title: Invasive potential of cattle fever ticks in the southern United States.
abstract: For >100 years cattle production in the southern United States has been threatened by cattle fever. It is caused by an invasive parasite-vector complex that includes the protozoan hemoparasites Babesia bovis and B. bigemina, which are transmitted among domestic cattle via Rhipicephalus tick vectors of the subgenus Boophilus. In 1906 an eradication effort was started and by 1943 Boophilus ticks had been confined to a narrow tick eradication quarantine area (TEQA) along the Texas-Mexico border. However, a dramatic increase in tick infestations in areas outside the TEQA over the last decade suggests these tick vectors may be poised to re-invade the southern United States. We investigated historical and potential future distributions of climatic habitats of cattle fever ticks to assess the potential for a range expansion.
  
  
  METHODS
  We built robust spatial predictions of habitat suitability for the vector species Rhipicephalus (Boophilus) microplus and R. (B.) annulatus across the southern United States for three time periods: 1906, present day (2012), and 2050. We used analysis of molecular variance (AMOVA) to identify persistent tick occurrences and analysis of bias in the climate proximate to these occurrences to identify key environmental parameters associated with the ecology of both species. We then used ecological niche modeling algorithms GARP and Maxent to construct models that related known occurrences of ticks in the TEQA during 2001-2011 with geospatial data layers that summarized important climate parameters at all three time periods.
  
  
  RESULTS
  We identified persistent tick infestations and specific climate parameters that appear to be drivers of ecological niches of the two tick species. Spatial models projected onto climate data representative of climate in 1906 reproduced historical pre-eradication tick distributions. Present-day predictions, although constrained to areas near the TEQA, extrapolated well onto climate projections for 2050.
  
  
  CONCLUSIONS
  Our models indicate the potential for range expansion of climate suitable for survival of R. microplus and R. annulatus in the southern United States by mid-century, which increases the risk of reintroduction of these ticks and cattle tick fever into major cattle producing areas.
authors.forename: John R
authors.initials: JR
authors.lastname: Giles
authors.forename: A Townsend
authors.initials: AT
authors.lastname: Peterson
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Busch
authors.forename: Pia U
authors.initials: PU
authors.lastname: Olafson
authors.forename: Glen A
authors.initials: GA
authors.lastname: Scoles
authors.forename: Ronald B
authors.initials: RB
authors.lastname: Davey
authors.forename: J Mathews
authors.initials: JM
authors.lastname: Pound
authors.forename: Diane M
authors.initials: DM
authors.lastname: Kammlah
authors.forename: Kimberly H
authors.initials: KH
authors.lastname: Lohmeyer
authors.affiliation: Center for Microbial Genetics and Genomics, Northern Arizona University, PO Box 4073, Flagstaff, AZ 86011, USA. dave.wagner@nau.edu.
authors.forename: David M
authors.initials: DM
authors.lastname: Wagner
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology / Q000469:parasitology*; D057231:Climate Change; D058865:Introduced Species; D008954:Models, Biological; D048494:Rhipicephalus / Q000145:classification* / Q000502:physiology*; D013984:Tick Infestations / Q000453:epidemiology / Q000469:parasitology / Q000662:veterinary*; D014481:United States / Q000453:epidemiology
references.citation: J Med Entomol. 1991 Mar;28(2):223-40
references.pmid: 2056504
references.citation: Vet Parasitol. 2012 Feb 10;183(3-4):338-42
references.pmid: 21824728
references.citation: J Med Entomol. 2005 Sep;42(5):912-7
references.pmid: 16363176
references.citation: Science. 2002 Jun 21;296(5576):2158-62
references.pmid: 12077394
references.citation: Vet Parasitol. 2010 Sep 20;172(3-4):214-20
references.pmid: 20605333
references.citation: Parasitology. 2004;129 Suppl:S353-66
references.pmid: 15938518
references.citation: J Med Entomol. 1997 Jul;34(4):461-84
references.pmid: 9220682
references.citation: Vet Parasitol. 1999 Feb 1;81(1):73-82
references.pmid: 9950331
references.citation: Ann N Y Acad Sci. 2008 Dec;1149:249-54
references.pmid: 19120223
references.citation: J Med Entomol. 1993 Sep;30(5):843-57
references.pmid: 8254630
references.citation: Parasit Vectors. 2014 Apr 17;7:188
references.pmid: 24742041
references.citation: Philos Trans R Soc Lond B Biol Sci. 2011 Jul 12;366(1573):2045-54
references.pmid: 21624924
references.citation: Ecology. 2009 Apr;90(4):906-12
references.pmid: 19449684
references.citation: Proc Natl Acad Sci U S A. 2013 Dec 24;110(52):20871-7
references.pmid: 21576468
references.citation: Vet Parasitol. 2011 May 11;177(3-4):298-304
references.pmid: 21194841
references.citation: Naturwissenschaften. 2008 Jun;95(6):483-91
references.pmid: 18320161
references.citation: Clin Microbiol Rev. 2004 Jan;17(1):136-73
references.pmid: 14726459
references.citation: J Econ Entomol. 2010 Apr;103(2):211-8
references.pmid: 20429430
references.citation: Vet Parasitol. 2010 Feb 10;167(2-4):92-4
references.pmid: 19833440
references.citation: Vet Parasitol. 2006 Dec 20;142(3-4):350-8
references.pmid: 16956729
references.citation: Vet Parasitol. 1991 Nov;40(3-4):305-13
references.pmid: 1788937
references.citation: J Med Entomol. 1977 Jun 20;13(6):629-58
references.pmid: 328882
references.citation: Front Physiol. 2012 Jun 14;3:195
references.pmid: 22712018
references.citation: J Exp Biol. 2010 Mar 15;213(6):946-54
references.pmid: 20190119
references.citation: Int J Parasitol. 1998 Jun;28(6):935-45
references.pmid: 9673872
references.citation: J Med Entomol. 1996 Jul;33(4):619-27
references.pmid: 8699457
references.citation: Adv Parasitol. 2000;47:217-43
references.pmid: 10997208
references.citation: J Med Entomol. 2011 Jul;48(4):770-4
references.pmid: 21845935
references.citation: Exp Appl Acarol. 2006;38(4):307-16
references.pmid: 16612672
references.citation: Ecology. 2009 Apr;90(4):888-900
references.pmid: 19449681
references.citation: Proc Natl Acad Sci U S A. 2009 Nov 17;106 Suppl 2:19644-50
references.pmid: 19805041
references.citation: J Med Entomol. 2002 May;39(3):405-16
references.pmid: 12061432
references.citation: J Clin Microbiol. 2007 Oct;45(10):3155-9
references.pmid: 17687016
references.citation: Ann N Y Acad Sci. 2000;916:583-8
references.pmid: 11193677
references.citation: Ann N Y Acad Sci. 2000;916:546-54
references.pmid: 11193670
references.citation: Bull Math Biol. 2007 Jan;69(1):265-88
references.pmid: 17083005
references.citation: Exp Appl Acarol. 2006;38(2-3):219-35
references.pmid: 16596355
references.citation: Parasitology. 2004;129 Suppl:S247-69
references.pmid: 15938514
references.citation: J Med Entomol. 2007 Mar;44(2):308-15
references.pmid: 17427702
references.citation: J Med Entomol. 2005 May;42(3):285-94
references.pmid: 15962776