The repellent effects of eight Chinese herbal essential oils on red imported fire ants, Solenopsis invicta Buren (Hymenoptera: Formicidae), and analysis of active components

Abstract

The red imported fire ant (RIFA), Solenopsis invicta Buren, is an invasive pest that is extremely aggressive and thus poses a strong threat to human health, agricultural production, equipment and the environment. In this study, we evaluated the repellent effects of eight Chinese herbal essential oils (EOs) on RIFAs, and identified the main repellent components in the EOs. Results showed that all eight EOs had outstanding repellency to RIFAs, among which A. argyi and S. album EOs had the strongest repellent effects on RIFAs. GC-MS revealed 34 ingredients in A. argyi EO, among which sesquiterpenoids and their oxygenated derivatives accounted for the greatest proportion (50 %), followed by monoterpenes and their oxygenated derivatives (47.06 %) and unknown components (2.94 %). Dipentene, 1-caryophyllene, p-cymene, α-terpineol, and Δ-cadinene were the most abundant compounds. A total of 61 ingredients were identified in S. album EO, including monoterpenes and their oxygenated derivatives (40.98 %), sesquiterpenoids and their oxygenated derivatives (39.34 %), diterpenoids and their oxygenated derivatives (3.28 %), aromatic compounds (3.28 %), and unknown components (13.12 %). Among them, the most abundant compounds were diethyl phthalate, α-cetone, 2-phenylethanol and sandacanol. The GC-EAD results showed that RIFA workers exhibited strong electroantennographic responses to dipentene, α-terpineol and 1-caryophyllene from A. argyi EO, as well as to linalool, 2-phenylethanol and benzyl acetate from S. album EO. Furthermore, all of the above six ingredients had significant repellent effects against RIFAs based on behavioral experiments. In conclusion, A. argyi and S. album EOs have good repellent effects on RIFAs, and the active ingredients include dipentene, α-terpineol, 1-caryophyllene, linalool, 2-phenylethanol and benzyl acetate. Our findings provide new information for the development of green, safe, and efficient repellents against RIFAs.