小菜蛾对阿维菌素B_1抗药性选育及交互抗性

用阿维菌素B_1(abamectin)对小菜蛾敏感种群在室内进行抗性品系选育。经过25代连续汰选,获得抗性种群Laba-R,与选育前比较,抗性提高100倍。Laba-R种群在不接触任何药剂条件下饲养20代,抗性逐渐下降,很难恢复到选育前的敏感状态。抗性汰选前后分别测定10种药剂的剂量-死亡率毒力回归线,发现Laba-R抗性种群对乙酰甲胺磷、锐劲特、灭多威、敌敌畏不存在交互抗性;对溴氰菊酯、氯氰菊酯、杀虫双、巴丹和Bt的敏感性略有下降,但无明显交互抗性。活体增效剂试验表明,增效醚(PBO)和磷酸三苯酯(TPP)对阿维菌素B_1均有明显的增效作用,其中PBO的增效活性尤为显著,它能使对阿维菌素B_1产生100多倍抗药性的小菜蛾完全恢复其敏感性。说明多功能氧化酶解毒代谢增强可能是小菜蛾对阿维菌素B_1产生抗性的主导因素之一。

SELECTION FOR ABAMECTIN RESISTANT STRAINS IN DIAMOND BACK MOTH AND PATTERNS OF CROSS-RESISTANCE

An abamectin resistant strain (Laba-R) of diamond back moth, Plutella xylostella L. was obtained by laboratory selection of a susceptible strain with abamectin in successive generations. After 25 generation s selection, the resistance of the moth to abamectin increased 100-fold. The slow reversion to susceptibility of Laba-R strain was observed when the moth was kept without exposure to the chemical pressure. The susceptibility of the Laba-R strain to other insecticides were tested. The results showed that the resistant strain had no cross-resistance to acephate, methomyl, dichlorvos and fipronil, but the susceptibility to deltamethrin, cypermethrin, dimehypo, cartap and microbial insecticide Bt had slightly decreased. The results of the synergist tests showed that PBO and TPP significantly increased the toxicity of abamectin in Laba-R strain, especially PBO. The syn-ergism ratio was 110 times for PBO and 5 times for TPP. It seems that MFO is an important factor for the resistance of moth to abamectin.