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

虫害是当前和未来粮食安全的主要威胁，全世界每年平均有20%的作物因食草性昆虫而损失。这一问题在巴西尤为严重，农业是巴西经济的重要组成部分，占国内生产总值的26%。巴西的农民和种植者广泛使用合成杀虫剂，试图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出现了对许多用于控制的化学品具有抗性的昆虫害虫种群。在这方面，两个最具经济意义的物种是新热带区的褐蝽（Euschistus heros）和秋粘虫（Spodoptera frugiperda）。E.英雄虫是大豆和蔬菜作物的主要害虫，对棉花和玉米造成严重危害，而S. frugiperda以80多种植物为食，但对玉米的破坏性特别大。对几种重要杀虫剂的抗药性现已在这些物种中出现，并威胁到它们的可持续控制。尽管这个问题很严重，但很少有研究来了解大肠杆菌耐药性的演变。heros和S.并利用这一知识来开发打击其出现和传播的手段。这部分是由于缺乏这些关键害虫物种的基因组资源，特别是在E。英雄该项目建立在关键的“组学”（基因组和转录组）和生物资源的E。heros和S.在第一阶段的泵启动项目中产生的frugiperda，以了解这两种害虫抗性的分子基础。具体地说，我们获得了一个高质量的E.英雄和E. heros和S.这两种昆虫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2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，将有利于两个物种的基因表达图谱的生成，其中将包括数据库和用户友好的网络应用程序，用于研究基因在不同组织的成人或幼虫的表达。这些资源将用于该项目，以确定候选抗性基因在哪里表达，以了解它们如何赋予抗性。更广泛地说，他们的出版物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。这些基因组和生物材料将被用于第二阶段的项目，以了解这些微生物如何以及在多大程度上有助于抗药性，以及如何破坏它们以克服抗药性。这些实验的数据将从根本上推进我们对昆虫如何进化抗药性的理解。此外，所产生的知识将直接应用的重要性，可持续控制这两种害虫。为了将本项目中获得的知识转化为对抗抗药性，我们将开发简单的基于DNA的诊断方法，并使用这些方法来确定田间抗药性的频率和分布，以便为合理的控制决策提供信息，并制定杀虫剂抗药性管理策略。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耐药性破坏化学。

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.