INSECTICIAL ACTIVITY OF ACANTHOPSPERMUM HISPIDUM LEAF AND STEM N-HEXANE EXTRACTS ON CALLOSOBRUCHUS MACULATUS FABRICIUS (COLEOPTERA: BRUCHIDAE) ON STORED COWPEA SEEDS (VIGNA UNGUICULATA L.)

Conventional pesticides are synthetic chemicals that are toxic, have hazardous effects on living organisms. Plants based pesticides are chemicals isolated from various plants which could be used to control pests in a non-toxic mechanism. Several plants have certain bioactive compounds which could be used as alternatives to hazardous synthetic pesticides for pest control. Some beetles could damage stored grains and thus causes huge economic losses. For example, Callosbruchus maculatus is a stored grain pest which causes more than 90% damage to sored grains in a few months. In this work, the insecticidal potentials of leaves and stem of Acanthospermu hispidum (common name: Bristly starbur, Yoruba: Dagunro) were investigated against C. maculatus. The leaves and stems were extracted with n-hexane, using Soxhlet extractor. The n-hexane extracts of this plant parts at different dosages were checked against C. maculatus and mortality, oviposition and adult emergence were observed. The leaf and stem extracts were able to cause 100 % adult mortality when treated with 2.0 mL within 96 h of exposure. Oviposition and adult emergence were totally prevented in cowpea seeds exposed to 2.0 mL leaf and stem extracts of A. hispidium. The results of this study revealed that the extracts of this plant could be used for the control of stored cowpea seeds and can serve as an alternative way using less hazardous and more ecofriendly methods in controlling stored grains.