【目的】 明确外源茉莉酸甲酯（Methyl jasmonate，MeJA）诱导的棉花防御对棉蚜Aphis gossypii及斜纹夜蛾Spodoptera litura发育的影响。【方法】 采用4种浓度（0.5、1.0、2.0、4.0 mmol·L^－1）的MeJA处理4片真叶期的棉苗，在处理后的1、3、5、7、15 d测定棉叶中过氧化物酶（POD）、多酚氧化酶（PPO）的活性及总酚含量；选择2种浓度（1.0 mmol·L^－1、2.0 mmol·L^－1）的MeJA处理棉苗，在处理后的棉苗叶片上接入棉蚜或斜纹夜蛾幼虫，记录并统计棉蚜若蚜的发育历期及单雌产蚜量、斜纹夜蛾幼虫的发育历期及幼虫重量的变化。【结果】 不同浓度的MeJA处理后，棉苗POD、PPO活性及总酚含量均显著提高。0.5、1.0、2.0 mmol·L^－1 MeJA处理棉苗5 d后，棉苗POD活性达到最高水平，分别为对照的4.11倍、5.71倍、4.74倍。4种不同浓度MeJA处理棉苗15 d后，棉苗POD活性均显著高于对照（P<0.05）；4种不同浓度MeJA处理棉苗3 d后，棉苗PPO活性达到最高水平，分别为对照的1.7倍、2.1倍、2.16倍、2.71倍。2.0、4.0 mmol·L^－1 MeJA处理棉苗15 d后，棉苗PPO活性均显著高于对照（P<0.05）；0.5、1.0 mmol·L^－1 MeJA处理棉花15 d后，棉苗总酚含量达到最高水平，分别为对照的1.73倍、1.58倍。2.0 、4.0 mmol·L^－1 MeJA处理棉苗7 d后，棉苗总酚含量达到最高水平，分别为对照的1.6倍、1.7倍；1.0、2.0 mmol·L^－1 MeJA处理棉苗后，棉蚜若蚜的发育历期均为对照的1.07倍；棉蚜单雌产蚜量比对照减少20%、39.4%。斜纹夜蛾幼虫的重量比对照减少12.7%、34.2%；幼虫的发育历期为对照的1.22倍、1.25倍。【结论】 4种浓度的外源MeJA处理均可显著提高棉花主要防御酶的活性及总酚含量，外源MeJA诱导的棉花防御对棉蚜、斜纹夜蛾的发育具有显著的抑制作用。

[Objectives]  To investigate the effect of exogenous MeJA treatment of cotton on the development of Aphis gossypii and Spodoptera litura. [Methods]  The activity of defensive enzymes (POD and PPO) and the total phenol content of cotton seedling leaves treated with four concentrations of exogenous MeJA (0.5, 1.0, 2.0, and 4.0 mmol·L^－1) were determined 1, 3, 5, 7, and 15 d post treatment. A. gossypii or S. litura larvae were placed on cotton seedling leaves treated with one of two concentrations (1.0 mmol·L^－1, 2.0 mmol·L^－1) of exogenous MeJA and the developmental duration of nymphs, female fecundity, larval weight and the overall developmental duration of the two groups of larvae were measured. [Results]  Defense enzyme activity and total phenol content of cotton seedling leaves treated with different concentrations of exogenous MeJA increased markedly. POD activity in cotton seedling leaves treated with the three concentrations of exogenous MeJA (0.5, 1.0, and 2.0 mmol·L^－1) peaked 5 d post treatment at 4.11, 5.71, and 4.74 times that of control, respectively. POD Activity in cotton seedling leaves treated with four concentrations of exogenous MeJA was significantly higher than the control (P<0.05) 15 d post treatment. PPO activity in cotton seedling leaves treated with four concentrations of exogenous MeJA peaked 3 d post treatment at 1.2, 2.1, 2.16, and 2.71 times that of control, respectively. PPO activity in cotton seedling leaves treated with 2.0 and 4.0 mmol·L^－1 exogenous MeJA was significantly higher than the control (P<0.05) after 15 d post treatment. The total phenol content of cotton seedling leaves treated with 0.5 and 1.0 mmol·L^－1 exogenous MeJA peaked 15 d post treatment at 1.73, and 1.58 times that of control, respectively. The total phenol content of cotton seedling leaves treated with 2.0 and 4.0 mmol·L^－1 exogenous MeJA peaked 7 d post treatment at 1.6 and 1.7 times that of control, respectively. The developmental duration of A. gossypii nymphs fed on cotton treated with 1.0 and 2.0 mmol·L^－1 MeJA were 1.07 higher than that of the control and female fecundity was 20% and 39.4% lower than that of the control, respectively. The weight of S. litura larvae fed on cotton treated with 1.0 and 2.0 mmol·L^－1 MeJA was 12.7% and 34.2% less than the control, respectively and the developmental duration of S. litura larvae was 1.22 and 1.25 times that of control, respectively. [Conclusion]  Treatment of cotton seedling leaves with four concentrations of exogenous MeJA both significantly increased defensive enzyme activity and the total phenol content of the leaves, and also significantly inhibited the development of A. gossypii and S. litura larvae feeding on these leaves.