Evaluation of insecticides and their application frequency for the management of Russian wheat aphid (Diuraphis noxia M.) on durum wheat in Southeastern Ethiopia

Russian wheat aphid (Diuraphis noxia) is a major pest of durum wheat in Bale, Southeastern Ethiopia, resulting yield losses of 69-93%. This study tested the efficacy of five synthetic insecticides, Dimeto 40% EC, Odimeto 40% EC, Lefothoate 40% EC, Profit 72% EC, and Malamar 50% EC against RWA under field conditions at Sinana, Selka, and Robe during the 2022/23 and 2023/24 growing seasons. Insecticides were applied thrice (tillering, booting, and milky stages) using a randomized complete block design with three replications. Among the evaluated insecticides, Dimeto 40% EC and Odimeto 40% EC showed that the highest efficacy of RWA control with 86.7% and 84.35%, respectively, and yielding 5021.2 kg/ha and 4943.5 kg/ha. These treatments significantly reduced leaf rolling (1.10 and 1.26), leaf chlorosis (1.60 and 1.67), and RWA populations (0.42 and 0.49 per tiller) compared to the untreated control (2.47, 3.20, and 10.41, respectively). Economic analysis revealed net benefits of 223,604 ETB/ha and 220,077.5 ETB/ha for Dimeto and Odimeto, with marginal rates of return of 951.51% and 925.53%, respectively. Lefothoate 40% EC was moderately effective, while Profit 72% EC and Malamar 50% EC showed lower efficacy. Dimeto 40% EC and Odimeto 40% EC are recommended for RWA management, integrated with cultural practices for sustainable control.