【目的】 中红侧沟茧蜂Microplitis mediator是棉铃虫Helicoverpa armigera生物防控的重要因子，通过温室内对未被寄生和被中红侧沟茧蜂寄生棉铃虫幼虫在棉花植株上的行为观察，分析中红侧沟茧蜂寄生对棉铃虫在棉花植株上行为活动及分布位置的影响。【方法】 采用“固定时间间隔扫描抽样”观察法，监测寄生后1-10 d被寄生与未被寄生棉铃虫幼虫在棉花植株上的取食和空间位移等行为的变化。【结果】 中红侧沟茧蜂寄生可以极显著降低棉铃虫幼虫在棉花植株上的取食行为比例（P < 0.01）；被寄生棉铃虫幼虫在棉株上的空间位移比例于寄生后的1-2 d极显著高于未被寄生棉铃虫（P < 0.01），而在发育后期极显著低于未被寄生棉铃虫幼虫（P < 0.01）；被寄生棉铃虫幼虫在棉铃上的分布比例显著降低而在花上的分布比例显著升高（P < 0.05）；棉铃虫发育后期，被寄生棉铃虫在棉叶背面的分布比例极显著高于未被寄生棉铃虫（P < 0.01）。【结论】 中红侧沟茧蜂寄生对棉铃虫幼虫的取食、活动和栖境选择具有显著影响。

[Objectives]  The parasite Microplitis mediator is an important biological control for the cotton bollworm Helicoverpa armigera. To analyze the impact of parasitism by M. mediator on the behavior of H. armigera larvae we compared the behavior of parasitized and unparasitized larvae in a green house. [Methods]  Using the fixed-interval time scan sampling method, the feeding behavior and spatial displacement of unparasitized and parasitized H. armigera larvae were investigated and recorded from 1 to 10 days post-infection by M. mediator. [Results]  Parasitized larvae spent significantly  (P < 0.01) less time feeding on cotton plants than unparasitized larvae, and, spatial displacement was significantly (P < 0.01) higher in parasitized larvae than in unparasitized larvae 1-2 days after infection. Spatial displacement among parasitized larvae declined significantly (P < 0.01) over time with significantly less parasitized larvae found on cotton plant bolls than on cotton flowers (P < 0.05). Later in the developmental period significantly more parasitized larvae were found on the abaxial blade of cotton leaves than unparasitized larvae (P < 0.01). [Conclusion]  Parasitism by M. mediator had a significant impact on the feeding behavior and within-plant distribution of H. armigera larvae.