Factors affecting pheromone production and behavioral responses by Prostephanus truncatus (Coleoptera : Bostrichidae)

With a 4-arm olfactometer, we studied the pheromone production of male Pros tephanus truncatus (Horn) and responses of both sexes to synthetic pheromon e components. Single males and groups of males on maize were highly attract ive to both sexes when the males had been separated from females for some d ays. Maize cultures infested with low numbers of males and females were sli ghtly preferred, whereas cultures at high densities elicited no positive re sponses. Males on foamed polysytrene and on wood of Balanites aegyptiaca (L .) (Zygophyllaceae) evoked no positive responses, but males on wood of Comm iphori riparia Engl. and Commiphora africana (A. Rich.) (both Burseraceae) were as attractive as males on maize. Male and female P. truncatus always r esponded strongly to the synthetic pheromone. The responses of females were significantly greater than those of males; their response intensity was li ttle affected by their state of activity before the experiment or by a prev ious extensive exposure to the pheromone. We discuss the results with respe ct to pheromone production strategies and control methods.