Pesticide Residues and Bees – A Risk Assessment

Bees are essential pollinators of many plants in natural ecosystems and agricultural crops alike. In recent years the decline and disappearance of bee species in the wild and the collapse of honey bee colonies have concerned ecologists and apiculturalists, who search for causes and solutions to this problem. Whilst biological factors such as viral diseases, mite and parasite infections are undoubtedly involved, it is also evident that pesticides applied to agricultural crops have a negative impact on bees. Most risk assessments have focused on direct acute exposure of bees to agrochemicals from spray drift. However, the large number of pesticide residues found in pollen and honey demand a thorough evaluation of all residual compounds so as to identify those of highest risk to bees. Using data from recent residue surveys and toxicity of pesticides to honey and bumble bees, a comprehensive evaluation of risks under current exposure conditions is presented here. Standard risk assessments are complemented with new approaches that take into account time-cumulative effects over time, especially with dietary exposures. Whilst overall risks appear to be low, our analysis indicates that residues of pyrethroid and neonicotinoid insecticides pose the highest risk by contact exposure of bees with contaminated pollen. However, the synergism of ergosterol inhibiting fungicides with those two classes of insecticides results in much higher risks in spite of the low prevalence of their combined residues. Risks by ingestion of contaminated pollen and honey are of some concern for systemic insecticides, particularly imidacloprid and thiamethoxam, chlorpyrifos and the mixtures of cyhalothrin and ergosterol inhibiting fungicides. More attention should be paid to specific residue mixtures that may result in synergistic toxicity to bees.

蜜蜂作为自然生态系统及农业作物中众多植物的重要传粉者，其不可或缺性不言而喻。近年来，野生蜜蜂种群的衰退与消失，以及蜜蜂数量的锐减，已成为生态学家和养蜂业者关注的焦点。他们致力于探究这一问题背后的原因及解决方案。尽管诸如病毒性疾病、螨虫及寄生虫感染等生物因素无疑扮演了角色，但农业作物上使用的杀虫剂对蜜蜂产生的负面影响亦不容忽视。大多数风险评估主要集中于蜜蜂对喷洒漂移中的农用化学品的直接急性暴露。然而，在花粉和蜂蜜中发现的大量农药残留要求对所有残留化合物进行全面评估，以便识别对蜜蜂风险最高的化合物。本研究利用最近残留调查数据和农药对蜜蜂和熊蜂的毒性，对当前暴露条件下的风险进行了全面评估。在标准风险评估的基础上，引入了新的方法，这些方法考虑了时间累积效应，尤其是与饮食暴露相关的效应。尽管总体风险似乎较低，但我们的分析表明，菊酯类和烟碱类杀虫剂的残留通过蜜蜂与受污染花粉的接触暴露，构成了最高的风险。然而，尽管这两种杀虫剂类别的联合残留较为罕见，但与抑制麦角甾醇的杀菌剂相互作用，导致风险显著增加。对于系统杀虫剂，如噻虫胺和噻虫嗪、毒死蜱以及菊酯类和抑制麦角甾醇的杀菌剂混合物，通过摄入受污染花粉和蜂蜜的风险亦应引起关注。因此，应更加重视可能导致蜜蜂产生协同毒性的特定残留混合物。