Insecticidal Activities of Jatropha curcas L. against Callosobruchus maculatus (F.) in Stored Cowpea

Abstract

The aim of the experiment was to determine the insecticidal activities of Jatropha curcas L. seed oil against cowpea seed bruchid, Callosobruchus maculatus (F.) in storage under prevailing temperature (27±2ºC) and relative humidity (68±3%). The seed oil was applied at the rates of 0.2, 0.3, 0.5, and 1.0 ml/50 g cowpea seeds while untreated control and solvent-treated seeds were included. Jatropha curcas seed oil was found to exert varying degrees of mortality on the seed beetles in small-scale farm produce storage. The highest rate of treatment was not significantly different (P>0.05) compared to 0.5 ml but gave 100% adult mortality within 3 days of treatment. The effects were however, significantly different (P<0.05) compared with the untreated control or the solvent-treated seeds. The persistence of the oil at 15 and 30 days after initial cowpea seeds treatments was assessed in separate experiment. The potency of the J. curcas seed oil was reduced with increasing exposure period. Jatropha seed oil therefore, can be incorporated in the insect pest management programme.

Keywords: Cowpea, mortality, persistence, plant product, repellence, seed oil