Exploring bioactive molecules with fumigation toxicity against the red imported fire ant Solenopsis invicta Buren from commercial essential oils by GC-MS combined with chemometrics

Metabolomics approaches are becoming a powerful analytical technique for exploring bioactive molecules in essential oils. The prevalence of imported red fire ants affected the environment, biodiversity of wildlife, infrastructure, and hypersensitivity reactions of people. Due to public health and environmental issues, essential oils as environmentally friendly alternatives to synthetic chemical insecticides in fire ant management have attracted great attention. However, there is a lack of an objective strategy suitable for identifying bioactive molecules that can guarantee the quality of essential oil biopesticides. Therefore, a metabolomics approach with four main steps, including bioassays, GC-MS analysis of chemical constitution, construction of multivariate OPLS and univariate Pearson correlation statistical models, and feature selection, was proposed in this study to verify its potential to find bioactive molecules in essential oils that are effective against red imported fire ants. The fumigation mortalities of 20 commercial essential oils ranged from 0 to 100%. A total of 296 mass features were deconvoluted, and 121 of them were identified. Then, 52 potential bioactive molecules were selected by both VIP > 1.0 and P < 0.05. Finally, 6 of these potential bioactive molecules, (+)- 2-bornanone,.beta.-pinene, eucalyptol, isoborneol, linalool, and L-.alpha.-terpineol, have shown good fumigation toxicity against minor and/ or major red imported fire ant workers. This study has, in certain aspects, supported the feasibility of this metabolomics approach. It could be helpful for natural molecules to be alternatives to synthetic chemical insecticides, leading to more environmentally friendly and sustainable management policies for red imported fire ants.