Laboratory evaluation of four medicinal plant essential oils as protestants against the cowpea weevil callosobruchus maculatus (coleoptera : bruchidae)

K. Krishnappa, S. Lakshmanan, K. Elumalai and S. Jayakumar

The four medicinal plant essential oils; Anethum sowa, Cinnamomum zeylanicum, Cuminum cyminum and Citrus reticulata, were evaluated as grain protectant against the Cowpea weevil Callosobruchus maculatus in the laboratory at 250, 500 and 750 ppm Concentrations, parameters assessed were adult mortality, rate of adult emergence, grain damage effect and weevil perforation index (WPI). There was increase in adult mortality with days of exposure in all concentrations. A. sowa followed by C.zeylanicum were most potent both in adult mortality and adult emergence. This study reveals A.sowa to be a potent biopesticide, for protecting cowpea grains from C. maculatus infection and damage. The details of the bioassay procedures used and the results obtained in the present experimentation were discussed in the light of recent literature. These findings are first hand information about efficacy of selected oils against C. maculatus.