Response of Callosobruchus maculatus (Coleoptera: Chrysomelidae: Bruchinae) to extracts of cashew kernels

Abstract

Cashew kernels were extracted with six different solvents namely methanol, ethanol, water, acetone, pet-ether and n-hexane. The different extraction products were evaluated on C. maculatus adults for their mortality, ovicidal and adult emergence effects. The long-term protectant ability of the cashew kernel extracts and water absorption capacity of the treated cowpea seeds were also investigated. The results obtained showed that the steam distillate was most toxic to C. maculatus. The least toxic extracts on the insect were those of methanol and ethanol. The extracts drastically reduced oviposition in C. maculatus. The cowpea seeds treated with steam distillate had the lowest water absorption capacity, while the highest water absorption capacity was obtained in grains treated with ethanol and methanol. At 2.0% v/w cashew kernel extracts, the percentage water absorption capacity of cowpea seeds increased with increase in the interval of submergence.