【目的】 近年来，农药的长期使用使害虫产生抗性，同时造成了环境污染，目前多数研究侧重于化学农药对昆虫酶活性的影响，而植物源农药对昆虫的免疫毒理研究较少。【方法】 通过给中华稻蝗Oxya chinensis（Thunberg）注射不同浓度的印楝素，用Wright-Giemsa染液染色和光学显微镜观察感染后血细胞的形态，对各种类型细胞进行数量统计；酶联免疫测定SOD，POD，PO，AchE，P450氧化酶和CES的活性变化。【结果】 实验组血细胞发生固缩、空泡、脱粒和细胞变形等现象；与空白对照组相比，感染后不同时间段浆血胞的数量先升高后降低，粒血胞的数量先降低后升高，感染后期囊血胞数量显著增加；与溶剂组相比，60 μg/L和120 μg/L的SOD活性被极显著（P<0.01）激活；60 μg/L和120 μg/L的POD活性在注射后6-24 h间被显著（P<0.05）激活；120 μg/L的PO活性在6-24 h被极显著（P<0.01）激活；实验组中AchE活性均在10-24 h被极显著（P<0.01）激活；30 μg/L的CES活性被极显著（P<0.01）激活；P450活性均被激活，但激活效果不明显。【结论】 研究表明：植物源农药使稻蝗血细胞的形态和数量发生显著变化，血细胞中相关酶活性的变化情况可推测出稻蝗对印楝素的毒害产生免疫反应，进一步探讨了稻蝗的免疫机理。本研究不仅为稻蝗的预防和治理提供了理论依据，也为昆虫的免疫毒理学提供了参考。

[Objectives]  Long-term use of pesticides has selected for pesticide resistance in pests and environmental pollution. Currently most studies focus on the effects of chemical pesticides on insect enzymes and there have been relatively little research on the immunotoxicity of plant-derived pesticides to insects. [Methods]  Different concentrations of azadirachtin were injected into Oxya chinensis (Thunberg) and hemocyte morphology and the number of various cell types were observed at different times under an optical microscope after Wright-Giemsa dyeing. An enzyme linked immunosorbent assay (ELISA) was used to detect the activity of SOD, POD, PO, AchE, P450 oxidase and CarE. [Results]  The hemocytes of treatment groups showed signs of contracting, vacuole development, threshing and cell deformation. Compared to the control group, the number of plasma cells at different times after injection first increased then decreased, and the number of granulocytes first decreased then increased. The number of hemocytes dramatically increased. SOD and POD activity of the 60 μg/L and 120 μg/L treatment groups were significantly (P<0.01 and P<0.05, respectively) higher than those of the control group between 6 h and 24 h. PO activity of the 120 μg/L treatment group was also significantly (P<0.01) higher than that of the control group over the same time period and AchE activity in all treatment groups was significantly (P<0.01) higher than that in the control group between 10 h and 24 h. CES activity in the 30 μg/L treatment group was also significantly (P<0.01) higher than that of the control group. Although P450 activity was also higher, it was not significantly different to that in the control. [Conclusion]  Treatment with plant-derived pesticides changed the morphology, and quantity, of hemocytes in O. chinensis. Changes in related enzymes activity in hemocytes could be used to infer the immune response of O. chinensis to azadirachtin, and further explore the immune response mechanisms of this species. These results not only provide a theoretical basis for the prevention and control of O. chinensis, but also general a reference for insect immunotoxicology.