Efficacy of Botanical Oils on Adult Mortality, Egg Laying, Hatchability and Adult Emergence of Callosobruchus. Maculatus (F.) (Coleoptera: Chrysomelidae: Bruchidae)

Abstract

The cowpea weevil Callosobruchus maculatus Fabricius, is the major insect pest that threatens effective legume storage. The laboratory experiment was conducted to assess the efficacy of four different botanical oils (Clove, Eucalyptus, Jojoba and Lemon) against the cowpea weevil, C. maculatus by using residual film technique. All the botanical oils were applied at two different concentration levels (0/50 and 0.75%). The results showed that all used oils significantly increased the mortality and reduced the mean number of eggs laying, hatchability and emergence percentages compared to the untreated control. The treatment of cowpea seeds with oils reduced slightly the germination but swelling percentage was higher in treated seeds than control. The results also indicated variation in the activity of botanical oils regarding the stage of the insect, the plant origin of the oils and concentration level. The present study suggested that botanical oils (Clove, Eucalyptus, Jojoba and Lemon) may be preferred option than conventional pesticides far the protecting stored pulse grains against stored products insect pests’ infestation, especially C. maculatus.