Responses of normal and active males of Callosobruchus subinnotatus to female sex pheromone

Rearing of Callosobruchus subinnotatus (Pic) under crowded condition at 30 degrees C and 80% RH produced active males and females. The active individu als emerged later than normal individuals and were lighter in weight. The r esponses of normal and active males of C, subinnotatus to sex pheromone wer e compared in electroantennogram (EAG) and olfactometry bioassays. The olfa ctometry 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 no rmal males. More normal males reached the source and spent more time on the source compared with active males. The normal males clearly demonstrated p reference for 2 blends of the sex pheromone containing the (E)-3-methyl-2-h eptenoic 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 fo r blends comprising >50% of the Z isomer. The EAG bioassay showed that resp onses of normal males to female pheromone extracts were twice those of acti ve males.