The direct and indirect effects of environmental toxicants on the health of bumble bees and their microbiomes

Bumble bees (Bombus spp.) are important and widespread insect pollinators, but the act of foraging on flowers can expose them to harmful pesticides and chemicals such as oxidizers and heavy metals. How these compounds directly influence bee survival and indirectly affect bee health via the gut microbiome is largely unknown. As toxicants in floral nectar and pollen take many forms, we explored the genomes of bee-associated microbes for their potential to detoxify cadmium, copper, selenate, the neonicotinoid pesticide imidacloprid, and hydrogen peroxide - which have all been identified in floral nectar and pollen. We then exposed Bombus impatiens workers to varying concentrations of these chemicals via their diet and assayed direct effects on bee survival. Using field-realistic doses, we further explored indirect effects on bee microbiomes. We found multiple putative genes in core gut microbes that may aid in detoxifying harmful chemicals. We also found that while the chemicals are largel...熊蜂属（Bombus spp.）是一类分布广泛且至关重要的昆虫传粉者，但访花觅食的行为会使其暴露于有害农药与各类化学物质中，例如氧化剂与重金属。目前学界对这类化合物如何直接影响熊蜂存活，以及如何通过肠道微生物组（gut microbiome）间接损害熊蜂健康的认知仍十分有限。鉴于花蜜与花粉中的有毒物质形态多样，本研究针对熊蜂共生微生物的基因组展开探索，以分析其对镉、铜、硒酸盐、新烟碱类农药（neonicotinoid pesticide）吡虫啉（imidacloprid）以及过氧化氢的解毒潜力——上述物质均已在花蜜与花粉中被检出。随后，我们通过饲喂不同浓度的上述化学物质给熊蜂（Bombus impatiens）工蜂，检测其对熊蜂存活的直接影响。我们进一步采用符合野外实际暴露浓度的给药剂量，探究了这些化学物质对熊蜂肠道微生物组的间接影响。本研究在核心肠道微生物中发现了多个推定基因，这些基因或可辅助降解有害化学物质。此外我们还发现，尽管此类化学物质大多……（原文未完整呈现）