Imidacloprid (IMI) is used in integrated farming like the rice-crayfish co-culture system to prevent water weevil. However, the toxic effect of IMI on the freshwater crayfish Procambarus clarkii is unknown. In the current study, the effects of IMI on the locomotion, antioxidative status, digestion and intestinal microbiota of P. clarkii were investigated. The results showed that IMI caused locomotion impairment with reduced crawl velocity, and attenuated their dark preference, aggressiveness and reversal ability. Inhibited AChE in muscle and hepatopancreas indicates the neurotoxicity of IMI which may directly lead their locomotion dysfunction. The increase of antioxidative enzymes activity and MDA level were found after 25 μg/L and 250 μg/L exposure. Significant up-regulation of several antioxidative and immune-related genes, including CZ-SOD, CAT, GPx, GST, AFL, proPO, HSP27 and HSP70 confirmed that oxidative stress was induced in all treatments when exposed to IMI. In addition, there was significant increase of LDH, indicating the different energy allocation during the exposure. Meanwhile, results from DNA damage analysis showed elevated OTM value and 8-OHdG level in hepatopancretic cells. On the other hand, decreases of alpha-amylase, lipase and increase of trypsin in hepatopancreas was observed at 25 and 250 μg/L. In addition, significant changes of composition of intestinal microbiota at both phylum and genus levels were observed according to the 16S rRNA sequencing results. Increase of pathogenic genera and decrease of beneficial bacterial communities revealed the disequilibrium of intestinal flora of crayfish. In summary, results in the present study suggest that IMI at environmentally realistic concentration could induce AChE inhibition and oxidative stress, conjointly leading the locomotion impairment in crayfish. IMI also affected the digestive functions by enzymes inhibition and gut microbiota dysbiosis.

吡虫啉 (IMI) 用于水稻-小龙虾共养系统等综合农业中，以预防水象甲。然而，IMI对淡水小龙虾克氏原螯虾的毒性作用尚不清楚。在当前的研究中，研究了IMI对克氏疟原虫的运动、抗氧化状态、消化和肠道微生物群的影响。结果表明，IMI导致运动障碍，爬行速度降低，并减弱了它们的黑暗偏好、攻击性和逆转能力。肌肉和肝胰腺中的 AChE 受到抑制表明 IMI 具有神经毒性，可能直接导致其运动功能障碍。 25μg/L和250μg/L暴露后发现抗氧化酶活性和MDA水平增加。一些抗氧化和免疫相关基因（包括CZ-SOD、CAT、GPx、GST、AFL、proPO、HSP27和HSP70 ）的显着上调证实，当暴露于 IMI 时，所有治疗都会诱导氧化应激。此外，LDH 显着增加，表明暴露期间能量分配的不同。同时，DNA损伤分析结果显示肝胰腺细胞中OTM值和8-OHdG水平升高。另一方面，在 25 和 250 μg/L 浓度下观察到肝胰腺中 α-淀粉酶、脂肪酶的降低和胰蛋白酶的增加。此外，根据16S rRNA测序结果，在门和属水平上观察到肠道菌群组成发生了显着变化。致病菌属的增加和有益菌群的减少揭示了小龙虾肠道菌群的不平衡。 总之，本研究的结果表明，环境中实际浓度的 IMI 可以诱导 AChE 抑制和氧化应激，共同导致小龙虾的运动障碍。 IMI 还通过酶抑制和肠道微生物群失调影响消化功能。