Impact of Beneficial Microorganisms Inoculated Cotton Plants on Spodoptera exigua (Lepidoptera: Noctuidae)

This study discusses plant-mediated effects of beneficial soil-borne microorganisms on population growth parameters of Spodoptera exigua (Lepidoptera: Noctuidae), a major cotton pest. In particular, we investigated the impact of these microorganisms on oxidative stress, chlorophyll content, and sugar and protein levels in cotton plants, and how these changes in the plant affect the survival, development, reproduction, and ultimately population growth of the pest. A longer preadult period, lower preadult survival rate, and lower reproduction were obtained for the pest cohort feeding on treated plants, which resulted in lower population parameters, i.e., intrinsic growth rate, finite growth rate, and net reproduction rate. The population projection results showed the same trend as the population parameters. These results can be attributed to the changes caused by microorganisms in the treated plants. There was no oxidative stress in the treated plants. Instead, the chlorophyll content in these plants increased, and the protein-carbohydrate ratio decreased. Additionally, we assessed the effects of plant-insect-microorganisms interaction on total glutathione levels, glutathione S-transferase, and esterase enzyme activities in S. exigua. Overall results indicate that beneficial microorganisms tested enhance the plant's ability to defend against the pest. Additionally, the findings from this study provide valuable insights into the complex interplay among plants, microorganisms, and pests, offering potential strategies for incorporating these interactions into pest management practices.