Evaluation of Bio-Rational Insecticides for Controlling Hemipteran Sucking Pests and Their Impact on Natural Enemies in Tomato (Lycopersicon esculentum Mill.) Cultivation at Sylhet Region in Bangladesh

Purpose: The purpose of this study was to comprehensively evaluate bio-rational insecticides in controlling major hemipteran-sucking pests of tomatoes and to assess their impact on natural enemies during the winter season of 2023-2024.
Research Method: The experiment was conducted with six treatments applied at 10-days intervals: Spinosad 45 SC, Matrine 1EC, Abamectin 1.8 EC, Azadirachtin 0.03% EC, Cypermethrin 10 EC, and an untreated control. The insecticides’ effectiveness in reducing pest populations (aphids, jassids, and whiteflies) and the number of marketable and infested fruits, yield, adjusted net return, and BCR were recorded to compare the treatments.
Findings and Values: Spinosad 45 SC significantly reduced pest populations, recording the lowest abundance of aphids (3.25-4.18), jassids (0.75-0.90), and whiteflies (1.02-1.18) per six leaves per plant. It produced 88.36% increase in marketable fruits than control. Increases in marketable fruits of other treatments over the control were 63.58%, 44.61%, 36.85%, and 31.25%. Untreated control plots had the highest number of predatory insects, while Spinosad 45 SC-treated plots supported the second highest count (2.85-3.22), followed by Abamectin 1.8 EC (2.42-3.17), Matrine 1EC (2.59-2.94), and Azadirachtin 0.03% EC (2.24-2.79). All bio-rational insecticides were relatively safe for natural enemies, with Cypermethrin 10 EC showing moderate toxicity. The highest yield (21.07 t ha-1), adjusted net return, and Benefit Cost Ratio (BCR) (7.94) were observed in the Spinosad 45 SC treatment, followed by Azadirachtin 0.03% EC (5.51), Abamectin 1.8 EC (4.56), and Cypermethrin 10 EC (3.49). Overall, Spinosad 45 SC proved effective and eco-friendly for managing hemipteran pests in tomato.