Estimate of Physiological Age in Females of PASSALUS (Insecta, Coleoptera)

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ESTIMATE 0F PHYSIOLOGICAL A G E IN FEMALES OF P A S S A L U S (INSECTA, COLEOPTERA) (:!)

Cláudio Ruy V . Fonseca (**) P a u l o F. B u h r n h e i m (***)

SUMMARY

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INTRODÜCTION

In recent years knowledge of the bionomics o f some beetles has progressed rapidly w i t h the publication of w o r k s that have clarified details of d e v e l o p m e n t of these

insects. With the a p p e a r a n c e o f techniques that permit e s t i m a t e s o f physiologica 1 age based on o v a r i a n morphology ( T y n d a1e-Bíscoe,

1978),

c u t i c u í a r growth ( N e v i l l e ,

1963;

Shlein & G r a t z ,

1972),

p r e s e n c e of yellow body ( T y n d a1e-Biscoe & Hughes,

1969),

c o l o r -ation of the integument and presence of m e c o n i a (Corbert, 1960) and ovarian tracheation

(Detinova, 1 9 ^ 5 ) , understanding of reproductive behavior of some g r o u p s of insects has become c l e a r e r .

The association of these techniques has been employed to verify estimates o f a g e .

T y n d a 1 e - B i s c o e (op.cit.) studying the physiologica 1 age of female Euoniticellus intermedius (Reiche) employed ovarian morphology, associated with the degree of wear of

tibial teeth and the presence. of yel low body to obtain satisfactory results for C o l e o p t e r a .

(*) Part of thesis presented to the G r a d u a t e School of Instituto Nacional de P e s q u i  sas da A m a z ô n i a (INPA) and F u n d a ç ã o U n i v e r s i d a d e do A m a z o n a s (FUA) by the first author, in partial fulfillment of r e q u i r e m e n t s for M a s t e r of Science Degree (**) Instituto Nacional de P e s q u i s a s d a Amazônia - INPA

(***) D e p a r t a m e n t o de Z o o l o g i a da UNICAMP

Instituto Nacional d e Pesquisas da A m a z o n i a

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S a u n d e r s (1962) m a d e e s t i m a t e s based o n o v a r i a n d e v e l o p m e n t and hardening in G l o s s i n a pal lípides Austen; Nelson (1966) estimated the age of C u l e x t a r s a l i s Coqui 11 e t , based o n ovarian development and tracheation; Tyndale-Biscoe & Kitching (197^) used c u t i c u l a r growth together w i t h o v a r i a n d e v e l o p m e n t to c a l c u l a t e a g e in L u c i l i a c u p r i n a

( W i 1 d e m a n n ) .

In the present s t u d y , a c o m b i n a t i o n of several m e t h o d s w a s used to estimate the physiological age of female p a s s a l u s c o n v e x u s Dalman, 1817 and P a s s a l u s latifrons Per-c h e r o n , ]84l. M o d i f i Per-c a t i o n s arising in the o v a r i e s during d e v e l o p m e n t of the folliPer-cles c o n s t i t u t e c h a r a c t e r i s t i c s that permit recognition of nuliparous and parous f e m a l e s . T h e s e c h a r a c t e r i s t i c s together w i t h m a n d i b u l a r w e a r and the p r e s e n c e o f y e l l o w body are useful in the e s t i m a t e s of the a g e o f females in the studied s p e c i e s .

MATERIAL A N D M E T H O D S

A d u l t s of P a s s a l u s c o n v e x u s and P a s s a l u s l a t i f r o n s were captured from rotting tree trunks in primary f o r e s t , located at Km 14, on the M a n a u s - C a r a c a r a f Federal Highway ( B R - 1 7 ^ ) , State of A m a z o n a s , B r a s i l .

The female individuais encountered were placed in glass dishes and maintained a l i v e in the laboratory to e x a m i n e a l t e r a t i o n s in their o v a r i e s . Wood fragments from the trunks w h e r e beetles had been e n c o u n t e r e d w e r e a l s o placed in the dishes to serve as food.

In the l a b o r a t o r y , a d u l t s w e r e killed in petri dishes w i t h c h l o r o f o r m . Immediately a f t e r w a r d s , a d i s s e c t i o n w a s performed to o b s e r v e the o v a r i e s , using the m e t h o d of Kamm & Ri tcher ( 1 9 7 2 ) .

W i t h fine-pointed s c i s s o r s , two lateral incisions w e r e m a d e in the pleural m e m b r a n e o f the e x o s k e l e t o n , from the anal a p e r t u r e to the fourth abdominal s t e r n o n . T h e n , o p e n i n g the e x o s k e l e t o n v e n t r a l i y , the s t e r n i t e s w e r e removed, e x p o s i n g the o v a r i e s

(Fig. 1 ) . T h e s e w e r e then placed on a glass slide w i t h several drops of 0.9¾ saline s o l u t i o n . Under a d i s s e c t i n g m i c r o s c o p e , and w i t h the aid of f o r c e p s , tracheae that remained a d h e r i n g to the o v a r i e s w e r e removed to f a c i l i t a t e clear observation of o v a r i a n m o r p h o l o g y .

T h e s p e c i m e n s collected have been deposited in the S y s t e m a t i c Entomology C o l l e c t i o n of INPA, M a n a u s .

R E S U L T S

After e m e r g e n c e o f a d u l t s , the o v a r i e s are o f a reduced s i z e , w i t h transparent w h i t e c o l o r a t i o n and the ovaries have approximate)γ 1/3 of their final volume. (FJg.2A,

Fig. 3 A ) .

A t c o m p l e t i o n of a d u l t s c l e r o t i z a t i o n , m a l e s and females come t o g e t h e r , no doubt to initiate r e p r o d u c t i v e a c t i v i t y .

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Examination o f the spermatheca shows that soon a f t e r hardening of e x o s k e l e t o n , copulation is effected, and if this does not o c c u r , m a t u r a t i o n of oocytes remains suspended; however, it is very difficult to find a d u l t s that have not m a t e d .

Copulation probably s t i m u l a t e s the hormonal m e c h a n i s m s and noticeable m o d i f i c a tions in o v a r i a n morphology begin to be recognized. T h e o o c y t e s begin a m a t u r i n g phase

in succesive o r d e r , and the o v a r i a n volume i n c r e a s e s , w h i l e the o v i d u c t s pass through a process o f wall t h i c k e n i n g , a type of reinforcement that even m o d i f i e s the color of the o v i d u c t s . This o v i d u c t reinforcement is e v i d e n t , in such manner t h a t , during o v u l a t i o n , it is apt to support the tension provoked by passage of the o v u l e in the direction of the distal third of common o v i d u c t , w h e r e 4t is fertilized and chorion added (Fig. 2 A , B , C ) .

The m o d i f i c a t i o n s seen in the o v a r i e s during the life o f the femal es permits the i r classification into two c a t e g o r i e s : n u l l i p a r o u s and p a r o u s . N u l l i p a r o u s are those which h a v e not oviposited and w h o s e o v a r i e s show no o o c y t e s d e v e l o p i n g . Parous are those w h i c h have a l r e a d y o v i p o s i t e d o r w h o s e o v a r i e s show oocytes developing o r v e s t i g e s

of past a c t i v i t y . T h e o v a r i e s o f these females a r e well developed and very characteristic , as they are t w i c e as large as nulliparous o v a r i e s , and the oviducts

are stronger w i t h w a l l s that show well marked d i s t e n s i o n , and a l s o differentiated by milky w h i t e c o l o r , w i t h o u t the initial transparency (Fig. 3 C, D ) . When the period of oviposition t e r m i n a t e s , the parous females h a v e o v i d u c t s extremely d i l a t e d , similar to very stretched e l a s t i c , that by the force exerted, remains distended (Fig. 2 C ) .

The yellow body is not encountered very frequently because it is a l w a y s torn by the following o v u l e during o v u l a t i o n .

The o v a r i o l e s a l s o h a v e volume altered during m a t u r a t i o n of o o c y t e s . T h e r e is a sequential order in m a t u r a t i o n that is noted in the different sizes of follicles in ovarioles (Fig, 3 D ) . One egg is produced and laid each time. In all ovaries e x a m i n e d , never w a s m o r e than o n e egg encountered in the distal third of common o v i d u c t , a w a i t i n g o v i p o s i t i o n . The large volume taken up by the egg does not leave space for m o r e than o n e egg at the s i t e destined to receive the c h o r i o n and final intraovarian m a t u r a t i o n .

In the species s t u d i e d , the d i f f e r e n c e between nulliparous and parous females can be easily established by direct o b s e r v a t i o n of the o v a r i e s , m a n d i b1 e and exoskeleton (Table I ) .

D I S C U S S I O N

M o d i f i c a t i o n s presented by the o v a r i e s during d e v e l o p m e n t o f the follicles , together w i t h the degree of mandibular w e a r and hardening o f the e x o s k e l e t o n w e r e utilized as c h a r a c t e r s to estimate the ages of female P. c o n v e x u s and P. l a t i f r o n s . Ovarian a l t e r a t i o n s , distension and milky color a r e o f irreversible n a t u r e , thus allowing recognition of n u l l i p a r o u s and parous females through a simple o b s e r v a t i o n of the o v i d u c t s .

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T h e isolated u t i l i z a t i o n o f o n e character o f f e r s littie security in the estimate o f f e m a l e a g e s . For e x a m p l e , m a n d i b u l a r w e a r can give false information as to a g e , by v i r t u e o f being related to wood hardness w h e r e t h e insect is living. If the wood

is s o f t e r , m a n d i b u l a r w e a r will b e l e s s , a n d v i c e - v e r s a , if the wood has greater r e s i s t a n c e . T y n d a l e - B i s c o e (1978) thought that the rate o f w e a r by p a r t s o f exoskeleton subject to a t t r i t i o n is reasonably c o n s t a n t , for insects o r i g i n a t i n g from the s a m e a r e a ; thus passaiids taken from the same trunk will show parallel m a n d i b u l a r w e a r . However, for a population located in various t r u n k s , w h o l e wood content is o f a variable n a t u r e , and it b e c o m e s prudent to u s e only m a n d i b u l a r w e a r as a character to d e t e r m i n e a g e .

T y n d a l e - B i s c o e S Kitching (197*0 studying a g e in L u c i l i a based oncuticular growth and o v a r i a n d e v e l o p m e n t , noted delays in d e v e l o p m e n t o f o v a r i e s and o v i p o s i t i o n , when they compared the o v a r i e s w i t h rings o f c u t i c u l a r g r o w t h . T h u s , a g e as measured only by o v a r i a n d e v e l o p m e n t showed a younger insect than w h e n estimated by cuticular growth r i n g s . In this w a y , the a s s o c i a t i o n s o f characters brings the e s t i m a t i o n closer to rea1i ty.

Estimates o f a g e based o n presence o f the y e l l o w body have been valid for ali species o f c o p r o p h a g o u s beetles examined from África a n d A u s t r á l i a (Tynda 1 e-B i s c o e , 1978). H o w e v e r , for p a s s a i i d s , this c h a r a c t e r has not been safe for a g e d e t e r m i n a t i o n , because the y e l l o w body is torn by the following o v u l e during o v u l a t i o n , not leaving any v e s t i g e after the last o v u l a t i o n . T h e number o f y e l l o w bodies encountered does not c o r r e l a t e with the number o f o v i p o s i t i o n s that h a v e o c c u r r e d .

À C K N O W L E D G E M E N T S

W e w o u l d 1ike to a c k n o w l e d g e D r . Norman Penny for reviewing and translating this

p a p e r .

R E S U M O

Estados sobre, o desenvolvimento do aparelho re.prodtxtoi feminino em insetos tem demonstrado utilidade, na determinação da idade fisiológica. A/i alterações ovarianas de, caráter irreversível, associadas ao desgaste mandibular e a presença do corpo amarelo,

foram aplicáveis paAa estimar a idade, fisiológica em fenieas de Vassalas convexuò Q. V. latifrons, obtendo-se resultados comparáveis com outros estudos, indicando o valor destes métodos na determinação da idade, fisiológica.

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Figure 1, P a s s a l í d a e . a. V e n t r a l view of the body without prothorax and head. For rapid removal of the female reproductive system apply lateral cuts to abdomen at the level marked by a r r o w s , b . The last t h r e e s t e r n i t e s separated with the adhering o v a r i e s .

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Figure 2 . Schematic drawing showing the ovarian changes d u r i n g adult p h a s e .

A . Ovary of n u l l i p a r o u s f e m a l e ; B. S t r e t c h i n g of common oviduct d u r i n g o v u l a t i o n ; C. V i e w of the oviducts after a complete ovarian c y c l e . P a r o u s f e m a l e .

Figure 3. Ovaries of P a s s a l u s c o n v e x u s Dalm.; A . N u l l i p a r o u s o v a r i e s ; B . N u l l i p a r o u s ovaries initiating activity; C . Initial parous o v a r i e s ; D . Parous ovaries w i t h an egg d e s c e n d i n g the common o v i d u c t ; the s e q u e n c e of m a t u r i n g follicles can b e seen.

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R E F E R E N C E S

C o r b e r t , P . S . - 1 9 6 0 . R e c o g n i t i o n of n u l l i p a r o u s m o s q u i t o e s w i t h o u t d i s s e c t i o n . Nature 1 8 7 : 5 2 5 - 5 2 6 .

Detitiova, T . S . - 1 9 4 5 . D e t e r m i n a t i o n of the p h y s i o l o g i c a l age of f e m a l e Anopheles by the changes in the tracheal system of the o v a r i e s . M e d s k a y a P a r a z i t . , 14:45-49.

Rannti, J.A. & R i c h e r , P.O. - 1 9 7 2 . Rapid d i s s e c t i o n of insects to determine ovarial d e v e l o p m e n t . A n n . E n t , Soc. Am., 6 5 : 2 7 1 - 2 7 3 .

N e l s o n , R. L, - 1 9 6 6 . A comparison of two techniques for d i s t i n g u i s h i n g parous from n u l l i p a r o u s C u l e x tarsalis C o q u i l l e t t . M o s q u i t o N e w s , 2 6 : 1 1 - 1 3 .

N e v i l l e , A . C . - 1 9 6 3 . Daily growth layers in locust r u b b e r - l i k e cuticle influenced by an external rhythm. J, Insect P h y s i o l . , 9: 1 1 7 - 1 8 6 .

S a u n d e r s , D . S . - 1 9 6 2 . Age d e t e r m i n a t i o n for female tsetse flies and the age compositions of samples of G l o s s i n a pallidipes N e w s t . and G. b r e v i p a l p i s Newst. B u l l . E n t . R e s . , 5 3 : 5 7 9 - 5 9 5 .

S h l e i n , Y. & G r a t z , N . G . - 1 9 7 2 . Age d e t e r m i n a t i o n of some flies and mosquitoes by daily growth layers of skeletal a p o d e m e s . B u l l . W l d . H l t h . O r g . , 4 7 : 7 1 - 7 6 .

T y n d a l e - B i s c o e , M. - 1 9 7 8 . P h y s i o l o g i c a l a g e - g r a d i n g in f e m a l e s of the dung beetle E u o n i t i c e l l u s intermedius (Reiche) ( C o l e o p t e r a : S c a r a b a e i d a e ) . B u l l . E n t . R e s , , 68: 2 0 7 - 2 1 7 .

T y n d a l e - B i s c o e , M . & H u g h e s , R.D. - 1 9 6 9 . Changes in female r e p r o d u c t i v e system as age indicators in the b u s h f l y M u s c a v e t u s t i s s i m a W l k . B u l l . E n t . R e s . , 5 9 : 129-141.

T y n d a l e - B i s c o e , M . & K i t c h i n g , R . L , - 1 9 7 4 . Cuticular bands as age criteria in the sheep b l o w f l y L u c i l i a c u p r i n a (Wie.d.) (Diptera, C a l l i p h o r i d a e ) . B u l l . E n t . R e s . ,64: 1 6 1 - 1 7 4 .