チャノコカクモンハマキ（チョウ目：ハマキガ科）に対するBacillus thuringiensis製剤の殺虫活性に及ぼす寄主植物の影響とそれに関与するポリフェノール

抄録

The smaller tea tortrix, Adoxophyes honmai Yasuda（Lepidoptera: Tortricidae）, a polyphagous pest insect, is a serious pest on 43 plants, including tea. It is well known that tea leaves contain a variety of polyphenols such as catechin derivatives. Since some polyphenols in tea may have an influence on Bacillus thuringiensis activity against A. honmai, we examined how different host plants and the polyphenols of tea leaves influence B. thuringiensis activity. We evaluated B. thuringiensis activity by the leaf dipping method using the leaves of tea, Japanese pear, grape, and peach. The LC₅₀ value for tea was 0.158 g/L（formulation weight/water volume）, whereas Japanese pear, grape, and peach showed significantly lower LC₅₀ values ranging from 0.0095–0.0111 g/L. Hence, it was evident that tea leaves suppressed B. thuringiensis activity compared with other tree leaves. We identified that（−）epigallocatechin gallate（hereafter referred to as EGCG）, （−）epigallocatechin（hereafter referred to as EGC）, （−）epicatechin gallate（hereafter referred to as ECG）, and（−）epicatechin were the major components of tea polyphenols. The influences of polyphenols on B. thuringiensis activity were evaluated by the oral administration method, and EGCG, EGC, ECG, （＋）catechin, and myricetin showed higher inhibitory effects on B. thuringiensis activity compared to other polyphenols. These results indicate that tea leaves can deteriorate the insecticidal activity of B. thuringiensis mainly due to the influence of EGCG, EGC, and ECG.