Effects of field simulated warming on feeding behavior of Sitobion avenae (Fabricius) and host defense systems

Climate warming affects crop phenology, physiology and biochemistry in agricultural ecosystems and has cascading effects on the performance and abundance of herbivorous insect pests. In this study, a field-simulated warming experiment was conducted using MSR-2420 infrared radiation lamps to assess its effects on the population size and feeding behavior of Sitobion avenae (Hemiptera: Aphididae). Additionally, the activity of the salicylic acid (SA) and jasmonic acid (JA) pathway-related enzymes and their gene expressions in wheat were recorded. Results revealed the population of S. avenae significantly increased in the warming treatment and significantly prolonged the average duration of the E-1 and E-2 waves of S. avenae. Enzymatic assays showed the activities of phenylalaninammo-nia lyase (PAL) and beta-1,3-glucanase (beta-1,3-GA), involved in the SA pathway, and polyphenol oxidase (PPO), involved in the JA pathway, decreased following exposure to elevated warming whereas the activity of lipoxygenase (LOX), involved in the JA pathway, increased. The expression of PAL, beta-1,3-GA, involved in the SA pathway, and LOX and PPO, involved in the JA pathway, were similar to the changes in enzyme activity. Results indicated that S. avenae population increase was positively correlated with its feeding behavior and fitness, and these were correlated with decreasing wheat resistance through the SA and JA signaling pathways.