Decline of Control Effects of Neonicotinoid Insecticides against Tea Green Leafhopper, Empoasca onukii Matsuda, in Tea Fields

Abstract

Imidacloprid and related neonicotinoid insecticides have been used since 1995 in tea fields in Shizuoka Prefecture against tea green leafhopper, Empoasca onukii Matsuda. Field control tests on E. onukii using imidacloprid or related neonicotinoids have been conducted in our research center every year. These results showed injury prevention rate on new shoots were over 97% until 2002, although the results showed rates less than 50% since 2004. The explanation for this is that the pesticide resistance to neonicotinoids of E. onukii populations in tea fields increased since around 2003.