ABSTRACT The common bean, Phaseolus vulgaris L., is an important legume crop worldwide, mainly in developing countries, due to its nutritional value as a source of protein, vitamins, minerals, and fiber. However, the cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) is a significant pest of common beans in Ethiopia and other countries growing common beans, causing considerable yield losses. The objective of this study is to evaluate the efficacy of different botanicals for the management of cotton bollworm on common bean. The effects of different botanical leaf extracts (leaf extracts of Solanum incanum (2, 5, and 8% w/v), Calpurnia aurea (10, 15, and 20% w/v) and Moringa oleifera (10, 15, and 20% w/v)) at three different concentration levels, on the third larval stage of H. armigera were studied under laboratory conditions. Square dip and larval immersion methods were used in completely randomized design (CRD) arranged laboratory bioassay. The field experiment was conducted under randomized complete block design (RCBD) with three replications to determine the efficacy of botanical extracts against H. armigera. In the square dip method, S. incanum (8%) significantly caused the highest larval mortality at 96 h, (76%), followed by leaf extracts of C. aurea 20% (70%) and M. oleifera 15% (66.67%). In the larval immersion method, S. incanum (8%) significantly caused the highest mortality of 70% followed by M. oleifera (20%) which caused 63.3% mortality, while C. aurea (20%) caused 56.7% mortality at 96 h. Field application of leaf extracts of S. incanum 8%, C. aurea 20% and M. oleifera 15% was most effective in reducing the larval population of H. armigera by 88%, 71.3% and 59.9%, respectively, and pod damage from 29.67% to 13.48% while increasing yields compared to control treatment after 7 days of second round application. On the basis of these findings, it could be concluded that the application of botanical plant extracts in common beans reduced the population of H. armigera while also improving common bean yield. However, more studies should investigate the effect of season and location, as well as the mode of action of potential botanical extracts against the pest.
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