Behavioral Response of Sitobion avenae (Hemiptera: Aphididae) to Volatile Compounds Emitted by Healthy and Infected Wheat Plants

Abstract

The grain aphid, Sitobion avenae, is a key pest of wheat, causing significant yield losses through direct feeding and virus transmission. Plant–aphid interactions are strongly mediated by volatile organic compounds (VOCs), which vary between healthy and pathogen-infected plants. The present study evaluates the behavioral response of S. avenae to VOCs emitted by healthy wheat plants and those infected with foliar pathogens under controlled laboratory conditions. Volatile blends were collected from both plant groups and analyzed using gas chromatography–mass spectrometry (GC–MS) to identify key chemical constituents. Behavioral assays were conducted using a Y-tube olfactometer to determine aphid preference, attraction, or repellence. Results indicated that aphids exhibited a significant preference for VOCs emitted by infected wheat plants compared to healthy plants, suggesting altered chemical signaling in response to pathogen infection. GC–MS analysis revealed qualitative and quantitative differences in volatile profiles, with infected plants emitting increased levels of stress-induced compounds such as green leaf volatiles and terpenoids. These compounds likely acted as semiochemical cues influencing aphid host selection behavior. Conversely, certain VOCs associated with healthy plants showed neutral or weakly deterrent effects on aphid movement. The study demonstrates that pathogen-induced changes in plant volatile emissions can significantly modify herbivore behavior and may enhance host plant attractiveness to S. avenae. These findings highlight the ecological complexity of tritrophic interactions involving plants, pathogens, and insect herbivores. Overall, the results provide important insights into the role of plant volatiles in aphid behavioral ecology and suggest potential applications in developing semiochemical-based pest management strategies for wheat agroecosystems.