Abstract
Laboratory and field studies were conducted to determine the persistence and efficacy of termiticides used as preconstruction treatments against subterranean termites. Bifenthrin (0.067%), chlorpyrifos (0.75%), and imidacloprid (0.05%) ( [AI]; wt:wt) were applied to soil beneath a monolithic concrete slab at their minimum labeled rates. Soil samples were taken from three depths (0-2.5, 2.6-7.6, and 7.7-15.2 cm) at six sampling times (0,3, 6,9, 12 and 48 mo) from sites in Harrison and Oktibbeha counties in Mississippi. Residue analyses were conducted on the 0-2.5- and 2.6-7.5-cm depths, and bioassays were conducted using all three depths. In field studies, significant termiticide degradation occurred between sampling times 0 and 48 mo for all termiticides. At all sampling times, the top 2.5 cm of soil contained more termiticide than the other depths. Time to 50% dissipation of termiticide in the 0-2.5-cm depth was 9,6, and 2 mo for bifenthrin, chlorpyrifos, and imidacloprid, respectively. Termite mortalities in contact bioassays remained high for bifenthrin and chlorpyrifos throughout the 48-mo sampling period; however, mortality of termites exposed to imidacloprid-treated soil dropped after the initial sampling. Termites readily penetrated all termiticide-treated soil in bioassays of 52-mm soil cores at 48 mo. Percentage of mortality in these bioassays was 15,43, and 13 for bifenthrin, chlorpyrifos, and imidacloprid respectively.
Keywords
termiticide,
residue,
toxicity
Citation
Mulrooney, J.E.; Davis, M.K.; Wagner, T.L.; Ingram, R.L. 2006. Persistence and efficacy of termiticides used in preconstruction treatments to soil in Mississippi. J. Econ. Entomol., Vol. 99(2): 469-475