Submitted to: Imported Fire Ants Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: March 22, 2005
Publication Date: May 22, 2005
Citation: Chen, J. Effect of Fire Ant Digging Behavior on Efficacy of Fipronil Against Workers: Results of a Laboratory Study. Imported Fire Ants Conference Proceedings. 2005. Interpretive Summary: Individual mound treatment and broadcast application using contact insecticides are common practices in fire ant management. Effective treatments require contact between ants and insecticides. This study found that effectiveness of contact insecticides against fire ant can be improved by enhancing digging behavior without increasing the dose. Such enhancement may be achieved by using non-repellant insecticides and chemicals which elicit digging behavior.
Technical Abstract: The effect of the digging behavior of fire ant workers on the efficacy of fipronil was investigated using digging bioassays. Workers excavated fipronil treated sand in 99.5% cases at concentration level up to 10.0 ppm. In no-choice bioassays at 1.5 and 2.0 ppm, workers from a less sensitive colony had significantly higher mortality rates than those from a more sensitive colony, which could be due to the significantly higher digging activity of the less sensitive colony. In two-choice bioassays where untreated sand was also available, at 1.0 and 10.0 ppm, mortalities were positively correlated to digging effort in treated sand; however, such correlation was significant only at 1.0 ppm level.