Using targeted poisoning of red imported fire ants to improve Texas horned lizard habitat

Abstract

The spread of red imported fire ants (Solenopsis invicta; RIFA) is often cited as a factor contributing to the decline of the Texas horned lizard (Phrynosoma cornutum; THL). Many studies have attempted broadcast poison application to eradicate RIFA; however, this could have unintended consequences for non-target invertebrates that THL need for food. Using a targeted application method, we sought to reduce RIFA abundance over the summers of 2022 and 2023 at Mason Mountain WMA in central Texas, a locality with an ongoing THL reintroduction program. At treated sites, one teaspoon of ant poison (Amdro®) was applied to bait stations with RIFA present thirty minutes after placement. Effects of each targeted poisoning were evaluated using pitfall traps and bait stations. Pitfall trapping was likely a more accurate estimate of ant abundance and revealed that targeted poisoning decreased RIFA abundance for both years and had variable effects on hatchling THL prey abundance.