Potentials of Annona muricata Linnaeus (Annonaceae) as a botanical insecticide against Callosobruchus maculatus Fabricius (Coleoptera:Bruchidae)

Abstract

A study was carried out on the bioactivity of ethanolic extract of Annona muricata Linn. (Annonaceae) as protectant at different concentrations (0, 0.25, 0.50, 0.75, 1.00g/L). against Callosobruchus maculatus Fabricius (Coleptera: Bruchidae) in stored cowpea seeds. Its effect was also investigated on adult mortality, oviposition, emergence of F₁progeny, and seed weight under ambient laboratory conditions of 26°C-32°C and 65-88% Relative Humidity. Results showed that ethanolic leaf extract of A.muricata at 1.0g/L significantly (P<0.05) caused 40,80 and 98% mortality of C. maculatus at 24, 48 and 72 hours post-treatment respectively. Similarly, ethanolic leaf extract of A. muricata at 1.0g/L significantly (P<0.05) reduced the oviposition of C. maculatus and the grain weight loss in the treated cowpea seeds. The extract however had no significant effect on the mean number of F1 progeny at the various concentrations. The results clearly showed that the extract of A. muricata had potential as protectant against C. maculatus in stored cowpea. Therefore further work is needed on the characterization of the active ingredient in the leaf and seed extracts of A. muricata and their mechanism of action on this storage insect pest of cowpea.

Keywords: Adult mortality, ethanolic extract, oviposition, F₁progeny.