Tea Pesticide Residue Condition In Hunan And Screening High Insecticides Against The Ectropis Oblique Prout

Tea production was seriously restricted by the high pesticide residue level. In order to ascertain the pesticide residue origin, we detected 680 tea samples in Hunan province, the results were as follows:1. Residue of 15.6% samples were higher than their MRL in green tea, and 26.1% samples were higher in black tea.2. S421, Fenvalerate, Fenpropathrin, Esfenvalerate were serious and universal in Hunan.3. The detected rate of S421 in the north tea area was 25.57%. It was also high in east tea area of Hunan, Esfenvalerate was the second, the detected rate was7.95%. Esfenvalerate was the highest in central Hunan, the detected rate was 7.39%, the second was Fenvalerate ,with the 5.11% detected rate.4. Fenvalerate, Esfenvalerate were all detected in 14 fresh leaf samples, but below their MRL.The Ectropis oblique Prout is a major tea pest in Hunan. The pest status has increased recently in various areas of Hunan. It is very difficult to control because of its resistance to action of pesticide. The screening of high insecticides against the Ectropis oblique Prout were studied.1. Laboratory studies were carried out on the toxicity of fifteen insecticides to 3rd instar larvae. LC₅₀'s showed that 0.2% emamectin benzoate, 10% chlorfenapyr, 0.3% azadirachtin and 5% hexafluazuron were more effective on the Ectropis oblique Prout, the LC₅₀ were 0.475mg/L (48h) ,9.877mg/L (48h) ,8.02mg/L (72h) and 25.954mg/L.2. In the field the control efficiency of 0.2% emamectin benzoate on the Ectropis oblique Prout was 95.99% as this pesticide was diluted to 2000 times and the...