College of Plant Protection, Nanjing Agricultural University/Key Laboratory of Integrated Management of Crop Disease and Pests, Ministry of Education/Key Laboratory of Integrated Pest Management on Crops in East China, Ministry of Agriculture, Nanjing 210095, China.
Institute of Plant Protection, Xinjiang Academy of Agricultural Sciences/Key Laboratory of Integrated Pest Management on Crop in Northwestern Oasis, Ministry Agriculture P.R. China, Urumqi, China.
Pestic Biochem Physiol. 2023 Sep;195:105558. doi: 10.1016/j.pestbp.2023.105558. Epub 2023 Jul 26.
The Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), is an extremely destructive notifiable quarantine pest. Over the last two decades, neonicotinoid insecticides, particularly thiamethoxam and imidacloprid, have been used to control it in Xinjiang, and local field populations have developed different levels of resistance in consequence. However, the contributions of nicotinic acetylcholine receptors (nAChRs) to neonicotinoid resistance are currently poorly understood in CPB. Previous studies have shown that nAChRα1, α3, α8 and β1 are major target subunits for neonicotinoids in some model and important agricultural insects including nAChRα1 subunit of L. decemlineata (Ldα1). In this study, the expression levels of Ldα3, Ldα8 and Ldβ1 following 72 h of treatments with median lethal doses of thiamethoxam and imidacloprid were compared using real-time quantitative PCR. These genes were then individually and simultaneously knocked down with Ldα1 by RNA interference (RNAi) using a double-stranded RNA (dsRNA) feeding method for six days to explore their roles in CPB susceptibility to imidacloprid and thiamethoxam. The results showed that the expressions of Ldα3, Ldα8 and Ldβ1 were significantly decreased by 36.99-74.89% after thiamethoxam and imidacloprid treatments, compared with the control. The significant downregulation of the target genes resulting from RNAi significantly reduced the mortality of adults exposed to thiamethoxam and imidacloprid by 34.53% -56.44% and 28.78%-43.93%, respectively. Furthermore, the adult survival rates were not affected by every dsRNA-feeding treatment, while the body weight of the test adults significantly deceased after four and six days of individual gene RNAi. This study showed that Ldα3, Ldα8 and Ldβ1 are down-regulated by thiamethoxam and imidacloprid and play important roles in the tolerance of CPB to neonicotinoids.
科罗拉多马铃薯甲虫（CPB），Leptinotarsa decemlineata（Say），是一种极具破坏性的法定检疫害虫。在过去的二十年中，新烟碱类杀虫剂，特别是噻虫嗪和吡虫啉，已被用于新疆防治该虫，因此当地田间种群已产生不同程度的抗性。然而，CPB 对新烟碱类杀虫剂的抗性的烟碱型乙酰胆碱受体（nAChRs）的贡献目前知之甚少。先前的研究表明，nAChRα1、α3、α8 和 β1 是一些模型和重要农业昆虫包括 L. decemlineata（Ldα1）的新烟碱类杀虫剂的主要靶标亚基。在这项研究中，使用实时定量 PCR 比较了噻虫嗪和吡虫啉的致死剂量处理 72 小时后 Ldα3、Ldα8 和 Ldβ1 的表达水平。然后，通过 RNA 干扰（RNAi）用双链 RNA（dsRNA）喂养法单独和同时敲低 Ldα1，持续六天，以探索它们在 CPB 对吡虫啉和噻虫嗪的敏感性中的作用。结果表明，与对照相比，噻虫嗪和吡虫啉处理后 Ldα3、Ldα8 和 Ldβ1 的表达分别显著降低了 36.99%-74.89%。RNAi 导致靶基因的显著下调显著降低了接触噻虫嗪和吡虫啉的成虫死亡率 34.53%-56.44%和 28.78%-43.93%。此外，每个 dsRNA 喂养处理均不影响成虫的存活率，而单独基因 RNAi 后四天和六天，测试成虫的体重显著下降。本研究表明，Ldα3、Ldα8 和 Ldβ1 受噻虫嗪和吡虫啉下调，并在 CPB 对新烟碱类杀虫剂的耐受性中发挥重要作用。
