Table_4_Genome Mining and Expression Analysis of Carboxylesterase and Glutathione S-Transferase Genes Involved in Insecticide Resistance in Eggplant Shoot and Fruit Borer, Leucinodes orbonalis (Lepidoptera: Crambidae).XLSX

The shoot and fruit borer, Leucinodes orbonalis (Lepidoptera: Crambidae) is the major cause of low productivity in eggplant and insecticides being the mainstay of management of L. orbonalis. However, field control failures are widespread due to the evolution of insecticide resistance. Taking advantage of the whole genome sequence information, the present study investigated the level of insecticide resistance and the expression pattern of individual carboxylesterase (CE) and glutathione S-transferases (GSTs) genes in various field collected populations of L. orbonalis. Dose-mortality bioassays revealed a very high level of resistance development against fenvalerate (48.2–160-fold), phosalone (94-534.6-fold), emamectin benzoate (7.2–55-fold), thiodicarb (9.64–22.7-fold), flubendiamide (187.4–303.0-fold), and chlorantraniliprole (1.6–8.6-fold) in field populations as compared to laboratory-reared susceptible iso-female colony (Lo-S). Over-production of detoxification enzymes viz., CE and GST were evident upon enzyme assays. Mining of the draft genome of L. orbonalis yielded large number of genes potentially belonging to the CE and GST gene families with known history of insecticide resistance in other insects. Subsequent RT-qPCR studies on relative contribution of individual genes revealed over-expression of numerous GSTs and few CEs in field populations, indicating their possible involvement of metabolic enzymes in insecticide resistance. The genomic information will facilitate the development of novel resistance management strategies against this pest.

茄梢果实螟（Leucinodes orbonalis，鳞翅目：草螟科）是导致茄子产量低下的主要害虫，而杀虫剂始终是防治该螟虫的核心手段。然而，随着抗药性的演化，田间防治失败的案例已广泛蔓延。本研究依托全基因组序列信息，对多份田间采集的茄螟种群的抗药性水平，以及各羧酸酯酶（carboxylesterase, CE）、谷胱甘肽S-转移酶（glutathione S-transferases, GSTs）基因的表达模式展开了系统探究。剂量-死亡率生物测定结果显示，相较于实验室饲养的敏感单雌种群（Lo-S），田间种群对氰戊菊酯（fenvalerate，48.2~160倍）、伏杀硫磷（phosalone，94~534.6倍）、甲氨基阿维菌素苯甲酸盐（emamectin benzoate，7.2~55倍）、硫双威（thiodicarb，9.64~22.7倍）、氟苯虫酰胺（flubendiamide，187.4~303.0倍）以及氯虫苯甲酰胺（chlorantraniliprole，1.6~8.6倍）均产生了极高水平的抗药性。酶活性检测结果证实，解毒酶类即羧酸酯酶与谷胱甘肽S-转移酶存在显著的过量表达现象。通过对茄螟草图基因组的挖掘，本研究获取了大量潜在隶属于羧酸酯酶与谷胱甘肽S-转移酶基因家族的基因，这类基因在其他昆虫中已被证实与杀虫剂抗药性密切相关。后续针对单个基因相对贡献的实时定量逆转录PCR（RT-qPCR）分析显示，田间种群中大量谷胱甘肽S-转移酶基因与少量羧酸酯酶基因出现了过量表达，表明这些代谢酶可能参与了杀虫剂抗药性的形成过程。该基因组信息将为针对该害虫的新型抗药性防治策略研发提供重要支撑。