Caron V, Myers J H
University of British Columbia, Department of Zoology, Vancouver, BC, Canada.
Bull Entomol Res. 2008 Jun;98(3):317-22. doi: 10.1017/S0007485307005597. Epub 2008 Feb 7.
Development of resistance to insecticides has generally been associated with fitness costs that may be magnified under challenging conditions. Lepidopterans which are resistant to the biopesticide Bacillus thuringiensis subsp. kurstaki (Btk) have been shown to have reduced fitness, such as lower survival when subjected to overwintering stress. Recently, resistance to Btk has been found in some populations of Trichoplusia ni Hübner in greenhouses in British Columbia. This situation provides an opportunity to investigate potential trade-offs between overwintering survival and insecticide resistance in a major pest species. Here, we assess the survival and eventual fecundity of Btk resistant and susceptible T. ni pupae exposed to cool temperatures. Contrary to our expectations, resistant T. ni had higher overwintering survival than susceptible individuals. This is the first account of a potential advantage associated with Btk resistance. Resistant and susceptible moths had reduced fecundity and smaller progeny after cold exposure compared to controls, and this may counteract the survival advantage. Nevertheless, it seems unlikely that this is sufficient to select out the resistant phenotype in the presence of strong selection for resistance and in the absence of immigration of susceptible moths. The appearance of resistance without evidence of a trade-off in overwintering survival presents a major challenge to management in production greenhouses.
对杀虫剂产生抗性通常与适合度代价相关，而在具有挑战性的条件下，这种代价可能会被放大。对生物杀虫剂苏云金芽孢杆菌库尔斯塔克亚种（Btk）具有抗性的鳞翅目昆虫已被证明适合度降低，例如在越冬压力下存活率较低。最近，在不列颠哥伦比亚省温室中的一些粉纹夜蛾种群中发现了对Btk的抗性。这种情况为研究一种主要害虫物种在越冬存活和抗杀虫剂性之间潜在的权衡提供了机会。在此，我们评估了暴露于低温下的抗Btk和敏感粉纹夜蛾蛹的存活率及最终繁殖力。与我们的预期相反，抗Btk的粉纹夜蛾越冬存活率高于敏感个体。这是首次报道与Btk抗性相关的潜在优势。与对照组相比，经冷暴露后，抗性和敏感蛾的繁殖力降低且后代较小，这可能会抵消存活优势。然而，在存在对抗性的强烈选择且没有敏感蛾迁入的情况下，这似乎不足以淘汰抗性表型。在越冬存活方面没有权衡证据的情况下抗性的出现，给生产温室中的管理带来了重大挑战。
