茶皂素对茶尺蠖幼虫及蜘蛛的毒性测定

Determination of the bioactivities of tea saponin solution to 3rd-instar larvae of Ectropis obliqua and two species of spider

茶尺蠖Ectropisobliqua是我国茶园的主要害虫之一。本研究测定了茶皂素水溶液对茶尺蠖3龄幼虫的毒性及30％（W／v）茶皂素5h表面残留对两种茶园优势种蜘蛛的驱避作用。结果表明：浓度300mg／mL茶皂素处理96h后，茶尺蠖3龄幼虫死亡率为76．66％，致死中浓度LC50为95．65mg／mL。30％茶皂素5h表面残留对三突伊氏蛛Ebrechte Uatricuspidata和白斑猎蛛Evarchaalbaria的驱避率分别为23．38％、14．34％，显著的低于50％丁醚脲乳油（1500×）、10％联苯菊酯乳油（750×）处理（P〈0．05），表明30％茶皂素对蜘蛛的驱避作用低于化学杀虫剂。茶皂素水溶液具有直接作为杀虫剂防治茶尺蠖幼虫的潜力。

Ectropis obliqua Prout is one of the main pests of tea garden in China. In this study, we investigated the toxicity of tea saponin （TS） solution on the 3rd-instar larvae ofE. obliqua and the repellent effect of 5-hour-old residue of 30% tea saponin to two dominant species of spiders in tea garden. The results revealed that the mortality of 3rd-instar larvae of E. oblique was 76.55% after treated by the concentration of 300 mg/ mL TS solution, and LCs0 was 95.55 mg/mL at 95 h. The repellent rates of 5-hour-old residue of 30% （w/v） TS on EbrechteUa tricuspidata, Evarcha albaria was 23.38%, 14.34%, respectively, which significantly lower than 50% diafenthiuron EC （1500 ×） and 10% bifenthrin EC （750 ×） （P 〈 0.05）. The results showed that the repellent effect of 5-hour-old residue of 30% TS was lower than the chemical insecticide. Our experimental results indicated that 30% TS has the potential as insecticide to control the larvae ofE. obliqua.