Chlorantraniliprole emulsified with botanical oils effectively controls invasive pest Spodoptera frugiperda larvae in corn plant

Spodoptera frugiperda (J.E. Smith) is an invasive pest, causing significant corn yield losses. Currently, its control is largely dependent on foliar spray with insecticides. Application of insecticides on the cuticular wax and linear long leaves of corn, however, is sometimes ineffective because sprayed droplets may bounce off the leaves and also S. frugiperda larvaes are deeply embedded in the corn whorl and usually emerge at night. Improving insecticide adhesion on corn leaves could increase control efficacy. In this study, three 20% chlorantraniliprole emulsifiable concentrates (CECs) were formulated using neem, sunflower, and grape seed oils. The wettability, emulsion stability, physicochemical properties, control efficiency, and absorption levels of CECs were evaluated by comparison with a 200 g L −1 chlorantraniliprole suspension concentrate (SC). Results indicated that CECs had appropriate emulsification and wetting properties. The work of adhesion of SC was over 1.4-fold higher than CECs, and the surface tension and contact angle of CECs were 1.87–1.94 and 1.69–2.05-fold lower than SC, respectively, which was effective in reducing chlorantraniliprole drift and improving the deposition. CECs and SC were used for controlling S. frugiperda larvae in corn plants in Guangzhou and Nanning, respectively. Results showed that CECs were 1.45–1.60-fold more effective than SC in reducing S. frugiperda larvae in 14 days. The enhanced control efficacy of CECs was related to its improved adhesion performance on corn leaves as chlorantraniliprole on corn leaves were significantly higher, and half-lives of CECs were longer than SC. Our study suggests that improving adhesion performance of a popular insecticide can significantly improve control efficacy of S. frugiperda larvae in corn plants.