Effectiveness of botanical powders against Callosobruchus maculatus (Coleoptera: Bruchidae) in some stored leguminous grains under laboratory conditions

Abstract

The study investigated the comparative efficacy of some botanicals (Aframomum melegueta (K. M. Schumann) seed, Capsicum nigrum (L.) seed, Allium sativum (Woodwill) bulb, Zingiber officinale (Roscoe) rhizome, Azadiracta indica (A. Juss) leaves and Ocimum gratissimum (L.) leaves) and pirimiphos methyl powder in the suppression of Callosobruchus maculatus (Fabricius) damage in some stored legume (Vigna unguiculata (L.), Vigna subterranea (L.) and Cajanus cajan (L.) seeds. The botanicals were applied at the rate of 0 and 1 g. The pirimiphos methyl powder was applied at 0.1 g. The experiment was laid out in split plot design of eight treatments replicated ten times. Five pairs of oneday old adult C. maculatus were introduced into each jar. Mortality of adult C. maculatus was recorded daily. O. gratissimum was more effective in causing C. maculatus mortality. The LD50 revealed O. gratissimum powder to be the most effective biopesticide. All treatments recorded higher significant (p<0.05) mortality than the experimental control. The proximate analysis of the legumes revealed that the protein content of V. unguiculata was more than others. The phytochemical analysis revealed that alkaloids, steroids, glycosides and terpenoids were present in the botanicals. Out of the six botanicals investigated, O. gratissimum powder was the most effective biopesticide and thus recommended.