Field evaluation of whorl application of sand mixed or spray insecticides against Spodoptera frugiperda (Lepidoptera: Noctuidae) on yield of maize

Background Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), the fall armyworm (FAW), has recently invaded Egypt and poses serious threats to maize farmers as it causes huge economic costs and yield losses. Selection of efficient insecticides and appropriate methods of application can be a problem to control this pest. Methods Two-year field studies to effectiveness of whorl application (sand mixed or spray) of seven insecticides comprising new insecticides generations with conventional insecticides from different groups at maximum recommended dosage field rate against FAW on yield of maize was evaluated in maize fields at El-Qualubia Governorate, Egypt. Results In plots treated with insecticide mixed in sand, all tested insecticides recorded a significant decrease in FAW larvae with significantly higher yields than those treated with spraying or untreated plots. However, among tested insecticides in both applications, chlorantraniliprole was found to be the most effective followed by emamectin benzoate and spinosad and these insecticides gave better control FAW with higher yield than conventional insecticides tested. In this context, the highest decrease in FAW density was recorded in plots treated with chlorantraniliprole mixed in sand or sprayed (93.69% for 2021; 91.59% for 2022) and (84.74% for 2021; 85.78% for 2022), respectively, as well as a significantly high yield. However, lambda-cyhalothrin recorded the highest density of FAW (33.86% for 2021; 32.72% for 2022) in the treated plots with spraying with lowest significant yield during the 2021 and 2022 seasons in the treated plots with spraying by 8.98 and 8.00%, respectively, increase over control plots. Conclusions These results indicate that insecticides mixed in sand application are more efficacious against FAW larvae along with yield increase than spraying.