UC Riverside

The Argentine ant, Linepithema humile (Mayr), is an extremely invasive ant species that has spread to urban, commercial and natural areas worldwide. This pervasive expansion has had detrimental ecological and economic effects, resulting in the allocation of vast amounts of resources to its control in urban and agricultural areas. New efforts are underway to control Argentine ants in ecologically sensitive habitats, such as California’s Channel Islands. I tested the treatment efficacy of application of thiamethoxam liquid bait in ecologically sensitive habitats using polyacrylamide beads as a delivery matrix to eradicate Argentine ants. This matrix is shown to be a promising eradication tool on San Clemente Island, CA with a 99.86% reduction in Argentine ant activity across five sites (176.95 hectares). As these eradication efforts are implemented, a standardized detection protocol becomes essential to gauge the success of such efforts and to ensure that remnant ant populations don’t go undetected during pre- or post-treatment stages. In aid of creating such protocols, I conducted field trials to assess 1) attractant efficacy for Argentine ant detection throughout the year and 2) pre- and post-treatment detection rates of Argentine ants. Traditional sucrose water bait traps can be enhanced with the addition of sugar-egg or a synthetic pheromone of the Argentine ant. The sugar-egg and pheromone bait traps performed equally well at detecting Argentine ants in areas with low levels of ant density. This information will be used to standardize detection protocols in a diversity of ecosystems and to refine Argentine ant eradication efforts on the Channel Islands.