Application of insecticides by soil drenching before seedling transplanting combined with anti-insect nets to control tobacco whitefly in tomato greenhouses.

Application of chemical pesticides is currently the main effective method to control tobacco whitefly (Bemisa tabaci) in tomato in China. The B. tabaci control efficacy of three systemic insecticides (thiamethoxam, sulfoxaflor and cyantraniliprole) by pre-transplant soil drenching with anti-insect nets throughout the tomato growth period was evaluated in two tomato greenhouses in the suburbs of Beijing, China, in 2018 and 2019. In two greenhouse trials, thiamethoxam 25% water dispersible granules (WDG) at a field rate of 21 g a.i./hm, sulfoxaflor 22% aqueous suspension (AS) at 18 g a.i./hm or cyantraniliprole 10% oil-based suspension concentrate (OD) at 18 g a.i./hm applied via soil drenching before seedling transplanting in combination with white anti-insect nets (50 mesh) all effectively controlled the damage to B. tabaci and resulted in a low density of adults and eggs during the entire growing season, which was significantly lower than application of thiamethoxam, sulfoxaflor or cyantraniliprole via soil drenching before seedling transplanting without anti-insect net treatments or anti-insect nets alone (P < 0.05). All of the above treatments provided significantly better results than the untreated control (P < 0.05). All chemically treated tomato fruits had acceptable insecticide residuals that were lower than the corresponding maximum residue limits. The results suggest that application of thiamethoxam 25% WDG at a field rate of 21 g a.i./hm, sulfoxaflor 22% AS at 18 g a.i./hm or cyantraniliprole 10% OD at 18 g a.i./hm by pre-transplant soil drenching combined with anti-insect nets could be recommended to control B. tabaci throughout the tomato growth period as part of integrated pest management programs in China.