Bifenthrin longevity at the termiticidal application rate

The longevity, mobility and insecticidal activity of bifenthrin at the termiticidal application rate for perimeter treatment were investigated in packed-soil columns in the laboratory and greenhouse.

Bifenthrin was not detected in the eluates of packed-soil cones over a period of 6 months. In larger pipe plots incorporating bifenthrin into the top 15 cm of the soil, the compound degraded in a biphasic fashion. Within the treated soil, the effect of vegetation on the amount of bifenthrin remaining in the soil depended on soil depth and time, and soil half-lives were longer in non-vegetated soil. Bifenthrin residues were higher in the top 7.5 cm of soil and declined over time. Movement of bifenthrin into the top untreated soil depth was observed, but much less was observed in lower depths. The soil remained toxic to termites in 3 day and 7 day forced exposure bioassays for the 30 month duration of the study.

Concentrations of bifenthrin will remain in the soil at levels sufficient to kill termites for more than 30 months.