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) 用于综合养殖，如稻-小龙虾共养系统，以防止水象甲。然而，IMI 对淡水小龙虾Procambarus clarkii的毒性作用尚不清楚。在目前的研究中，IMI 对P. clarkii的运动、抗氧化状态、消化和肠道微生物群的影响被调查。结果表明，IMI 会随着爬行速度的降低而导致运动障碍，并减弱它们的黑暗偏好、攻击性和逆转能力。肌肉和肝胰腺中被抑制的 AChE 表明 IMI 的神经毒性可能直接导致其运动功能障碍。在 25 μg/L 和 250 μg/L 暴露后发现抗氧化酶活性和 MDA 水平增加。多种抗氧化和免疫相关基因的显着上调，包括CZ-SOD、CAT、GPx、GST、AFL、proPO、HSP27和HSP70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不同。同时，DNA 损伤分析的结果显示肝胰腺细胞中的 OTM 值和 8-OHdG 水平升高。另一方面，在 25 和 250 μg/L 时观察到肝胰腺中 α-淀粉酶、脂肪酶和胰蛋白酶增加。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的显着变化。病原菌增加，有益菌群减少，表明小龙虾肠道菌群失衡。总之，本研究的结果表明，环境现实浓度的 IMI 可诱导 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。