Christen Verena, Bachofer Sara, Fent Karl
University of Applied Sciences and Arts Northwestern Switzerland, School of Life Sciences, Gründenstrasse 40, CH-4132 Muttenz, Switzerland.
University of Applied Sciences and Arts Northwestern Switzerland, School of Life Sciences, Gründenstrasse 40, CH-4132 Muttenz, Switzerland; University Basel, Department of Pharmaceutical Sciences, Institute of Molecular and System Toxicology, CH-4056 Basel, Switzerland.
Environ Pollut. 2017 Jan;220(Pt B):1264-1270. doi: 10.1016/j.envpol.2016.10.105. Epub 2016 Nov 11.
Among the many factors responsible for the decline of bee populations are plant protection products such as neonicotinoids. In general, bees are exposed to not only one but mixtures of such chemicals. At environmental realistic concentrations neonicotinoids may display negative effects on the immune system, foraging activity, learning and memory formation of bees. Neonicotinoids induce alterations of gene transcripts such as nicotinic acetylcholine receptor (nAChR) subunits, vitellogenin, genes of the immune system and genes linked to memory formation. While previous studies focused on individual compounds, the effect of neonicotinoid mixtures in bees is poorly known. Here we investigated the effects of neonicotinoids acetamiprid, clothianidin, imidacloprid and thiamethoxam as single compounds, and binary mixtures thereof in honeybees. We determined transcriptional changes of nAChR subunits and vitellogenin in the brain of experimentally exposed honeybees after exposure up to 72 h. Exposure concentrations were selected on the basis of lowest effect concentrations of the single compounds. Transcriptional induction of nAChRs and vitellogenin was strongest for thiamethoxam, and weakest for acetamiprid. To a large extent, binary mixtures did not show additive transcriptional inductions but they were less than additive. Our data suggest that the joint transcriptional activity of neonicotinoids cannot be explained by concentration addition. The in vivo effects are not only governed by agonistic interaction with nAChRs alone, but are more complex as a result of interactions with other pathways as well. Further studies are needed to investigate the physiological joint effects of mixtures of neonicotinoids and other plant protection products on bees to better understand their joint effects.
导致蜜蜂数量下降的众多因素中包括新烟碱类等植物保护产品。一般来说，蜜蜂接触到的不仅是一种此类化学物质，而是多种化学物质的混合物。在环境现实浓度下，新烟碱类可能对蜜蜂的免疫系统、觅食活动、学习和记忆形成产生负面影响。新烟碱类会诱导基因转录本发生改变，如烟碱型乙酰胆碱受体（nAChR）亚基、卵黄蛋白原、免疫系统基因以及与记忆形成相关的基因。虽然之前的研究聚焦于单一化合物，但新烟碱类混合物对蜜蜂的影响却知之甚少。在此，我们研究了新烟碱类中的啶虫脒、噻虫胺、吡虫啉和噻虫嗪作为单一化合物及其二元混合物对蜜蜂的影响。我们测定了实验暴露的蜜蜂在暴露长达72小时后大脑中nAChR亚基和卵黄蛋白原的转录变化。暴露浓度是根据单一化合物的最低效应浓度来选择的。噻虫嗪对nAChRs和卵黄蛋白原的转录诱导最强，啶虫脒最弱。在很大程度上，二元混合物并未表现出相加的转录诱导作用，而是小于相加作用。我们的数据表明，新烟碱类的联合转录活性不能用浓度相加来解释。其体内效应不仅受与nAChRs的激动相互作用单独支配，而且由于与其他途径的相互作用而更加复杂。需要进一步研究来调查新烟碱类与其他植物保护产品混合物对蜜蜂的生理联合效应，以便更好地理解它们的联合作用。
