Preparation of a Chlorantraniliprole–Thiamethoxam Ultralow-Volume Spray and Application in the Control of Spodoptera frugiperda

[Image: see text] Traditional pesticide spraying methods such as knapsack sprayers are inefficient. Ground application equipment is restricted by the terrain and damages the crops. Pesticides cannot be sprayed over a large area in a short time; thus, when there are concentrated outbreaks of pests with strong migration capacity, such as Spodoptera frugiperda, pests could not be controlled in a small area. Therefore, it is difficult to achieve a satisfactory control effect. Plant protection unmanned aerial vehicles (UAVs) have high efficiency and spray pesticides at low altitude and can suitably prevent and control the outbreak of pests. However, pesticide formulations suitable for UAVs are rare. In this study, we developed ultralow-volume (ULV) sprays suitable for plant protection UAVs. We studied their properties and found that the ULV sprays have good wettability and can be fully spread. The minimum contact angle on corn leaves is up to 19°, and the maximum retention is 2.7 times that of the reference product. They also have superior resistance to rain washout and can effectively extend the duration and utilization of pesticides. When sprayed by plant protection UAVs, the decrease rate of the ULV spray at 3 L/ha to S. frugiperda larvae is 81.31% and the control effect is 83.01%, both higher than those of the reference product 40% chlorantraniliprole–thiamethoxam water-dispersible granules (decrease rate 67.39%, control effect 70.35%), sprayed with a knapsack sprayer.