Understanding the evolution of insecticide resistance in Brazilian crop pests: Towards effective Insecticide Resistance Management (IRM)

害虫是当前和未来粮食安全的主要威胁，全世界每年平均有20%的作物因食草昆虫而损失。这个问题在巴西尤为严重，因为农业是经济的关键组成部分，占国内生产总值（GDP）的26%。巴西的农民和种植者广泛使用合成杀虫剂，以减少虫害造成的产量损失。不幸的是，对杀虫剂的日益依赖导致了害虫种群的出现，这些种群对用于控制的许多化学品具有抗药性。在这方面最重要的两个经济物种是新热带褐臭虫（Euschistus heros）和秋粘虫（Spodoptera frugiperda）。e .英雄是大豆和蔬菜作物的重要害虫,导致严重破坏棉花和玉米,而美国frugiperda以超过80植物物种但尤其具有破坏性的玉米。这些物种现已出现对几种重要杀虫剂的抗药性，并威胁到对它们的可持续控制。尽管这一问题很严重，但很少进行研究来了解E. heros和S. frugiperda的耐药性演变，并利用这一知识制定对抗其出现和传播的方法。这在一定程度上是由于缺乏这些主要害虫物种的基因组资源，特别是在英雄e的情况下。该项目建立在第1阶段泵-prime项目中获得的英雄棘球绦虫和frugiperda的关键“组学”（基因组和转录组学）和生物学资源的基础上，以了解这两种害虫抗性的分子基础。具体来说，我们生成了高质量的英雄和英雄菌株的基因组序列草图，英雄和S. frugiperda具有共同的遗传背景，但对几种杀虫剂的敏感性不同。这些资源将在第二阶段项目中利用，以确定与抗性相关的候选基因和遗传变异，并使用转基因方法验证其因果作用。了解这些基因在抗性中的作用将有助于这两个物种的基因表达图谱的生成，该图谱将包括数据库和用户友好的web应用程序，用于研究成虫或幼虫不同组织中的基因表达。这些资源将用于该项目，以确定候选抗性基因在何处表达，以便了解它们如何赋予抗性。更广泛地说，他们的出版将加速这些害虫物种的广泛功能基因组研究，超出了本项目的范围。第一阶段项目的另一个关键成果是描述了两种害虫肠道中存在的微生物群落（微生物组），并鉴定了降解农药的肠道细菌。所产生的基因组和生物材料将用于第二阶段项目，以了解这些微生物如何以及在多大程度上促成耐药性，以及如何破坏它们以克服耐药性。这些实验的数据将从根本上促进我们对昆虫如何进化出对杀虫剂的抗性的理解。此外，所产生的知识将对可持续地控制这两种有害生物具有直接的应用重要性。为了将本项目获得的知识转化为对抗耐药性，我们将开发简单的基于dna的诊断方法，并利用这些方法确定田间耐药性的频率和分布，以便为合理的控制决策提供信息，并制定杀虫剂耐药性管理战略。此外，我们将开发筛选工具（重组酶测定或转基因昆虫系），可用于学术界和工业界开发抗性突破化学。

Insect pests represent a major threat to current and future food security with an average of 20% of crops worldwide lost annually to herbivorous insects. This issue is particularly acute in Brazil where agriculture forms a key component of the economy accounting for 26% of gross domestic product (GDP). Synthetic insecticides are widely used by farmers and growers in Brazil in an attempt to reduce yield loss from insect pests. Unfortunately, the growing reliance on insecticides has resulted in the emergence of insect pest populations that are resistant to many of the chemicals used for control. Two of the most economically important species in this regard are the neotropical brown stink bug, Euschistus heros, and the fall armyworm, Spodoptera frugiperda. E. heros is a major pest of soybean and vegetable crops and causes severe damage to cotton and maize, while S. frugiperda feeds on more than 80 plant species but is particularly destructive on maize. Resistance to several important insecticides has now emerged in these species and threatens their sustainable control. Despite the seriousness of this issue very little research has been carried out to understand the evolution of resistance in E. heros and S. frugiperda and to use this knowledge to develop means to combat its emergence and spread. This is, in part, due to a lack of genomic resources for these key pest species - particularly in the case of E. heros. This project builds on key 'omic' (genomic and transcriptomic) and biological resources for E. heros and S. frugiperda generated in a stage 1 pump-prime project to understand the molecular basis of resistance in the two pest species. Specifically, we generated a high quality draft genome sequence of E. heros and strains of E. heros and S. frugiperda that share a common genetic background but differ in their susceptibility to several insecticides. These resources will be exploited in the stage 2 project to identify candidate genes and genetic variation associated with resistance and their causal role validated using transgenic approaches. Understanding the role of these genes in resistance will be facilitated by the generation of gene expression atlases for both species which will comprise databases and user-friendly web applications for studying the expression of genes in different tissues of adults or larvae. These resources will be used in the project to identify where candidate resistance genes are expressed in order to understand how they confer resistance. More broadly their publication will accelerate broad functional genomic research in these pest species beyond the scope of this project. Another key output of the stage 1 project was characterisation of the microbial community (the microbiome) present in the gut of both pest species and the identification of gut bacteria that degrade pesticides. The genomic and biological material generated will be used in the stage 2 project to understand how and to what extent these microbes contribute to resistance, and how they might be disrupted in order to overcome resistance.The data from these experiments will fundamentally advance our understanding of how insects evolve resistance to insecticides. Furthermore, the knowledge generated will be of direct applied importance in relation to the sustainable control of both pest species. To translate the knowledge gained in this project to combat resistance we will develop simple DNA-based diagnostics, and use these to determine the frequency and distribution of resistance in the field in order to inform rational control decisions and develop insecticide resistance management strategies. Furthermore, we will develop screening tools (recombinant enzyme assays or transgenic insect lines) that can be used by academia and industry to develop resistance-breaking chemistry.