Sex ratio distorters and resistance management

害虫每年造成价值数十亿英镑的作物损失，昆虫病媒介传播的疾病导致数百万人死亡。我们依靠“杀菌剂”——化学杀虫剂、生物害虫控制剂等等来控制这些不受欢迎的动物，但它们经常对我们现有的药物产生抗药性，在全球范围内造成了最严重的问题。了解导致抗性进化的机制对于我们管理害虫以避免这种情况是必要的。动物生物学的一个方面可能对耐药性的进化有重要影响，那就是性别比例扭曲者的存在——要么是共生微生物，要么是导致许多昆虫和其他节肢动物的性别比例（通常）偏向雌性的特定基因。如果性别比例偏向于女性，进化的速度可能会降低，我们可以预测进一步的影响，这将减缓进化的速度，例如，当男性稀缺时，“低质量”男性成为后代父亲的可能性增加。当抗性已经进化时，性别比例扭曲的进一步影响可能会出现：在这种情况下，如果通过停止使用杀虫剂来消除抗性的选择，那么我们可以预测，存在性别比例扭曲的种群应该会更慢地失去抗性。尽管这些性别比例扭曲的存在可能带来非常重要的后果，尽管它们非常普遍，在许多害虫物种中都有发现，但这些影响从未在实验或理论上进行过研究。我们提出了一个项目，该项目将通过实验和使用数学模拟模型来解决这一知识差距。因为实验室实验将把果蝇种群暴露在一种叫做氯菊酯的拟除虫菊酯杀虫剂中20代，并比较没有性别比例扭曲的“普通”种群与有共生性别比例扭曲的种群或有遗传性别比例扭曲的种群产生抗药性的速度。我们还将比较一旦一个种群不再接触杀虫剂，这些种群之间抵抗力丧失的速度。在建模工作中，我们将使用实验室实验的结果来帮助建立杀虫剂挑战害虫物种的模拟模型。然后，这些数据将被用来检查在各种管理方案下对抗性进化的潜在影响，这些方案要么是现有的性别比例扭曲者存在，要么是向害虫种群引入一种扭曲者，要么是失去一种扭曲者。这将使我们能够为性别比例扭曲对抗性进化和管理的影响产生一个理论框架，然后对害虫和抗性管理从业者有用。

Pest insects cause the loss of billions of pounds worth of crops every year, and insect disease vectors spread diseases that kill millions of people. We rely on "biocides" - chemical pesticides, biological pest control agents and so on to control these unwelcome animals, but they often evolve resistance to the agents that we have available, causing a most serious problem throughout the globe. An understanding of the mechanisms that lead to the evolution of resistance is necessary to allow us to manage pests in order to avoid this. One aspect of an animal's biology that might have important effects on the evolution of resistance is the presence of sex ratio distorters - either symbiotic microorganisms or specific kinds of genes which cause (usually) female-biased sex ratios in many species of insect and other arthropods. If the sex ratio is biased towards females the speed of evolution might be reduced, and we can predict further effects which should slow the speed of evolution which will be caused by, for example, the increased possibility that "low quality" males will father offspring when there is a scarcity of males. A further effect of sex ratio distorters could arise when resistance has already evolved: in this case, if the selection for resistance is removed, by ceasing use of a pesticide for example, then we would predict that populations with a sex ratio distorter present should lose their resistance more slowly.Despite these potentially very important consequences of the presence of these sex ratio distorters, and despite the fact that they are extremely common and found in many pest species, these effects have never been studied experimentally or theoretically. We propose a project which would address this knowledge gap both experimentally and also by the use of mathematical simulation models. For the laboratory experiments would would expose fruit fly populations to a pyrethroid pesticide called permethrin for twenty generations, and compare how rapidly "ordinary" populations without a sex ratio distorter develop resistance with populations with either a symbiont sex ratio distorter or a genetic one. We would also compare the speed by which resistance is lost once a population is no longer exposed to a pesticide between these populations.For the modelling work, we would use the results from our laboratory experiments to help build simulation models of pest species being challenged with biocides. These would then be used to examine the potential effects on resistance evolution under a variety of management schemes with either an existing sex ratio distorter present, the introduction of one to the pest population or the loss of one. This would allow us to generate a theoretical framework for the impacts of sex ratio distorters on resistance evolution and management which would then be of use to pest and resistance management practitioners.