Plant Extracts as Natural Insecticides: A Study on Bean and Maize Weevils

Abstract

A study was conducted to evaluate the insecticidal action of hexane extracts of three locally available plants
namely: Lantana camara (Verbenaceae), African nutmeg [Monodora myristica (Gaerth) Dunal] and Enuopiri
[Euphorbia lateriflora, Schum and Thonner] against 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. African nutmeg extracts had greater mortality
action against both the beans weevil (100%) and maize weevil (96%) after 24 h of treatment. Lantana extracts
were observed to have moderate mortality effect; bean weevil (93%) and maize weevil (73.3%) while Enuopiri had
average mortality effect; bean weevil (46.7%) and maize weevil (50%) 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 height mortality rate.