Residual toxicity of selected insecticides against Chrysoperla zastrowi sillemi (Esben-Petersen)

A laboratory study was conducted during 2022-23 to assess the relative susceptibility of Chrysoperla zastrowi sillemi (Esben-Petersen) to various insecticides under controlled conditions. Among the treatments, larval and adult mortality was lowest with dimethoate (0.03%), imidacloprid (0.0045%) and thiamethoxam (0.005%), resulting in 2.6, 5.5, and 20.0% larval mortality and 23.3, 44.8, and 47.3% adult mortality, respectively, at 72 h, classifying these insecticides as harmless. In contrast, higher larval and adult mortality was observed with acephate (0.1125%), acephate + cypermethrin (0.0675 + 0.0075%) and fipronil (0.02%), at 77.2, 75.0 and 74.3% for larval and 87.7, 84.4 and 82.7% for adult, respectively, categorizing them as slightly harmful to larva and harmful to adult. These findings highlighting their differential impacts on this beneficial predator, is crucial for integrated pest management strategies.