Effect of exogenous MeJA treatment of cotton on the development of Aphis gossypii (Hemiptera: Aphididae) and Spodoptera litura (Lepidptera: Noctuidae)
Author of the article:MA Guang-Min；LIU Shou-Zhu；DU Xue-Lin；DAI Ming-Xun；YUAN Feng-Ying；MEN Xing-Yuan
Author's Workplace：College of Agriculture, Liaocheng University, Liaocheng 252000, China; Institute of Plant Protection, Shandong Academy of Agricultural Sciences, Jinan 250100, China
Key Words： methyl jasmonate, cotton, inducible defence, Aphis gossypii, Spodoptera litura
Abstract：
[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.