取食不同寄主植物的小菜娥对溴氰菊酯和氯氰菊酯敏感性的变化

取食不同寄主植物的小菜蛾３龄幼虫对溴氰菊酯和氯氰菊酯的敏感性发生了变化。其中，以取食萝卜的小菜蛾３龄幼虫最为敏感，其次是甘蓝、菜心、白菜和西洋菜，取食花椰菜的最不敏感。但用不同寄主植物饲养小莱蛾１个完整的世代，再用菜心统一饲养至３龄，用上述药剂生测的结果是，其敏感性差异不明显。本文还对因不同寄主植物诱导的小菜蛾药剂敏感性变化的实质进行了讨论。

EFFECTS OF CRUCIFEROUS HOSTS ON SUSCEPTIBILITY OFDELTAMETHRIN AND CYPERMETHRIN IN THE DIAMONDBACK MOTH,PLUTELLA XYLOSTELLA(L.) (LEPIDOPTERA:PLUTELLIDAE)

The larvae of diamondback moths, Plutella xylostella L.,were fed with pak-choi(Brassica campestris L.ssp. chinensis (L.) Makino var. communis Tsen et Lee),flowering Chineses cabbage(B. campestris L.ssp. chinensis var.utilis Tsen et Lee),cabbage (B. oleracea L. var. capitata L.),cauliflower(B. oleracea L.var botrytis L.),radish(Raphanus sativus L.),and watercress (Nasturtium officinale R.Br)untill they weresprayed with deltamethrin and cypermethrin when larvae developed to the third instar.The observed mortalities were analysed with linear correlation regression models, andthe LC50 calculated.The result of bioassays showed that the larvae of diamondbackmoths fed with different host plants had remarkable differences in susceptibilities toboth of the insecticides sprayed.Compared with the larvae feeding on the other six kindsof food plants,the larvae feeding on radish were the most sensitive and those feeding oncauliflower were the most resistant to both insecticides.The order of susceptibility to allthe insecticides induced by food plants was radish>cabbage>flowering Chinese cabbage>pak-choi>watercress>cauliflower. The quality of the variation in insecticide susceptibility induced by different host plants was also discussed in the paper.