Some Chemical Ecological Approaches to the Control of Stored

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Downloaded by UNIV OF CALIFORNIA SAN DIEGO on December 17, 2015 | http://pubs.acs.org Publication Date: April 26, 1985 | doi: 10.1021/bk-1985-0276.ch014

Some Chemical Ecological Approaches to the Control of Stored-Product Insects and Mites IZURU YAMAMOTO Tokyo University of Agriculture, Setaga-ku, Tokyo 156, Japan

Three novel approaches to the control of insects are described and evaluated. Each involves modification of behavior. Control of mating. A new type of sex pheromone was found present in Callosobruchus chinensis, which is not a conventional sex attractant, but rather induces the male to extrude his genital organ and to effect copulation. A female dummy bearing the pheromone mimic, elicits copulation and ejaculation by the male. Control of oviposition. C. chinensis and C. maculatus develop a strategy to reduce competition among larvae by first marking the beans and then elimi nating the excess eggs, using the same marker at accumulated doses. The marking pheromone is a mix ture of lipids, and precoating the beans with certain edible oils kills the deposited eggs and prevents the injury. Control of feeding. Many bean weevils Callosobruchus spp. deposit eggs on kidney beans, but the penetrated larvae do not develop. An unidentified fraction of the bean was found as the growth inhibitor, but it is not lectin. I f a crop i s c o m p l e t e l y p r o t e c t e d from p e s t s , i t s y i e l d may be expected t o double. T h i s g o a l has been e a r n e s t l y pursued i n t h e f i e l d t o improve crop p r o d u c t i o n . L a t e l y , t h e need t o p l a c e more emphasis on p r o t e c t i o n from i n s e c t s d u r i n g p o s t - h a r v e s t f o o d s t o r a g e has been r e c o g n i z e d . There a r e s e v e r a l reasons why t h i s a r e a has been n e g l e c t e d : f i r s t , i n s u f f i c i e n t r e s e a r c h has been conducted; second, because l o s s e v a l u a t i o n i s d i f f i c u l t and s e e m i n g l y no problem e x i s t s w i t h the modern p r o d u c t i o n t e c h n o l o g y , t h e r e i s l i t t l e i n c e n t i v e ; t h i r d , t h e r e i s an assumption t h a t food s t o r a g e i s u n n e c e s s a r y under c o n d i t i o n s where t h e r e i s no f o o d surplus. We a r e more o r l e s s accustomed t o handle s t o r a g e problems w i t h our advanced t e c h n o l o g y , b u t i n d e v e l o p i n g c o u n t r i e s , p o s t -

0097-6156/ 85/0276-0219$06.00/ 0 © 1985 American Chemical Society

In Bioregulators for Pest Control; Hedin, P., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.


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h a r v e s t l o s s e s a r e about 30%, thus n u l l i f y i n g much o f the e f f o r t invested i n f i e l d production strategies. The major r e a s o n f o r t h e s e l o s s e s i s i n s e c t p e s t s . U n t i l the p r e s e n t , p e s t i c i d e s have p l a y e d a major r o l e i n p e s t c o n t r o l . However, t h e i r n e g a t i v e e n v i r o n m e n t a l impact i s b e i n g s e v e r e l y c r i t i c i z e d , making the con c e p t o f i n t e g r a t e d p e s t management r e l a t i v e l y more a t t r a c t i v e . D i f f e r e n t c o n t r o l methods have been e x p l o r e d i n s t o r a g e i n s e c t management, but examples of a t r u l y i n t e g r a t e d approach a r e few and t h e assessment o f the p r a c t i c a l i t y of any of t h e s e new approaches has not been completed. Considering p e s t i c i d e s for storage insect c o n t r o l , p a r t i c u l a r l y f u m i g a n t s , the use of some of the e x i s t i n g ones i s d e c r e a s i n g because of problems of t o x i c i t y , r e s i d u e s and resistance. The development of new p e s t c o n t r o l c h e m i c a l s based on new c o n c e p t s i s a d e s i r a b l e g o a l and may be r e w a r d i n g . The emerging c o u n t r i e s i n the t r o p i c s , h a v i n g a f a v o r a b l e c l i m a t i c con d i t i o n f o r p e s t emergence, do not have t h e economic r e s o u r c e s t o p r o v i d e f o r p r o p e r s t o r a g e space and/or f u m i g a t i o n . T h e r e f o r e , a simp1er t e c h n o l o g y w h i c h can be u t i l i z e d i n s u c h c o u n t r i e s i s needed. P e s t Management w i t h

Ecochemicals

The p r e s e n t c o n c e p t s o f p e s t management have e v o l v e d from b a s i c knowledge o f the c h e m i c a l i n t e r a c t i o n s between organisms. C h e m i c a l s d i r e c t l y i n v o l v e d i n the e c o l o g i c a l r e l a t i o n s h i p between organisms a r e c a l l e d e c o c h e m i c a l s , ecomones, o r s e m i o c h e m i c a l s ; t h o s e a c t i n g between d i f f e r e n t s p e c i e s a r e c a l l e d kairomones, a l l o mones, o r a l l e l o c h e m i c s , w h i l e t h o s e a c t i n g w i t h i n the same s p e c i e s a r e c a l l e d pheromones. R e s e a r c h on e c o c h e m i c a l s i s most advanced i n the case of i n s e c t s , thus p r o v i d i n g the o p p o r t u n i t y f o r i t s a p p l i c a t i o n t h r o u g h p e s t management. Through e v o l u t i o n a r y p r o c e s s e s , i n s e c t s have a c q u i r e d h a b i t s w h i c h a r e c o n d i t i o n e d by pheromones and/or a l l o m o nes. The r e a c t i o n s t o t h e s e s u b s t a n c e s by i n s e c t s d i f f e r from t h a t t o p o i s o n o u s i n s e c t i c i d e s i n t h a t i t i n v o l v e s a normal and s p e c i f i c response. In g e n e r a l , e c o c h e m i c a l s have been found t o be e f f e c t i v e a t v e r y low l e v e l s because t h e i r d i r e c t e f f e c t i s m a g n i f i e d through behavioral responses. Moreover, t h e s e e c o c h e m i c a l s g e n e r a l l y have a s i m p l e c h e m i c a l s t r u c t u r e and o f t e n t h e i r a n a l o g s a r e a v a i l a b l e . The p r e s e n t emphasis o f u t i l i z i n g t h e s e c h e m i c a l s i s t o r e g u l a t e p e s t a c t i v i t i e s i n o r d e r t o p r e v e n t c r o p and f o o d i n j u r y r a t h e r t h a n t o k i l l p e s t s . In the remainder o f t h i s r e p o r t , r e s e a r c h con d u c t e d a t our l a b o r a t o r i e s w i l l be d e s c r i b e d and d i s c u s s e d . Control of Feeding

Behavior

I n s e c t p r e f e r e n c e s f o r c e r t a i n t y p e s of f o o d can be c o n s i d e r e d from a c h e m i c a l e c o l o g i c a l p o i n t o f view as f o l l o w s : p r e s e n c e of a t t r a c t a n t , f i x i n g f a c t o r o v i p o s i t i o n - s t i m u l a n t , and f e e d i n g s t i m u l a n t ; absence of r e p e l l e n t , o v i p o s i t i o n d e t e r r e n t , f e e d i n g d e t e r r e n t , n u t r i t i o n a l d e f e c t , and g r o w t h - d e t e r r e n t . Conversely, t h e o p p o s i t e i s t r u e f o r c e r t a i n f o o d t y p e s u n d i s t u r b e d by i n s e c t s .



14. YAM AMOTO

Control of Stored-Product Insects and Mites

A t t r a c t a n t s i n c e r e a l g r a i n s o f S i t o p h i l u s zeamais. J5. zeamais i s known as the r i c e w e e v i l i n Japan, but as the maize w e e v i l i n the U.S., w h i l e S^. o r y z a e i s the s m a l l r i c e w e e v i l i n Japan, but the r i c e w e e v i l i n the U.S. Both i n s e c t s cause i n j u r y to r i c e , maize and wheat, or t o t h e i r p r o c e s s e d p r o d u c t s , thus b e i n g the most i m p o r t a n t i n j u r i o u s i n s e c t s to c e r e a l s . T h e r e i s e v i d e n c e t h a t o l f a c t o r y s t i m u l u s i s i n v o l v e d i n the h o s t s e l e c t i o n . In warm a r e a s , the i n s e c t s m i g r a t e d u r i n g the h a r v e s t o f r i c e , maize or wheat i n t o the f i e l d s from the s t o r e - h o u s e s , t h e r e b y c a u s i n g p o s t harvest injury a f t e r harvest. We began t h i s s t u d y w i t h the o b j e c t i v e of e l u c i d a t i n g chemical f a c t o r s i n g r a i n s i n v o l v e d i n h o s t - f i n d i n g b e h a v i o r of JS. zeamais. U s i n g o l f a c t o m e t e r s , the f o l l o w i n g samples, f r a c t i o n s , e x t r a c t s , or compounds were shown t o p o s s e s s a t t r a c t a n c y : 1. p o l i s h e d r i c e , brown r i c e , maize and wheat; 2. e t h e r , methanol, a c e t o n e or hexane e x t r a c t s o f the above samples, among which the e t h e r e x t r a c t showed the h i g h e s t a c t i v i t y ; 3. a c i d i c and n e u t r a l f r a c t i o n s of the e t h e r e x t r a c t . These o b s e r v a t i o n s suggested t h a t t h e c o m p o s i t i o n o f the a t t r a c t i v e c o n s t i t u e n t s i s of a complex r a t h e r than a s i m p l e n a t u r e . The a t t r a c t a n t s i n r i c e and maize g r a i n s were found t o be a m i x t u r e of C$ and Cj c a r b o x y l i c a c i d s , γl a c t o n e s of C3 h y d r o x y c a r b o x y l i c a c i d s , and p h e n y l e t h a n o l . Of t h e s e , h e x a n o i c a c i d and 2 - n o n e n - 4 - o l i d e p l a y the major r o l e . S i m i l a r a t t r a c t a n t s were a l s o found i n wheat. The a t t r a c t a n c y o f r e l a t e d c a r b o x y l i c a c i d s was i n v e s t i g a t e d e x t e n s i v e l y , however no o t h e r s were found t o be a t t r a c t i v e beyond the above-mentioned com pounds. As f o r the l a c t o n e s , s e v e r a l s y n t h e s i z e d compounds were found t o be a t t r a c t i v e . The above f o o d a t t r a c t a n t appears t o be i m p o r t a n t i n u n d e r s t a n d i n g the h o s t - f i n d i n g b e h a v i o r o f the r i c e weevil. S t u d i e s s h o u l d be conducted to d e t e r m i n e whether t h e r e i s a c o r r e l a t i o n between the c o n c e n t r a t i o n of a t t r a c t a n t s i n g r a i n s and o b s e r v e d s u s c e p t i b i l i t y . Then, b r e e d i n g f o r r e s i s t a n t v a r i e t i e s c o u l d be conducted on a r a t i o n a l b a s i s . A t t r a c t a n t i n Cheese o f Tyrophagus p u t r e s c e n t i a e . T. p u t r e s c e n t i a e ( f o r m e r l y T\ d i m i d i a t u s ) i s a g r a i n mite t h a t f e e d s on s t o r e d f o o d s t u f f s s u c h as d a i r y p r o d u c t s , g r a i n powders, c h o c o l a t e , s p i c e s , soybean p a s t e and d r i e d f i s h . The m i t e has been found to p r e f e r cheese, and i s thus commonly c a l l e d the cheese m i t e . A q u e s t i o n a r i s e s as t o whether these f o o d s t u f f s have the same or d i f f e r e n t f a c t o r s t h a t g o v e r n h o s t - f i n d i n g by the m i t e . For t h i s , an o l f a c t o m e t e r b i o a s s a y was d e s i g n e d u s i n g cheddar cheese w h i c h i s e a s i l y a v a i l a b l e and p o s s e s s e s a s t r o n g a t t r a c t a n c y as the s o u r c e material. Upon f r e e z e d r y i n g the cheese, the a t t r a c t a n c y was condensed i n t h e c o l d t r a p w i t h the v o l a t i l e s and f u r t h e r c o n c e n t r a t e d i n t o a n e u t r a l f r a c t i o n , which was s e p a r a t e d i n t o 3 f r a c t i o n s by chroma t o g r a p h y . E a c h f r a c t i o n was assayed to d e t e r m i n e i t s a t t r a c t a n c y . F r a c t i o n I gave no a c t i v i t y ; f r . I I gave 1/6 of the s t a r t i n g a c t i v i t y , and f r . I l l gave f a i n t a c t i v i t y , but when f r . I I was combined w i t h f r . I or I I I , the a t t r a c t a n c y i n c r e a s e d t o 1/2; e v i d e n c e o f s y n e r g i s m between f r a c t i o n s . By combining a l l o f the f r a c t i o n s , t h e o r i g i n a l a t t r a c t a n c y was r e s t o r e d . 8-Nonen-2-one o f f r . I I showed some a c t i v i t y , but o t h e r m e t h y l k e t o n e s i n the same f r a c t i o n


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were not a c t i v e . However, a m i x t u r e of 8-nonen-2-one w i t h heptan-2-one, octan-2-one and nonan-2-one showed s t r o n g a c t i v i t y , a s y n e r g i s t i c e f f e c t among m e t h y l k e t o n e s . F r . I l l c o n t a i n e d lower a l c o h o l s , but the a t t r a c t a n c y of f r . I l l appeared t o be due t o 3 - m e t h y l b u t a n o l a l o n e which f u r t h e r s y n e r g i z e d the a c t i v i t y o f the m i x t u r e of the above-mentioned m e t h y l k e t o n e s . M e t h y l k e t o n e s a r e p r e s e n t i n d a i r y p r o d u c t s , formed from t r i g l y c e r i d e s t h r o u g h $ - k e t o a c i d s . 3 - M e t h y l b u t a n o l o r i g i n a t e s from L - l e u c i n e and i s p r e s e n t i n v a r i o u s fermented p r o d u c t s . The p r e sence of such common c o n s t i t u e n t s i s thought t o be i n v o l v e d i n h o s t f i n d i n g f o r d i f f e r e n t k i n d s of f o o d s t u f f s by the m i t e . Much l e s s r e s e a r c h has been done on f o o d a t t r a c t a n t s than on sex pheromones. More emphasis on the u n d e r s t a n d i n g of such a l l o m o nes and t h e i r p o t e n t i a l use f o r i n s e c t c o n t r o l i s needed. Growth i n h i b i t o r i n k i d n e y bean o f bean w e e v i l s . A l a r v a o f the a z u k i bean w e e v i l , C a l l o s o b r u c h u s c h i n e n s i s , grows i n s i d e the a z u k i bean and o t h e r beans, but d i e s a t the f i r s t i n s t a r i n s i d e the k i d ney bean. I s h i i (1) had presumed t h a t t h i s was due t o a c e r t a i n growth i n h i b i t o r i n the bean, and o t h e r workers had attempted t o grow r e s i s t a n t bean p l a n t s by g r a f t i n g . J a n z e n e t a l . (2) c l a i m e d t h a t the cowpea w e e v i l , (Σ. macula t u s , i s not a b l e t o grow i n s i d e t h e k i d n e y bean due t o the a c t i o n of l e c t i n . We have attempted t o show t h e s e same r e l a t i o n s h i p s w i t h chinensis. The l e c t i n f r a c t i o n , p u r i f i e d by a f f i n i t y chromatography, d i d not show any growth i n h i b i t o r y a c t i v i t y , however. A p o s s i b i l i t y t h a t a t r y p s i n i n h i b i t o r i s r e s p o n s i b l e f o r the growth i n h i b i t i o n remains. Such a s t u d y i n c o m b i n a t i o n w i t h e f f o r t s t o breed beans f o r r e s i s t a n c e c o u l d c o n t r i b u t e t o the a t t a i n m e n t of a w e e v i l - f r e e bean. C o n t r o l of M a t i n g

Behavior

The use o f sex a t t r a c t a n t s seems p r o m i s i n g p a r t i c u l a r l y w i t h s t o r e d p r o d u c t i n s e c t s because t h e y must l i v e i n a r e s t r i c t e d space; t h i s has been w e l l documented by B u r k h o l d e r ( 4 ) . R e c e n t l y , a new type of sex pheromone was found from C^. c h i n e n s i s by u s . M a t i n g pheromones of C. c h i n e n s i s . Two sex pheromones a r e i n v o l v e d i n t h e m a t i n g b e h a v i o r o f C^. c h i n e n s i s : a female sex a t t r a c t a n t , and a c o p u l a t i o n r e l e a s e pheromone. The former a t t r a c t s the male t o the female, but does not i n d u c e f u r t h e r responses. The l a t t e r i n d u c e s the male t o e x t r u d e h i s g e n i t a l o r g a n and t o attempt c o p u l a t i o n , and thus i s named " e r e c t i n " ( 3 ) . E r e c t i n i s r e l e a s e d by b o t h the male and the female (more by the f e m a l e ) , but o n l y the male responds t o i t . The e v i d e n c e f o r c o p u l a t i o n r e l e a s e a c t i v i t y has been demonstrated w i t h s e v e r a l i n s e c t s : Costelytra zealandica; Trogoderma glabrum; L i m o n i u s canus; T r i b o l i u m confusum; T e n e b r i o m o l i t o r , and C a l l o s o b r u c h u s m a c u l a t u s ( F . ) ( 4 ) . However, e r e c t i n of c h i n e n s i s was the f i r s t to be i d e n t i f i e d , and i t i s i n v o l v e d only i n copulation release a c t i v i t y . C h e m i c a l l y , e r e c t i n c o n s i s t s of two s y n e r g i s t i c a l l y a c t i n g f r a c t i o n s , n e i t h e r h a v i n g any a c t i v i t y . One i s a m i x t u r e of C26-C35 h y d r o c a r b o n s and the o t h e r i s a d i c a r b o x y l i c a c i d , named



14.

YAMAMOTO

Control of Stored-Product insects and Mites

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"callosobruchusic a c i d " , (E)-3,7-dimethyl-2-octene-l,8-dioic acid. (5). I f e r e c t i n can be made a v a i l a b l e i n s u f f i c i e n t q u a n t i t i e s f o r p r a c t i c a l use, and i f the c o p u l a t i o n of males w i t h female dummies b e a r i n g e r e c t i n can e f f e c t the l o w e r i n g of the p o p u l a t i o n d e n s i t y , t h i s a p p a r e n t r e v e r s a l of the s t e r i l i z e d male t e c h n i q u e c o u l d become a new c o n t r o l a p p r o a c h . The f i r s t r e q u i s i t e f o r p r a c t i c a l use was a c h i e v e d by the s y n t h e s i s of c a l l o s o b r u c h u s i c a c i d , and the s u b s t i t u t i o n of a complex h y d r o c a r b o n m i x t u r e by o c t a d e c a n e . Only the (E) form was active. S y n t h e s i s of the two o p t i c a l forms was a l s o a c h i e v e d , but b o t h forms showed the same a c t i v i t y as the n a t u r a l c a l l o s o b r u c h u s i c a c i d , thus making i t i m p o s s i b l e t o a s s i g n the a b s o l u t e con f i g u r a t i o n ( 5 ) . The second r e q u i r e m e n t has been pursued by s e l e c t i n g d i f f e r e n t dummies. When an amount of e r e c t i n e q u i v a l e n t t o t h a t of one female was a p p l i e d t o a g l a s s r o d , the male a t t e m p t e d c o p u l a t i o n , but d i d not e j a c u l a t e . However, the male d i d show the i n s e r t i o n and e j a c u l a t i o n b e h a v i o r w i t h a dummy of a l u m i num f o i l tube b e a r i n g e r e c t i n . C o n t r o l of O v i p o s i t i o n B e h a v i o r Examples of the c o n t r o l o f o v i p o s i t i o n b e h a v i o r w i t h c h e m i c a l s have been demonstrated i n t h i s l a b o r a t o r y w i t h an o v i p o s i t i o n s t i m u l a n t for c h i n e n s i s and m a c u l a t u s and an o v i p o s i t i o n r e g u l a t o r . O v i p o s i t i o n s t i m u l a n t from bean seed c o a t . O v i p o s i t i o n on k i d n e y , cowpea and a z u k i beans by JC. c h i n e n s i s and _C. m a c u l a t u s i s stimu l a t e d by a t l e a s t two f a c t o r s . T h i s was shown u s i n g g l a s s beads of d i f f e r e n t s i z e s t r e a t e d w i t h the e x t r a c t of the bean seed c o a t s as the o v i p o s i t i o n s u b s t r a t e . jC. m a c u l a t u s o v i p o s i t e d o n l y when a c h e m i c a l s t i m u l a n t was p r o v i d e d , whereas c h i n e n s i s r e q u i r e d ade q u a t e p h y s i c a l s t i m u l i s u c h as s i z e , and the c h e m i c a l s t i m u l a n t played only a secondary r o l e . I s o l a t i o n o f the c h e m i c a l (5) i s i n progress. Such an o v i p o s i t i o n s t i m u l a n t w i t h a s u i t a b l e s u b s t r a t e c o u l d m o d i f y the o v i p o s i t i o n b e h a v i o r of t h e s e p e s t i n s e c t s . O v i p o s i t i o n r e g u l a t o r of C. c h i n e n s i s and C. m a c u l a t u s . There a r e two prominent phenomena t h a t govern the o v i p o s i t i o n b e h a v i o r o f the two w e e v i l s . F i r s t , under low d e n s i t y c o n d i t i o n s , f e m a l e s o v i p o s i t e v e n l y among beans. Second, under h i g h d e n s i t y c o n d i t i o n s where e a c h bean h o l d s many eggs, the egg d i s t r i b u t i o n becomes random and o n l y a few eggs h a t c h , l e a v i n g the r e s t t o d i e . The bean s u r f a c e becomes more s h i n y as o v i p o s i t i o n p r o g r e s s e s . An e t h e r - s o l u b l e s u b s t a n c e which i m p a r t s t h i s s h i n i n e s s was shown t o have marking activity. The w e e v i l p r e f e r s l e s s e r marked beans f o r f u r t h e r o v i p o s i t i o n , thus r e s u l t i n g i n an even d i s t r i b u t i o n of the eggs. Moreover, as t h i s s u b s t a n c e i n c r e a s e s t o a l e v e l of 100 pg/bean, c a u s i n g many eggs t o be d e p o s i t e d , the s u b s t a n c e shows o v i c i d a l a c t i o n , thus e l i m i n a t i n g most of the eggs e x c e p t t h o s e o v i p o s i t e d i n e a r l i e r s t a g e s t h a t had a l r e a d y h a t c h e d and p e n e t r a t e d i n t o the beans. These i n s e c t s thus have d e v e l o p e d a s t r a t e g y t o reduce com p e t i t i o n among l a r v a e , and t o m a x i m a l l y u t i l i z e the h o s t beans by u s i n g the same s u b s t a n c e a t d i f f e r e n t l e v e l s .


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This pheromone consists of t r i g l y c e r i d e s , f a t t y acids, and hydrocarbons, and each has some marking and o v i c i d a l a c t i v i t y . The f a t t y acid composition of the t r i g l y c e r i d e s i s similar to that of edible o i l s , and treatment of the azuki bean with certain edible o i l s (200 pg/bean) could protect the beans from injury by maculatus, chinensis, and Zabrotes subfaciatus.


Conclusion As i l l u s t r a t e d , new approaches to pest control are being developed that have the p o t e n t i a l i t y to lessen i n j u r i e s by lowering the insect population without direct k i l l . One future d i r e c t i o n may well be that of i d e n t i f y i n g ecochemicals of natural o r i g i n as a forerunner to the development of synthetic " p e s t i s t a t i c s " which mimic the function of the former. The methods of crop and food protection w i l l c e r t a i n l y change with the transformation of s o c i a l consciousness and with progress of science and technology. Along with this trend, the form of chemicals now c a l l e d pesticides w i l l inevitably be altered. Literature 1. 2. 3. 4. 5.

Cited

Ishii, S. Bull. Natl. Inst. Agric. Sci. Ser. C., No. 1. 1952, 185. Janzen, D. H.; Juster, H. B.; Liener, I. E. Science 1976, 192, 795. Tanaka, K.; Ohsawa, K.; Honda, H.; Yamamota, I. J. Pesticide Sci. 1981, 6, 75. Yun-Tai Qi; Burkholder, W. E. J. Chem. Ecol. 1982, 8, 527. Mori, K.; Ito, T.; Tanaka, K.; Honda, H.; Yamamoto, I. Tetrahedron 1983, 39, 2303.

RECEIVED

December 14, 1984


Some Chemical Ecological Approaches to the Control of Stored

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