Behavioral preferences of Solenopsis invicta Buren to essential oils and active compounds from amiaceae plants

Abstract

The red imported fire ant (RIFA) (Solenopsis invicta Buren) has caused serious ecological and public safety problems in invasive areas. While extensive use of pesticides to control RIFA may negatively affect human health and environment, essential oils (EOs) of Lamiaceae possessing aromatic smell and multiple biological activities are potential alternatives of chemical pesticides. In this study, we evaluated the behavioral preferences of different castes of RIFA towards the EOs from five species of Lamiaceae plants (Salvia miltiorrhiza, Perilla frutescens, Pogostemon cablin, Schizonepeta tenusfolia, Mentha canadensis), and then investigated the active compounds in these EOs that trigger insect behavioral preferences by gas chromatography-electroantennographic detection (GC-EAD). The results of behavioral experiment indicated that three EOs strongly altered the behavior of RIFA. Notably, all concentrations of P. frutescens EO showed a significant repellent activity on virgin queen ants, with a repellent rate of 62.50% at the lowest concentration of 2 μg/ml. The repellent effect of S. tenusfolia EO against small worker ants reached a very significant difference between control and treatment groups, with the highest repellent rate of 85.00% observed at 1000 μg/ml. Save for the lowest concentration 2 μg/ml, other doses of M. canadensis EO showed a remarkable repellent effect on small worker ants, demonstrating a positive dose-effect relationship (with repellent rates of 77.50% and 65.00% at 1000 and 8 μg/ml, respectively). A total of 39 EAD-active compounds were detected in these EOs, and 12 of them were subsequently evaluated for behavioral preferences of RIFA. Our findings indicated that six compounds (menthone, menthol, caryophyllene oxide, pulegone, 3-methylcyclopentanol, eugenol) consistently triggered behavioral preferences in worker ants. Meanwhile, six compounds, including borneol, eugenol, phenylethyl alcohol, perilla ketone, 3-methylcyclopentanol, α-guaiene, were found to significantly alter the behavioral selectivity of virgin queen ants. These results may help to develop application value of selected Lamiaceae plants EOs and contribute to the exploration of new green control methods for invasive pests.