Development of Resistance in the Tea Leaf Roller, Caloptilia theivora (Lepidoptera: Gracillariidae), to Diamide Insecticides in Kagoshima Prefecture, Japan

Reduction of control effects by diamide insecticides against eggs and young larvae of the tea leaf roller, Caloptilia theivora (Lepidoptera: Gracillariidae), one of the major pests of tea, was confirmed by field and laboratory tests throughout the tea fields in Minamikyushu, Kagoshima Prefecture, Japan. In the field, chlorantraniliprole, cyantraniliprole and ginotefran were less effective than spinetram and methoxyphenozide, while the latter two showed 95 % or more control effect. In the laboratory, larval mortality by flubendiamide was between 6.9 % and 23.3 % to the Minamikyushu population while 100 % in the other population. Chlorantraniliprole and cyantraniliprole showed similar tendency but the mortality was 26.7 %-70.0 % and 60.4 %-100 %, respectively, depending on the larval stage of treatment. LC50-value of chlorantraniliprole determined in 2018 was drastically increased from the values determined in 2013. The reasons for development of resistance are discussed.