Maximizing crop yields relies on the use of agrochemicals to control insect pests. One of the most widely used classes of insecticides are neonicotinoids that interfere with signalling of the neurotransmitter acetylcholine, but these can also disrupt crop-pollination services provided by bees. Here, we analysed whether chronic low dose long-term exposure to the neonicotinoid thiamethoxam alters gene expression and alternative splicing in brains of Africanized honey bees, Apis mellifera, as adaptation to altered neuronal signalling. We find differentially regulated genes that show concentration-dependent responses to thiamethoxam, but no changes in alternative splicing. Most differentially expressed genes have no annotated function but encode short Open Reading Frames, a characteristic feature of anti-microbial peptides. As this suggested that immune responses may be compromised by thiamethoxam exposure, we tested the impact of thiamethoxam on bee immunity by injecting bacteria. We show that intrinsically sub-lethal thiamethoxam exposure makes bees more vulnerable to normally non-pathogenic bacteria. Our findings imply a synergistic mechanism for the observed bee population declines that concern agriculturists, conservation ecologists and the public.

最大化作物产量依赖于使用农用化学品来控制害虫。使用最广泛的一类杀虫剂是新烟碱类杀虫剂，它会干扰神经递质乙酰胆碱的信号传递，但它们也会破坏蜜蜂提供的作物授粉服务。在这里，我们分析了慢性低剂量长期接触新烟碱类噻虫嗪是否会改变非洲蜜蜂Apis mellifera 大脑中的基因表达和选择性剪接，作为适应改变的神经元信号。我们发现差异调节基因显示对噻虫嗪的浓度依赖性反应，但可变剪接没有变化。大多数差异表达的基因没有注释功能，但编码短的开放阅读框，这是抗微生物肽的一个特征。由于这表明接触噻虫嗪可能会损害免疫反应，因此我们通过注射细菌测试了噻虫嗪对蜜蜂免疫力的影响。我们表明，本质上亚致死性的噻虫嗪暴露会使蜜蜂更容易受到通常非致病性细菌的侵害。我们的研究结果暗示了观察到的蜜蜂数量下降的协同机制，这引起了农业学家、保护生态学家和公众的关注。