A cost-efficient and alternative technique of managing fall armyworm Spodoptera frugiperda (J.E. Smith) larvae in maize crop

An experiment was conducted to test the efficacy of grease and emamectin benzoate in a randomized complete block design with five replications to reduce fall armyworm, Spodoptera frugiperda (J.E. Smith) larvae load from a maize field in the winter seasons of 2020 and 2021 in Sarlahi, Nepal. Standard agronomic package of practices followed for crop proper growth and development, and plant spacing maintained at 20 × 60 cm(2) with a plot size of 390 m(2). The treatments were applied when the maize crop was at knee height and larvae damaged nearly 5–8% of the total plants. Emamectin benzoate sprayed at 0.4 g/liter of water and grease of about 0.15 g applied to the maize whorl or tip of a drooping leaf that touched the soil. A significant reduction in larval infestation was observed after 7-days of treatment applications. Fall armyworm larvae were found dead in the chemical-sprayed plots, but they were absent in the grease-applied fields. No crop damage was observed among the grease-treated plants, which might be due to restrictions in the movement of larvae on the maize crop. The armyworm larvae might get irritated, feel insecure, and move far away from the test plots searching for food materials. Thus, an eco-friendly material like grease can be used as an agroecological method for managing fall armyworm larvae among small-scale land-holding maize farmers.