Ticks infesting white-tailed deer in South Texas

Authors: Thomas, Donald; DUHAIME, ROBERTA - ANIMAL AND PLANT HEALTH INSPECTION SERVICE (APHIS)

Submitted to: Livestock Insect Worker's Conference Annual Meeting
Publication Type: Other
Publication Acceptance Date: 3/20/2019
Publication Date: N/A
Citation: N/A

Interpretive Summary: White-tailed deer were examined for ticks during the 2018 hunting season at the Laguna Atascosa National Wildlife Refuge in Cameron county TX. Only four of the 73 deer examined were not infested by ticks. A total of 3380 ticks were counted and identified to one of seven species. Five of the encountered tick species are found in tropical areas and just enter the United States in the border area of Texas: the inornate tick, the cayenne tick, the imitator tick, the tropical horse tick and the southern cattle fever tick. The latter two species, the tropical horse tick and the southern Cattle Fever Tick, both one-host ticks, are important economic pests of livestock and thus, it is of some concern that they use white-tailed deer as a wild animal host. Notably, although deer have been reported as an incidental host, the very high numbers (2922) including juvenile as well as adult ticks, suggests that deer are the typical host of the “Horse tick” given that horses are not native to the western hemisphere and the horse tick does not occur in the Old World. The gulf coast tick, another pest of livestock was common and coexistent with the other wood ticks in this deer herd. Finally, the detection of 21 specimens of the black-legged tick, the carrier of Lyme disease, suggests that this tick may not be as rare in south Texas as previous surveys have indicated.

Technical Abstract: White-tailed deer were scratch inspected for ticks during the 2018 hunting season at the Laguna Atascosa National Wildlife Refuge in Cameron county TX. Only four of the 73 deer examined were negative for infestation by ticks. A total of 3380 ticks were counted and identified to one of seven species. Five of the encountered tick species are precinctive to the neotropics and just enter the United States in the border area of Texas: Amblyomma inornatum, A. mixtum, A. tenellum, Anocentor nitens and R. Boophilus microplus. The latter two species, the tropical horse tick and the southern Cattle Fever Tick, both one-host ticks, are important economic pests of livestock and thus, it is of some concern that they use white-tailed deer as a sylvatic reservoir. Notably, although deer have been reported as an incidental host, the very high numbers (2922) including larvae and nymphs as well as adults, suggests that deer are the native host of the “Horse tick” given that horses are not native to the western hemisphere and A. nitens does not occur in the Old World. The gulf coast tick, another pest of livestock was common and coexistent with the other Amblyomma spp. in this deer herd. Finally, the detection of 21 specimens of Ixodes scapularis, the vector of Lyme disease, suggests that this species may not be as rare in south Texas as previous surveys have indicated.