Texas pasture grass repellency to the red imported fire ant



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Texas Tech University


The Red Imported Fire Ant (RIFA) is an invasive pest that causes ecological disturbance and economic damage to habitats it invades. Since its introduction to the U.S. 75 years ago, RIFA have spread across the southeastern U.S. and are now found in California, with current research showing further territorial expansion in North America and internationally. In Texas, RIFA-related damages and expenditures are estimated to exceed $1.2 billion. Often studied, conventional RIFA control methods have not proven effective or long-lasting. New research efforts that concentrate on habitat characteristics may result in methods can repel or reduce RIFA density. This study examined different pasture grasses in Texas, focusing on WW-B.Dahl, to determine if particular grass types limit or reduce RIFA infestation compared to other grasses. Results show that WWB. Dahl grass has significantly fewer RIFA mounds than other grasses such as Bermuda and native. However, this study failed to find a difference in ant bait cup collections in the grass types tested. Fewer mounds will improve efficiency of harvesting operations for growers and reduce vegetation loss due to RIFA mounds. Little correlation was found between ant numbers in bait cups and mound counts or mound vitality ratings, suggesting that more than one measure of ant infestation is needed to accurately determine RIFA numbers. Additionally, WW-B.Dahl grass showed some grass spread beyond its original field of planting, which increased with age of field. Due to the lack of information on the environmental conditions in which WW-B.Dahl grows, primary abiotic characteristics were compiled where B.Dahl is successfully grown in central and northern Texas.