Submitted to: Sociobiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/10/2010
Publication Date: 10/28/2010
Citation: Wiltz, B.A. 2010. Laboratory evaluation of effects of soil properties on termiticide performance against Formosan Subterranean Termites (Isoptera: Rhinotermitidae) Sociobiology 56(3):755-773.
Interpretive Summary: Fourteen soils representing a range of soil properties were treated with three termiticides at two rates of each. Two weeks post-treatment, core samples were divided into three 5-cm sections, and evaluated for toxicity to Formosan subterranean termites. Bifenthrin treatments had the highest overall mortality, followed by fipronil, then chlorfenapyr treatments after 24 and 48h exposure. Clay content of soil affected the performance of all treatments. Some soil treatments were also affected by soil pH and organic carbon content. Soils will be evaluated annually to determine how soil properties affect degradation and movement of termiticides.
Technical Abstract: Fourteen Mississippi soils representing a range of soil properties were treated with bifenthrin, chlorfenapyr, or fipronil at two rates of each termiticide. Treated soils were placed in well-drained containers, then watered. Two weeks post-treatment, core samples were removed, divided into three 5-cm sections, and evaluated in constant exposure assays for efficacy against the Formosan subterranean termite, Coptotermes formosanus Shiraki. Bifenthrin treatments had the highest overall mortality, followed by fipronil, then chlorfenapyr treatments after 24 and 48h exposure. After 24h, untreated controls and all termiticide treatments had highest mortality in low clay soils. In 0.06% bifenthrin treatments, mortality was highest at low pH. At both rates of chlorfenapyr and fipronil, there were interactions between clay and pH. When differences among soils occurred, mortality was highest at low pH. After 48h exposure, all treatments had highest mortality on low clay soils. In 0.06% bifenthrin, 0.125% chlorfenapyr, and 0.25% chlorfenapyr treatments, mortality was highest on low pH soils. Clay-pH interactions occurred at both fipronil rates, with higher mortality at low pH occurring only among medium clay soils. Effects of organic carbon could not be interpreted independently of clay and pH effects because not all combinations of soil properties were available for testing. Within a treatment, termite mortality did not differ with section of the core sample (top, center, or bottom) after 24 or 48h exposure.