Analysis of Chemical Communications Systems of Lepidoptera

1 Analysis of Chemical Communications Systems of Lepidoptera J. H. TUMLINSON, R. R. HEATH, and P. E. A. TEAL

Downloaded by 91.238.114.254 on October 5, 2016 | http://pubs.acs.org Publication Date: June 18, 1982 | doi: 10.1021/bk-1982-0190.ch001

U.S. Dept. of Agriculture, Agricultural Research Service, Insect Attractants, Behavior, and Basic Biology Research Laboratory, Gainesville, F L 32604

Recent research has shown that the pheromone medi ated behavior of lepidopterous i n s e c t s i s very com p l e x . The chemical components of the pheromones are u s u a l l y simple molecules, but complex mixtures i n v o l v ing permutations of geometry, f u n c t i o n a l i t y , and c h a i n length are often required to elicit the complicated b e h a v i o r a l r e p e r t o i r e that e v e n t u a l l y culminates i n mating. To e l u c i d a t e the chemical and b e h a v i o r a l aspects of t h i s communications system, we have used a combination of methods i n c l u d i n g collection of the volatiles emitted by the female, a n a l y s i s by high r e s o l u tion capillary gas chromatography (GC), and the sequen tial and temporal a n a l y s i s of the male's b e h a v i o r a l response to the pheromone blend and components t h e r e o f . New liquid phases and s t a t e of the a r t techniques have been developed f o r capillary GC to separate all the components of a pheromone b l e n d . With these methods the chemical communication systems of H e l i o t h i s v i r e s c e n s ( F . ) and H . subflexa (Gn.) have been analyzed and c e r t a i n aspects have been e l u c i d a t e d . Numerous i n v e s t i g a t i o n s o f t h e pheromone c o m m u n i c a t i o n s y s t e m s o f L e p i d o p t e r a have been c o n d u c t e d d u r i n g t h e l a s t two decades, p r o b a b l y because L e p i d o p t e r a a r e u b i q u i t o u s phytophagous p e s t s and b e c a u s e , s u p e r f i c i a l l y , t h e i r pheromones and r e l a t e d b e h a v i o r a p p e a r s i m p l e . Most o f t h e s e i n v e s t i g a t i o n s have i n v o l v e d t h e c h e m i c a l i d e n t i f i c a t i o n o f t h e pheromone o r pheromone b l e n d o b t a i n e d f r o m t h e f e m a l e s and s u b s e q u e n t e v a l u a t i o n o f s y n t h e s i z e d pheromones t o d e t e r m i n e w h e t h e r o r n o t t h e y "work" a s t r a p b a i t s f o r m a l e s , o r c o m m u n i c a t i o n d i s r u p t a n t s i n the f i e l d . However, i n t h e l a s t f i v e y e a r s t h e r e h a s been a g r o w i n g body o f e v i d e n c e t h a t l e p i d o p t e r a n pheromones and p h e r o mone m e d i a t e d b e h a v i o r i s much more c o m p l e x t h a n f i r s t b e lieved. I t i s now c l e a r t h a t i n f o r m a t i o n r e g a r d i n g t h e c h e m i c a l c o m p o s i t i o n o f t h e pheromone and t h e pheromone e l i c i t e d b e h a v i o r This chapter not subject to U.S. copyright. Published 1982 American Chemical Society.

Leonhardt and Beroza; Insect Pheromone Technology: Chemistry and Applications ACS Symposium Series; American Chemical Society: Washington, DC, 1982.


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i s i n c o m p l e t e f o r most s p e c i e s . Thus, m o n i t o r i n g s y s t e m s e m p l o y i n g pheromone b a i t e d t r a p s do not a l w a y s g i v e c o n s i s t e n t r e s u l t s , r e p r e s e n t a t i v e o f p o p u l a t i o n d e n s i t i e s , and r e d u c t i o n o r m a t i n g b e l o w t h e economic t h r e s h o l d i s o f t e n d i f f i c u l t t o a c h i e v e by c o m m u n i c a t i o n d i s r u p t i o n w i t h t h e pheromones t h a t have been i d e n t i f i e d f o r a s p e c i e s . The d e v e l o p m e n t o f e f f e c t i v e p r a c t i c a l i n s e c t c o n t r o l s y s t e m s b a s e d on t h e use o f s e m i o c h e m i c a l s w i l l depend on t h e d e v e l o p m e n t o f a t h o r o u g h knowledge and u n d e r s t a n d i n g o f t h e c h e m i c a l c o m m u n i c a t i o n s systems of these i n s e c t s . F o r t h e s e r e a s o n s we d e c i d e d t o c o n d u c t an i n - d e p t h s t u d y o f the c h e m i c a l c o m m u n i c a t i o n s y s t e m s o f c e r t a i n l e p i d o p t e r a n s p e cies. We chose t o f i r s t i n v e s t i g a t e H e l i o t h i s v i r e s c e n s ( F . ) ( L e p i d o p t e r a : N o c t u i d a e ) b e c a u s e i t i s an i m p o r t a n t economic p e s t and b e c a u s e o f o u r p r e v i o u s e x p e r i e n c e w i t h i t { I ) . Addit i o n a l l y , m a l e s o f t h i s s p e c i e s can be mated w i t h H e l i o t h i s s u b f l e x a (Gn.J f e m a l e s t o p r o d u c e s t e r i l e h y b r i d m a l e s (2). T h i s phenomenon i s t h e b a s i s o f g e n e t i c s t r a t e g i e s f o r c o n t r o l o f H. v i r e s c e n s . I t a l s o p r o v i d e s an o p p o r t u n i t y t o s t u d y t h e p r o d u c t i o n and p e r c e p t i o n o f pheromones by h y b r i d s . Our i n i t i a l g o a l was t o a c c u r a t e l y d e f i n e t h e c h e m i c a l comp o s i t i o n o f t h e pheromone p r o d u c e d by H. v i r e s c e n s f e m a l e s and t o a n a l y z e and d e s c r i b e t h e male b e h a v i o r e l i c i t e d by the p h e r o mone and components t h e r e o f . U l t i m a t e l y we p l a n t o d e l i n e a t e the c h e m i c a l c o m m u n i c a t i o n s y s t e m s o f b o t h s p e c i e s and t o a n a l y z e pheromone p r o d u c t i o n and male b e h a v i o r o f h y b r i d s and b a c k crosses. H o p e f u l l y t h e r e s u l t s o f the l a t t e r p a r t o f t h e i n v e s t i g a t i o n w i l l provide u s e f u l c o r r e l a t i o n s with biochemical g e n e t i c i n v e s t i g a t i o n s b e i n g c o n d u c t e d on t h e s e h y b r i d s by o t h e r scientists. Thus f a r o u r i n v e s t i g a t i o n s have been f o c u s e d on t h e c h r o m a t o g r a p h i c a n a l y s i s o f pheromones p r o d u c e d and e m i t t e d by f e m a l e s and a n a l y s i s o f male b e h a v i o r evoked by t h e s e pheromones. The methods d e v e l o p e d t o c o n d u c t t h e s e i n v e s t i g a t i o n s , u s i n g H. v i r e s c e n s and H. s u b f l e x a as m o d e l s , a r e p r e s e n t e d h e r e . These methods a r e d i r e c t l y a p p l i c a b l e t o s i m i l a r i n v e s t i g a t i o n s o f other species. C a p i l l a r y Gas

Chromatography

A l t h o u g h , w i t h a few e x c e p t i o n s , t h e c h e m i c a l components o f l e p i d o p t e r a n pheromones a r e s i m p l e m o l e c u l e s , c o m p l e x m i x t u r e s t h a t i n c l u d e p e r m u t a t i o n s o f g e o m e t r y , f u n c t i o n a l i t y , and c h a i n l e n g t h a r e o f t e n p r o d u c e d and e m i t t e d by f e m a l e s . A n a l y s i s o f t h e s e pheromones r e q u i r e s a s y s t e m c a p a b l e o f s e p a r a t i n g compounds d i f f e r i n g i n geometry and p o s i t i o n o f an o l e f i n i c bond and r e s o l v i n g t h e m i x t u r e s p r o d u c e d by t h e f e m a l e s . Additiona l l y , s e n s i t i v i t y s u f f i c i e n t t o d e t e c t nanogram o r s m a l l e r



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q u a n t i t i e s o f t h e s e compounds i s r e q u i r e d t o a n a l y z e t h e p h e r o mone p r o d u c e d by o n l y one o r a few f e m a l e s . The o n l y method h a v i n g the c a p a b i l i t i e s r e q u i r e d f o r these a n a l y s e s i s c a p i l l a r y GC w i t h h i g h r e s o l u t i o n g l a s s o r f u s e d - s i l i c a c o l u m n s . This method has t h e added a d v a n t a g e t h a t t h e c a p i l l a r y columns can be c o u p l e d t o a mass s p e c t r o m e t e r and a g r e a t amount o f i n f o r m a t i o n c o n c e r n i n g t h e i d e n t i t y o f e a c h e l u t e d compound can be obtained. The mass s p e c t r a l d a t a p l u s r e t e n t i o n i n d i c e s o f a compound on two o r t h r e e c a p i l l a r y c o l u m n s t h a t s e p a r a t e compounds b a s e d on d i f f e r e n t c h a r a c t e r i s t i c s p r o v i d e c o m p l e t e and a c c u r a t e i d e n t i f i c a t i o n o f most compounds. The r e s o l u t i o n ( R s ) o f compounds on c a p i l l a r y GC columns i s a f u n c t i o n o f t h e c o l u m n e f f i c i e n c y (N e f f e c t i v e ) , t h e a b i l i t y o f t h e s t a t i o n a r y phase t o s e p a r a t e t h e compounds ( s e p a r a t i o n f a c t o r , a ) , and t h e r a t i o o f t h e amount o f t i m e t h e compounds spend i n t h e s t a t i o n a r y phase v s . t h e t i m e t h e compounds spend i n t h e c a r r i e r gas phase ( p a r t i t i o n r a t i o , k ' ) . Resolution of two compounds can be d e f i n e d by t h e e q u a t i o n :

Rs = 1/4

(a-1) WJ

( k'

)

1

N /

2

(k'+l)

Improvements i n r e s o l u t i o n on a c a p i l l a r y c o l u m n a f t e r i t has been p r e p a r e d can be made o n l y by t h e a d j u s t m e n t o f r e t e n t i o n t i m e , w h i c h a l t e r s t h e p a r t i t i o n r a t i o o f t h e compounds, and by t h e o p t i m i z a t i o n o f t h e c a r r i e r gas u s e d . Increases i n r e t e n t i o n time which r e s u l t i n a p a r t i t i o n r a t i o of g r e a t e r than 5 a f f o r d v e r y l i t t l e improvement i n r e s o l u t i o n and a r e done a t t h e expense of a n a l y s i s time. S i m i l a r l y , t h e use o f n i t r o g e n i n s t e a d o f h e l i u m as a c a r r i e r gas r e s u l t s i n an i n c r e a s e i n r e s o l u t i o n o f 1.14 a t the e x p e n s e o f d o u b l i n g t h e a n a l y s i s t i m e . The g r e a t e s t change i n r e s o l u t i o n o f components i s o b t a i n e d t h r o u g h the use o f a s t a t i o n a r y phase t h a t r e s u l t s i n an i n c r e a s e i n the s e p a r a t i o n f a c t o r (a) (see l a t e r ) . The amount o f r e s o l u t i o n r e q u i r e d i s dependent on t h e need t o a n a l y z e and q u a n t i t a t e m i n o r components t h a t e l u t e c l o s e t o a m a j o r component o f t h e pheromone b l e n d . F i g u r e 1 shows t h e e f f e c t t h a t t h e r e d u c t i o n i n c o l u m n e f f i c i e n c y (peak B ) , and t h e i n t r o d u c t i o n o f peak asymmetry (peak C) have on t h e s e p a r a t i o n o f a 1% m i n o r component e l u t i n g b e f o r e and a f t e r a m a j o r component peak. The a c c u r a t e d e t e r m i n a t i o n o f t h e 1% component peak w h i c h i s p o s s i b l e i n F i g u r e 1A i s s e v e r e l y l i m i t e d i n IB and 1C. The d e t e c t i o n o f a 10% component ( F i g u r e ID) i s s t i l l p o s s i b l e w i t h t h e r e d u c e d column e f f i c i e n c y . A column coated w i t h a s t a t i o n a r y phase t h a t i m p r o v e s a by c a . 0.01 as i l l u s t r a t e d i n F i g u r e IE i s c a p a b l e o f p r o v i d i n g an a d e q u a t e d e t e r m i n a t i o n o f IZ components e v e n a t r e d u c e d column e f f i c i e n c y . The s e p a r a t i o n s o f A7- and A 9 - t e t r a d e c e n - l - o l a c e t a t e s on 4 c a p i l l a r y columns c o a t e d w i t h d i f f e r e n t s t a t i o n a r y p h a s e s a r e compared i n F i g u r e 2. The n o n p o l a r OV-1 phase and t h e


3


s

a

8

s

s

8

Figure 1. Effect of separation (a), column efficiency ( N eff.), and peak asymmetry on the resolution and accurate quantitation of minor peaks. Key: A, a = 1.04, N eff. = 2000/M, R — 1.87; B,« = 1.04, N eff. = 1600/M, R = 7.66; C , a = 1.04, N = 2000/M, peak assym. = 10%, R = 1.66; D, = 1.04, N eff. = 1600/M, R = 1.66; am* £ , a = 1.05, N = 1600/M, R = 2.11.

c

1%


3 1

H W

0 w

W

H

w o

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P - C L CHOL. 25M L I Q U I D

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S P - 2 3 4 0 ( 2 5 M1 HIGH POLARITY

C W - 2 0 M ( 5 0 M) MEDIUM P O L A R I T Y

OV-1 (50M) NON P O L A R

Z&E

7-14:AC

2

:1

Z&E

9-14:AC

2:1

Figure 2. Separation of (Z)- and (E)-7-tetradecen-l-ol acetate (Z & E7-14:Ac) and (Z)- and (E)-9-tetradecen-l-ol acetates (Z & E9-14:Ac) on four different stationary phases on capillary columns. The OV-1 and Carbowax 20M (CW-20M) are coated on fused silica and the SP-2340 and p-chlorocholesteryl cinnamate on glass.



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medium p o l a r i t y Carbowax 20M are commercially a v a i l a b l e (Hewlett-Packard) f u s e d s i l i c a c a p i l l a r y c o l u m n s . The u s e f u l n e s s o f t h e s e h i g h l y e f f i c i e n t (N e f f e c t i v e ) f u s e d s i l i c a columns i s s e v e r e l y l i m i t e d b e c a u s e t h e s e p a r a t i o n f a c t o r , a, on Carbowax 20M and OV-1 i s i n s u f f i c i e n t t o r e s o l v e most p o s i t i o n a l and g e o m e t r i c a l i s o m e r s f o u n d i n t h e pheromone b l e n d s o f l e p i d o p t e r a n i n s e c t s . The h i g h p o l a r i t y p h a s e s c o n t a i n i n g l a r g e amounts o f c y a n o g r o u p s s u c h as SP-2340 ( S u p e l c o ) and S i l a r IOC ( A p p l i e d S c i e n c e ) p r o v i d e good r e s o l u t i o n o f many p o s i t i o n a l and g e o m e t r i c a l i s o m e r s o f m o n o - u n s a t u r a t e d compounds f o u n d i n l e p i d o p t e r a n i n s e c t s ( 3 ) . These h i g h p o l a r i t y c a p i l l a r y columns a r e c o m m e r c i a l l y a v a i l a b l e . S u p e r i o r r e s o l u t i o n o f t h e g e o m e t r i c a l i s o m e r s o f mono and d i u n s a t u r a t e d compounds i s o b t a i n e d w i t h l i q u i d c r y s t a l phases, a l t h o u g h the s e p a r a t i o n of p o s i t i o n a l i s o m e r s i s compromised as t h e d o u b l e bond p o s i t i o n a p p r o a c h e s t h e m i d d l e o f t h e compound i n some c a s e s . The comp a r i s o n of the s e p a r a t i o n s of the analogous s e r i e s of t e t r a d e c e n - l - o l a c e t a t e s on the l i q u i d c r y s t a l and cyano phase c a p i l l a r y columns i s shown i n F i g u r e 3. The E - i s o m e r s e l u t e p r i o r t o Z - i s o m e r s f r o m t h e cyano phase ( S P - 2 3 4 0 ) . However, on the l i q u i d c r y s t a l c o l u m n , the Z - i s o m e r s e l u t e f i r s t when t h e o l e f i n i c bond i s n e a r t h e m i d d l e o f t h e c h a i n . As t h e d o u b l e bond i s moved t o w a r d t h e h y d r o c a r b o n end o f t h e c h a i n Z and E l l - 1 4 : A c c o - e l u t e and t h e n t h e e l u t i o n o r d e r r e v e r s e s f o r Z_ and E12-14:Ac. The use o f b o t h t h e l i q u i d c r y s t a l columns and t h e cyano c o l u m n s , combined w i t h mass s p e c t r a l d a t a on compounds e l u t e d f r o m t h e s e c o l u m n s , o f f e r s t h e most p o w e r f u l a n a l y t i c a l p r o c e d u r e a v a i l a b l e f o r t h e i d e n t i f i c a t i o n o f compounds l i k e those found i n l e p i d o p t e r a n b l e n d s . S i n c e use o f l i q u i d c r y s t a l c a p i l l a r y columns f o r t h e s e p a r a t i o n o f a l i p h a t i c o l e f i n i c i n s e c t pheromones i s a r e c e n t d e v e l o p m e n t , some d i s c u s s i o n o f t h e i r properties i s worthwhile. The use o f a l i q u i d c r y s t a l as a GC s t a t i o n a r y phase was f i r s t r e p o r t e d i n 1963 ( 4 ) . The a p p l i c a t i o n o f o r d e r e d p h a s e s to pheromone r e s e a r c h d i d not o c c u r u n t i l 1978 when L e s t e r r e p o r t e d the s e p a r a t i o n of conjugated dienes w i t h d i e t h y l - 4 , 4 ' a z o x y d i c i n n a m a t e ( a s m e c t i c l i q u i d c r y s t a l ) on p a c k e d columns (_5). S u b s e q u e n t l y we c o a t e d c h o l e s t e r y l c i n n a m a t e ( a c h o l e s t e r i c l i q u i d c r y s t a l ) on c a p i l l a r y columns w h i c h r e s u l t e d i n c o u p l i n g t h e s e p a r a t i n g power o f t h e l i q u i d c r y s t a l p h a s e s w i t h t h e h i g h r e s o l v i n g c a p a b i l i t y o f w a l l - c o a t e d open t u b u l a r columns (6^). S e v e r a l l i q u i d c r y s t a l p r o p e r t i e s must be c o n s i d e r e d when u s i n g t h i s t y p e o f phase i n GC ( 7 ^ * As i l l u s t r a t e d i n F i g u r e 4, t h e use o f a l i q u i d c r y s t a l s u c h as c h o l e s t e r y l cinnamate below the temperature r e q u i r e d f o r l i q u i f i c a t i o n of t h e phase i s o f no u t i l i t y . A t i t s mesophase t r a n s i t i o n t e m p e r a t u r e ( t e m p e r a t u r e r e q u i r e d f o r t h e phase t o go f r o m c r y s t a l l i n e t o o r d e r e d l i q u i d ) , w h i c h i s c a . 158°C f o r c h o l e s t e r y l c i n n a m a t e , good s e p a r a t i o n o f t h e g e o m e t r i c a l i s o m e r s o f t e t r a d e c e n - l - o l acetate i s observed. Increase i n the temperat u r e o f t h e phase t o i t s i s o t r o p i c p o i n t ( t e m p e r a t u r e a t w h i c h


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25M SP-2340 HIGH POLARITY

P-CL CHOL. CINNAMATE LIQUID CRYSTAL

Figure 3. Separation of the (Z)- and (E)-isomers of tetradecen-l-ol acetates on SP-2340 and p-chlorocholesteryl cinnamate liquid crystal capillary columns. The ratio of Z : E is 2:1 in each set.


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8


TECHNOLOGY

l i q u i d c r y s t a l becomes u n o r d e r e d ) r e s u l t s i n d e c r e a s e d r e t e n t i o n t i m e ( k ' ) o b s e r v e d w i t h i s o t r o p i c p h a s e s . The d e c r e a s e o f t h e a l i g n m e n t o f t h e l i q u i d c r y s t a l m o l e c u l e s as t h e t e m p e r a t u r e a p p r o a c h e s t h e i s o t r o p i c p o i n t a l s o r e s u l t s i n d e c r e a s e d a, e f f e c t i v e p l a t e s , and r e s u l t a n t r e s o l u t i o n . I f t h e l i q u i d c r y s t a l phase i s f i r s t r a i s e d t o i t s mesophase t r a n s i t i o n tempe r a t u r e and t h e n g r a d u a l l y c o o l e d ( s u p e r c o o l i n g , F i g u r e 4 ) , t h e n d e c r e a s i n g t h e t e m p e r a t u r e b e l o w t h e mesophase t r a n s i t i o n p o i n t imparts a h i g h e r degree of alignment to the l i q u i d c r y s t a l molec u l e s . As w i t h an i s o t r o p i c p h a s e , r e t e n t i o n t i m e i n c r e a s e s . The more o r d e r e d phase a l s o d e m o n s t r a t e s i n c r e a s e d a, e f f e c t i v e p l a t e s , and a r e s u l t a n t i m p r o v e d r e s o l u t i o n . A p l o t o f t e m p e r a t u r e o f t h e l i q u i d c r y s t a l v s . k , a, N/m, and r e s u l t a n t r e s o l u t i o n i s shown i n F i g u r e 5. The use o f l i q u i d c r y s t a l p h a s e s a t t e m p e r a t u r e s above t h e i r mesophase t r a n s i t i o n t e m p e r a t u r e d r a m a t i c a l l y d e t e r i o r a t e s the phase's s e p a r a t i o n c h a r a c t e r i s t i c s ; however, t h e s e p a r a t i o n s a r e b e t t e r t h a n t h o s e o b t a i n e d w i t h i s o t r o p i c p h a s e s l i k e OV-1 and Carbowax 20M. Supercooling l i q u i d c r y s t a l p h a s e s b e l o w t h e i r mesophase t r a n s i t i o n t e m p e r a t u r e s r e s u l t s i n i n c r e a s e d performance at the expense of i n c r e a s e d r e t e n t i o n t i m e o f t h e compounds. A d e c r e a s e o f 20°C b e l o w t h e mesophase t r a n s i t i o n t e m p e r a t u r e r e s u l t s i n a c a . 1 . 5 - f o l d i n c r e a s e i n r e s o l u t i o n , compared w i t h t h a t o b t a i n e d a t t h e c r y s t a l ' s mesophase t e m p e r a t u r e , w h i c h i s e q u i v a l e n t t o i n c r e a s i n g column l e n g t h 2 - f o l d . A l t h o u g h t e m p e r a t u r e c o n s i d e r a t i o n s a p p e a r cumbersome when u s i n g l i q u i d c r y s t a l p h a s e s , t h e s e p a r a t i o n s shown i n F i g u r e 6 p r o v i d e t h e j u s t i f i c a t i o n f o r u s i n g s u c h p h a s e s i n pheromone r e s e a r c h . The d i e t h y l - 4 , 4 ' a z o x y d i c i n n a m a t e phase u s e d i n F i g u r e 6 was f i r s t d e s c r i b e d by Dewar {S) and r e c e n t l y by L e s t e r ( 5 ) f o r s e p a r a t i n g pheromones on p a c k e d c o l u m n s . W h i l e t h i s phase c a n n o t be recommended b e c a u s e i t i s t h e r m a l l y u n s t a b l e and c a n n o t be u s e d on c a p i l l a r y columns f o r l o n g p e r i o d s a t h i g h t e m p e r a t u r e s , i t does demons t r a t e the p o t e n t i a l s e p a r a t i o n s p o s s i b l e u s i n g l i q u i d c r y s t a l phases. I n v e s t i g a t i o n s are i n progress at our l a b o r a t o r y t o d e v e l o p p h a s e s t h a t combine t h e r e s o l v i n g power o f t h e a z o x y c i n n a m a t e phase w i t h the t e m p e r a t u r e s t a b i l i t y o f c h o l e s t e r y l cinnamate phases. H a v i n g d e t e r m i n e d t h a t t h e h i g h p o l a r i t y cyano phase and t h e l i q u i d c r y s t a l phase p r o v i d e t h e b e s t s e p a r a t i o n o f t h e compounds l i k e l y t o be f o u n d as components o f t h e pheromone b l e n d o f H. v i r e s c e n s and H. s u b f l e x a , we a n a l y z e d a c o m p l e x m i x t u r e o f p o s i t i o n a l and g e o m e t r i c a l i s o m e r s o f 16 c a r b o n a l d e h y d e s , a l c o h o l s , and a c e t a t e s on t h e s e two columns ( F i g u r e 7 ) . As n o t e d e a r l i e r , t h e e l u t i o n o r d e r o f Z- and E - i s o m e r s i s o p p o s i t e on t h e two p h a s e s . A l d e h y d e s e l u t e f i r s t on b o t h p h a s e s . The a l c o h o l s a r e r e t a i n e d more t h a n t h e a c e t a t e s on t h e h i g h p o l a r i t y c y a n o p h a s e , but t h e e l u t i o n o r d e r o f a l c o h o l s and a c e t a t e s i s r e v e r s e d on t h e l i q u i d c r y s t a l p h a s e . W h i l e n e i t h e r phase s e p a r a t e d a l l o f the s y n t h e t i c m i x t u r e , t h e c o m b i n a t i o n o f s e p a r a t i o n s o b t a i n e d on b o t h columns e n a b l e d us t o p u r s u e t h e


1


TUMLINSON E T A L .

Chemical

Communications

Systems

158


u

155

150'

145

140

HEATING

COOLING

Figure 4. Effect on the separation of isomers on a liquid crystal column (20 m cholesteryl cinnamate) when increasing column temperature to mesophase transition temperature and beyond (left), and then gradually cooling (right) below mesophase transition. Peaks represent, in increasing retention time, hexadecane, heptadecane, (Z)-, and (E)-9-tetradecen-l-ol acetate.



10


TECHNOLOGY

- (c)

.

- W)

135

ito

\\S

150

155

160

TEMPERATURE

165

170

175

180

°c

Figure 5. Effect on k' (a), a (b), N / m (1000) (c), and R (d) jor (Z)- and (E)-9tetradecen-l-ol acetate of increasing ( ) and decreasing ( ) the temperature of a cholesteryl cinnamate liquid crystal column.


TUMLINSON E T A L .

Chemical

Communications

Systems

22

3,13-18:AC


EE

Figure 6.

Separation of various compounds on a 20 m X 0.25 mm glass capillary column coated with diethyl-4 4 -azoxydicinnamate. y

f



TECHNOLOGY


12

Figure 7. Separation of a mixture of 16 carbon compounds on a liquid crystal and a cyanosilicon capillary column. S above a peak indicates the saturated compound.


1.

TUMLINSON E T A L .

Chemical

Communications

13

Systems

i d e n t i f i c a t i o n o f t h e components o f t h e pheromone b l e n d v i r e s c e n s and H. s u b f l e x a .

o f H.


Pheromone E x t r a c t i o n and A n a l y s i s The most common method o f o b t a i n i n g t h e pheromone f r o m a l e p i d o p t e r a n f e m a l e i s t o c l i p t h e l a s t few segments o f t h e abdomen f r o m t h e f e m a l e ' s body and e x t r a c t t h i s a b d o m i n a l t i p w i t h an o r g a n i c s o l v e n t . O t h e r methods i n c l u d e w a s h i n g t h e body o r p a r t s o f t h e body w i t h s o l v e n t . N a t u r a l l y , a v a s t number o f compounds i n a d d i t i o n t o t h e pheromone components a r e e x t r a c t e d by t h e s e methods and must be s e p a r a t e d . This requires a s e r i e s o f c h r o m a t o g r a p h i c p u r i f i c a t i o n s m o n i t o r e d by a b i o a s s a y t o o b t a i n t h e " a c t i v e " compounds. The b i o a s s a y , d e p e n d i n g on i t s d e s i g n , may d i s c r i m i n a t e f o r o r a g a i n s t c e r t a i n components o f t h e pheromone. Thus, t h i s method o f t e n l e a d s t o t h e i d e n t i f i c a t i o n o f o n l y p a r t o f t h e components o f t h e pheromone. I n an e a r l i e r i n v e s t i g a t i o n o f t h e H. v i r e s c e n s s e x p h e r o mone we i d e n t i f i e d two compounds, ( Z ) - l l - h e x a d e c e n a l and ( Z ) - 9 ~ t e t r a d e c e n a l i n a r a t i o o f 16:1, r e s p e c t i v e l y , f r o m e t h e r washes o f c a l l i n g f e m a l e b o d i e s (JL). These compounds were a l s o i d e n t i f i e d as H. v i r e s c e n s s e x pheromones by R o e l o f s ejt a d . ( 9 ) . Howe v e r , f i e l d e v a l u a t i o n o f c r u d e e x t r a c t s and s y n t h e s i z e d p h e r o mone l e d us t o s p e c u l a t e t h a t o t h e r pheromone components m i g h t be p r e s e n t . S u b s e q u e n t l y K l u n e t a l . (J-0) i d e n t i f i e d s e v e n comp o n e n t s i n t h e o v i p o s i t o r r i n s e s o f H. v i r e s c e n s f e m a l e s by c a p i l l a r y GC. Our a n a l y s i s o f H. v i r e s c e n s o v i p o s i t o r washes by methods s i m i l a r t o K l u n ' s gave r e s u l t s c o n s i s t e n t w i t h h i s data. The s e v e n components and t h e r e l a t i v e amounts f o u n d w e r e : t e t r a d e c a n a l (14:A1) ( 1 . 6 ) , ( Z ) - 9 - t e t r a d e c e n a l (Z9-14:A1) ( 2 ) , h e x a d e c a n a l (16:A1) ( 9 . 5 ) , ( Z ) - 7 - h e x a d e c e n a l (Z7-16:A1) ( 1 ) , ( Z ) - 9 - h e x a d e c e n a l (Z9-16:A1) ( 1 . 3 ) , ( Z ) - l l - h e x a d e c e n a l (Z11-16:A1) ( 8 1 . 4 ) , and ( Z ) - l l - h e x a d e c e n o l (Z11-16:0H) ( 3 . 2 ) . A l t h o u g h t h e f e m a l e ' s pheromone g l a n d s w o u l d be e x p e c t e d t o c o n t a i n many compounds i n a d d i t i o n t o t h e pheromone, e x t r a c t i o n o f t h e s e g l a n d s , e x c l u s i v e o f o t h e r t i s s u e s , s h o u l d p r o v i d e more a c c u r a t e i n f o r m a t i o n r e g a r d i n g pheromone p r o d u c t i o n and comp o s i t i o n t h a n p r e v i o u s methods o f e x t r a c t i o n . Thus a h i s t o l o g i c a l s t u d y o f t h e l i k e l y s i t e s o f pheromone p r o d u c t i o n i n t e r m i n a l a b d o m i n a l segments o f f e m a l e H. v i r e s c e n s was c o n d u c t e d (_11) • Two m o r p h o l o g i c a l l y d i s t i n c t a r e a s o f g l a n d u l a r t i s s u e were r e v e a l e d — t h e most e x t e n s i v e s i t u a t e d i n t h e i n t e r s e g m e n t a l membrane (ISM) b e t w e e n a b d o m i n a l segments 8 and 9 + 1 0 . A s e c o n d a r e a o f g l a n d u l a r t i s s u e was f o u n d t h r o u g h o u t t h e d o r s a l v a l v e s ( D V ) . When t h e s e two g l a n d u l a r s i t e s were e x c i s e d s e p a r a t e l y and e x t r a c t e d w i t h e t h e r , b e h a v i o r a l a n a l y s e s ( s e e l a t e r ) o f H. v i r e s c e n s male r e s p o n s e s i n d i c a t e d b o t h g l a n d s c o n t a i n e d a c t i v e m a t e r i a l s . However, n e i t h e r e x t r a c t was as e f f e c t i v e as t h e w h o l e o v i p o s i t o r e x t r a c t i n e l i c i t i n g t h e c o m p l e t e sequence o f male r e p r o d u c t i v e b e h a v i o r ( 1 1 ) .



14


TECHNOLOGY

C a p i l l a r y GC a n a l y s e s on SP-2340 and OV-101 columns o f t h e e x t r a c t s o f t h e DV and t h e ISM i n d i c a t e d d i s t i n c t d i f f e r e n c e s i n t h e c o n t e n t s o f t h e s e two g l a n d u l a r s i t e s . The DV c o n t a i n e d p r e d o m i n a n t l y t h e 1 4 - c a r b o n a l d e h y d e s w h i l e t h e ISM c o n t a i n e d p r i m a r i l y t h e 1 6 - c a r b o n compounds. C o n t a m i n a t i o n o f e i t h e r s i t e by s m a l l q u a n t i t i e s o f m a t e r i a l f r o m t h e o t h e r i s l i k e l y b e c a u s e of the d i f f i c u l t y i n e x c i s i n g the i n d i v i d u a l g l a n d s . However, t h e r e were d i s t i n c t d i f f e r e n c e s i n c o n t e n t s o f pheromone comp o n e n t s i n t h e two s i t e s . Although the s i g n i f i c a n c e of t h i s f i n d i n g i s n o t c l e a r a t t h i s t i m e , i t s h o u l d be n o t e d t h a t t h e 1 4 - c a r b o n a l d e h y d e s have n o t been f o u n d i n o t h e r H e l i o t h i s s p e c i e s and Z9-14:A1 i s a m a j o r f a c t o r i n s e p a r a t i n g H. v i r e s c e n s and H. z e a ( 1 2 ) . The p r e s e n c e o f a compound i n a g l a n d u l a r e x t r a c t does n o t a s s u r e i t s e m i s s i o n i n t o t h e a i r as a pheromone component. F u r t h e r m o r e , t h e r e l a t i v e amounts o f components e m i t t e d f r o m t h e g l a n d may d i f f e r c o n s i d e r a b l y f r o m t h o s e c o n t a i n e d i n t h e gland. There are s e v e r a l r e p o r t s i n the l i t e r a t u r e t h a t c o n f i r m t h i s (13,14). Thus, t o i d e n t i f y t h e pheromone a c c u r a t e l y , we must d e t e r m i n e what compounds an i n s e c t e m i t s and t h e r a t i o s o f t h e e m i t t e d compounds. The o n l y way t o d e t e r m i n e t h i s i s t o c o l l e c t and a n a l y z e t h e pheromone e m i t t e d by a " c a l l i n g " female. F u r t h e r m o r e , we s h o u l d a n a l y z e d i r e c t l y t h e c o l l e c t e d m a t e r i a l s i n c e f u r t h e r p u r i f i c a t i o n may change t h e c o n t e n t s o r component r a t i o s o f t h e pheromone. The method d e s c r i b e d by Grob and Z u r c h e r (JJ>) i n w h i c h a v e r y s m a l l amount o f c h a r c o a l i s u s e d t o c o l l e c t v o l a t i l e compounds has been m o d i f i e d s l i g h t l y by P. S. B e e v o r and coworkers> T r o p i c a l P r o d u c t s I n s t i t u t e , London (1_6) t o c o l l e c t pheromones from i n s e c t s . We have a d a p t e d and f u r t h e r m o d i f i e d t h i s method. B r i e f l y , i t c o n s i s t s o f a s m a l l c h a r c o a l f i l t e r p r e p a r e d by s e a l i n g 3-5 mg o f c h a r c o a l between two 325-mesh s t a i n l e s s s t e e l f r i t s i n a 6 mm (O.D.), 3.7 mm ( I . D . ) P y r e x tube ( F i g u r e 8 ) . T h i s f i l t e r i s t h e n p l a c e d a t t h e e x i t end o f an a e r a t i o n chamber, and a i r i s drawn t h r o u g h t h e a e r a t i o n a p p a r a t u s a t a f l o w r a t e o f 2.5 l i t e r s / m i n . When a e r a t i o n i s comp l e t e , t h e f i l t e r i s r i n s e d w i t h s i x a l i q u o t s (15-20 y l ) o f d i s t i l l e d d i c h l o r o m e t h a n e ; t h e combined a l i q u o t s a r e c o n c e n t r a t e d t o about 5-10 y l by g e n t l y w a r m i n g , and i s o o c t a n e o r a n o t h e r s o l v e n t o f c h o i c e f o r a n a l y s i s by c a p i l l a r y GC w i t h s p l i t l e s s i n j e c t i o n i s added. E v a l u a t i o n of t h i s system w i t h standards (Table I ) i n d i c a t e d t h a t most 14- and 1 6 - c a r b o n a l d e h y d e s , a c e t a t e s , and a l c o h o l s c o u l d be r e c o v e r e d w i t h good e f f i c i e n c y . Recoveries vary with c o n d i t i o n s , and t h u s i t i s n e c e s s a r y t o c a l i b r a t e an a p p a r a t u s w i t h s t a n d a r d s u n d e r t h e e x a c t c o n d i t i o n s t o be u s e d w i t h insects. F o r e x a m p l e , l a r g e r d i a m e t e r a e r a t i o n chambers r e d u c e the e f f i c i e n c y of c o l l e c t i o n because of the g r e a t e r s u r f a c e area o f g l a s s a v a i l a b l e t o a d s o r b t h e pheromone and l o w e r w i n d v e l o c i t i e s f o r a given flow rate. T h e r e f o r e , the s m a l l e s t a e r a t i o n



ZTTpT

Figure 8.

12.7mm Width Teflon Tape 6.4mm O.D. 6.4mm I.D. Tubing with Teflon Tubing Flared Tip

Rubber Tubing

VacuumS^JL

To

Charcoal Entrainment Filter

Volatile collection apparatus.

Coarse *A" Frit Charcoal; Air Inlet Filter Insect 19/22mm Aeration Ground Glass Glass Joints Chamber Spring Wool Attachment Plug Tips


16


TECHNOLOGY


chamber c o n s i s t e n t w i t h t h e s i z e and c a l l i n g b e h a v i o r o f an i n s e c t s h o u l d be u s e d . N e v e r t h e l e s s , r e l i a b l e r e s u l t s can be o b t a i n e d when c o l l e c t i n g pheromone w i t h t h i s s y s t e m . A d d i t i o n a l l y , i f c a r e i s t a k e n t o use p u r e s o l v e n t s , c l e a n g l a s s w a r e , and f i l t e r e d i n c o m i n g a i r , pheromones c a n be c o l l e c t e d w i t h minimal background i m p u r i t i e s t h a t i n t e r f e r e w i t h a n a l y s e s . A n a l y s i s o f the v o l a t i l e pheromone c o l l e c t e d f r o m c a l l i n g f e m a l e H. v i r e s c e n s i s n o t y e t c o m p l e t e . However, p r e l i m i n a r y r e s u l t s i n d i c a t e t h a t 14:A1 and Z9-14:A1 a r e e m i t t e d i n g r e a t e r q u a n t i t i e s , r e l a t i v e t o Z11-16:A1, t h a n a r e p r e s e n t i n t h e gland. Thus o u r d a t a s u g g e s t t h a t t h e t r u e e m i t t e d pheromone o f H. v i r e s c e n s f e m a l e s may c o n s i s t p r e d o m i n a n t l y o f 14:A1, Z9-14:A1, 16:A1, and Z11-16:A1.

TABLE I P e r c e n t o f s t a n d a r d compounds r e c o v e r e d f r o m c h a r c o a l f i l t e r when c a . 0.5 y g o f e a c h was a l l o w e d t o evaporate from a s t a i n l e s s s t e e l p l a n c h e t i n the v o l a t i l e c o l l e c t i o n apparatus.

Compound

Z9-14:0H Z9,E12-14:OH Z11-16:0H Z9-14:Ac Z9,Ell-14:Ac Z9,E12-14:Ac Zll-16:Ac Z9-14:A1 Z11-16:A1 Z11,Z13-16:A1

% R e c o v e r e d (no. r e p l i c a t e s )

81 67 57 83 86 86 61 78 69 82

+

3

+ 5 + 6 + 6 + 0 + 2 + 10 + 6 + 9 + 3

(2) (2) (6) (2) (2) (2) (6) (4) (6) (2)

R e c e n t l y , c o n s i d e r a b l e e m p h a s i s has been p l a c e d on t h e c o n t r o l o f H. v i r e s c e n s by g e n e t i c s t r a t e g i e s . The b a s i s o f t h i s a p p r o a c h l i e s i n the p r o d u c t i o n o f s t e r i l e male h y b r i d s f r o m m a t i n g s between H. v i r e s c e n s m a l e s and f e m a l e s o f a r e l a t e d s p e c i e s , H. s u b f l e x a (.2). Subsequent m a t i n g s o f H. v i r e s c e n s m a l e s w i t h h y b r i d or backcross h y b r i d females produces s t e r i l e males and f e r t i l e b a c k c r o s s h y b r i d f e m a l e s . O b v i o u s l y , the success of a c o n t r o l p r o g r a m b a s e d on t h i s s t r a t e g y w o u l d depend h e a v i l y on t h e a b i l i t y o f H. v i r e s c e n s m a l e s t o l o c a t e and mate w i t h b a c k cross h y b r i d females. Since these species are r e p r o d u c t i v e l y i s o l a t e d i n t h e f i e l d d e s p i t e s y m p a t r i c d i s t r i b u t i o n s and o v e r l a p p i n g m a t i n g p e r i o d s and b e c a u s e i n t e r s p e c i f i c m a t i n g s a r e



1.

TUMLINSON E T A L .

Chemical

Communications

Systems

d i f f i c u l t t o o b t a i n i n t h e l a b o r a t o r y , i t seemed l o g i c a l t h a t r e p r o d u c t i v e i s o l a t i o n m i g h t be a f f e c t e d by d i s p a r a t e s e x p h e r o mones. Thus, we deemed i t i m p o r t a n t t o a n a l y z e and d e f i n e t h e p h e r o m o n a l c o m m u n i c a t i o n s y s t e m o f H. s u b f l e x a and e v e n t u a l l y we w i l l a n a l y z e pheromone p r o d u c t i o n and pheromone m e d i a t e d b e h a v i o r o f h y b r i d s and b a c k c r o s s e s o f t h e s e two s p e c i e s . The a n a l y s e s o f t h e H. s u b f l e x a o v i p o s i t o r e x t r a c t s ( 1 7 ) r e v e a l e d e i g h t m a j o r components c o i n c i d i n g i n r e t e n t i o n t i m e s on SP-2340 and p - c h l o r o c h o l e s t e r y l c i n n a m a t e c a p i l l a r y columns ( F i g u r e 9) w i t h 16:A1, Z9-16:A1, Z11-16:A1, (Z)-7-hexadecen-l-ol a c e t a t e , (Z7-16:Ac), (Z)-9-hexadecen-l-ol acetate (Z9-16:Ac), ( Z ) - l l - h e x a d e c e n - l - o l a c e t a t e , ( Z l l - 1 6 : A c ) , Z9-16:0H, and Z11-16:0H. S e v e r a l o t h e r peaks were a l s o v a r i a b l y p r e s e n t b u t , when p r e s e n t , e a c h composed l e s s t h a n 1% o f t h e t o t a l m i x t u r e . Mass s p e c t r a l d a t a c o n f i r m e d t h e i d e n t i t y o f t h e m a j o r components. The d i f f e r e n c e s i n t h e g l a n d u l a r pheromone c o n s t i t u e n t s between H. v i r e s c e n s and H. s u b f l e x a a r e d i s t i n c t . H. s u b f l e x a c o n t a i n s a c e t a t e s o f 1 6 - c a r b o n a l c o h o l s n o t f o u n d i n H. v i r e s c e n s and does n o t c o n t a i n t h e 1 4 - c a r b o n a l d e h y d e s w h i c h a p p e a r t o be u n i q u e t o H. v i r e s c e n s among H e l i o t h i s s p e c i e s s t u d i e d t h u s f a r . I t w i l l be i n t e r e s t i n g t o see what b l e n d s t h e h y b r i d s o f t h e s e s p e c i e s p r o d u c e and r e l a t e t h i s t o d a t a f r o m i n v e s t i g a t i o n s of the genetics of t h i s h y b r i d i z a t i o n . Behavioral

Analysis

The u l t i m a t e g o a l o f any pheromone b i o a s s a y i s t o d e f i n e t h a t p a r t i c u l a r b l e n d o f pheromone components w h i c h i n d u c e s t h e r e c e i v e r t o p e r f o r m a sequence o f b e h a v i o r s i n d i s t i n g u i s h a b l e from t h a t performed d u r i n g i n t e r - o r g a n i s m i c communication. T y p i c a l l y , such a n a l y s e s a r e c o n d u c t e d u n d e r l a b o r a t o r y c o n d i t i o n s t h e r e b y e n a b l i n g t h e c o n t r o l o f s u c h v a r i a b l e s as l i g h t , h u m i d i t y , t e m p e r a t u r e , and i n s e c t e x p e r i e n c e , a l l o f w h i c h have marked e f f e c t s on i n s e c t p e r f o r m a n c e . However, s u c h a r t i f i c i a l c o n t r o l s make i t v i r t u a l l y i m p o s s i b l e t o d e s i g n a l a b o r a t o r y b i o a s s a y i n w h i c h an i n s e c t w i l l r e s p o n d t o a s e m i o c h e m i c a l b l e n d i n t h e same f a s h i o n t h a t i t w o u l d i n n a t u r e . Hence, t h e f i r s t step i n the assessment o f the b e h a v i o r a l e f f e c t s e l i c i t e d by a s e m i o c h e m i c a l b l e n d i s a c r i t i c a l a n a l y s i s o f i n t e r o r g a n i s m i c c o m m u n i c a t i o n f r o m w h i c h b e h a v i o r a l c r i t e r i a c a n be s e l e c t e d f o r use i n f u r t h e r s t u d i e s . The b e h a v i o r a l r e s p o n s e s o f m a l e s o f H. v i r e s c e n s and H. s u b f l e x a t o s e m i o c h e m i c a l s have been o f c o n s i d e r a b l e i n t e r e s t t o us f o r r e a s o n s a l r e a d y m e n t i o n e d . Two a s s a y s y s t e m s were employed t o a n a l y z e b o t h p r e c o u r t s h i p and c l o s e - r a n g e c o u r t s h i p b e h a v i o r s ( 1 8 ) . The f i r s t , u s e d i n t h e a n a l y s i s o f male a c t i v a t i o n , o r i e n t a t i o n , and i n i t i a l a n a l y s i s o f c o u r t s h i p i n t e r a c t i o n s , c o n s i s t e d o f a 1.5 x 0.5 x 0.5-m p l e x i g l a s s w i n d t u n n e l t h r o u g h w h i c h a i r was p u l l e d a t a c o n s t a n t r a t e . I n o u r i n i t i a l


17

18


TECHNOLOGY

16 Carbon BHT Aldehydes

Acetates

Alcohols


Z1 1

16 Carbon Aldehydes

Alcohols

Acetates

BHT B

Z1 1

211

Figure 9. Analysis of H. subflexa ovipositor extract (1.5 female equivalent) on 66 m SP-2340 (A) and 30 m cholesteryl cinnamate capillary columns (B). S indicates the saturated compound.



1.

TUMLINSON

ET AL.

Chemical

Communications

Systems

s t u d i e s , f e m a l e s were p l a c e d i n t h e u p w i n d end o f t h e t u n n e l , and i n d i v i d u a l m a l e s were l o w e r e d i n t o t h e a i r s t r e a m 10 cm f r o m t h e downwind e n d . M a l e b e h a v i o r s were m o n i t o r e d and r e c o r d e d on audio c a s s e t t e tapes. I n t h e second a s s a y , c l o s e - r a n g e c o u r t s h i p i n t e r a c t i o n s were o b s e r v e d i n a 20 x 10 x 10-cm p l e x i g l a s s c a g e . Groups o f t h r e e t o f i v e f e m a l e s were p l a c e d i n t h e chamber d u r i n g t h e p h o t o p h a s e p r e c e d i n g e a c h t e s t , and m a l e s were r e l e a s e d i n d i v i d u a l l y d u r i n g t h e s c o t o p h a s e when f e m a l e s had been o b s e r v e d c a l l i n g f o r a 5-min p e r i o d . B e h a v i o r s were r e c o r d e d on v i d e o t a p e . The b e h a v i o r a l r e s p o n s e s o f male H. v i r e s c e n s t o c o n s p e c i f i c f e m a l e s i n t h e s e a s s a y s y s t e m s a r e d e s c r i b e d i n d e t a i l by T e a l e t a l . (_18). A n a l y s i s o f t h e s e r e s p o n s e s a l l o w e d c a l c u l a t i o n o f t h e s t a t i s t i c a l p r o b a b i l i t y o f a b e h a v i o r a l e v e n t o c c u r r i n g and enabled the s e l e c t i o n o f b e h a v i o r s used i n t h e assessment o f e x t r a c t s o b t a i n e d f r o m d i f f e r e n t pheromone g l a n d s i t e s . The sequence o f b e h a v i o r s p e r f o r m e d by H. v i r e s c e n s m a l e s i n r e s p o n s e t o t h e pheromone p r o d u c e d by c a l l i n g H. v i r e s c e n s f e m a l e s and t h e p r o b a b i l i t y o f e a c h t r a n s i t i o n o c c u r r i n g a r e g i v e n i n F i g u r e 10. T h i s f i g u r e a l s o shows t h e r e s p o n s e o f m a l e s t o e x t r a c t s o b t a i n e d f r o m d i f f e r e n t pheromone g l a n d s i t e s and t o the v o l a t i l e s c o l l e c t e d from c a l l i n g females. A l t h o u g h t h e sequence o f b e h a v i o r s p e r f o r m e d by m a l e s i n r e s p o n s e t o c a l l i n g f e m a l e s and t h e w h o l e o v i p o s i t o r e x t r a c t a r e e s s e n t i a l l y t h e same, t h e r e i s a much h i g h e r p r o b a b i l i t y t h a t a male w i l l c o m p l e t e t h e sequence when r e s p o n d i n g t o a f e m a l e . T h i s r e s u l t s from a s i g n i f i c a n t l y g r e a t e r p r o b a b i l i t y t h a t a male w i l l e n t e r i n t o t a x i s i n r e s p o n s e t o a f e m a l e , w h i c h s u b s e quently leads to increased p r o b a b i l i t i e s of performing f u r t h e r b e h a v i o r s . O b v i o u s l y , t h e r e a r e d i f f e r e n c e s between t h e b l e n d s r e l e a s e d by c a l l i n g f e m a l e s and t h o s e e x t r a c t e d f r o m t h e w h o l e o v i p o s i t o r (see e a r l i e r chemical analyses). A d d i t i o n a l l y , the r e s p o n s e t o e i t h e r t h e ISM o r DV i s i n c o m p l e t e a l t h o u g h t h e r e s p o n s e t o t h e combined ISM and DV (whole o v i p o s i t o r ) i s complete. This i s c o n s i s t e n t with the r e s u l t s of the chemical a n a l y s i s ( s e e e a r l i e r ) which i n d i c a t e d t h a t each g l a n d s i t e p r o duced o n l y p a r t o f t h e t o t a l pheromone b l e n d . The v o l a t i l e b l e n d c o l l e c t e d f r o m c a l l i n g f e m a l e s e l i c i t s responses h a v i n g p r o b a b i l i t i e s i n t e r m e d i a t e between those p e r formed i n r e s p o n s e t o c a l l i n g f e m a l e s and w h o l e o v i p o s i t o r extracts. However, t h e v o l a t i l e b l e n d t e s t e d was n o t c o r r e c t e d f o r t h e d i f f e r e n t i a l r e c o v e r i e s o f t h e v a r i o u s pheromone comp o n e n t s ( s e e e a r l i e r ) and when c o r r e c t e d may i n c r e a s e t h e p r o b a b i l i t i e s of behaviors o c c u r r i n g considerably. Nonetheless, a f i e l d t r a p p i n g s t u d y u s i n g P h e r o c o n 1C s t i c k y t r a p s b a i t e d w i t h t h r e e Conrel® b l a c k f i b e r s i n d i c a t e d t h a t t h e v o l a t i l e b l e n d was a s i g n i f i c a n t l y b e t t e r t r a p l u r e t h a n were e i t h e r t h e b l e n d i d e n t i f i e d by K l u n e t a l . ( 1 0 ) o r t h e s t a n d a r d " v i r e l u r e " b l e n d (I) ( T a b l e I I ) . Hence, t h i s method o f c o l l e c t i n g p h e r o mone may be t h e most a c c u r a t e way t o o b t a i n t h e " t r u e " b l e n d e m i t t e d by t h e f e m a l e . When t h e c h e m i c a l a n a l y s i s o f t h i s



TECHNOLOGY


20



1.

Chemical

TUMLINSON E T A L .

Communications

Systems

m a t e r i a l i s c o m p l e t e , i t w i l l be i n t e r e s t i n g t o o b s e r v e t h e b e h a v i o r of males t o s y n t h e t i c blends t h a t correspond i n c o m p o s i t i o n t o t h e v a r i o u s b l e n d s o b t a i n e d by d i f f e r e n t methods o f e x t r a c t i o n and c o l l e c t i o n . H o p e f u l l y we c a n t h e n d e t e r m i n e t h e r o l e t h a t e a c h component p l a y s i n e l i c i t i n g t h e sequence o f behavioral events. A d d i t i o n a l l y , we s h o u l d be a b l e t o p u t t o g e t h e r a s y n t h e t i c b l e n d o f compounds t h a t w i l l be h i g h l y e f f e c t i v e i n t r a p p i n g w i l d males i n the f i e l d . As i n d i c a t e d e a r l i e r H. s u b f l e x a has r e c e n t l y become t h e s u b j e c t o f numerous p e s t c o n t r o l s t u d i e s due t o t h e p o t e n t i a l f o r p o p u l a t i o n c o n t r o l o t H. v i r e s c e n s by a s t e r i l e h y b r i d r e l e a s e p r o g r a m . However, t h e s e two s p e c i e s m a i n t a i n r e p r o d u c t i v e i s o l a t i o n d e s p i t e b r o a d l y o v e r l a p p i n g r a n g e s and i n t e r s e c t i n g r e p r o d u c t i v e p e r i o d s . Hence, b a r r i e r s t o i n t e r s p e c i f i c gene f l o w a r e most l i k e l y due t o d i f f e r e n c e s i n t h e i r r e s p e c t i v e sex pheromone c o m m u n i c a t i o n s y s t e m s a n d , as i n d i c a t e d e a r l i e r , t h e r e a r e c o n s i d e r a b l e d i f f e r e n c e s i n t h e pheromone g l a n d c o n t e n t s of each.

TABLE 11 T r a p c a p t u r e s o f male H. v i r e s c e n s i n s t i c k y t r a p s o v e r 56 d a y s u s i n g t h r e e C o n r e l f i b e r d i s p e n s e r s l e a . 8 ng/min r e l e a s e r a t e ) .

Synthetic blend

a

Male t r a p

K l u n b l e n d : 14:A1 ( 1 . 6 ) + Z9-14:A1 ( 2 ) + 16:A1 ( 9 . 5 ) + Z7-16:A1 ( 1 ) + Z9-16:A1 ( 1 . 3 ) + Z l l - 1 6 : A 1 ( 8 1 . 4 ) + Z11-16:0H ( 3 . 2 ) + 1% BHT

10

" V i r e l u r e " : Z9-14:A1 ( 1 ) + Z11-16:A1 ( 1 6 ) + 1% BHT

50

C

V o l a t i l e b l e n d : 14:A1 ( 2 4 ) + Z9-14:A1 ( 1 6 ) + 16:A1 ( 1 2 ) + Z11-16:A1 ( 4 8 ) + 1% BHT

captures

111

a

Numbers i n p a r e n t h e s e s i n d i c a t e r e l a t i v e amounts o f each component. ^Mean d a i l y t r a p c a p t u r e s were s i g n i f i c a n t l y d i f f e r e n t f o r a l l t h r e e b l e n d s a t a 0.05 l e v e l u s i n g Duncan's M u l t i p l e Range T e s t . BHT = 2,6-di-^-butyl-4-methylphenol. C


21


22


TECHNOLOGY

T h e r e f o r e , f i e l d t r a p p i n g t e s t s were c o n d u c t e d i n F l o r i d a i n 1980 t o s t u d y t h e e f f e c t i v e n e s s o f s y n t h e t i c b l e n d s i n c a p t u r i n g H. s u b f l e x a m a l e s and t o a s s e s s t h e s p e c i e s s p e c i f i c i t y o f t h e pheromones o f H. s u b f l e x a , H. v i r e s c e n s and H. z e a . The s y n t h e t i c b l e n d i d e n t i c a l i n c o m p o s i t i o n t o t h e H. s u b f l e x a gland e x t r a c t (see e a r l i e r ) f o r m u l a t e d i n e i t h e r p o l y e t h y l e n e v i a l s (30 mg o f m i x t u r e ) o r on f i l t e r p a p e r (75 ng) was as e f f e c t i v e i n c a p t u r i n g m a l e s as e i t h e r f e m a l e s o r g l a n d e x t r a c t s i n cone t r a p s ( 1 9 ) . A d d i t i o n a l l y , o n l y H. s u b f l e x a m a l e s were c a p t u r e d , w h i l e t r a p s i n t h e same f i e l d s b a i t e d w i t h H. v i r e s c e n s o r H. z e a f e m a l e s o r s y n t h e t i c b l e n d s (10) a l s o captured only c o n s p e c i f i c males. S t u d i e s t o a s s e s s the e f f e c t s o f d e l e t i n g components o f t h e H. s u b f l e x a b l e n d were c o n d u c t e d w i t h s t i c k y t r a p s w h i c h r e q u i r e the r e s p o n d i n g male t o l a n d t o be c a p t u r e d . Landing i s also a p r e r e q u i s i t e f o r m a t i n g . The r e s u l t s ( T a b l e I I I ) i n d i c a t e d t h a t r e m o v a l o f e i t h e r t h e a l d e h y d e o r a c e t a t e components d i d n o t comp l e t e l y eliminate trap capture. W h i l e the whole s y n t h e t i c b l e n d was as e f f e c t i v e as v i r g i n f e m a l e s i n cone t r a p c a p t u r e s , a s i g n i f i c a n t d e c r e a s e i n c a p t u r e s r e l a t i v e t o f e m a l e s was n o t e d when t h e w h o l e b l e n d was employed i n s t i c k y t r a p s . F u r t h e r , c o n s i d e r a b l y more m a l e s were c a p t u r e d i n s t i c k y t r a p s when t h e a l c o h o l s were d e l e t e d , s u g g e s t i n g t h a t t h e a l c o h o l s may a c t as an i n h i b i t o r t o l a n d i n g . T h i s i s a l s o s u p p o r t e d by v i s u a l o b s e r v a t i o n s i n the f i e l d . However, t h e r u b b e r s e p t a u s e d as pheromone d i s p e n s e r s i n t h e s e t e s t s have been f o u n d t o r e l e a s e m o n o u n s a t u r a t e d a l c o h o l s at a c o n s i d e r a b l y h i g h e r r a t e than the corresponding aldehydes. F u r t h e r , subsequent t e s t i n g u s i n g C o n r e l f i b e r s i n d i c a t e d t h a t t h e a l c o h o l s do n o t i n h i b i t l a n d i n g when d i s p e n s e d i n the i d e n t i f i e d r a t i o . T h e r e f o r e , i t appears t h a t the a l c o h o l s a r e i n h i b i t o r y o n l y when d i s p e n s e d a t r a t i o s f a r above t h o s e found w i t h i n the g l a n d . A l t h o u g h many a s p e c t s o f b o t h t h e male and f e m a l e r e p r o d u c t i v e b e h a v i o r s o f H. s u b f l e x a a r e s i m i l a r t o t h o s e o f H. v i r e s c e n s , s m a l l d i f f e r e n c e s do e x i s t (_11 ,_18). F l i g h t tunnel s t u d i e s of the s e m i o c h e m i c a l l y induced b e h a v i o r a l i n t e r a c t i o n s between H. s u b f l e x a and H. v i r e s c e n s i n d i c a t e d t h a t m a l e s o f t h e two s p e c i e s r e s p o n d q u i t e d i f f e r e n t l y t o t h e n a t u r a l l y r e l e a s e d sex pheromone o f t h e o t h e r s p e c i e s . T h i r t e e n o f t h e 20 male H. s u b f l e x a r e l e a s e d i n t o t h e p h e r o mone plume c r e a t e d by c a l l i n g H. v i r e s c e n s f e m a l e s e x h i b i t e d a c t i v a t i o n b e h a v i o r s i n c l u d i n g w i n g f a n n i n g , a m b u l a t i o n , and g e n i t a l e x p o s u r e . However, o n l y one male e n t e r e d t a x i s up the plume and none were s u c c e s s f u l i n l o c a t i n g f e m a l e s . R e s u l t s o f a s t u d y u s i n g one f e m a l e e q u i v a l e n t o f t h e H. v i r e s c e n s pheromone g l a n d e x t r a c t were s i m i l a r , but t h e r e was a s l i g h t d e c r e a s e i n t h e number o f H. s u b f l e x a m a l e s t h a t became a c t i v e and none entered t a x i s .



+ +

+ + + + +

+ + +

+

+

+

+

+ + +

+ + +

+ +

Z11-16:A1

Z9-16:A1

16:A1

+ +

+

+ +

+

Z9-16:Ac

+ +

+

E x p e r i m e n t no. 2

+ +

+

+

+

+

+

Zll-16:Ac

E x p e r i m e n t no. 1

Z7-16:Ac

+

+

+

+ +

Z9-16:OH

c

e

+

+

+ + +

2.899 1.000 0.941 0.803 0.578 0.148 0.148 0.000

2.742 1.912 0.774 0.706 0.045 0.000

(c,d) (d)

(a) (b) (b; (b,c) u,d;

a a b b c c

Mean Z11-16:0H ( m a l e s / n i g h t )

a

blends. >^» »^»

e

c

R a w d a t a t r a n s f o r m e d t o log^Q ( X + l ) p r i o r t o a n a l y s i s (16 r e p l i c a t e s o v e r 8 n i g h t s e x p e r i m e n t 1; 10 r e p l i c a t e s o v e r 5 n i g h t s e x p e r i m e n t 2 ) . ^Means f o l l o w e d by t h e same l e t t e r a r e n o t s i g n i f i c a n t l y d i f f e r e n t i n a Duncan's m u l t i p l e r a n g e t e s t a t a 0.05 l e v e l . M e a n s f r o m t h e 2 e x p e r i m e n t s a r e n o t compared w i t h one a n o t h e r . ^The p r e s e n c e o f a compound i n a t e s t b l e n d i s i n d i c a t e d by a +. T h e r e l a t i v e c o n c e n t r a t i o n s o f t h e compounds i n e a c h b l e n d were i d e n t i c a l t o t h e r e l a t i v e c o n c e n t r a t i o n s o f t h o s e p a r t i c u l a r compounds i n t h e b l e n d e x t r a c t e d f r o m H. s u b f l e x a f e m a l e s .

a

Three females

TABLE I I I C o m p a r i s o n o f s t i c k y t r a p c a p t u r e s o f H. s u b f l e x a m a l e s u s i n g d i f f e r e n t



24


TECHNOLOGY

The b e h a v i o r a l r e p e r t o i r e e x h i b i t e d by male H. v i r e s c e n s i n r e s p o n s e t o t h e pheromone b l e n d p r o d u c e d by c a l l i n g H. s u b f l e x a f e m a l e s was q u i t e d i s t i n c t f r o m t h a t d e s c r i b e d a b o v e . The m a j o r i t y (90%) o f t h e i n i t i a l l y i n a c t i v e male H. v i r e s c e n s f l e w d u r i n g these t e s t s and, i n f a c t , the p r o b a b i l i t y o f undergoing t a x i s t o w a r d c a l l i n g H. s u b f l e x a f e m a l e s was n o t s i g n i f i c a n t l y d i f f e r e n t f r o m t h a t f o u n d i n c o n s p e c i f i c m a t i n g s t u d i e s . Howe v e r , o n l y 75% o f t h e r e s p o n d i n g m a l e s l a n d e d and a p p r o a c h e d H. s u b f l e x a females w h i l e 93% performed these behaviors i n c o n s p e c i f i c studies. Further, the p r o b a b i l i t y of i n t e r s p e c i f i c m a t i n g was o n l y 1 5 % . R e s u l t s o f e x p e r i m e n t s u s i n g one FE o f t h e H. s u b f l e x a s e x pheromone g l a n d e x t r a c t were c o n s i d e r a b l y d i f f e r e n t f r o m t e s t s i n w h i c h c a l l i n g f e m a l e s were u s e d . In fact, none o f t h e H. v i r e s c e n s m a l e s e n t e r e d t a x i s up t h e plume. This s u g g e s t s t h a t t h e b l e n d o f compounds r e l e a s e d f r o m t h e e x t r a c t was q u i t e d i f f e r e n t f r o m t h a t r e l e a s e d by c a l l i n g f e m a l e s . The b l e n d o f pheromone components i d e n t i f i e d f r o m H. s u b f l e x a f e m a l e g l a n d e x t r a c t s h a s two components i n common w i t h 3.' v i r e s c e n s , Z9-16:A1 and Z11-16:A1 and t h r e e n o t f o u n d i n H. virescens, (Z)-7-hexadecen-l-ol acetate (Z7-16:Ac), (Z)-9-hexad e c e n - l - o l a c e t a t e ( Z 9 - 1 6 : A c ) and ( ^ ) - l l - h e x a d e c e n - l - o l a c e t a t e (Zll-16:Ac). F i e l d s t u d i e s ( T a b l e 111) i n d i c a t e t h a t a t t h e v e r y l e a s t , t h e two aldehydes plus Zll-16:Ac are of i m p o r t a n c e t o t h e c a p t u r e o f male H. s u b f l e x a . Hence, t h e a b s e n c e o f t h e s e t h r e e a c e t a t e components f r o m t h e H. v i r e s c e n s pheromone ( 1 0 ) , and d i f f e r e n t r a t i o s o f Z9-16:A1 t o Z11-16:A1 p r o b a b l y a c c o u n t f o r t h e s e m i o c h e m i c a l i s o l a t i o n between H. s u b f l e x a m a l e s and H. v i r e s c e n s f e m a l e s . However, t h e r e l e a s e o f pheromone components by f e m a l e H. v i r e s c e n s s u c h as 14:A1 and Z9-14:A1 may be d i s o r i e n t i n g t o male H. s u b f l e x a and c a n n o t be d i s c a r d e d as a p o s s i b l e mechanism f o r r e p r o d u c t i v e i s o l a t i o n . I t appears t h a t semiochemically imparted r e p r o d u c t i v e i s o l a t i o n between H. v i r e s c e n s m a l e s and H. s u b f l e x a f e m a l e s r e s u l t s f r o m t h e r e l e a s e o f a pheromone b l e n d t h a t does n o t p r o v i d e a s t i m u l u s o f s u f f i c i e n t magnitude t o induce a h i g h percentage o f t h e m a l e s t o l a n d and s u b s e q u e n t l y e n t e r i n t o c o u r t s h i p . Chemi c a l l y , t h i s may r e s u l t f r o m t h e d i s t i n c t r a t i o o f Z9-16:A1 t o Z11-16:A1 p r o d u c e d by f e m a l e H. s u b f l e x a , and t h e p r o b a b l e a b sence o f b o t h 14:A1 and Z9-14:A1 f r o m t h e H. s u b f l e x a b l e n d . However, b e c a u s e a number o f m a l e s do p e r f o r m c o u r t s h i p b e h a v i o r s a f t e r c o n t a c t i n g t h e f e m a l e , d i s p a r i t i e s between t h e pheromone b l e n d s o f H. v i r e s c e n s and H. s u b f l e x a a r e n o t s o l e l y responsible for reproductive i s o l a t i o n . R a t h e r , i t seems t h a t b o t h t h e pheromone b l e n d and t h e f e m a l e s ' a b i l i t y t o e s c a p e f r o m c o u r t i n g m a l e s f u n c t i o n as m a j o r i n p u t s t o r e p r o d u c t i v e i s o l a tion. Acknowledgments M e n t i o n o f a c o m m e r c i a l o r p r o p r i e t a r y p r o d u c t does n o t c o n s t i t u t e an endorsement by t h e U. S. D e p t . o f A g r i c u l t u r e .


1.

TUMLINSON E T A L .

Chemical

Communications

Systems


Literature Cited 1. Tumlinson, J. H . ; Hendricks, D. E.; Mitchell, E . R.; Doolittle, R. E.; Brennen, M. M. J . Chem. Ecol. 1975, 1, 203-214. 2. Laster, M. L . Environ. Entomol. 1972, 1, 682-687. 3. Heath, R. R.; Burnsed, G. E.; Tumlinson, J . H.; and Doolittle, R. E . J . Chromatogr. 1980, 189, 199-208. 4. Kelker, H. Anal. Chem. 1963, 198, 254. 5. Lester, R. J . Chromatogr. 1978, 156, 55-62. 6. Heath, R. R.; Jordan, J. R.; Sonnet, P. E . ; and Tumlinson, J . H. J . HRC & CC 1979, 2, 712-714. 7. Heath, R. R.; Jordan, J. R.; Sonnet, P. E. J . HRC & CC 1981, 4, 328-332. 8. Dewar, M. J. S.; Schroeder, J . P. J . Org. Chem. 1965, 30, 3485-90. 9. Roelofs, W. L., Hill, A. S., Carde, R. T . , and Baker, T. C. Life Sciences 1974, 14, 1555-1562. 10. Klun, J . A . ; Bierl-Leonhardt, B. A . ; Plimmer, J . R.; Sparks, A. N . ; Primiani, M.; Chapman, O. L.; Lepone, G. P.; and Lee, G. H. J . Chem. Ecol. 1980, 6, 177-183. 11. Teal, P. E . A. Ph.D. Dissertation, University of Florida, Gainesville, FL, 1981. 12. Tumlinson, J . H. "Advances in Pesticide Science" Geissbühler, H . ; Brooks, G. T . ; Kearney, P. C . , Eds., Pergamon Press, 1979, Vol. II, p. 315-322. 13. Cross, J . H . ; Byler, R. C . ; Cassidy, R. F.; Silverstein, R. M.; Greenblatt, R. E.; Burkholder, W. E.; Levinson, A. R.; Levinson, H. Z. J . Chem. Ecol. 1976, 2, 457-468. 14. Hill, A. S.; Carde, R. T . ; Kido, A . ; Roelofs, W. L . J . Chem. Ecol. 1975, 1, 215-224. 15. Grob, K . ; Zürcher, F. J. Chromatogr. 1976, 117, 285-294. 16. Beevor, P. S.; personal communication. 17. Teal, P. E . A . ; Heath, R. R.; Tumlinson, J. H . ; McLaughlin, J . R. J . Chem. Ecol. 1981, 7, 1011-1022. 18. Teal, P. E . A . ; McLaughlin, J. R.; Tumlinson, J. H. Ann. Entomol. Soc. Am. 1981, 74, 324-330. 19. Hartstack, A. W.; Witz, J. A . ; Buck, D. R. J . Econ Entomol. 1979, 72, 519-522. R E C E I V E D March 1, 1982.


Analysis of Chemical Communications Systems of Lepidoptera

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