Dissipation rate of thiacloprid and its control effect against Bemisia tabaci in greenhouse tomato after soil application

摘要

BACKGROUND: Thiacloprid is a chloronicotinyl insecticide that is quite effective against sucking insects. In this study, when thiacloprid was applied at two different rates (normal rate 15 kg ha~(-1), double rate 30 kg ha~(-1)), the systemic distribution and residue of thiacloprid as well as its control effect against whitefly {Bemisia tabaci) were investigated in greenhouse tomato after soil application. RESULTS: The results showed that thiacloprid was present in the tomato leaves until day 25, and then its amount was less than 0.005 mg kg~(-1) and could not be detected. Thiacloprid residue in the tomato stems basically remained at a stable low level throughout the experimental period. Thiacloprid in soil had half-lives of 11.8 and 12.5 days for the normal treatment and the double treatment respectively. The control efficiency of whiteflies was about 90% from day 1 to day 10. This was followed by a slow decline, but efficiency was still higher than 50% until day 21. In addition, no significant differences were noted in the control effect of thiacloprid on whiteflies between the two different rates. CONCLUSION: Soil application of thiacloprid at the normal rate can effectively control whiteflies, with high efficiency and long persistence.