SEX-PHEROMONE OF CADDISFLY HESPEROPHYLAX-OCCIDENTALIS (BANKS) (TRICHOPTERA, LIMNEPHILIDAE)

The main component of the sex pheromone of the caddisfly Hesperophylax occidentalis (Banks) (Trichoptera: Limnephilidae) was identified as 6 -methylnonan-3-one (enantiomeric composition has not yet been determin ed). Extracts of adult females elicited strong electroantennogram (EAG ) responses from adult male antennae, but elicited significantly small er EAG responses from adult female antennae. Extracts of adult males d id not elicit appreciable EAG responses from antennae of either sex. R acemic 6-methylnonan-3-one was synthesized and elicited EAG responses from male antennae as strong as those obtained with female extracts. I n field tests with baited sticky traps near lakes and streams, traps b aited with synthetic racemic 6-methylnonan-3-one caught significantly more males than control traps. Female adults contained approximately 1 mu g of 6-methylnonan-3-one per individual. Related ketones and alcoh ols of other chain lengths were also tentatively identified, being pre sent in tiny amounts in female extracts. Extraction of different body parts showed that 6-methylnonan-3-one occurs only in a region near the intersegmental membrane between the fourth and fifth abdominal sterni tes of the female (no discrete glands were observed). Extracts of male s did not contain 6-methylnonan-3-one, nor did pupae of either sex.