Mbata, GN; Shu, Shengqiang; Ramaswamy, SB

Annals of the Entomological Society of America [Ann. Entomol. Soc. Am.], vol. 92, no. 4, pp. 594-600, Jul 1999

Rearing of Callosobruchus subinnotatus (Pic) under crowded condition at 30'C and 80% RH produced active males and females. The active individuals emerged later than normal individuals and were lighter in weight. The responses of normal and active males of C. subinnotatus to sex pheromone were compared in electroantennogram (EAG) and olfactometry bioassays. The olfactometry bioassay involved observing males in Y-tubes containing blends of the components of the sex pheromone in one arm and a blank filter paper in the other. Behavioral characteristics of males were analyzed as they walked upwind in the tubes. The latency periods were shorter in active than in normal males. More normal males reached the source and spent more time on the source compared with active males. The normal males clearly demonstrated preference for 2 blends of the sex pheromone containing the (E)-3-methyl-2-heptenoic acid (E32C7) and (Z -3-methyl-2-heptenoic acid (Z32C7) isomers in the ratio of 75%:25% and 50%:50%, whereas active males showed preference for blends comprising >50% of the Z isomer. The EAG bioassay showed that responses of normal males to female pheromone extracts were twice those of active males.