Liu Shouzhu, Niu Hongtao, Xiao Ting, Xue Chaobin, Liu Zhongde, Luo Wanchun
College of Agriculture, Liaocheng University, Liaocheng 252059, China.
Open Biochem J. 2009;3:9-13. doi: 10.2174/1874091X00903010009. Epub 2009 Jan 26.
Using microtitration method, the relationship between Phenoloxidase activity and the resistance of the diamondback moth Plutella xylostella (Linnaeus) to the novel insecticide butane-fipronil was determined in vitro. After selection of the tenth-generation by butane-fipronil, the resistance of the fourth instar larvae was increased 83.80-fold as compared to the susceptible strain. Phenoloxidase activity of the resistant strain (PO(r)) was 1.29-fold higher than the susceptible one (PO(s)). However, the Km and optimum pH values were similar in resistant and susceptible strains, which were 1.11 mM and 6.5, respectively. Both PO(r) and PO(s) have maximum stability at pH values less than 7.0, although PO(s) was less stable at lower pH values than PO(r). In addition, the thermal stabilities of the two phenoloxidase were very similar. It is suggested that PO may play an important role in the increasing resistance of pests to pesticides.
采用微量滴定法，在体外测定了小菜蛾（Plutella xylostella (Linnaeus)）酚氧化酶活性与对新型杀虫剂丁氟虫腈抗性之间的关系。经丁氟虫腈筛选十代后，四龄幼虫的抗性相较于敏感品系提高了83.80倍。抗性品系的酚氧化酶活性（PO(r)）比敏感品系（PO(s)）高1.29倍。然而，抗性品系和敏感品系的米氏常数（Km）和最适pH值相似，分别为1.11 mM和6.5。尽管在较低pH值下PO(s)比PO(r)更不稳定，但PO(r)和PO(s)在pH值小于7.0时都具有最大稳定性。此外，两种酚氧化酶的热稳定性非常相似。这表明酚氧化酶可能在害虫对杀虫剂抗性增强中起重要作用。
