Neonicotinoids disrupt memory, circadian behaviour and sleep, Tasman et al

Globally, neonicotinoids are the most used insecticides, despite their well-documented sublethal effects on beneficial insects. Neonicotinoids are nicotinic acetylcholine receptor agonists. Memory, circadian rhythmicity and sleep are essential for efficient foraging and pollination and require nicotinic acetylcholine receptor signalling. The effect of field-relevant concentrations of the European Union-banned neonicotinoids: imidacloprid, clothianidin, thiamethoxam and thiacloprid were tested on Drosophila memory, circadian rhythms and sleep. Field-relevant concentrations of imidacloprid, clothianidin and thiamethoxam disrupted learning, behavioural rhythmicity and sleep whilst thiacloprid exposure only affected sleep. Exposure to imidacloprid and clothianidin prevented the day/night remodelling and accumulation of pigment dispersing factor (PDF) neuropeptide in the dorsal terminals of clock neurons. Knockdown of the neonicotinoid susceptible Dα1 and Dβ2 nicotinic acetylcholine receptor subunits in the mushroom bodies or clock neurons recapitulated the neonicotinoid like deficits in memory or sleep/circadian behaviour respectively. Disruption of learning, circadian rhythmicity and sleep are likely to have far-reaching detrimental effects on beneficial insects in the field.全球范围内，新烟碱类杀虫剂（neonicotinoids）是使用量最高的杀虫剂，尽管其对益虫存在已被充分证实的亚致死效应。新烟碱类杀虫剂属于烟碱型乙酰胆碱受体（nicotinic acetylcholine receptor）激动剂。 记忆、昼夜节律与睡眠对于高效觅食与传粉至关重要，且该过程依赖烟碱型乙酰胆碱受体信号通路。 本研究针对欧盟禁用的新烟碱类杀虫剂：吡虫啉（imidacloprid）、噻虫胺（clothianidin）、噻虫嗪（thiamethoxam）与噻虫啉（thiacloprid）的田间相关浓度，检测其对果蝇（Drosophila）记忆、昼夜节律与睡眠的影响。 田间相关浓度的吡虫啉、噻虫胺与噻虫嗪会破坏学习能力、行为节律与睡眠，而噻虫啉仅会影响睡眠。 暴露于吡虫啉与噻虫胺会阻断时钟神经元背侧末梢中色素分散因子（pigment dispersing factor, PDF）神经肽的昼夜重塑与积累。 对果蝇蘑菇体或时钟神经元中对新烟碱类敏感的Dα1与Dβ2烟碱型乙酰胆碱受体亚基进行敲低，可分别重现新烟碱类暴露引发的记忆缺陷或睡眠/昼夜行为缺陷。 学习能力、昼夜节律与睡眠的破坏，可能会对田间益虫造成深远的不利影响。