Molecular analysis of Boophilus spp. (Acari : Ixodidae) tick strains

Boophilus spp. (Acari: Ixodidae) parasitize cattle and other farm and wild animals in tropical and subtropical regions of the world. Ticks belonging t o the genus Boophilus have undergone evolutionary processes associated with habitat adaptation following biogeographical separation, resulting in stra ins with marked morphological differences. We have characterized at the mol ecular level B. microplus strains from Latin America and Australia, employi ng sequences derived from the bm86 coding region, an intron located within the bm86 gene, and DNA short tandem repeats (STR). A B. annulatus strain wa s employed for comparison. The results indicated that variation within the bm86 coding region is higher between B. microplus strains than between some B. microplus strains and B. annulatus. The sequence of the intron was not informative for phylogenetic analysis, varying among individuals of the sam e strain. Two STRs were identified in B. microplus (STRs BmM1 and BmM2) and one in B. annulatus (STR Ba1). Southern hybridization experiments with STR s BmM1 and BmM2 as a probe revealed the prevalence of dispersed moderately repeated DNA in the genome of B. microplus. The analysis of polymorphism at STR locus BmM1 evidenced differences within and between populations of B. microphs. These results support at the molecular Level the existing differe nces between B, microplus strains and suggest tools to characterize these p opulations. (C) 2000 Elsevier Science B.V. All rights reserved.