Comparative assessment of toxicity of selected insecticides against key sucking insect pests of cotton

Abstract

Sucking insect pests, including Bemisia tabaci (whitefly), Amrasca devastans (jassid), and Thrips tabaci (thrips), cause substantial yield losses in cotton, with reported reductions of up to 40%. To evaluate effective management options, a field experiment was conducted in Muzaffargarh, South Punjab, Pakistan, to assess the toxicity of five insecticides, Nitenpyram, Acephate, Amidecloprid, Buprofezin, and Diafenthiuron, against Bt cotton (Gossypium hirsutum L. cv. IUB-B). The experiment was laid out in a randomized complete block design with three replications, and pest populations were recorded at 24, 48, and 72 h after insecticide application. The results revealed that all insecticidal treatments significantly reduced pest populations compared with the untreated control (p < 0.05). Among the tested insecticides, Acephate exhibited the highest overall efficacy, reducing B. tabaci populations to 3.64 individuals at 48 h compared with 15.56 individuals in the control, and completely suppressing T. tabaci populations by 72 h (control: 4.02 individuals). Diafenthiuron was particularly effective against A. devastans, reducing its population to zero within 48 h, compared with 14.9 individuals in the untreated plots. Nitenpyram and the remaining insecticides also caused significant population reductions, though to a comparatively lesser extent. These findings demonstrate the strong field efficacy of Acephate and Diafenthiuron against major cotton sucking pests. However, prolonged reliance on chemical insecticides may accelerate resistance development and pose environmental risks. Therefore, the integration of these insecticides into an Integrated Pest Management framework, incorporating insecticide rotation, biological control agents, and reduced chemical inputs, is strongly recommended to ensure sustainable and long-term pest management in cotton production systems.