Toxicity of three plant extracts against bean weevil, callosobruchus maculatus (f.) and maize weevil, sitophilus zeamais motsch

A study was conducted to evaluate the insecticidal action of hexane extracts of three locally available plants namely: Anisomeles malabarica, Vitex negundo and Murraya koenigii against the bean weevil Callosobruchus maculatus (F.) and maize weevil, Sitophilus zeamais) Motsch with response to the insect mortality. Results revealed that all test materials exhibited mortality action against bean weevil and maize weevil. Anisomeles malabarica extracts had greater mortality action against both the beans weevil (100%) and maize weevil (96.2%) after 24 h of treatment. Vitex negundo extracts were observed to have moderate mortality effect; bean weevil (92.3%) and maize weevil (74.6%) while Murraya koenigii had average mortality effect; bean weevil (48.7%) and maize weevil (54.1%) all with extract concentration of 10 g/100 ml (extract/solvent). The overall results showed that bean weevil was much more susceptible to all the extracts than maize weevil, having recorded the highest mortality rate.