Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 11, 2000
Publication Date: N/A
Interpretive Summary: White-tailed deer are the main hosts for ticks that transmit agents that cause Lyme disease, human ehrlichiosis, and other diseases in humans. They also are significant hosts for cattle fever ticks that transmit agents that may cause fatal diseases in cattle. These ticks were eradicated from the U.S., but they continue to re-infest areas along our border with Mexico. The increase in numbers of deer has increased numbers of ticks and thus caused more cases of tick transmsitted diseases in humans, and deer also are compromising the fever tick eradication zone along the Texas border with Mexico. In an attempt to reduce numbers of ticks by treating deer, the deer in a deer-fenced pasture treated themselves with pesticide as they fed from an ARS patented '4-poster' treatment device, and after 3 seasons of treatment, numbers of nymphs and adults in the pasture were reduced by 92 and 94%, respectively. As a result of this study, the '4-poster' technology was shown to be an efficient, effective, and environmentally friendly method of reducing numbers of ticks in infested areas. This topical treatment technology is an important development in the control of ticks, and may become an integral part of control efforts aimed at reducing the risk of Lyme disease, human ehrlichiosis, and other debilitating and potentially fatal diseases that are transmitted to humans, livestock, and wildlife as a result of being bitten by ticks.
Technical Abstract: White-tailed deer treated themselves with a commercial pour-on acaricide formulation containing 2% amitraz as they fed from an ARS patented '4- poster' topical treatment device. Whole kernel corn attracted deer to a single device placed in each of 2 deer-fenced pastures. In the treatment pasture, the rollers of the treatment device were charged with the acaricide, while the rollers of the device in the other pasture remained untreated. Deer were allowed to use the '4-posters' during periods of larval, nymphal, and adult tick activity for 3 consecutive years. Pretreatment samples of ticks during 1995 showed no significant differences in population indices between the 2 pastures, however, following the third year of treatment, control of nymphal and adult ticks in the treated pasture was 91.9 and 93.7%, respectively, when compared to the untreated pasture. Control of larval masses increased from 68.4% in 1996 to 96.4% in n1997, but declined to 88.0% in 1998, likely because of the presence of feral hogs. This study demonstrated that passive application of amitraz to white-tailed deer through free-choice interaction with a '4-poster' device significantly reduced the abundance of free-living lone star ticks in the deer-fenced experimental pasture.