Evaluation of phytochemicals from lemon and curry leaves as potential protectants against the beans weevil, Callosobruchus maculatus (Fabs) (Coleoptera: Bruchidae)

Abstract

Three phytochemicals; saponins, flavonoids and alkaloids from two medicinal plants, Cymbopogon citratus (DC.) Stapf, and Murraya koeinigi (L.) Spreng, were evaluated as grain protectant against the beans weevil, Callosobruchus
maculatus (Fabs), in the laboratory at 0.2g, 0.4g, and 0.6g/ml concentration per 100 grains of cowpea. Parameters assessed were adult mortality, adult emergence, grain damage effect and weevil perforation index (WPI). There was increase in adult mortality with increase in concentrations of phytochemicals irrespective of plant type. Phytochemicals from the test plants showed similar mortality pattern with more effectiveness in the first 3 days of treatment. Saponins from both test plants were most potent in adult mortality whereas, flavonoids and alkaloids showed better potency in
adult emergence. The results of the study reveal saponin as a potent botanical against adult C. maculatus, and flavonoid and alkaloid as more potent botanicals against the immature stages of the stored product pest. Hence, flavonoid and alkaloid from both test plants are better bioinsecticide for protecting cowpea grains from C. maculatus infestation and damage.