小菜蛾对几种常用药剂的敏感性测定

采用叶片浸溃法，在2001年10月和2002年10月分别测定了福州上街蔬菜基地的小菜蛾，对10种杀虫剂的敏感性。结果表明，上街菜区小菜蛾对灭多威、杀虫双、辛硫磷、毒死蜱、杀灭菊酯和功夫菊酯等农药极不敏感，已不能有效控制小菜蛾的危害。而小菜蛾对氟啶脲、阿维菌素、氟虫腈和虫螨腈比较敏感。通过两次毒力测定比较(2002年10月的LC50；2001年10月的LC50)，结果表明，大多数杀虫剂敏感性变化较小。但小菜蛾对阿维菌素敏感性明显下降，毒力倍数达6．65倍，对氟虫腈毒力倍数相差1．48倍。此外，2002年10月小菜蛾对功夫菊酯的LC50为2001年10月的2．02倍。用浸叶法和浸溃法测定多杀菌素、氟虫腈与虫螨腈推荐浓度对小菜蛾幼虫的毒杀作用。结果表明3种药剂浸叶法处理效果均较理想。

Susceptability of the diamondback moth Plutella xylostella (L.) to insecticides

Susceptibility levels of diamondback moth to 10 insecticides in Fuzhou were monitored for 2 times in October, 2001 and October, 2002 respectively by leap-dip bioassay. The results showed that larvae of Plutella xylostella were less susceptible to bisultap, methomyl, chlorpyriphos, phoxim, cypermethrin and fenvalerate. However, Plutella xylostella was much more susceptible to fipronil, chlorfenapyr, avermectin and chlorfluazuron. Toxicity ratio of pesticides between 2001 and 2002 showed that susceptibility levels of Plutella xylostella to most tested insecticides fluctuated slightly. Toxicity ratio for avermectin, fipronil and cyhalothrin were 6.65-fold,1.48-fold and 2.02-fold, respectively. The effects of poison of spinosad, fipronil and chlorfenapyr applied by the recommended concentration on larvae of Plutella xylostella (L.) were monitored by leap-dip and leap-dip bioassay. The results showed that the effects of 3 insecticides on Plutella xylostella (L.) by leaf-dip bioassay were all satisfied.