The onion thrip, Thrips tabaci (Thysanoptera: Thripidae) is a major polyphagous pest that attacks a wide range of economically important crops, especially Allium species. The thrip’s damage can result in yield loss of up to 60% in onions (Allium cepa). In the past few decades, thrip resistance to insecticides with various modes of actions have been documented. These include resistance to spinosad, a major active compound used against thrips, which was reported from Israel. Little is known about the molecular mechanisms underlying spinosad resistance in T. tabaci. We attempted to characterize the mechanisms involved in resistance to spinosad using quantitative transcriptomics. Susceptible (LC50 = 0.6 ppm) and resistant (LC50 = 23,258 ppm) thrip populations were collected from Israel. An additional resistant population (LC50 = 117 ppm) was selected in the laboratory from the susceptible population. De novo transcriptome analysis on the resistant and susceptible population was conducted to identify differently expressed genes (DGEs) that might be involved in the resistance against spinosad. In this analysis, 25,552 unigenes were sequenced, assembled, and functionally annotated, and more than 1500 DGEs were identified. The expression levels of candidate genes, which included cytochrome P450 and vittelogenin, were validated using quantitative RT-PCR. The cytochrome P450 expression gradually increased with the increase of the resistance. Higher expression levels of vitellogenin in the resistant populations were correlated with higher fecundity, suggesting a positive effect of the resistance on resistant populations. This research provides a novel genetic resource for onion thrips and a comprehensive molecular examination of resistant populations to spinosad. Those resources are important for future studies concerning thrips and resistance in insect pests regarding agriculture.

中文翻译：

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从头转录组学方法揭示涉及蓟马烟粉虱对多杀菌素的抗性基因。

洋葱蓟马（Thrips tabaci）（Thysanoptera：Thripidae）是一种主要的多食性害虫，攻击多种重要的经济作物，尤其是葱属。蓟马的损害可能导致洋葱（葱属）的产量损失高达60％。在过去的几十年中，已记录了各种作用方式对杀虫剂的蓟马抗性。这些包括对多杀菌素的抵抗力，这是一种用于抵抗蓟马的主要活性化合物，据以色列报道。烟粉虱多杀性耐药的分子机制知之甚少。我们试图使用定量转录组学来表征涉及对多杀菌素抗性的机制。从以色列收集了易感人群（LC50 = 0.6 ppm）和耐药人群（LC50 = 23,258 ppm）。在实验室中，从易感人群中选择了另外的抗性人群（LC50 = 117 ppm）。对耐药和易感人群进行了从头转录组分析，以鉴定可能与多杀菌素抗性有关的不同表达的基因（DGE）。在此分析中，对25,552个单基因进行了测序，组装和功能注释，并鉴定出1500多个DGE。使用定量RT-PCR验证了候选基因的表达水平，其中包括细胞色素P450和玻璃体生成素。细胞色素P450的表达随着抗性的增加而逐渐增加。卵黄蛋白原蛋白在抗性人群中的较高表达水平与较高的繁殖力相关，表明抗性在抗性人群中具有积极作用。这项研究为洋葱蓟马提供了新的遗传资源，并为对多杀菌素的抗性种群进行了全面的分子检查。这些资源对于有关农业害虫的蓟马和抗性的未来研究非常重要。这项研究为洋葱蓟马提供了新的遗传资源，并为对多杀菌素的抗性种群进行了全面的分子检查。这些资源对于有关农业害虫的蓟马和抗性的未来研究非常重要。这项研究为洋葱蓟马提供了新的遗传资源，并为对多杀菌素的抗性种群进行了全面的分子检查。这些资源对于有关农业害虫的蓟马和抗性的未来研究非常重要。