Plant‐systemic neonicotinoid (NN) insecticides can exert non‐target impacts on organisms like beneficial insects and soil microbes. NNs can affect plant microbiomes, but we know little about their effects on microbial communities that mediate plant‐insect interactions, including nectar‐inhabiting microbes (NIMs). Here we employed two approaches to assess the impacts of NN exposure on several NIM taxa. First, we assayed the in vitro effects of six NN compounds on NIM growth using plate assays. Second, we inoculated a standardised NIM community into the nectar of NN‐treated canola (Brassica napus) and assessed microbial survival and growth after 24 h. With few exceptions, in vitro NN exposure tended to decrease bacterial growth metrics. However, the magnitude of the decrease and the NN concentrations at which effects were observed varied substantially across bacteria. Yeasts showed no consistent in vitro response to NNs. In nectar, we saw no effects of NN treatment on NIM community metrics. Rather, NIM abundance and diversity responded to inherent plant qualities like nectar volume. In conclusion, we found no evidence that NIMs respond to field‐relevant NN levels in nectar within 24 h, but our study suggests that context, specifically assay methods, time and plant traits, is important in assaying the effects of NNs on microbial communities.

中文翻译：

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新烟碱类杀虫剂对花蜜微生物的非目标影响

植物内吸新烟碱类（NN）杀虫剂可以对有益昆虫和土壤微生物等生物体产生非目标影响。神经网络可以影响植物微生物组，但我们对其对介导植物与昆虫相互作用的微生物群落（包括花蜜微生物（NIM））的影响知之甚少。在这里，我们采用两种方法来评估 NN 暴露对几个 NIM 类群的影响。首先，我们使用平板测定法测定了六种 NN 化合物对 NIM 生长的体外影响。其次，我们将标准化的 NIM 群落接种到 NN 处理的油菜花蜜中（甘蓝型油菜）并评估 24 小时后微生物的存活和生长。除少数例外，体外 NN 暴露往往会降低细菌生长指标。然而，减少的幅度和观察到效果的 NN 浓度在不同细菌中存在很大差异。酵母对 NN 没有表现出一致的体外反应。在花蜜中，我们没有看到 NN 处理对 NIM 群落指标的影响。相反，NIM 的丰度和多样性与花蜜量等植物固有品质有关。总之，我们没有发现任何证据表明 NIM 在 24 小时内对花蜜中与田间相关的 NN 水平有反应，但我们的研究表明，环境，特别是测定方法、时间和植物性状，对于测定 NN 对微生物群落的影响非常重要。