Insecticidal and anti-ovipositional activities of the leaf powder of Jatropha curcas (L.) (euphorbiaceae) against Callosobruchus maculates (F.) (Coleoptera: Chrysomelidae)

Abstract

This study investigated the insecticidal and anti-ovipositional activities of the leaf powder of J. curcas against the cowpea beetle, Callosobruchus maculatus. Five pairs of sexed freshly emerged adults of C. maculatus were exposed to cowpea grains (20 g) treated with different concentrations (0.0, 1.0, 2.0 and 3.0 g) of the leaf powder of J. curcas for 24, 48, 72, 96 and 120 hours after which percentage mortality was calculated. In the same experimental setup, anti-ovipositional activity of the leaf powder of J. curcas was determined by counting the number of eggs on each cowpea grain after 120 hours of mating and oviposition by C. maculatus. Mortality of C. maculatus caused by the leaf powder of J. curcas was high and observed to be independent of the concentrations used, but dependent on the duration of exposure. At all concentrations (excluding the control – 0.0 g), the leaf powder of J. curcas demonstrated significant insecticidal activities (94 – 98 %) against C. maculatus following a 120 hour exposure period. At the lowest concentration (1.0 g), the leaf powder of J. curcas reduced oviposition rate in C. maculatus by 81.04 % after 120 hours of mating and oviposition. In summary, this study suggests the use of the leaf powder of J. curcas as an attractive alternative to conventional insecticides in the control of C. maculatus infestation in Nigeria and elsewhere.

Keywords: Cowpea, Jatropha curcas, Callosobruchus maculatus, Leaf powder, Mortality, Antioviposition