Field Evaluation of Different Insecticides against Shoot Fly [Atherigona approximata (Diptera: Muscidae)] in Browntop Millet

Abstract

Shoot fly is an important seedling pest of millets, but crop-specific evidence for browntop millet remains limited. A two-season field experiment was conducted during the 2023 and 2024 kharif seasons at the Zonal Agricultural Research Station, University of Agricultural Sciences, GKVK, Bengaluru, India, to evaluate nine insecticidal treatments and an untreated control in browntop millet cultivar GPUBT-1. The experiment was arranged in a randomised complete block design with three replications. Three treatments were applied to the seed before sowing and six were applied as foliar sprays seven days after germination. Dead-heart incidence was recorded one day before foliar application and at 3, 5, and 10 days after application. Among the seed treatments, thiamethoxam 30 FS at 10 ml kg-1 seed produced the lowest descriptive seasonal mean dead-heart incidence in both years (14.45% in 2023 and 15.56% in 2024), corresponding to reductions of 50.00% and 55.56%, respectively, relative to the untreated control. Cyantraniliprole 19.8% + thiamethoxam 19.8% FS was the next most consistent seed treatment. Among the foliar treatments, lambda-cyhalothrin 5% EC at 1 ml L-1 produced the lowest incidence at 10 days after application (10.00% in 2023 and 11.11% in 2024). The highest recorded grain yield and descriptive benefit-cost ratio were obtained with thiamethoxam 30 FS seed treatment (805.56 kg ha-1 and 4.39, respectively), followed by lambda-cyhalothrin 5% EC (736.11 kg ha-1 and 3.90). The findings identify thiamethoxam seed treatment and lambda-cyhalothrin foliar application as promising options within their respective application categories. Multi-location validation and compliance with current crop-specific pesticide labels are required before broad operational recommendations.