Early Season Applications of Bifenthrin Suppress Host-seeking Ixodes scapularis and Amblyomma americanum (Acari: Ixodidae) Nymphs

We assessed the efficacy of bifenthrin to suppress Ixodes scapularis Say and Amblyomma americanum (L.) nymphs when applied prior to the initiation of spring host-seeking activity versus when nymphs were already active. Treatment and control plots were sampled for host-seeking ticks every week from mid-April through June, and single occasion bifenthrin applications were done in different sets of treatment plots on 15 April, 29 April, 13 May, and 27 May. Ixodes scapularis nymphs and A. americanum nymphs and adults were effectively suppressed after each application, with at or near 100% suppression of all ticks being observed for up to 8-wk postapplication. Irrespective of the bifenthrin application date, the level of suppression of I. scapularis nymphs never declined below 70% during the study period. However, with the exception of the last application, the suppression of A. americanum nymphs decreased dramatically to below 25% by the conclusion of the trial. The results of this study demonstrated that preseason applications of bifenthrin can mitigate acarological risk of exposure to ticks throughout much of their spring peak activity period.