Guseman Alex J, Miller Kaliah, Kunkle Grace, Dively Galen P, Pettis Jeffrey S, Evans Jay D, vanEngelsdorp Dennis, Hawthorne David J
Department of Entomology, University of Maryland, College Park, Maryland, United States of America.
Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina, United States of America.
PLoS One. 2016 Feb 3;11(2):e0148242. doi: 10.1371/journal.pone.0148242. eCollection 2016.
Annual losses of honey bee colonies remain high and pesticide exposure is one possible cause. Dangerous combinations of pesticides, plant-produced compounds and antibiotics added to hives may cause or contribute to losses, but it is very difficult to test the many combinations of those compounds that bees encounter. We propose a mechanism-based strategy for simplifying the assessment of combinations of compounds, focusing here on compounds that interact with xenobiotic handling ABC transporters. We evaluate the use of ivermectin as a model substrate for these transporters. Compounds that increase sensitivity of bees to ivermectin may be inhibiting key transporters. We show that several compounds commonly encountered by honey bees (fumagillin, Pristine, quercetin) significantly increased honey bee mortality due to ivermectin and significantly reduced the LC50 of ivermectin suggesting that they may interfere with transporter function. These inhibitors also significantly increased honey bees sensitivity to the neonicotinoid insecticide acetamiprid. This mechanism-based strategy may dramatically reduce the number of tests needed to assess the possibility of adverse combinations among pesticides. We also demonstrate an in vivo transporter assay that provides physical evidence of transporter inhibition by tracking the dynamics of a fluorescent substrate of these transporters (Rhodamine B) in bee tissues. Significantly more Rhodamine B remains in the head and hemolymph of bees pretreated with higher concentrations of the transporter inhibitor verapamil. Mechanism-based strategies for simplifying the assessment of adverse chemical interactions such as described here could improve our ability to identify those combinations that pose significantly greater risk to bees and perhaps improve the risk assessment protocols for honey bees and similar sensitive species.
蜜蜂蜂群的年损失率仍然很高，农药暴露是一个可能的原因。添加到蜂箱中的农药、植物产生的化合物和抗生素的危险组合可能导致或促成蜂群损失，但要测试蜜蜂接触的这些化合物的多种组合非常困难。我们提出了一种基于机制的策略来简化化合物组合的评估，这里重点关注与外源性物质处理ABC转运蛋白相互作用的化合物。我们评估了伊维菌素作为这些转运蛋白的模型底物的用途。增加蜜蜂对伊维菌素敏感性的化合物可能会抑制关键转运蛋白。我们发现蜜蜂常见的几种化合物（烟曲霉素、百菌清、槲皮素）显著增加了伊维菌素导致的蜜蜂死亡率，并显著降低了伊维菌素的半数致死浓度（LC50），这表明它们可能干扰转运蛋白的功能。这些抑制剂还显著增加了蜜蜂对新烟碱类杀虫剂啶虫脒的敏感性。这种基于机制的策略可能会大幅减少评估农药之间不良组合可能性所需的测试数量。我们还展示了一种体内转运蛋白测定法，通过追踪这些转运蛋白的荧光底物（罗丹明B）在蜜蜂组织中的动态，提供了转运蛋白受到抑制的物理证据。在用较高浓度的转运蛋白抑制剂维拉帕米预处理的蜜蜂的头部和血淋巴中，罗丹明B的残留量明显更多。像这里所描述的基于机制的简化不良化学相互作用评估的策略，可以提高我们识别那些对蜜蜂构成更大风险的组合的能力，也许还能改进蜜蜂和类似敏感物种的风险评估方案。
