Abstract:
Honey bees are commonly co-exposed to pesticides during crop pollination, including the fungicide captan and neonicotinoid insecticide thiamethoxam. We assessed the impact of exposure to these two pesticides individually and in combination, at a range of field-realistic doses. In laboratory assays, mortality of larvae treated with captan was 80-90% greater than controls, dose-independent, and similar to mortality from the lowest dose of thiamethoxam. There was evidence of synergism (i.e., a non-additive response) from captan-thiamethoxam co-exposure at the highest dose of thiamethoxam, but not at lower doses. In the field, we exposed whole colonies to the lowest doses used in the laboratory. Exposure to captan and thiamethoxam individually and in combination resulted in minimal impacts on population growth or colony mortality, and there was no evidence of synergism or antagonism. These results suggest captan and thiamethoxam are each acutely toxic to immature honey bees, but whole colonies can potentially compensate for detrimental effects, at least at the low doses used in our field trial, or that methodological differences of the field experiment impacted results (e.g., dilution of treatments with natural pollen). If compensation occurred, further work is needed to assess how it occurred, potentially via increased queen egg laying, and whether short-term compensation leads to long-term costs. Further work is also needed for other crop pollinators that lack the social detoxification capabilities of honey bee colonies and may be less resilient to pesticides.
摘要:
蜜蜂通常在作物授粉期间共同接触农药,包括杀真菌剂和新烟碱类杀虫剂噻虫嗪。我们评估了单独和组合接触这两种农药的影响,在一定范围的现场现实剂量。在实验室化验中,用captan处理的幼虫死亡率比对照组高80-90%,剂量无关,与最低剂量噻虫嗪的死亡率相似。有协同作用的证据(即,在最高剂量的噻虫嗪下,来自captan-thiamethoxam共暴露的非累加反应),但不是在较低的剂量。在田野里,我们将整个菌落暴露在实验室使用的最低剂量下。单独或联合使用captan和thiamethoxam对人口增长或殖民地死亡率的影响最小。没有证据表明有协同作用或拮抗作用。这些结果表明,captan和噻虫嗪对未成熟的蜜蜂都有剧毒,但是整个殖民地可能会补偿有害的影响,至少在我们现场试验中使用的低剂量,或现场实验的方法差异影响了结果(例如,用天然花粉稀释处理)。如果发生了补偿,需要进一步的工作来评估它是如何发生的,可能通过增加女王产卵,以及短期薪酬是否会导致长期成本。其他作物传粉者也需要进一步的工作,这些作物传粉者缺乏蜜蜂殖民地的社会解毒能力,并且可能对农药的抵抗力较差。