Recent declines in honey bee populations and increasing demand for insect-pollinated crops raise concerns about pollinator shortages. Pesticide exposure and pathogens may interact to have strong negative effects on managed honey bee colonies. Such findings are of great concern given the large numbers and high levels of pesticides found in honey bee colonies. Thus it is crucial to determine how field-relevant combinations and loads of pesticides affect bee health. We collected pollen from bee hives in seven major crops to determine 1) what types of pesticides bees are exposed to when rented for pollination of various crops and 2) how field-relevant pesticide blends affect bees’ susceptibility to the gut parasite Nosema ceranae. Our samples represent pollen collected by foragers for use by the colony, and do not necessarily indicate foragers’ roles as pollinators. In blueberry, cranberry, cucumber, pumpkin and watermelon bees collected pollen almost exclusively from weeds and wildflowers during our sampling. Thus more attention must be paid to how honey bees are exposed to pesticides outside of the field in which they are placed. We detected 35 different pesticides in the sampled pollen, and found high fungicide loads. The insecticides esfenvalerate and phosmet were at a concentration higher than their median lethal dose in at least one pollen sample. While fungicides are typically seen as fairly safe for honey bees, we found an increased probability of Nosema infection in bees that consumed pollen with a higher fungicide load. Our results highlight a need for research on sub-lethal effects of fungicides and other chemicals that bees placed in an agricultural setting are exposed to.
蜜蜂种群数量的近期下降和对昆虫授粉作物继续增长的需求引起了我们对授粉短缺问题的关注。 农药接触以及病原体可能会互相影响从而对有序蜜蜂群体产生较强负面影响。该研究发现蜂蜜群体中发现的大量高浓度农药，这引起了我们的关注。因此，确定领域相关的组合和农药的负载量如何影响蜜蜂健康十分重要。我们从七种主要作物中的蜂箱收集花粉来确定（1） 当蜜蜂为各种作物授粉时接触了什么类型的农药以及（2）领域相关的农药混合物如何影响了蜜蜂对肠道病原微孢子虫的易感性。 我们的样本代表了觅食蜂群为使用而采集的花粉，且未必表明觅食者就是传粉者。在我们抽样中，蜜蜂几乎完全从蓝莓，小红莓，黄瓜，南瓜和西瓜的杂草和野花中采集花粉。因此我们更需着重关注蜜蜂如何在被放置的区域外接触农药。我们在花粉样本中检测到35种不同农药且发现高杀菌剂负载量。在不止一个花粉样本中发现，杀虫剂氰戊菊酯和亚胺硫磷浓度高于他们的半数致死剂量。通常杀菌剂被认为对于蜜蜂来说是相当安全的，我们发现那些采集较高杀真菌剂负载量花粉的蜜蜂感染微孢子虫的概率增加。我们的研究结果强调了对蜜蜂在被置放的农业环境接触到的杀菌剂和其它化学物质的亚致死效应需展开更深入的研究。