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

We investigated the efficacy of insecticides to control the tea leaf roller, Caloptilia theivora, which is a major pest of tea fields throughout Kagoshima Prefecture. Benzoylurea analog insect growth regulator insecticides（IGRs）exhibited low efficacy against the tea leaf roller in the Nansatsu region（Makurazaki City, Minamikyushu City）. In a subsequent investigation on the sensitivity of different tea leaf roller populations in different regions of Kagoshima Prefecture, the LC50 for flufenoxuron in the Nansatsu population was found to range from 21.5 to 57.0 ppm（resistance ratio of 239- to 356-fold）, confirming the population’s reduced sensitivity. We speculate that this is due to the continuous use of this chemical to control a range of insects, including the tea leaf roller, for more than ten years. In addition, benzoylurea analog IGRs exhibited high efficacy in all other populations outside the Nansatsu region. Meanwhile, diacylhydrazine analog IGRs（methoxyfenozide）, neonicotinoid（dinotefuran）, and diamide（chlorantraniliprole）were confirmed to be effective against the tea leaf roller in all regions of the prefecture. In the future, it will be important to implement integrated pest management using insecticides with different modes of action depending on the region.