Evaluating a deer-targeted acaricide applicator for area-wide suppression of blacklegged ticks, Ixodes scapularis (Acari: Ixodidae), in Rhode Island.

Over a 5-year period, September 1997 through May 2002, as many as 25 U. S. Department of Agriculture-Agricultural Research Service "4-Poster" acaricide applicators were distributed in areas of high deer activity throughout a 518-hectare area in a rural Rhode Island community. Corn consumption and acaricide levels for each device were monitored weekly during each treatment season to assess the degree of deer use. The efficacy of acaricide treatment was determined by comparing relative blacklegged tick (Ixodes scapularis) densities in the 4-Poster treatment site to a separate, similar-sized nontreatment area. The tendency of white-tailed deer to use the 4-Poster was variable temporally, and appeared to be largely dependent on the availability of alternative food sources. Total corn consumption was nearly fourfold lower during large oak masting years when compared with no/low mast years. Moreover, habitat characteristics, such as the presence of maintained hay lands consisting of alfalfa and clover, also appeared to influence the frequency and amount of 4-Poster use. After 2 years of adequate treatment (nearly 12,000 kg of corn consumed), we achieved nearly 50% control of nymphal blacklegged ticks within the treatment site compared with tick abundance levels in the nontreated area. Moreover, that level of tick control was maintained for 1 year after removal of the 4-Poster devices but began to wane 2 years after treatment ended.