Chemical Ecology and Management of Imported Fire Ants

Authors: Chen, Jian

Submitted to: Annual Review of Entomology
Publication Type: Review Article
Publication Acceptance Date: 6/26/2026
Publication Date: N/A
Citation: N/A

Interpretive Summary: Imported fire ants, first introduced to the U.S. in the early 1900s, have spread across the southern states and now infest more than 140 million hectares. These invasive insects pose serious threats to public health, agriculture, and ecosystems. Ants rely heavily on chemical signals called pheromones to coordinate their complex social lives, yet many of these pheromones remain unidentified. Without this knowledge, designing effective, targeted control methods remains difficult.An ARS researcher has reviewed decades of work on fire ant chemical ecology and synthesized recent advances in understanding how these ants use pheromones. The review outlines why identifying these chemicals has been so challenging - pheromones often occur in trace amounts, function only in specific combinations, and some behaviors (such as mating flights) cannot be reproduced in the laboratory. By mapping out what is known and what remains uncertain, the review provides a clearer picture of the scientific landscape and helps bridge the gap between current knowledge and persistent unknowns. By proposing innovative strategies to accelerate pheromone discovery, the review points toward more effective fire ant management. Ultimately, this work could support the development of safer, more precise tools for controlling invasive fire ants and reducing their impact on communities, farms, and natural environments.

Technical Abstract: Imported fire ants (Solenopsis invicta and S. richteri) are invasive pests introduced to the U.S. via Mobile, Alabama in the early 20th century. As these species spread, interbreeding led to the emergence of hybrid populations. Their rapid expansion and ecological dominance prompted extensive control efforts, including chemical eradication campaigns and biologically informed strategies. Today, fire ants infest over 140 million hectares across the southern U.S., impacting public health, agriculture, and ecosystems. Despite decades of research, many key pheromones remain unidentified due to complex social behavior and multi-component pheromone systems, often present in trace amounts. Aerial mating, which cannot be replicated in laboratory conditions, complicates sex pheromone identification. Additionally, components often lack activity unless presented in specific combinations. These challenges limit traditional bioassay-guided structure elucidation. This review summarizes recent advances in fire ant chemical ecology, highlights persistent knowledge gaps, and proposes innovative strategies to accelerate pheromone discovery and improve management.