Department of Evolutionary Developmental Genetics, Göttingen Center for Molecular Biosciences, University of Göttingen, 37077 Göttingen, Germany; Bayer AG, Crop Science Division, R&D, Pest Control, Alfred-Nobel-Str. 50, 40789 Monheim, Germany.
Bayer AG, Crop Science Division, R&D, Pest Control, Alfred-Nobel-Str. 50, 40789 Monheim, Germany.
Pestic Biochem Physiol. 2020 Jun;166:104569. doi: 10.1016/j.pestbp.2020.104569. Epub 2020 Mar 31.
In recent years, substantial effort was spent on the exploration and implementation of RNAi technology using double-stranded RNA (dsRNA) for pest management purposes. However, only few studies investigated the geographical variation in RNAi sensitivity present in field-collected populations of the targeted insect pest. In this baseline study, 2nd instar larvae of 14 different European populations of Colorado potato beetle (CPB), Leptinotarsa decemlineata, collected from nine different countries were exposed to a foliarly applied diagnostic dose of dsactin (dsact) to test for possible variations in RNAi response. Only minor variability in RNAi sensitivity was observed between populations. However, the time necessary to trigger a dsRNA-mediated phenotypic response varied significantly among populations, indicated by significant differences in mortality figures obtained five days after treatment. An inbred German laboratory reference strain D01 and a Spanish field strain E02 showed almost 100% mortality after foliar exposure to 30 ng dsactin (equal to 0.96 g/ha), whereas another Spanish strain E01 was least responsive and showed only 30% mortality. Calculated LD-values for foliarly applied dsact against strains D01 (most sensitive) and E01 (least sensitive) were 9.22 and 68.7 ng/leaf disc, respectively. The variability was not based on target gene sequence divergence or knock-down efficiency. Variability in expression of the core RNAi machinery genes dicer (dcr2a) and argonaute (ago2a) was observed but did not correlate with sensitivity. Interestingly, RT-qPCR data collected for all strains revealed a strong correlation between the expression level of dcr2a and ago2a (r 0.93) as well as ago2a and stauC (r 0.94), a recently described dsRNA binding protein in Coleopterans. Overall, this study demonstrates that sensitivity of CPB to sprayable RNAi slightly varies between strains but also shows that foliar RNAi as a control method works against all tested CPB populations collected across a broad geographic range in Europe. Thus, underpinning the potential of RNAi-based CPB control as a promising component in integrated pest management (IPM) and resistance management programs.
近年来，人们在探索和应用双链 RNA (dsRNA) 技术用于害虫管理方面投入了大量精力。然而，只有少数研究调查了目标害虫田间种群中存在的 RNAi 敏感性的地理变异。在这项基线研究中，从 9 个不同国家采集的 14 个不同欧洲地区的马铃薯甲虫（CPB）Leptinotarsa decemlineata 2 龄幼虫暴露于叶片应用的诊断剂量 dsactin (dsact) 中，以测试 RNAi 反应的可能变化。在种群之间观察到 RNAi 敏感性的变化很小。然而，触发 dsRNA 介导的表型反应所需的时间在种群之间存在显著差异，这表明处理后 5 天获得的死亡率存在显著差异。经过叶片暴露于 30ng dsactin（相当于 0.96g/ha）后，近交德国实验室参考品系 D01 和西班牙田间品系 E02 几乎达到 100%的死亡率，而另一个西班牙品系 E01 反应性最低，死亡率仅为 30%。计算针对品系 D01（最敏感）和 E01（最不敏感）的叶片应用 dsact 的 LD 值分别为 9.22 和 68.7ng/叶盘。这种变异性不是基于靶基因序列差异或击倒效率。观察到核心 RNAi 机制基因 dicer (dcr2a) 和 argonaute (ago2a) 的表达变异性，但与敏感性无关。有趣的是，对所有菌株收集的 RT-qPCR 数据表明，dcr2a 和 ago2a（r 0.93）以及 ago2a 和 stauC（r 0.94）之间存在很强的相关性，stauC 是最近在鞘翅目动物中描述的一种 dsRNA 结合蛋白。总体而言，这项研究表明，CPB 对喷雾 RNAi 的敏感性在菌株之间略有差异，但也表明叶片 RNAi 作为一种控制方法对在整个欧洲广泛地理范围内收集的所有测试 CPB 种群都有效。因此，为基于 RNAi 的 CPB 控制作为综合害虫管理 (IPM) 和抗性管理计划的有前途的组成部分提供了支持。
