Wirth M C, Marquine M, Georghiou G P, Pasteur N
Department of Entomology, University of California, Riverside 92521.
J Med Entomol. 1990 Mar;27(2):202-6. doi: 10.1093/jmedent/27.2.202.
Two highly active esterases, A2 and B2, were isolated in SeLax, a strain of Culex quinquefasciatus Say from California which demonstrated resistance levels of 19, 14, and 4.3 times to the organophosphate insecticides chlorpyrifos, temephos, and malathion, respectively. Selection of SeLax by temephos during 31 generations increased resistance to this insecticide to 65 times. This resistance was shown to be DEF-suppressible, monofactorial, and strongly associated with the presence of esterases A2 and B2. Although these two esterases are encoded by distinct structural genes, no disjunction was observed when SeLax was crossed to S-Lab, a susceptible strain, or to S54, a strain resistant to organophosphates by means of esterase A1. However, when SeLax was crossed to strain Tem-R, which is resistant to organophosphates because of a highly active esterase B1, all possible recombinants occurred. These results were discussed in relation to the recent discovery that increased activity of B esterases in the genus Culex is caused by gene amplification.
在采自加利福尼亚的致倦库蚊品系SeLax中分离出了两种高活性酯酶A2和B2，该品系对有机磷杀虫剂毒死蜱、双硫磷和马拉硫磷的抗性水平分别为19倍、14倍和4.3倍。在31代期间用双硫磷对SeLax进行选育，使其对该杀虫剂的抗性提高到了65倍。已证明这种抗性是可被DEF抑制的、单因子的，并且与酯酶A2和B2的存在密切相关。尽管这两种酯酶由不同的结构基因编码，但当SeLax与敏感品系S-Lab或通过酯酶A1对有机磷产生抗性的品系S54杂交时，未观察到分离现象。然而，当SeLax与因高活性酯酶B1而对有机磷产生抗性的Tem-R品系杂交时，出现了所有可能的重组体。结合最近发现库蚊属中B酯酶活性增加是由基因扩增引起的这一情况，对这些结果进行了讨论。
