Screening and identification of two repellent active volatiles to Hyphantria cunea

The invasion of Hyphantria cunea, also known as “smokeless fires”, poses a significant threat to artificial and natural forest resources. Therefore, it is urgent to adopt safe and effective control strategies to prevent the spread of and harm caused by of H. cunea. In this study, potential repellent active ingredients were screened from the volatiles of Larix gmelinii and Syringa oblata, the non-preferred hosts of H. cunea. The sensitive substances were identified in the H. cunea larvae and adults through electroantennographic (EAG) and behavioral responses. The results showed that fresh branches with leaves of L. gmelinii and S. oblata had significant repellent effects on the fifth and 6th instar larvae and virgin females, which were mainly related to α-pinene and (+)-limonene and other volatile substances. 100 μL/mL α-pinene and (+)-limonene were found to significantly stimulate the olfactory nervous system of H. cunea virgin females and male adults, and could induce significant EAG responses. They could induce avoidance behavior of 4-6th instar larvae, virgin females, and male adults, and also inhibit the selection behavior of fifth and 6th instar larvae and adults to Salix matsudana, the preferred food host. So α-pinene and (+)-limonene can be used as repellents for larvae and adults of H. cunea, with an effective concentration of 100 μL/mL. The two terpenes can induce avoidance behavior of H. cunea during the larval feeding period and before the mating of adults, thus inhibiting the outbreak and spread of the pest, providing an important control strategy for the integrated management of H. cunea.