s imp le g l a n d in H. 
le pons palustris s e e m s unl ike ly in v iew of t h e findings for o t h e r ixod ids , i n c l u d i n g 
a m e m b e r of t h e s a m e g e n u s , H. spinigera (see B i n n i n g t o n , 1978, for 
re fe rences) . 
S o m e of t h e h is to logica l differences b e t w e e n g r a n u l a r cell types of ixodid 
sa l iva ry g l a n d s a p p e a r to be m i n o r a n d s t r u c t u r a l a n d func t iona l s imi lar i t ies 
a r e e m e r g i n g . I n B. microplus, cell t ype a, s i t u a t e d close to the d u c t of a c i n u s 
I I , a n d cell types d a n d e, w h i c h a r e close to t he d u c t of a c i n u s I I I , a r e filled 
w i th sec re to ry g r a n u l e s c o n t a i n i n g bas i c p r o t e i n p r i o r to t he a t t a c h m e n t of 
e ach p a r a s i t i c i n s t a r (F igs . 4 .4 a n d 4 .11) . I n t h e female , these cells h a v e 
a p p a r e n t l y c o m p l e t e d the i r func t ion w i t h i n 72 h of a t t a c h m e n t . Cel l types 
a, d, a n d e of b o t h H. spinigera a n d B. microplus a r e cons ide red to c o n t a i n 
a t t a c h m e n t c e m e n t p r e c u r s o r s ( C h i n e r y , 1965; B i n n i n g t o n , 1978). S o m e , o r 
all , of t hese p r o p e r t i e s h a v e b e e n a t t r i b u t e d to s imi l a r cells in R. appendiculatus 
(Ti l l , 1961; K . C . B i n n i n g t o n , u n p u b l i s h e d d a t a ) a n d H. asiaticum (Ba l a shov , 
1965) . M o s t of t h e r e m a i n i n g g r a n u l a r cell types in B. microplus ( c i~c 3 of 
a c i n u s I I a n d f of a c i n u s I I I ) a r e s i t u a t e d fu r the r f rom the a c i n u s d u c t s a n d 
s ta in for g lycop ro t e in s a n d v a r i o u s e n z y m e s . I n sa l iva ry g l a n d s of B. microplus 
females , B i n n i n g t o n (1978) d e m o n s t r a t e d t h e p r e s e n c e of ace tycho l ine es ter -
ase a n d a t y p e - B c a r b o x y l e s t e ra se , p a r t i c u l a r l y in cell t ype C i of a c i n u s I I . 
R e a c t i o n s for t h e l a t t e r e n z y m e w e r e a lso found a t a lower in tens i ty in t ype 
b cells a n d t h e ap i ca l m e m b r a n e s of all t h r e e cell types in a c i n u s I I I . O t h e r 
e n z y m e s p r e s e n t i n c l u d e a p r o t e a s e , l euc ine a m i n o p e p t i d a s e , m o n o a m i n e 
ox idase , a n d p h o s p h a t a s e s . T h e r e w e r e s t r o n g e r r eac t ions for ac id p h o s p h a -
tase t h a n for a lka l ine p h o s p h a t a s e . Ce l l types a, d a n d e, w h i c h m a y secre te 
c e m e n t p r e c u r s o r s , r e a c t e d s t rong ly for p h e n o l ox idase , poss ib ly i n d i c a t i n g 
t h a t a t a n n i n g p roces s o c c u r s in t h e c e m e n t cone s imi l a r to t h a t invo lved in 
t he t a n n i n g of insec t cu t ic le ( B i n n i n g t o n , 1978) . T w e l v e e n z y m e s w e r e loca ted 
in cell t ypes a, b , a n d e ( = d of T i l l , 1961) of R. appendiculatus ( M a r t i n s , 
1978) a n d a non-spec i f ic e s t e ra se w a s d e m o n s t r a t e d in cell t y p e a of / . 
holocyclus ( B i n n i n g t o n & S t o n e , inp r e p a r a t i o n ) . I t is difficult to loca te t he 
e n z y m e s prec ise ly b u t s o m e a r e found in p a r t i c u l a r cell t ypes , w h e r e t hey 
a r e p r e s e n t in t h e g r a n u l e s o r t he c y t o p l a s m o r b o t h . O n e cell t y p e of B. 
microplus ( c 4 of a c i n u s I I ) c o n t a i n e d fine g r a n u l e s w h i c h r e m a i n e d u n s t a i n e d , 
r ega rd le s s of t h e s t a in s o r t he r e a c t i o n s e m p l o y e d ( B i n n i n g t o n , 1978) (Figs . 
4.4 a n d 4 .11) . 
TABLE 4.1. CELL TYPES AND NOMENCLATURE FROM RECENT STUDIES ON THE SALIVARY GLANDS OF IXODID TICKS. 
Method Light microscopy 
Authors 
Species 
Sex 
Acinus I 
Binnington 
(1978) 
Boophilus 
microplus 
F M 
Acinus I 
Till (1961) 
Rhipicephalus 
appendiculatus 
F M 
Acinus I 
Chinery (1965) 
Haemaphysalis 
spinigera 
F M 
Acinus I 
Balashov (1965) 
Ixodes 
nanus 
F M 
Pyrimidal 
Acinus 
Hyalomma 
asiaticum 
F M 
Pyrimidal 
Acinus 
a a a a a a a a a 
b b b b b b (orifice cell) b b 
Acinus II cl cl f f c c 
c2 c2 
c3 c3 
Epithe liai cells 
d d c c c c b d d 
Acinus III e e d d d d (fundus cell) e e 
f ft e e e e 
Acinus IV 
g Acinus IV 
g g h 
Epithe] liai cells 
134 
Method Electron microscopy 
Authors 
Species 
Sex/Instar 
Acinus I 
Coons and Roshdy 
(1973) 
Dermacentor 
variabilis 
M 
Acinus I 
Kirkland 
(1971) 
Haemaphysalis 
le ports palustris 
Nymph 
Acinus I 
Meredith and Kaufman 
(1973) 
Dermacentor 
andersoni 
F 
Acinus I 
Megaw 
(1976) 
Boophilus 
microplus 
F 
Acinus I 
M 
a a a 
b Granular cell b b 
Acinus II 
Cl Vacuolar cell 
water cell 
c c 
C 2 A feeding Al Cap cell 
Epithelial 
cells 
Epithelial 
cells 
c3 
Β Β 
C 
Epithelial cells 
» d d d 
Acinus III e 
Granular cell 
Vascuolar cell 
e feeding 
Vacuolar cell 
e 
f 
Water cell 
Cap cell 
Epithelial cells 
feeding J, 
f 
Epithelial cells 
Water cell 
Cap cell 
Epithelial 
cells 
135 
136 D. H. Kemp, B. F. Stone and K. C. Binnington 
FlG. 4.11. Acini I, II, and III of a female Boophilus microplus fed 24-48 h. Cells c 2 and fare now 
swollen with granules, acinus II being slightly enlarged and acinus III markedly enlarged 
(Binnington, 1978). 
Tick Attachment and Feeding 137 
4.3.2. Changes in Granular Salivary Cells During Feeding 
C h i n e r y (1973a , 1974) found t h a t t he p rocess of a t t a c h m e n t a n d feeding 
of A. persicus w a s a s soc ia t ed w i t h on ly m i n o r c h a n g e s in the m o r p h o l o g y of 
g r a n u l a r cells . By c o n t r a s t , G u i r g i s (1971) found t h a t s o m e cells d id no t 
c h a n g e whi l e o t h e r s s h o w e d a d r a m a t i c loss of g r a n u l e s . I n ixod ids , a t t a c h -
m e n t to t h e hos t a p p e a r s to t r igger t h e p r o d u c t i o n of g r a n u l e s in s o m e cells 
a n d , a t t h e s a m e t i m e , s t i m u l a t e t h e secre t ion of g r a n u l e s from o t h e r cells. 
T w o cell t ypes in B. microplus ( c 2 a n d f) s h o w a m a r k e d inc rease in g r a n u l e 
p r o d u c t i o n d u r i n g the first 48 h of a t t a c h m e n t ( B i n n i n g t o n , 1978) a n d , as 
o b s e r v e d a b o v e , cell types a, d, a n d e, t he p u t a t i v e " c e m e n t p r e c u r s o r ce l l s" 
of H. spinigera a n d B. microplus, h a v e sec re ted the i r g r a n u l e s by a b o u t 72 h 
( C h i n e r y , 1973b; B i n n i n g t o n , 1978) (Fig. 4 .4 ) . I t is s ignif icant t h a t the 
c o m p l e t i o n of b o t h p r i m a r y a n d s e c o n d a r y c e m e n t cone depos i t i on h a s a lso 
o c c u r r e d by th is t i m e ( M o o r h o u s e & T a t c h e l l , 1966; S tone & B i n n i n g t o n , 
in p r e p a r a t i o n ) . 
I n / . holocyclus, a n ixodid t ick w h i c h does n o t p r o d u c e c e m e n t b u t w h i c h 
causes pa r a ly s i s of its hos t (see §4 .7) , t w o of t h e four cell types lose the i r 
g r a n u l e s w i t h i n 24 h of a t t a c h m e n t , w h e r e a s a n o t h e r cell t ype shows a n 
inc rease in its g r a n u l a r c o n t e n t w h i c h is c o n c o m i t a n t w i th a n inc rease in 
g l a n d toxici ty ( B i n n i n g t o n & S tone , in p r e p a r a t i o n ) . Such r e l a t i onsh ips need 
to be i n t e r p r e t e d w i t h c a u t i o n s ince it is no t a l w a y s poss ib le to asse r t from 
m o r p h o l o g i c a l o b s e r v a t i o n t h a t g r a n u l e d e p l e t i o n co inc ides w i th t he t ime of 
m o s t ac t ive sec re t ion . U l t r a s t r u c t u r a l a n d a u t o r a d i o g r a p h i c s tud ies w o u l d 
obv ious ly be of v a l u e in p r o v i d i n g a m o r e d y n a m i c i n t e r p r e t a t i o n of ce l lu lar 
even t s d u r i n g a t t a c h m e n t a n d feeding. M o r e a d v a n c e d t e c h n i q u e s a r e a lso 
n e e d e d in s tud ie s on t he d e p l e t i o n of e s t e rase from cell type C\ of B. microplus 
d u r i n g ea r ly feeding ( B i n n i n g t o n , 1978) s ince it is no t k n o w n w h e t h e r the 
e n z y m e is loca ted w i t h i n sec re to ry g r a n u l e s o r w i th in o t h e r non - sec re to ry 
c y t o p l a s m i c o rgane l l e s . H o w e v e r , t h e finding t h a t local ized es te rase ac t iv i ty 
occu r s in t h e hos t skin a t t h e a t t a c h m e n t si te d u r i n g the ear ly s tages of tick 
feeding (Sch leger & L inco ln , 1976) sugges t s t h a t t he es te rase is secre ted as 
a c o m p o n e n t of tick sa l iva (Fig . 4 .16 a n d §4 .5 .1) . 
4.4 . T H E PROCESS O F A T T A C H M E N T , F E E D I N G , AND S A L I V A T I O N 
H o s t finding a n d the se lec t ion of a su i t ab l e a t t a c h m e n t site by ticks a r e 
c o m p l e x b e h a v i o u r a l a n d phys io log ica l p rocesses ( W a l a d d e & Rice , C h a p t e r 
3 ) . I n c o n t r a s t , p e n e t r a t i o n of t he hos t skin is a re la t ively s imp le b e h a v i o u r 
w h i c h h a s b e e n o b s e r v e d mic roscop ica l ly in severa l t icks (Lees , 1948; Lavo i -
p ie r re & Riek , 1955; G r e g s o n , 1960b; B a l a s h o v , 1972). G r i p p i n g the hos t 
w i th its legs, t he tick lifts its b o d y a t a n ang le to the surface, app l i e s the t ip 
of t he che l i ce rae to t he skin , a n d beg ins o u t w a r d c u t t i n g m o v e m e n t s w i th 
138 D. H. Kemp, B. F. Stone and K. C. Binnington 
t he d ig i ts (Lees , 1948) . I n Dermacentor andersoni c u t t i n g is br ief a n d superf ic ia l . 
I t is followed d u r i n g the nex t 10 m i n by secre t ion of t he c e m e n t w h i c h flows 
in to t h e p u n c t u r e , b e n e a t h t h e o u t e r ep i the l ia l layer , a n d g r a d u a l l y c l i m b s 
a r o u n d the m o u t h p a r t s ( G r e g s o n , 1960b) . B a l a s h o v (1972) found t h a t t icks 
f requent ly d e t a c h e d after 3 - 5 m i n , a n d m o v e d to a n e i g h b o u r i n g site to 
r e p e a t t he p rocess before s ecu r ing the a t t a c h m e n t w i th c e m e n t . G r a d u a l 
inse r t ion of t he h y p o s t o m e w a s a c c o m p a n i e d by rock ing m o v e m e n t s a n d by 
secre t ion of c e m e n t a r o u n d the m o u t h p a r t s , b o t h a b o v e a n d be low t h e 
s t r a t u m c o r n e u m . 
4.4 .1 . Attachment and the Formation, Composit ion, and Function of the 
Attachment Cement 
Cement Deposition A r g a s i d n y m p h s a n d a d u l t s feed r a p i d l y a n d d o no t a p p e a r 
to use a c e m e n t to ass is t a t t a c h m e n t . H o w e v e r , m a n y a rgas id l a r v a e feed 
slowly a n d re m a i n a t t a c h e d to the hos t for long pe r iods , r e s e m b l i n g ixodid 
ticks in this r e spec t . L a r v a e of only o n e species , Argas pusillus, h a s been 
r e p o r t e d to p r o d u c e c e m e n t (Sti l ler & R a n c h i t h a m , 1975); howeve r , the 
m a t e r i a l figured is s imi l a r in a p p e a r a n c e to the p l u g of hos t t i ssue o b s e r v e d 
a t t he a t t a c h m e n t si te of A. persicus l a r v a e ( M o o r h o u s e , 1975). 
All ixod id t icks, w i t h t he excep t ion of s o m e P r o s t r i a t a , ut i l ize c e m e n t for 
a t t a c h m e n t . T h e P r o s t r i a t a cons is t s of t he s ingle g e n u s Ixodes, m e m b e r s of 
w h i c h a p p e a r to h a v e t he m o s t p r i m i t i v e form of a t t a c h m e n t a m o n g the 
I x o d i d a e . T h e a t t a c h m e n t p rocess of t he P r o s t r i a t a is cons ide red to be 
i n t e r m e d i a t e in complex i ty b e t w e e n t h a t of t he a r g a s i d s a n d the m e t a s t r i a t e 
ixod ids . T h e r e n o w a p p e a r s to be ev idence of o v e r l a p p i n g complex i t i e s 
b e t w e e n all t h r e e g r o u p s . Ixodes holocyclus, I. pseudorasus, a n d / . trianguliceps 
a r e Ixodes species w h i c h d o no t p r o d u c e c e m e n t , w h e r e a s / . tasmani a n d / . 
japonensis p r o d u c e c e m e n t in t he form of a n e x t e r n a l cone . O t h e r species such 
as / . ricinus, I. hexagonus, a n d / . persulcatus persulcatus secre te c e m e n t to form 
a ca s ing a r o u n d the h y p o s t o m e after i n se r t ing it full l eng th i n to the hos t 
t i ssue . W i t h i n t h e M e t a s t r i a t a , t he L o n g i r o s t r a t a (Amblyomma, Aponomma, 
a n d Hyalomma) secre te a cas ing a r o u n d the long , fully inse r t ed h y p o s t o m e . 
I n t h e o t h e r m e t a s t r i a t e g r o u p , t he B r e v i r o s t r a t a (Dermacentor, Rhipicephalus, 
Boophilus, a n d Haemaphysalis), t he m o u t h p a r t s a r e sho r t a n d ba re ly p e n e t r a t e 
t he e p i d e r m i s . I n all species of b o t h m e t a s t r i a t e g r o u p s a n ex t e rna l s u p p o r t i n g 
c e m e n t cone is p r o d u c e d (Fig. 4 .12) . T h e r e a d e r is referred to t he rev iews 
of M o o r h o u s e (1969 , 1973) a n d the p a p e r by W h i t w e l l (1978) for fu r the r 
de ta i l s . 
A m i l k y - w h i t e free-flowing l iqu id h a s been o b s e r v e d by G r e g s o n (1960b) 
a t t he si te of a t t a c h m e n t of D. andersoni a n d this l iqu id h a r d e n s a l m o s t 
i m m e d i a t e l y i n t o a la tex- l ike , c e m e n t t u b e s u r r o u n d i n g the h y p o s t o m e . T h e 
s i t ua t i on is s imi l a r in B. microplus ( M o o r h o u s e & T a t c h e l l , 1966; S t o n e , 
Tick Attachment and Feeding 139 
IXODES (Group 1 ) IXODES (Group 2 ) 
HAEMAPHYSALIS RHIPICEPHALUS BOOPHILUS 
DERMACENTOR AMBLYOMMA APONOMMA 
FlG. 4.12. Schematic diagram of sections through host skin showing the pattern of attachment 
of female ixodid ticks of the named genera during the final stages of feeding. P, palps; C, cement; 
E, epidermis (Malpighian layer); D, dermis; FL, feeding lesion. (Adapted from Moorhouse, 
1 9 6 9 ) . 
B i n n i n g t o n & C o u r t , in p r e p a r a t i o n ) excep t t h a t the c e m e n t in l iqu id form 
is no t o b s e r v a b l e in t h e in i t ia l s t ages of feeding. Secre t ion of c e m e n t beg ins 
w i t h i n 5 - 3 0 m i n of a t t a c h m e n t a n d it a p p a r e n t l y h a r d e n s i n s t a n t a n e o u s l y 
to form t h e core o r " i n t e r n u m " of t he cone . As t h e lesion b e n e a t h t h e 
m o u t h p a r t s s t a r t s to form, b u t p r o b a b l y n o t before a b o u t 24 h after a t t a c h -
m e n t , t h e d e p o s i t i o n of t h e " c o r t e x " c e m e n t c o m m e n c e s . D e p o s i t i o n of 
a d d i t i o n a l c e m e n t c o n t i n u e s for a n a d d i t i o n a l 4 8 - 7 2 h (S tone , B i n n i n g t o n 
& C o u r t , in p r e p a r a t i o n ) . T h e cor t ica l c e m e n t p r o b a b l y flows d o w n in to the 
lesion a n d solidifies to form a w e d g e - s h a p e d , i n t e r n a l a n c h o r a g e , w h i c h is 
a d d e d to as t h e les ion e x t e n d s . C o r t i c a l c e m e n t a l so flows la te ra l ly over t h e 
skin of t h e hos t , t h u s s t r e n g t h e n i n g t h e cone , a n d it a lso p e n e t r a t e s b e t w e e n 
the s t r a t u m c o r n e u m a n d t h e m a l p i g h i a n l ayer (Fig . 4 .13) . The re fo r e , t he 
fluid m u s t b e s low se t t ing a n d m o b i l e . T h e cor t ica l c e m e n t of B. microplus 
h a s these p r o p e r t i e s as it h a s b e e n o b s e r v e d to b r e a k t h r o u g h sma l l perfor-
a t ions in t h e cy l i nde r of " i n t e r n u m " c e m e n t a n d flow d o w n to t he b a s e of 
t he cy l inde r before s e t t i ng (S tone & Y o u l t o n , u n p u b l i s h e d d a t a ) . 
140 D. H. Kemp, B. F. Stone and K. C. Binnington 
FlG. 4.13. Penetration of the tick attachment cement (C.) between the layers of the stratum 
corneum of the host skin and between the stratum corneum and the malpighian layer. 
Composition of Cement H i s t o c h e m i c a l ev idence sugges t s t h a t the c e m e n t cone 
of B. microplus is essent ia l ly p r o t e i n a c e o u s , a l t h o u g h the " i n t e r n u m " c o n t a i n s 
l ipid a n d t h e " c o r t e x " c o n t a i n s c a r b o h y d r a t e ( M o o r h o u s e & T a t c h e l l , 1966; 
S tone et ai, 1977). C h e m i c a l tests s h o w t h a t w h o l e c e m e n t cones ( " i n t e r n u m " 
+ " c o r t e x " ) f rom 4 . 5 - 6 . 0 m m B. microplus c o n t a i n a b o u t 1 8 % l ipid . O n a 
w a t e r a n d l ipid-free bas i s they c o n t a i n a t least 8 2 % p ro t e in . I n o r d e r of 
a b u n d a n c e t h e a m i n o ac ids in c e m e n t p r o t e i n w e r e g lyc ine , se r ine , l euc ine , 
ty ros ine , p ro l ine , va l ine , g l u t a m i c ac id , p h e n y l a l a n i n e , a l a n i n e , a r g i n i n e , 
a s p a r t i c ac id , t h r e o n i n e , i so leucine , lys ine, h i s t id ine , a n d cys te ine (as cyste ic 
a c i d ) . E l ec t ropho re s i s of w a t e r - s o l u b l e c o m p o n e n t s ex t r ac t ed from c e m e n t 
ind ica te s t h a t s o m e of t he l ip ids a n d c a r b o h y d r a t e s a r e in the form of l ipo-
a n d g lyco-p ro te ins , respec t ive ly (S tone et ai, 1977). Q u a l i t a t i v e solubi l i ty 
tests ( M o o r h o u s e & T a t c h e l l , 1966) sugges t t h a t a va r i e ty of p r o t e i n b o n d s 
m a y be involved; th is h a s b e e n conf i rmed q u a n t i t a t i v e l y for c o m p l e t e c e m e n t 
cones (S tone et al., 1977). O n a w a t e r a n d lipid-free bas i s only 1 5 % of the 
c e m e n t p r o t e i n is u n b o u n d a n d wa te r - so lub l e . I n the inso lub le r e s idue , 1 9 % 
is weak ly b o u n d by v a n d e r W a a l s forces, 2 2 % b o u n d by h y d r o g e n b o n d s , 
Tick Attachment and Feeding 141 
a n d 1 % s t rong ly b o u n d by e l e c t r o v a l e n t / c o v a l e n t o r d o u b l e b o n d s or b o t h . 
T h e b a l a n c e of t h e p r o t e i n ( 2 5 % ) is on ly so lub le in ho t s t r o n g alkal is a n d 
ac ids . T h i s f rac t ion m u s t be r e g a r d e d as very firmly b o u n d , poss ib ly cross-
l inked , p r o t e i n . C h i t i n is un l ike ly to be p r e s e n t as c e m e n t a p p e a r s to be 
to ta l ly so lub le in h o t 1 Ν N a O H a n d on ly a t r ace of g l u c o s a m i n e is d e t e c t a b l e 
in h o t ac id h y d r o l y s a t e s . T h e ch i t in c o n t e n t of B. microplus cut ic le is a lsok n o w n to b e low ( 3 . 8 % — H a c k m a n , 1975) . 
Hardening of Cement T r a c e s of free p h e n o l i c c o m p o u n d s a r e d e t e c t a b l e in 
c e m e n t h y d r o l y s a t e s , wh i l e p h e n o l a s e ac t iv i ty is p r e s e n t in c e m e n t itself a n d 
in sa l iva ry g l a n d cells ( B i n n i n g t o n , 1978) . T h e r e is n o d i rec t ev idence , 
h o w e v e r , to s u p p o r t t he sugges t ion of M o o r h o u s e a n d T a t c h e l l (1966) t h a t 
q u i n o n e t a n n i n g of s u l p h y d r y l g r o u p s m a y be r e spons ib le for t he h a r d e n i n g 
of c e m e n t a s h a s b e e n p o s t u l a t e d for h a r d e n i n g of m i t e cut ic le ( H u g h e s , 
1959). N o h u m i n w a s d e t e c t e d in ac id ic h y d r o l y s a t e s of c e m e n t w h i c h m i g h t 
h a v e c o n t a i n e d t h e s u l p h u r p a r a - q u i n o n e c o m p l e x w h i c h H u g h e s sugges ted 
(1959) to b e i nd i ca t i ve of q u i n o n e cross- l inked s u l p h u r g r o u p s (S tone , B in -
n i n g t o n & C o u r t , in p r e p a r a t i o n ) . I n a d d i t i o n , t he c e m e n t p ro t e in s c o n t a i n e d 
only 4.7 cys te ine r e s idues p e r 1000 to ta l a m i n o - a c i d r e s idues . If q u i n o n e 
t a n n i n g is r e spons ib l e for t h e h a r d e n i n g of c e m e n t p ro t e in s , it is m o r e likely 
t h a t c ross - l inkages a r e fo rmed by the r eac t ion of q u i n o n e w i th free a m i n o 
g r o u p s . C e m e n t is u sua l ly w h i t e o r ve ry p a l e b r o w n , whi le t a n n e d cut ic le is 
genera l ly , b u t n o t a l w a y s , m u c h d a r k e r . 
P a r t i a l exc lus ion of a i r f rom t h e j u n c t i o n of the h y p o s t o m e of a freshly 
a t t a c h e d female B. microplus a n d m o u s e skin by m e a n s of a soft paraff in col lar 
in terferes w i t h t h e sec re t ion a n d sol idif icat ion of c e m e n t b u t does no t c o m -
ple te ly p r e v e n t it (S tone & Y o u l t o n , u n p u b l i s h e d o b s e r v a t i o n ) . I t is no t 
ce r t a in if c o n t a c t w i t h a i r is neces sa ry for t h e d e h y d r a t i o n a n d d e n a t u r a t i o n 
of freshly sec re ted c e m e n t p r o t e i n s o r if t he r e is a c o m p l e x series of r eac t ions 
l e a d i n g to " c l o t t i n g " . P e r h a p s t he inso lub i l i za t ion of l iqu id c e m e n t is a n a l -
a g o u s to t h e c o a g u l a t i o n of h a e m o l y m p h . C o a g u l a t i o n is a r a p i d p rocess a n d 
m i g h t well be invo lved in t he i n s t a n t sol idif icat ion of t he i n t e r n u m c e m e n t . 
H o w e v e r , w a t e r - w a s h e d h a e m o l y m p h c o a g u l u m h a s a n a m i n o - a c i d c o m -
pos i t ion d i s s imi l a r to t h a t of w h o l e c e m e n t , a n d t h e a m i n o - a c i d c o m p o s i t i o n 
of t he w a t e r - i n s o l u b l e f ract ion of c e m e n t is u n k n o w n . E v e n t h o u g h h a e m o -
l y m p h c o a g u l u m is no t r ead i ly so lub le in w a t e r , it is unl ikely t h a t the 
t e m p o r a r y sea l ing of w o u n d s in t h e i n t e g u m e n t r equ i r e s t he level of insolu-
bil i ty neces sa ry for a t t a c h m e n t c e m e n t w h i c h m u s t pers i s t for a t least 7 - 1 0 
d a y s o n t h e hos t sk in . 
Function A l t h o u g h s o m e ea r l i e r w o r k e r s i n t e r p r e t e d t he c e m e n t cones as 
o u t g r o w t h s of t h e h o s t ' s skin a t t he tick a t t a c h m e n t si te ( S n o d g r a s s , 1948; 
A r t h u r , 1951) o r as t h e p r o d u c t of b o t h tick secre t ion a n d d e s t r o y e d hos t 
t i ssue ( H o e p p l i & F e n g , 1931) , it is n o w a c c e p t e d t h a t c e m e n t is p r o d u c e d 
exclusively by the t ick. T h e c e m e n t cone is p r i m a r i l y a holdfas t m e c h a n i s m 
142 D. H. Kemp, B. F. Stone and K. C. Binnington 
for those tick species w h i c h h a v e sho r t m o u t h p a r t s a n d possess a superf ic ia l 
form of a t t a c h m e n t to t h e skin. T h e r e is n o ev idence to s u p p o r t t he sugges t ion 
of Foggie ( 1959) t h a t lesion fo rma t ion m a y occu r as a resu l t of a foreign 
b o d y r eac t i on in r e s p o n s e to t he i n t e r n a l c e m e n t of / . ricinus w h i c h encases 
t he deep ly e m b e d d e d h y p o s t o m e . M o r e o v e r , M o o r h o u s e a n d T a t c h e l l (1966) 
p o i n t e d o u t t h a t a fo re ign-body r eac t ion w o u l d loosen r a t h e r t h a n s t r e n g t h e n 
a t t a c h m e n t . G r e g s o n (1970) ci ted ev idence for t he an t igen ic i ty of D. andersoni 
c e m e n t , b u t th is m a y b e d u e to t he c o n t a m i n a t i o n of c e m e n t w i t h o t h e r 
sa l ivary p r o t e i n s w h i c h w e r e no t r e m o v e d by cu r so ry w a s h i n g . 
Detachment I t is n o t k n o w n w h a t ac t ive m o v e m e n t s a r e necessa ry for t he 
d i s e n g a g e m e n t of t he h y p o s t o m e a n d che l ice rae from hos t t issues o r f rom 
the c e m e n t cone ( A r t h u r , 1973) . G r e g s o n (1960b) e q u a t e d t he h y p o s t o m e 
a n d the t w o che l i ce rae w i t h i n t h e c e m e n t cone to t h r ee fingers in a t ight ly 
fitting pocke t . W i t h d r a w a l of t he che l i ce rae w o u l d loosen the h y p o s t o m e 
sufficiently for d i s e n g a g e m e n t of t h e h y p o s t o m a l t ee th . C h e m i c a l a g e n t s s u c h 
as t he f o r m a m i d i n e s , c a u s e B. microplus to d e t a c h (S tone et al., 1974) . 
4.4.2. Mechanism of Feeding and Salivation 
T h e un i fo rmi ty of s t r u c t u r e in t he s a l i v a r i u m a n d feeding a p p a r a t u s of 
a r g a s i d t icks sugges t s t h e fol lowing c o m m o n m o d e of o p e r a t i o n ou t l i ned by 
B e r t r a m (1939) , S o n e n s h i n e a n d G r e g s o n (1970) , a n d Gu i rg i s (1971) . C o n -
t r ac t i on of m u s c l e s in se r t ed o n the floor of t he feeding c h a n n e l a n d wal ls of 
t he p h a r y n x o p e n s a p a s s a g e to t he feeding lesion, a n d this ac t ion d r a w s 
b lood in to t he p h a r y n x . A t t h e s a m e t i m e , nega t ive p r e s s u r e c r ea t ed in t h e 
p h a r y n x a lso d r a w s fluid i n to t he pos t e r io r sac- l ike ex tens ion of the l a b r u m 
in t h e roof of t h e p h a r y n x . T h i s co l lapses t h e l a b r u m , w h i c h fur ther o p e n s 
t he p h a r y n g e a l orifice. R e g u r g i t a t i o n of g u t c o n t e n t s is p r e v e n t e d by the 
ac t ion of t h e p r o v e n t r i c u l a r va lve (see §4 .2) . T h e reverse p rocess , c o n t r a c t i o n 
of t h e p h a r y n g e a l cons t r i c to r musc l e s , forces b lood t h r o u g h the o e s o p h a g u s 
in to t h e gu t . P u m p i n g m a y b e ass i s ted by the e las t ic recoil of t he c u t i c u l a r 
wal ls of t he p h a r y n x . R e g u r g i t a t i o n of p h a r y n g e a l c o n t e n t s w o u l d be p r e -
v e n t e d b y t h e pe r i s t a l t i c c los ing of t h e p h a r y n x (Ruse r , 1933) a n d by the 
d o w n w a r d m o v e m e n t of t h e rod- l ike t h i cken ing of t he l a b r u m in to t h e 
p h a r y n g e a l orifice a n d t h e feeding c h a n n e l . T h i s d o w n w a r d m o v e m e n t of 
t he l a b r u m m a y b e a c t i v a t e d by a pos i t ive p h a r y n g e a l p r e s s u r e a p p l i e d to 
the pos t e r io r sac- l ike ex tens ion of t he l a b r u m w i t h i n the p h a r y n x ( B e r t r a m , 
1939; S o n e n s h i n e & G r e g s o n , 1970) . 
I x o d i d t icks lack a n ex tens ive l a b r u m a n d its funct ion h a s b e e n t a k e n over 
by t h e m o r p ho l o g i c a l l y d i s t inc t p h a r y n g e a l va lve (Figs . 4 .2 , 4.5 a n d 4 .6 ) . 
T r a n s i l l u m i n a t i o n of B. microplus l a r v a e s h o w e d t h a t the va lve closed j u s t 
p r io r to t h e pe r i s t a l t i c c losure of t h e p h a r y n x . I t a p p e a r e d t h a t t h e flexed 
L - s h a p e d wal l s c losed b y e las t ic recoil a n d this w o u l d force t h e m a g a i n s t t h e 
Tick Attachment and Feeding 143 
d o r s a l t oo th p ro j ec t i ng i n t o t h e l u m e n ( K e m p & T a t c h e l l , 1971) . A n a l te r -
na t i ve i n t e r p r e t a t i o n c a n b e found in t he s tud ie s by G r e g s o n (1960a) a n d 
B a l a s h o v (1972) . T h e " g l o b u l a r , non-sc le ro t i zed s t r u c t u r e " (Fig . 4.2) m a y 
b é a p r i m a r y va lve in D. andersoni ( G r e g s o n , 1960a) , b u t its u l t r a s t r u c t u r e 
in B. microplus sugges t s t h e ex i s tence of a flexible l ink w h i c h p e r m i t s t he va lve 
to o p e r a t e i n d e p e n d e n t l y of t h e p h a r y n x (see a lso B a l a s h o v , 1972). S o m e 
con f i rma t ion of th is w a s o b t a i n e d w h e n e lec t r ica l r eco rd ings of feeding t icks 
w e r e m a d e b y p a s s i n g a s m a l l c u r r e n t t h r o u g h the t ick 's m o u t h p a r t s a n d 
in to t h e hos t . C h a n g e s in c o n d u c t i v i t y d e p e n d u p o n the o p e n i n g or c los ing 
of t h e feeding a n d sa l iva ry c h a n n e l s a n d on t h e ionic c o m p o s i t i o n of t he fluid 
w i t h i n these c h a n n e l s ( G r e g s o n , 1969; S w e a t m a n & G r e g s o n , 1970). T h e 
i nc rea se in c o n d u c t i v i t y w h i c h w a s a s soc ia t ed w i t h p h a r y n g e a l suck ing s o m e -
t imes a l so s h o w e d a s u b s i d i a r y p e a k w h i c h cou ld be a s soc ia t ed w i t h t h e 
expec t ed o p e n i n g of t h e va lve ( T a t c h e l l et al., 1972) (Fig. 4 .14) . 
E lec t r i ca l r e c o r d i n g s h a v e a lso h e l p e d in r e l a t i ng funct ion to t he s t r u c t u r e s 
in t h e sa l iva ry p a t h w a y s . E lec t r i ca l r e c o r d i n g s from ticks feeding from glass 
cap i l l a r i es , o r f rom t h e hos t , s h o w a s h a r p i nc rea se in conduc t iv i t y d u r i n g 
sa l iva t ion . T h i s i nc r ea se is m a i n t a i n e d as a s t e a d y top l ine d u r i n g t h e con-
t i n u o u s o u t p o u r i n g of sa l iva a n d t e r m i n a t e s in a n a b r u p t fall in conduc t iv i t y , 
o r a ser ies of t e r m i n a t i n g sp ikes , as sa l iva t ion ceases (Fig. 4.14) ( G r e g s o n , 
1969; T a t c h e l l et al., 1972) . T h e s e d a t a sugges t t h a t t h e sa l ivary c h a n n e l s a r e 
o p e n e d a n d c losed. T h e s a l i v a r i u m is t h e on ly s t r u c t u r e w i th t he necessa ry 
flexibility a n d m u s c l e a t t a c h m e n t s to o p e r a t e as a va lve . D u r i n g sa l iva t ion , 
t h e s a l i v a r i u m floor m a y b e l owered to o p e n the c h a n n e l , b u t it is difficult 
to a t t r i b u t e t h e s t e a d y o u t p o u r i n g of sa l iva , seen in vivo a n d in vitro, to s o m e 
d i r ec t func t ion of t h e s a l i v a r i u m ( G r e g s o n , 1960a, 1967). T h e force of t he 
cop ious flow of sa l iva is sufficient to o v e r c o m e t h e o p p o s i n g cap i l l a ry b lood 
p r e s s u r e a n d to close s o m e of t h e cap i l l a r ies a d j a c e n t to t he lesion ( G r e g s o n , 
1967) . A poss ib le e x p l a n a t i o n is t h a t sa l iva ry g l a n d ac in i t ype I I I , w h i c h fill 
w i t h fluid as a r e su l t of ac t ive t r a n s p o r t of w a t e r a n d ions , m a y ac t as 
reservoi r s of sa l iva u n d e r p r e s s u r e ( K a u f m a n & Phi l l ips , 1973; see C h a p t e r 
7) . T h e o v e r l a p p i n g of sa l iva ry d u c t cells in e lec t ron m i c r o g r a p h s sugges t s 
t h a t t h e d u c t s m a y a l so swell to form reservoi r s ( M e g a w , 1976). O p e n i n g 
of t h e s a l i v a r i u m w o u l d a l low sa l iva to be re leased in a s t e a d y flow un t i l 
t h e r e w a s insufficient p r e s s u r e to force it i n t o t h e les ion. As sa l iva t ion c o m e s 
to a n e n d , t h e e lec t r ica l r e c o r d i n g c h a n g e s from a s t e a d y t o p l ine to a 
d i m i n i s h i n g " t r i l l " ( G r e g s o n , 1969) e n d i n g in a s t e a d y base l ine (Fig . 4 .14) . 
T h i s ac t i on is r e m i n i s c e n t of t h e " f l u t t e r i n g " of insect s p i r a c u l a r va lves a t 
low oxygen c o n c e n t r a t i o n s ( W i g g l e s w o r t h , 1972) . A s imi la r fluttering of t h e 
tick s a l i v a r i u m w o u l d exp l a in t h e 2 - 3 spikes a s soc ia t ed w i th t he br ie f b u r s t s 
of sa l iva t ion c h a r a c t e r i s t i c of t h e ea r ly s t ages of feeding ( G r e g s o n , 1969; 
W a l a d d e et al., 1979) as wel l as t h e d i m i n i s h i n g " t r i l l " a t t he e n d of sa l iva t ion 
in l a t e r s t ages of feeding. 
144 D. H. Kemp, B. F. Stone and K. C. Binningto 
ι 1 
0 . 5 s e c 
1 s e c 
0 . 5 s e c 
\wvwwwww\ 
1 s e c ' 
f 
1 s e c 
1 s e c 1 s e c 
0 . 5 s e c 
FlG. 4.14. The distinctive wave-forms recorded on an oscilloscope during feeding of Boophilus 
microplus females, (a) Inactivity with a steady base line, (b) Low amplitude peaks increasing 
in frequency before the resumption of feeding (indicated by the arrow), (c) Slow feeding with 
minor loss in conductivity associated with closure of the pharyngeal valve followed by a fall 
below the baseline when both valve and pharynx are closed, (d) Rapid feeding showing the 
minor peak representing the opening of the pharyngeal valve, and a fall to the normal baseline 
as valve and pharynx close, (e) High amplitude feeding following salivation, and a diminished 
amplitude with a fall in the baseline as feeding continues, (f) Salivation indicated by a sharp 
increase in conductivity which was maintained at a high level until the appearance of rapid 
downward deflections, (g) A short period of salivation, (h) Unexplained "ripple" in the baseline, 
(i) A "short-series of humps" which may be poorly coordinated feeding (Tatchell et al., 1972). 
A fur the r c o m p l i c a t i o n d u r i n g sa l iva t ion is t he " f lu t t e r ing" m o v e m e n t s 
( a b o u t 10 p e r sec) o b s e r v e d in t r a n s i l l u m i n a t e d ticks a n d a p p a r e n t l y d u e to 
the c o n t r a c t i o n s of musc le s a t t a c h e d to t he a n t e r i o r po r t i on of t he p h a r y n g e a l 
va lve (Fig. 4 .2 ) . T h e s e m o v e m e n t s w e r e a c c o m p a n i e d by a s imi la r p u l s a t i o n 
of the m e m b r a n e over the h y p o s t o m a l g u t t e r (Gregson , 1960a) . E lec t r ica l 
Tick Attachment and Feeding 145 
I I I ! h I..I.J.I i ! In 
FlG. 4.15. Oscilloscope recording of Boophilus microplus female feeding on blood at 35°C. Electrode 
in prepharyngeal valve muscles. Recording taken during salivation; each spike (arrow) coincided 
with contraction of the muscles of the pharyngeal valve (Kemp, 1978). 
r eco rd ings t a k e n a t t h e e n d of a b u r s t of sa l iva t ion in D. andersoni ( G r e g s o n , 
1969) s h o w e d i m p u l s e s w i t h th is s a m e f requency (10 p e r sec) . I n B. microplus, 
e lec t rodes in t h e m u s c l e s of t h e p h a r y n g e a l va lve r e c o r d e d a series of w h a t 
a p p e a r e d to b e s ingle m u s c l e ac t ion po t en t i a l s a t a f requency of 8 p e r sec 
(Fig . 4.15) d u r i n g a p e r i o d of sa l iva t ion . I n t r a n s i l l u m i n a t e d ticks these 
co inc ided w i t h t h e t w i t c h i n g of t he p h a r y n g e a l va lvemusc le s ( K e m p , 1978) , 
a n d the t e r m i n a t i o n of d r i n k i n g by l a r v a e w a s s o m e t i m e s assoc ia ted w i t h 
o n e o r t w o p u l s a t i o n s of t h e va lve ( K e m p & T a t c h e l l , 1971). O n e e x p l a n a t i o n 
for t h e a b o v e o b s e r v a t i o n s is t h a t t he m u s c l e s of the p h a r y n g e a l va lve m a y 
be invo lved in l ower ing t h e m e m b r a n e over t h e h y p o s t o m a l g u t t e r to o p e n 
a p a t h w a y for sa l iva ( G r e g s o n , 1960a) ; a l t e rna t ive ly , the i r a t t a c h m e n t to t he 
wal l s of t h e va lve m a y i m p l i c a t e th is s t r u c t u r e in t he expu l s ion of sa l iva . 
M a n y q u e s t i o n s r e m a i n u n a n s w e r e d c o n c e r n i n g the m e c h a n i s m of tick feeding 
a n d sa l iva t ion . 
G r e g s o n (1967) o b s e r v e d r e g u r g i t a t i o n by females of D. andersoni. T h i s 
b e h a v i o u r ra ises i m p o r t a n t q u e s t i o n s r e l a t ed to t he t r a n s m i s s i o n of d i seases 
by t icks. Kloft (pe r s . c o m m . ) , h a s conf i rmed t h a t th is t ype of b e h a v i o u r 
occu r s a m o n g 0. moubata t icks feeding in vitro on rad io - l abe l l ed b lood . Aspec t s 
of d i sease t r a n s m i s s i o n v ia tick sa l iva ry g l a n d s or by r e g u r g i t a t i o n a r e 
cons ide r ed in a rev iew by B i n n i n g t o n a n d K e m p (1980) . 
4.5 . D E V E L O P M E N T O F T H E F E E D I N G LESION 
4.5 .1 . Ro le of the Mouthparts, Saliva, and Host Reactions in Deve lopment of 
the Feeding Lesion 
O b s e r v a t i o n s o n t r a n s i l l u m i n a t e d tick feeding lesions a n d o n the h is to logy 
of t he les ions s h o w t h a t c u t t i n g ac t ion of t he che l icera l d ig i t s is confined to 
in i t ia l p e n e t r a t i o n of t he e p i d e r m i s a n d poss ib ly s o m e d a m a g e to capi l la r ies 
a n d t i ssues a d j a c e n t to t h e si te of p e n e t r a t i o n (Lavo ip i e r r e & Riek, 1955; 
G r e g s o n , 1960b; B a l a s h o v , 1972; M o o r h o u s e , 1975). T i c k sa l ivary secre t ions 
a r e t h o u g h t to b e r e spons ib l e for d i l a t i on of skin cap i l l a r ies , for d e v e l o p m e n t 
146 D. H. Kemp, B. F. Stone and K. C. Binnington 
of a n ex tens ive h a e m o r r h a g e , for t i ssue d e s t r u c t i o n , a n d p r e v e n t i o n of b lood 
c o a g u l a t i o n in t h e tick feeding lesion. H o w e v e r , s o m e ca re m u s t b e t aken 
before these o b s e r v a t i o n s a r e a t t r i b u t e d to the ac t ion of p a r t i c u l a r sa l ivary 
c h e m i c a l s s ince t h e r e is ev idence t h a t t ick sa l iva c a n p r o m o t e hos t r eac t ions 
w h i c h d e s t r o y t h e h o s t ' s o w n t i ssues . T h i s i n v o l v e m e n t of hos t r e sponses w a s 
sugges t ed fol lowing a s t u d y of B. microplus feeding lesions on ca t t l e ( T a t c h e l l 
& M o o r h o u s e , 1968) a n d e x p e r i m e n t a l l y conf i rmed in dogs d e p l e t e d of 
n e u t r o p h i l s . T h e e x p e r i m e n t a l t r e a t m e n t r e d u c e d the n u m b e r of n e u t r o p h i l s 
inf i l t ra t ing t he feeding les ion of Rhipicephalus sanguineus a n d the cav i ty , w h i c h 
usua l ly fo rmed b e n e a t h t he t icks, w a s a b s e n t o r ins ignif icant , p r e s u m a b l y 
b e c a u s e of low n e u t r o p h i l n u m b e r s . I t is i n t e r e s t i ng t h a t t ick feeding w a s no t 
affected by this t r e a t m e n t ( T a t c h e l l & M o o r h o u s e , 1970) . 
I m p l i c a t i o n of sa l iva ry secre t ions in hos t au to lys i s a lso c o m e s f rom exper i -
m e n t s w i t h ex t r ac t s of D. variabilis sa l ivary g l a n d s . T h e s e ex t r ac t s r e ac t w i t h 
h u m a n a n d c a n i n e s e r u m to g e n e r a t e n e u t r o p h i l c h e m o t a c t i c factor from 
c o m p l e m e n t c o m p o n e n t C5. W h e n D. variabilis t icks fed on c o m p l e m e n t -
d e p l e t e d r a t s t hey d i d n o t p r o v o k e the s a m e d e g r e e of n e u t r o p h i l inf i l t ra t ion 
or t i ssue d e s t r u c t i o n ( B e r e n b e r g et al., 1972) . O t h e r e x a m p l e s of hos t au to lys i s 
i n c l u d e t h e d e s t r u c t i o n of co l lagen by n e u t r o p h i l s inf i l t ra t ing t he feeding 
lesion of R. sanguineus on dogs (The i s & B u d w i s e r , 1974), a n d the d e g r a n -
u l a t i on of m a s t cells in t he skin of ca t t l e a t 400 μηι f rom the a t t a c h m e n t site 
o f / , holocyclus (Al len et al., 1977) . B o t h e x a m p l e s a r e from hos t s w h i c h h a d 
n o p rev ious expe r i ence w i t h feeding t icks. A g e n t s c a u s i n g m a s t cell d e g r a n -
u l a t i on or l eucocy te inf i l t ra t ion m a y o r ig ina t e in tick sa l ivary g l a n d s , a n d 
these cou ld set in t r a i n a n u m b e r of hos t r eac t ions ( T a t c h e l l & M o o r h o u s e , 
1969; Al len etal., 1977) . 
T h e i n t r o d u c t i o n of sa l iva ry a n t i g e n s is likely to be a p o t e n t m e d i a t o r of 
hos t r eac t i ons . T h e i m m u n e r e s p o n s e m a y lead to o e d e m a , h a e m o r r h a g e , 
l eucocy te d e g r a n u l a t i o n , w i t h t i ssue d a m a g e , a n d p r e v e n t i o n of c lo t t ing . 
T h e s e r e sponses m a y s i m u l a t e m a n y of t he p o s t u l a t e d funct ions of t he 
p a r a s i t e s ' sa l iva ( T a t c h e l l , 1969a) . S ince hos t m e d i a t e d r eac t ions to tick 
a t t a c h m e n t s m a y o c c u r on i m m u n e a n d n o n - i m m u n e a n i m a l s , a n d s ince 
t icks h a v e t h e ab i l i ty to feed n o r m a l l y w h e n t i ssue d a m a g e is m i n i m a l , it is 
no t s u r p r i s i n g t h a t t i ssue d e s t r u c t i v e e n z y m e s or a n t i - c o a g u l a n t s w e r e a b s e n t 
from t h e sa l iva of B. microplus ( T a t c h e l l , 1969b) . 
D e s p i t e these r e se rva t i ons , t he r e is ev idence t h a t a n u m b e r of sa l iva ry 
c o m p o n e n t s a r e d i rec t ly involved in tick feeding. I t h a s b e e n sugges ted t h a t 
these sec re t ions a r e especia l ly i m p o r t a n t in a rga s id t icks w h e r e the i r ac t ions 
a r e m o r e v igo rous a n d d e s t r u c t i v e ( T a t c h e l l , 1969a) . T h i s sub jec t h a s b e e n 
rev iewed by A r t h u r (1965 , 1970, 1973) , S a u e r (1977) , a n d is t r e a t e d h e r e 
u n d e r h e a d i n g s s imi l a r to those u sed by Saue r . 
Anti-coagulant Secretion B a l a s h o v (1972) sugges ted t h a t tick a n t i - c o a g u l a n t s 
w e r e g lycop ro t e in s , m u c o p r o t e i n s , o r s o m e p r o t e i n - c a r b o h y d r a t e c o m p l e x , 
Tick Attachment and Feeding 147 
o r i g i n a t i n g from the g r a n u l a r sa l iva ry cells. C a r b o h y d r a t e a n d p r o t e i n p r e -
cu r so r s of t he a n t i - c o a g u l a n t m a y b e loca t ed in sa l iva ry g l a n d cells of A. 
persicus ( C h i n e r y , 1974, a n d see §4 .3 .1) . A n t i - c o a g u l a t i n g p r o p e r t i e s w e r e 
found in t h e sa l iva ry g l a n d s of A. persicus ( N u t t a l l & S t r i ck l and , 1908) , / . 
holocyclus (Ross , 1926; K a i r e , 1966) , / . ricinus (Foggie , 1959), a n d 0. moubata 
( H a w k i n s & H e l l m a n , 1966) . 
A t h r o m b o k i n a s e i n h i b i t o r w a s d e m o n s t r a t e d in g u t ex t r ac t s a n d h o m -
o g e n a t e s of w h o l e / . ricinus ( M a r k w a r d t , 1963) a n d a p ro teo ly t i c e n z y m e 
i n h i b i t o r w i t h a n t i - c o a g u l a t i n g p r o p e r t i e s in h o m o g e n a t e s of B. microplus 
l a r v