Management of Mexican Bean Beetle, Zabrotes subfasciatus (Boheman) (Coleoptera: Chrysomelidae) with Botanical powders and oils in Common Bean (Phaseolus vulgaris L.)

Abstract

Common bean (Phaseolus vulgaris L.) is an essential crop for food security and nutrition mainly for Sub-Saharan African’s smallholder farmers. However, the production and productivity of common bean is mainly constrained by Mexican bean beetles, Zabrotes subfasciatus (Boheman). Thus, the objectives of this study were to evaluate the effectiveness of plant seed powders of neem, Hochst and wild marigold, leaf powders of sweet fennel and broad-leaved croton, plant essential oils of neem and Hochst and African cabbage edible oil at different rates against Z. subfasciatus. All parameters at all botanical seed and leaf powder rates showed a significant difference over the untreated control, except for seed damage at 5 g leaf powders of sweet fennel and broad-leaved croton. Neem, wild marigold, and Hochst at the rates of 5, 10, 15 g/ 150 g, and sweet fennel at 10 and 15 g/ 150 g and broad-leaved croton at 15 g/150 g resulted in 96–100% seed protection, reduced emergence of F1 progeny, seed damage, seed weight loss, and were statistically at par with primphos-methyl. All tested botanical powders recorded 87–100% germination. The botanical oils and mustard cooking oil at rates of 0.5, 1.5, and 3 mL per 150 g common bean produced adult beetle mortality in the range of 93–100% and seed protection of 99–100%. Thus, smallholder farmers can use any of the above indicated botanical powders or oils for post-harvest storage depending on their availability against Z. subfasciatus. Further research on the botanical powders and oils under farmer’s storage condition is important.