Insecticidal properties of selected plants species used in controlling bean weevils in storage: a case study of Kyabiiri village Bukomansimbi district

Abstract

Bean weevils are granivores seed beetles that infest Phaseolus vulgaris L in storage which affect farmers. Botanicals and pesticides have been used in controlling bean weevils in storage, though these methods pause some challenges to farmers for example, pesticides use is expensive and hazardous and efficacy of botanicals has not been validated. The Objectives of the study included documentation, evaluation and bioassay of botanicals used in controlling bean weevil in storage, through interviews, phytochemical analysis of plant extract and bioassay tests on bean weevils. Our results show that farmers use various herbs such as Capsicum frutescens L, Nicotiana tabacum L and Cupressus lusitanica mill. Incidentally when these plants were tested in bioassay and phytochemical screening, they showed lethal effect on weevils. Active compounds found included alkaloids, phenols, tannins and terpenoids and this was confirmed by various authors who reported neurotoxic, insect repellant and phytoalexin properties of these compounds. From this study, we can conclude that indigenous knowledge when exploited and validated scientifically, it can be useful in controlling pests in storage which offers an economic benefit to most impoverished farmers who can’t afford use of modern pesticides.