Sex ratio distorters and resistance management

害虫每年造成价值数十亿英镑的农作物损失，昆虫疾病媒介传播的疾病导致数百万人死亡。我们依靠“杀生物剂”--化学杀虫剂、生物虫害控制剂等等来控制这些不受欢迎的动物，但它们往往会对我们现有的药剂产生抗药性，从而在整个地球仪上造成最严重的问题。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抗性的进化有重要影响，这就是性别比例扭曲因子的存在-共生微生物或特定类型的基因，这些基因通常会导致许多昆虫和其他节肢动物物种的雌性偏向性性别比例。如果性别比例偏向女性，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，这将是由，例如，增加的可能性，“低质量”的男性将父亲后代时，有一个稀缺的男性。当抵抗力已经进化时，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选择，那么我们可以预测，存在性别比例扭曲因子的种群应该更慢地失去抗性。尽管这些性别比例扭曲因子的存在可能会产生非常重要的后果，尽管它们在许多害虫物种中非常常见，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，这将解决这个知识差距的实验和数学模拟模型的使用。因为实验室实验将果蝇种群暴露于一种名为氯菊酯的拟除虫菊酯类杀虫剂20代，并比较没有性别比例扭曲的“普通”种群与具有共生体性别比例扭曲或遗传性的种群产生抗性的速度。我们还将比较这些种群之间一旦不再接触杀虫剂，抗性丧失的速度。在建模工作中，我们将使用实验室实验的结果来帮助建立害虫物种受到杀虫剂挑战的模拟模型。然后，这些将被用来检查各种管理方案下的抗性进化的潜在影响，无论是现有的性别比扭曲本，引进一个害虫种群或损失之一。这将使我们能够产生一个理论框架的性别比例扭曲的抗性进化和管理的影响，这将是有用的害虫和抗性管理从业者。

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.