TOXICITY OF SOME INSECTICIDES AND THEIR SUBLETHAL EFFECTS ON NUTRITIONAL INDICES OF FALL ARMYWORM IN SWEET CORN PLANT

ABSTRACT: Corn is a vital cereal crop in Bangladesh, significantly contributing to food security and economy. However, the fall armyworm Spodoptera frugiperda, poses a severe threat to corn cultivation. This study evaluates the toxicity of four insecticides and their effect on the nutritional indices of fall armyworm. Experiment was conducted from November 2022 to April 2023 with sweet corn variety BU Misty Vutta 1 at Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur, Bangladesh. In this research four insecticides: Winmax 40 WDG, Ripcord 10 EC, Marshal 20 EC, and Shobicron 425 EC, were tested on fall armyworm larvae at multiple concentrations. The mortality of fall armyworm larvae was observed at 24, 48, 72, and 96 hours after treatment. Results indicated significant differences in larval mortality across treatments, with Shobicron 425 EC showing the highest mortality rate (100% at 72 hours after treatment), while Winmax 40 WDG showed the lowest. The median lethal concentration (LC50) and lethal concentration for 95% mortality (LC95) values supported the findings, with Shobicron 425 EC demonstrating superior efficacy. Additionally, Shobicron 425 EC resulted in the lowest food consumption (0.1), consumption index (0.2), Approximate digestibility (19.5%), Efficiency of conversion of ingested food (3.9%) and Efficiency of conversion of digested food (1.1%). The study concludes that Shobicron 425 EC is the most effective insecticide for controlling fall armyworm in sweet corn, suggesting its potential for integrated pest management strategies. 

Keywords: Food consumption, digestibility, Zea mays, Spodoptera frugiperda, mortality