Impact of Biorational Insecticides on the Population of Syrphid Flies in Cowpea under Field Conditions

Abstract

Aim: This study evaluated the impact of selected biorational insecticides on the population of syrphid fly maggots in cowpea under field conditions. Study Design: The experiment was conducted in a randomised block design with eleven treatments, including an untreated control, and three replications. Cowpea variety CPD-119 was sown in plots of 3 m × 2 m at a spacing of 30 cm × 10 cm. Place and Duration of Study: The investigation was carried out at the Instructional Farm, S.K.N. College of Agriculture, Jobner, Jaipur, Rajasthan, India, during the Kharif seasons of 2024 and 2025. Methodology: Syrphid fly maggot populations were recorded from five randomly selected and tagged plants in each plot. Observations were taken one day before spraying and at one, three, seven and ten days after each insecticidal application. The percentage reduction in population was calculated using Henderson and Tilton’s formula and analysed statistically after angular transformation. Results: The pooled data indicated that the tested insecticides differed in their adverse effects on syrphid fly maggots. Fipronil 5 SC caused the greatest reduction in syrphid fly population, followed by spiromesifen 22.9 SC. Flubendiamide 39.35 SC, chlorantraniliprole 18.5 SC, spinosad 45 SC and emamectin benzoate 5 SG showed moderate adverse effects. NSKE 5% and azadirachtin 0.03 EC recorded the lowest reductions, followed by Metarhizium anisopliae 1.15 WP and Lecanicillium lecanii 1.15 WP. Conclusion: Botanical and microbial treatments were comparatively safer to syrphid fly maggots than fipronil and spiromesifen.