Abstract The melon/cotton aphid, Aphis gossypii Glover, is a notorious pest in many crops. The neonicotinoid insecticide thiamethoxam is widely used for A. gossypii control. To evaluate thiamethoxam resistance risk, a melon/cotton aphid strain with an extremely high level of resistance to thiamethoxam (>2,325.6-fold) was established after selection with thiamethoxam for 24 generations. Additionally, the cross-resistance pattern to other neonicotinoids and fitness were analyzed. The cross-resistance results showed the thiamethoxam-resistant strain had extremely high levels of cross-resistance against clothianidin (>311.7-fold) and nitenpyram (299.9-fold), high levels of cross-resistance against dinotefuran (142.3-fold) and acetamiprid (76.6-fold), and low cross-resistance against imidacloprid (9.3-fold). Compared with the life table of susceptible strain, the thiamethoxam-resistant strain had a relative fitness of 0.950, with significant decreases in oviposition days and fecundity and prolonged developmental duration. The molecular mechanism for fitness costs was studied by comparing the mRNA expression levels of juvenile hormone acid O-methyltransferase (JHAMT), juvenile hormone-binding protein (JHBP), juvenile hormone epoxide hydrolase (JHEH), ecdysone receptor (EcR), ultraspiracle protein (USP), and Vitellogenin (Vg) in the susceptible and thiamethoxam-resistant strains. Significant overexpression of JHEH and JHBP and downregulation of EcR and Vg expression were found in the thiamethoxam-resistant strain. These results indicate that A. gossypii has the potential to develop extremely high resistance to thiamethoxam after continuous exposure, with a considerable fitness cost and cross-resistance to other neonicotinoids.

中文翻译：

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甜瓜和棉蚜（半翅目：蚜科）对噻虫嗪的抗性的交叉抗性和适应成本分析

摘要 瓜/棉蚜虫 Aphis gossypii Glover 是许多作物中的一种臭名昭著的害虫。新烟碱类杀虫剂噻虫嗪广泛用于控制棉线虫。为了评估噻虫嗪的耐药风险，在用噻虫嗪选择 24 代后，建立了对噻虫嗪具有极高水平（> 2,325.6 倍）的甜瓜/棉花蚜虫品系。此外，还分析了对其他新烟碱类和适应性的交叉耐药模式。交叉耐药结果显示，噻虫嗪耐药菌株对噻虫胺（>311.7倍）和烯啶虫胺（299.9倍）的交叉耐药水平极高，对呋虫胺（142.3倍）和啶虫脒的交叉耐药水平高（76.6 倍）和对吡虫啉的低交叉耐药性（9.3 倍）。与敏感菌株生命表相比，噻虫嗪耐药菌株的相对适应度为0.950，产卵天数和繁殖力显着降低，发育持续时间延长。通过比较保幼激素酸性O-甲基转移酶（JHAMT）、保幼激素结合蛋白（JHBP）、保幼激素环氧化物水解酶（JHEH）、蜕皮激素受体（EcR）、超气门蛋白的mRNA表达水平，研究适应成本的分子机制(USP) 和 Vitellogenin (Vg) 在敏感和抗噻虫嗪的菌株中。在噻虫嗪耐药菌株中发现了 JHEH 和 JHBP 的显着过度表达以及 EcR 和 Vg 表达的下调。这些结果表明，棉曲霉在连续接触后有可能对噻虫嗪产生极高的耐药性，