Effectiveness of thiamethoxam and imidacloprid treated cotton seeds against Bemisia tabaci (Homoptera: Aleyrodidae)

Laboratory, greenhouse and field experiment were conducted to determine the efficacy of seed treatment with thiamethoxam and imidacloprid against Bemisia tabaci on cotton. Under laboratory condition, the two seed treatments caused direct adult mortality, reduced oviposition and increased mortality of hatched nymphs in 10, 20, 30 and 40 d after planting. They were not effective on eggs, and almost all nymphs hatched. The efficacy of the seed treatments against B. tabaci gradually decreased from 10 to 40 d after planting. The two seed treatments were more effective when B. tabaci adults were introduced into clip-on cages on cotton leaves for 24 h than 12 h. Thiamethoxam was more effective than imidacloprid. In greenhouse conditions, the two insecticide treatments were equally effective with higher adult and nymph mortality from10 d to 40 d after planting. Under field conditions, the seeds treated with both insecticides exhibited similar efficacies against B. tabaci for up to 60 days after planting.