Department of Entomology, China Agricultural University, Beijing, China.
J Econ Entomol. 2020 Aug 13;113(4):1946-1954. doi: 10.1093/jee/toaa090.
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.
棉蚜是一种在许多作物中臭名昭著的害虫，新烟碱类杀虫剂噻虫嗪被广泛用于防治棉蚜。为了评估噻虫嗪抗性风险，我们通过对棉蚜进行 24 代噻虫嗪选择，建立了一个对噻虫嗪具有极高抗性（>2325.6 倍）的棉蚜种群。此外，我们还分析了该种群对其他新烟碱类杀虫剂的交互抗性模式和适合度。交叉抗性结果表明，噻虫嗪抗性种群对噻虫胺（>311.7 倍）和吡虫啉（299.9 倍）具有极高的交互抗性水平，对噻虫啉（142.3 倍）和啶虫脒（76.6 倍）具有较高的交互抗性水平，对氯噻啉（9.3 倍）具有较低的交互抗性水平。与敏感种群的生命表相比，噻虫嗪抗性种群的相对适合度为 0.950，产卵天数、产卵量和发育持续时间显著减少。通过比较敏感种群和噻虫嗪抗性种群中保幼激素酸 O-甲基转移酶（JHAMT）、保幼激素结合蛋白（JHBP）、保幼激素环氧水解酶（JHEH）、蜕皮激素受体（EcR）、超气门蛋白（USP）和卵黄原蛋白（Vg）的 mRNA 表达水平，研究了适合度代价的分子机制。在噻虫嗪抗性种群中发现 JHEH 和 JHBP 的显著过表达，以及 EcR 和 Vg 表达的下调。这些结果表明，棉蚜在连续暴露于噻虫嗪后有可能产生对噻虫嗪的极高抗性，同时具有相当大的适合度代价和对其他新烟碱类杀虫剂的交互抗性。
