Honey bee dietary neonicotinoid exposure is associated with pollen collection from agricultural weeds

Neonicotinoid insecticides have been linked to bee declines. However, tracking the primary exposure route for bees in the field has proven to be a major logistical challenge, impeding efforts to restore pollinator health in agricultural landscapes. We quantified neonicotinoid concentrations and botanical species composition in 357 pollen samples collected from 114 commercial honey bee colonies placed along a gradient of agricultural intensity between June and September. Neonicotinoid concentrations increased through the season, peaking at the end of August. As a result, concentrations in pollen were negatively associated with collection from woody and crop plants that flower early-mid season, and positively associated with collection from herbaceous plants that flower mid-late season. Higher clothianidin and thiamethoxam residues were correlated with samples containing a greater proportion of pollen collected from agricultural weeds. The percentage of agricultural land within 1,500 m wa...烟碱类杀虫剂（Neonicotinoid insecticides）已被证实与蜂群数量下降存在关联。然而，追踪野外蜜蜂的主要暴露途径已被证明是一项重大实操挑战，这极大阻碍了农业景观中传粉者健康恢复工作的推进。本研究于6月至9月期间，对沿农业活动强度梯度布设的114个商业化饲养蜜蜂蜂群所采集的357份花粉样本中的烟碱类杀虫剂浓度与植物物种组成进行了定量分析。烟碱类杀虫剂浓度随季节推移逐步升高，于8月末达到峰值。分析结果显示，花粉中的烟碱类杀虫剂浓度与早-中期开花的木本植物及农作物花粉占比呈负相关，而与中-晚期开花的草本植物花粉占比呈正相关。噻虫胺（clothianidin）与噻虫嗪（thiamethoxam）残留量更高的样本，其花粉中源自农业杂草的占比也更高。1500米范围内的农业用地占比尚……