Laboratory toxicity and field efficacy of selected insecticides against fall armyworm, Spodoptera frugiperda (smith) on maize fields

Abstract

Fall armyworm, Spodoptera frugiperda (J.E Smith) (Lepidoptera: Noctuidae, is one of the most important invasive destructive pests. It has a wide range of host plants, from which are maize, rice, sorghum, cotton and vegetables. A laboratory study was conducted to compute baseline dose-mortality responses of 4th instar larvae of S. frugiperda to methomyl, chlorantraniliprole + abamectin and indoxacarb using leaf-dipping technique. In addition, two field experiments were conducted at Sakha (Kafrelsheikh Governorate) and Quotor (Gharbia Governorate), Egypt during 2024 maize season to evaluate the efficacy of the three insecticides against the pest. Indoxacarb was the most toxic insecticide, with LC50 of 15.26 μg/ml, followed by chlorantraniliprole+ abamectin (LC50 32.45 μg/ml), while methomyl was the least toxic (LC50 287.34 μg/ml). Toxicity index values of the three compounds were 5.31, 47.02 and 100.00, respectively. On the other hand, the initial kill ranged from 88.20 to 94.23%. However, residual effects of indoxacarb, chlorantraniliprole+ abamectin and methomyl were 88.41, 85.18 and 73.65%, at maize fields of Gharbia Governorate, and 86.08, 81.76, and 69.01% at fields of Kafrelsheikh Governorate, respectively. These results could be promising against S. frugiperda, and the three insecticides may be efficient candidates against the pest within integrated pest management programs