Response of Cotton jassids to four different insecticides under field condition

Cotton jassid, a key sucking insect pest, has recently become one of the most damaging threats to cotton production in Tanzania, leading to significant yield losses ranging between 30% and 60% when not effectively managed. In response to this growing concern, a field study was conducted during the 2024–2025 growing season at three locations: Misungwi and Bunda in the Western Cotton Growing Area (WCGA), and Kilosa in the Eastern Cotton Growing Area (ECGA). The objective was to evaluate the efficacy of four synthetic insecticides with active ingredient Lambda-cyhalothrin, Chlorpyrifos, Imidacloprid, and Profenofos in controlling jassid populations in cotton fields. The experiment was laid out in a Randomized Complete Block Design (RCBD) with three replications. Insecticides were applied using knapsack sprayers once jassid populations reached the economic threshold level (ETL = 1-2 jassid per plant), at spray intervals of 10 to 14 days. Each treatment was replicated three times across the study sites. Jassid populations were recorded before spraying and at 24, 48 and 72 hours post-application. Population reduction percentages were calculated using Abbott’s formula, and data were analyzed using ANOVA to assess the significance of treatment differences. Results showed that all four insecticides significantly reduced jassid populations compared to the untreated control. Imidacloprid was the most effective insecticide across all sites, followed by Profenofos. For nymphs, Imidacloprid achieved mean reduction rates of 66.95%, 67.89%, and 59.53% at Kilosa, Bunda, and Misungwi, respectively, while Profenofos achieved 57.42%, 52.32%, and 52.79%. For adult jassid, Imidacloprid showed reductions of 66.15%, 60.09%, and 67.86%, while Profenofos achieved 52.31%, 47.00%, and 58.84% at the respective sites. The study concludes that Imidacloprid, when applied at the recommended dosage, offers the most effective and consistent control of cotton jassid and is strongly recommended for inclusion in Integrated Pest Management (IPM) strategies in Tanzanian cotton farming systems