Laboratory evaluation of four medicinal plants as protectants against the maize weevil, Sitophilus zeamais (Mots)

The petroleum ether extract of four medicinal plants; Aristolochia ringens (Vahl), Allium sativum (L), Ficus exasperata (L) and Garcinia kola (H), were evaluated as grain protectant against the maize weevil, Sitophilus zeamais (Mots) in the laboratory at 0.5, 1.0 and 1.5% (w/v) concentrations. Parameters assessed were adult mortality, rate of adult emergence, grain damage effect and weevil peforation index (WPI). There was increase in adult mortality with days of exposure in all concentrations. Ar. ringens followed by Al. sativum were most potent both in adult mortality and adult emergence. This study reveals Ar. ringens to be a potent bioinsecticide for protecting maize grains from S. zeamais infestation and damage. The details of the bioassay procedure used and the results obtained are reported.