Female sex pheromone in Callosobruchus subinnotatus (Coleoptera : Bruchidae): Production and male responses

Factors affecting sex pheromone production and male responses in the bruchi d beetle, Callosobruchus subinnotatus (Pic), were studied using electroante nnogram (EAG) and behavior assays. Virgin females at emergence already had produced a significant amount of putative sex pheromone. As females grew ol der, sex pheromone production reached a maximum at age 2 d. Virgin females emitted pheromone throughout the day, but they emitted slightly less during the End half of photophase. immediately after mating, females produced sig nificantly less sex pheromone than did virgin females of the same age, but older mated females produced similar amounts of pheromone to those of virgi n females of the same age. The pygidium is the likely site of sex pheromone production, because extracts of pygidium elicited highest male EAG respons es among the extracts of various dissected body parts of newly emerged fema les. Male EAG responses increased with the male age.