Research Division Agroecology and Environment, Agroscope, Zurich, Switzerland.
Competence Division Method Development and Analytics, Agroscope, Zurich, Switzerland.
Pest Manag Sci. 2019 Oct;75(10):2652-2662. doi: 10.1002/ps.5370. Epub 2019 Mar 20.
One concern with the adoption of RNAi-based genetically engineered (GE) crops is the potential harm to valued non-target organisms. Species of Coccinellidae (Coleoptera) are important natural enemies and might be exposed to the insecticidal dsRNA produced by the plant. To assess their susceptibility to dietary RNAi, we fed Adalia bipunctata and Coccinella septempunctata with a dsRNA designed to target the vATPase A of the western corn rootworm, Diabrotica virgifera virgifera (Dvv dsRNA). Specific dsRNAs designed to target the vATPase A of the two ladybird beetle species served as positive controls.
Our results revealed that both species were sensitive to dietary RNAi when ingesting their own dsRNAs, with C. septempunctata being more sensitive than A. bipunctata. Dvv dsRNA also adversely affected the two ladybird beetles as indicated by a significantly (but marginally) prolonged developmental time for A. bipunctata and a significantly reduced survival rate for C. septempunctata. These results, however, were obtained at Dvv dsRNA concentrations that were orders of magnitude higher than expected to occur in the field. Gene expression analyses confirmed the bioactivity of the dsRNA treatments and the results from the feeding bioassays. These results are consistent with the bioinformatics analyses, which revealed a higher number of 21-nucleotide-long matches, a requirement for effective RNAi, of the Dvv dsRNA with the vATPase A of C. septempunctata (34 matches) than with that of A. bipunctata (six matches).
Feeding bioassays revealed that two ladybird species are responsive to dietary RNAi. The two species, however, differed in their sensitivity. © 2019 Society of Chemical Industry.
采用基于 RNAi 的基因工程（GE）作物的一个担忧是，其可能对有价值的非目标生物造成伤害。瓢虫科（鞘翅目）的物种是重要的天敌，可能会接触到植物产生的杀虫 dsRNA。为了评估它们对膳食 RNAi 的易感性，我们用靶向西方玉米根虫（Diabrotica virgifera virgifera，Dvv）vATPase A 的 dsRNA 喂养了 Adalia bipunctata 和 Coccinella septempunctata，该 dsRNA 是专门设计的。针对两种瓢虫物种 vATPase A 的特异性 dsRNA 作为阳性对照。
我们的结果表明，当两种物种摄入自身的 dsRNA 时，它们对膳食 RNAi 均敏感，其中 C. septempunctata 比 A. bipunctata 更为敏感。Dvv dsRNA 也对两种瓢虫产生不利影响，A. bipunctata 的发育时间显著（但略有）延长，C. septempunctata 的存活率显著降低。然而，这些结果是在用 Dvv dsRNA 浓度处理时获得的，该浓度比预计在田间出现的浓度高出几个数量级。基因表达分析证实了 dsRNA 处理的生物活性以及喂食生物测定的结果。这些结果与生物信息学分析一致，该分析显示 Dvv dsRNA 与 C. septempunctata 的 vATPase A 有 34 个 21 个核苷酸长的匹配物，这是有效 RNAi 的要求，而与 A. bipunctata 的匹配物有 6 个。
喂食生物测定表明，两种瓢虫物种对膳食 RNAi 有反应。然而，这两个物种在敏感性上有所不同。© 2019 化学工业协会。
