Herbal Plants as Alternatives for the Management of the Red Imported Fire Ant, Solenopsis Invicta (Hymenoptera: Formicidae)

Abstract

\n The red imported fire ant (RIFA) is one of the most detrimental invasive species, threatening native ecosystems, human health, and economic activities worldwide. In the quarantine zone of Taiwan, RIFA re-infestation frequently occurs despite the intensive application of synthetic pesticides, making its control costly and ineffective. Thus, there is an urgent need to identify effective, eco-friendly, and sustainable alternatives for controlling RIFA populations. In this study, we examined the efficacy and feasibility of planting herbal species for RIFA control. Five herbal species, Tagetes lemmonii, Armoracia rusticana, Cymbopogon citratus, Cymbopogon nardus, and Chrysopogon zizanioides, were planted in a RIFA-infested field with local weeds as controls. Bait and pitfall traps and RIFA intruded plants were used to compare the ant activity in the control fields and those containing herbal plants. The RIFA repellent activity of the five herbal plants and their basal soil was further evaluated through digging bioassays. Generally, the field surveys showed more ants and intruded plants in the control than in the herbal groups; however, the significance varied based on the trap type and plant species. The bioassays demonstrated the significant repellency of the aboveground parts of T. lemmonii, C. nardus, and C. citratus, and the belowground parts of T. lemmonii, C. citratus, and V. zizanioides against RIFA. The basal soil of T. lemmonii, C. citratus, and C. nardus also exhibited deterrent activity toward RIFA. Our results demonstrated that herbal plants are eco-friendly, sustainable alternatives for controlling and preventing RIFA infestation in severe infested and non-infested areas.