Efficacy of Selected Insecticides for the Management of Helicoverpa armigera (Hubner) in Tomato Cultivation

A two-year field investigation was conducted at the experimental farm to evaluate the efficacy of seven insecticides—malathion, novaluron, lambda-cyhalothrin, imidacloprid, quinalphos,fenazaquin and thiamethoxam against Helicoverpa armigera in tomato crops. Three dosage levels (1.25 times lower than the recommended, the recommended and double the recommended) were tested, with two applications per season at 10-day intervals. Among the treatments, T8-lambda-cyhalothrin @ 15 g ai ha^-1 and T14-quinalphos @ 250 g ai ha^-1 exhibited the highest efficacy, achieving pooled mean reductions of 83.8 and 82.8%, respectively. Notably, their recommended doses were as effective as double-dose treatments, suggesting minimal advantage from increased application rates. The lowest fruit damage was recorded in treatment T8 (9.4% in 2019 and 10.3% in 2020), followed by T14 (11.7% and 13.1%). In contrast, fenazaquin, thiamethoxam and imidacloprid were the least effective. These findings underscore the importance of selecting appropriate insecticides and adhering to recommended dosages to ensure effective pest management while promoting sustainable agricultural practices.