Efficacy of Vernonia Amygdalina and Calotropis Gigantea in the Control of Some Selected Field Insect Pests of Cowpea (vigna Unguiculata)

ABSTRACT Cowpea (Vigna unguiculata) is an important legume crop cultivated widely in tropical and subtropical regions, valued for its nutritional and economic benefits providing a valuable source of protein, vitamins, and minerals. However, However, its production is heavily threatened by insect pests, which cause serious damage and reduce yield if not properly managed. Chemical pesticides have traditionally been used to control this pest, but there is growing interest in exploring eco-friendly, plant-based alternatives that can effectively manage the pests while minimizing the environmental impact, In a bid to find safer, more environmentally friendly alternatives to chemical insecticides, this study evaluated the effectiveness of two locally available botanicals bitter leaf (Vernonia amygdalina) and giant milkweed (Calotropis procera) in controlling selected field insect pests of cowpea. The experiment was carried out using a Randomized Complete Block Design (RCBD) with four treatments: Aqueous bitter leaf extract, giant milkweed extract, cypermethrin (positive control), and an untreated control (negative control). Data were collected on aphids (Aphis craccivora), pollen beetles (Mylabris pustulata), legume pod borers (Maruca testulalis), and cotton leaf worms (Spodoptera littoralis). mortality, and yield parameters. Findings from the study showed that aqueous bitter leaf extract was the most effective, significantly reducing insect pest populations and resulting in better yield performance (153.33) compared to the other treatments. Although giant milkweed also had some level of insecticidal activity, its effects were less pronounced (32.33). Both botanicals performed far better than the untreated control, demonstrating their potential as bio-insecticides. The results highlight the value of botanical insecticides in sustainable agriculture. Bitter leaf, in particular, proved to be a promising alternative to synthetic chemicals, offering an affordable and eco-friendly option for local farmers. Its use could reduce environmental pollution, lower production costs, and improve food safety by minimizing chemical residues in food crops. This research supports the need for more awareness and practical adoption of botanical pest control methods in smallholder farming systems.