Climate Change and Alternative Hosts Complicate the Eradication of Cattle Fever Ticks (Acari: Ixodidae) in the Southern United States, a Review

Abstract

Abstract Potential reinvasion of the United States by cattle fever ticks, Rhipicephalus (Boophilus) annulatus (Say) and R. (B.) microplus (Canestrini), which are endemic in Mexico, threatens the domestic livestock industry because these ticks vector the causal agents (Babesia bovis (Babes) (Piroplasmida: Babesidae) and B. bigemina Smith & Kilborne) of bovine babesiosis. The Cattle Fever Tick Eradication Program safeguards the health of the national cattle herd preventing reemergence of bovine babesiosis by keeping the United States cattle fever tick-free. Free-living southern cattle tick, R. (B.) microplus, larvae have been collected from vegetation in the wildlife corridor of Cameron Co.- Willacy Co., Texas. Finding R. microplus larvae on vegetation complements reported infestations in wildlife hosts inhabiting the south Texas coastal plains. Substantial population expansion of native white-tailed deer Odocoileus virginianus (Zimmermann) (Artiodactyla: Cervidae), and exotic nilgai antelope Boselaphus tragocamelus (Pallas) (Artiodactyla: Bovidae), both of which are definitive hosts for the cattle fever tick, support local tick populations independent of cattle. Increasing prevalence of native and exotic wild ungulates, widespread tick acaracide resistance, and climate change, undermine efforts to control bovine babesiosis. Thus, ecological conditions have changed since cattle fever ticks were eradicated from the United States in 1943 using cattle-centric control strategies. These changes complicate efforts by the Cattle Fever Tick Eradication Program to keep cattle in the United States free of these cattle fever disease vectors. Technologies that could be applied to integrated eradication efforts are discussed.