Seed Coating with Thiamethoxam-Induced Plant Volatiles Mediates the Olfactory Behavior of Sitobion miscanthi

Pesticides can induce target plants to release odors that are attractive or repellent to their herbivore insects. But, to date, the activity of volatile organic compounds (VOCs), singly or as mixtures, which play a crucial role in the olfactory behavior of herbivore insects, remains unclear. The objective of our research was to investigate the impact of thiamethoxam (TMX), a pesticide, on the emission of odors by wheat plants, and how these odors influence the behavior of grain aphids (Sitobion miscanthi). S. miscanthi showed a greater repellent response to the volatiles emitted by Thx-induced plants compared to those emitted by uncoated plants. Using gas chromatography-mass spectrometry (GCMS), we discovered that TMX greatly induced the release of VOCs in wheat plants. For instance, the levels of Bornyl acetate, 2-Oxepanone, Methyl acrylate, Cyclohexene, α-Pinene, and 1-Nonanol in coated wheat plants were significantly higher as compared to uncoated wheat plants. Moreover, varying concentrations also had an impact on the olfactory behavior of S. miscanthi. For instance, Cyclohexene exhibited clear attractiveness to aphids at concentrations of 100 μL/mL, whereas it displayed evident repellent properties at concentrations of 1 μL/mL and 10 μL/mL. These new findings demonstrate how TMX-induced VOCs affect the behavior of S. miscanthi and could help in developing innovative approaches to manage aphids by manipulating the emission of plant volatiles. Furthermore, these findings can also be utilized to evaluate substances that either attract or repel aphids, with the aim of implementing early monitoring and environmentally friendly methods to manage aphids, while simultaneously impeding the spread of viruses.