Evaluation of the Insecticidal Efficacy of Aloe vera L. Leaf Powder on Adult Bean Weevil (Callosobruchus maculatus (F.))

Abstract

In Sub-Saharan Africa, Callosobruchus maculatus is a significant pest that grossly reduces cowpea yield, leading to economic crop losses and shortages in cowpea supply. Traditional plant powders prepared from indigenous plant parts have been used to provide ecologically tolerable and potentially safe pesticides against this pest. This study evaluated the insecticidal efficiency of Aloe vera leaf powder against adult C. maculatus in cowpea. The toxicity of A. vera leaf powder was assessed using contact toxicity method in cowpea variety black eye at 48 hours and 30 days post treatment. Seed damage rate of C. maculatus was assessed at six treatments (0g/20g, 0.5 g/20 g, 1.0 g/20 g, 1.5 g/20 g, 2.0 g/20 g and 2.5 g/20 g cowpea seeds) using a randomized design, estimating parameters like percentage damage, seed weight loss and adult exit hole after 30 days. The study found no mortality of C. maculatus after 48 hours of infested cowpea seed exposure to A. vera leaf powder. However, a concentration dependent increase in toxicity and decrease in seed damage was observed after 30 days exposure to A. vera leaf powder. Furthermore, maximum mortality of 10.33%, resulting in a 3.33% seed damage reduction, was observed at 2.0 grams of A. vera treatment. The results suggest that A. vera has a low insecticidal effects and low efficacy in protecting against C. maculatus seed damage rates. The bioactive chemicals of the A. vera leaf extracts should be explored to create a potent biopesticide for preventing cowpea loss and enhancing food security.