Efficacy of Cameroonian Ocimum canum Sims (Lamiaceae) leaf extract fractions against Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae), infesting Bambara groundnut

Abstract

Botanicals could berneco-friendly alternatives to chemical pesticides in stored product protection. Ocimumrncanum leaf powder was sequentially extracted in hexane, acetone andrnmethanol, and the fractions were tested for their potential in protectingrnstored Bambara groundnut seeds against the infestation of Callosobruchusrnmaculatus. Bambara groundnut seeds (50 g) were treated with 1 and 5 g/kg ofrnextract to evaluate the repellence, mortality, F1 progenyrnproduction, seed damage of the beetle as well the persistence of the testrnsubstances. The hexane fraction was more repellent than the other two,rnrecording repellence class V at 1 g/kg. Hexane fraction also showed superiorrntoxicity, causing 100% mortality of C. maculatus at 5 g/kg within 7 daysrnof exposure. All the fractions, at 5 g/kg, somewhat completely inhibitedrnprogeny emergence and seed damage. Hexane fraction had sufficient efficacy tornbe a component of storage pest management package of C. maculatus.