Effects of plant oils on oviposition preference and larval survivorship ofCallosobruchus chinensis (Coleoptera : Bruchidae) on azuki bean

The efficacy of four kinds of oils, neem, castor, sunflower and sesame, was evaluated for the control of infestation of stored azuki bean with Calloso bruchus chinensis. Neem and sesame oil-treated beans were less preferred an d oviposition of adults on these beans decreased. After three days of relea se, 100% adults were found dead on neem oil-treated beans and very few eggs were laid. Effects on the survival rate of immature beetles and percentage of seed weight loss were also recorded, Neem and sesame oils completely in hibited adult emergence and appeared to be most promising as a seed protect ant against C. chinensis. The oil-specific activity and delay in larval dev elopment in oil-treated beans suggest that the protective properties involv ed chemical rather than physical factors.