Gassmann Aaron J, Stock S Patricia, Carrière Yves, Tabashnik Bruce E
Department of Entomology, University of Arizona, Tucson, AZ 85721, USA.
J Econ Entomol. 2006 Jun;99(3):920-6. doi: 10.1603/0022-0493-99.3.920.
The widespread use of crop plants genetically engineered to produce toxins from the bacterium Bacillus thuringiensis (Bt) imposes selection on insect populations to evolve resistance. The pink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae), is a major pest of cotton in the southwestern United States that is currently controlled with transgenic cotton that produces Bt toxin Cry1Ac. Previously reported theoretical work suggests that, in conjunction with a high dose/refuge strategy, fitness costs of Bt resistance can slow or prevent the evolution of resistance. We report here that the entomopathogenic nematode Steinernema riobrave (Rhabditida: Steinernematidae) increased the fitness cost of resistance to Cry1Ac in P. gossypiella. Mortality of P. gossypiella from fourth instar to adult eclosion was significantly higher for a Bt-resistant strain than a susceptible strain in tests with two to 14 infective juveniles of S. riobrave per larva, but it did not differ between strains when nematodes were absent. Nematodes established in P. gossypiella larvae at all concentrations tested, and nematode reproduction in infected P. gossypiella larvae occurred at nematode concentrations of four to 14 infective juveniles per larva. Our results suggest that incorporation of entomopathogenic nematodes into an integrated resistance management strategy could help to delay pest resistance to Bt toxins.
广泛种植经基因工程改造以产生苏云金芽孢杆菌（Bt）毒素的作物，会对昆虫种群施加选择压力，促使其进化出抗性。棉铃虫，Pectinophora gossypiella（桑德斯）（鳞翅目：麦蛾科），是美国西南部棉花的主要害虫，目前通过产生Bt毒素Cry1Ac的转基因棉花进行防治。先前报道的理论研究表明，结合高剂量/庇护所策略，Bt抗性的适合度代价可以减缓或阻止抗性的进化。我们在此报告，昆虫病原线虫斯氏线虫Steinernema riobrave（小杆目：斯氏线虫科）增加了棉铃虫对Cry1Ac抗性的适合度代价。在每头幼虫接种2至14条斯氏线虫的试验中，Bt抗性品系的棉铃虫从四龄幼虫到成虫羽化的死亡率显著高于敏感品系，但在没有线虫的情况下，两个品系之间的死亡率没有差异。在所测试的所有浓度下，线虫都能在棉铃虫幼虫体内定殖，并且在每头幼虫接种4至14条感染性幼虫的线虫浓度下，感染的棉铃虫幼虫体内有线虫繁殖。我们的结果表明，将昆虫病原线虫纳入综合抗性管理策略中，有助于延缓害虫对Bt毒素的抗性。
