Optimization of Formulations for the Lethal Control of Feral Pigs

Feral pig populations continue to increase and disperse into unoccupied habitats in North America. Associated damages and control efforts cost U.S. taxpayers as much as $1.5 million/year. Toxicants show promise for feral pig control programs and may be more cost-effective than contemporary methods (i.e., trapping, aerial gunning, and dog-hunting). However, no toxicants are registered for feral pig control in the U.S. Development of sodium nitrite as an active ingredient in pig toxicants is ongoing in Australia, and a registration has been granted in New Zealand. Sodium nitrite is a strong oxidizer and is unpalatable to feral pigs, and thus it must be masked and stabilized to ensure effective dosing. We researched 3 different formulations of sodium nitrite loaded in a single bait matrix to evaluate mortality and acceptance in the context of U.S. registry requirements. Formulations were accepted by feral pigs but did not cause acceptable mortality rates in subjects. One formulation (TX1) produced mean mortality rates of 50%, which was well below our stated goal of 90%. Bait acceptance and mortality were diminished by insufficient masking of sodium nitrite. However, results indicate that our sodium nitrite formulation improved acceptance and mortality rates in feral pigs and could be the basis for improvements. Future investigations will focus on masking the taste of sodium nitrite