Molecular genetic key for the identification of 17 Ixodes species of the United States (Acari : Ixodidae): A methods model

A taxonomic key, based on restriction enzyme analysis of the second interna l-transcribed spacer (ITS-2) in the nuclear ribosomal DNA gene, was develop ed for identification of 17 Ixodes tick species in the United States. This key includes: Ixodes affinis, Neumann, Ixodes angustus Neumann, bodes baerg i Cooley and Kohls, Ixodes brunneus Koch, bodes cookei Packard, bodes denta tus Marx, Ixodes jellisoni Cooley and Kohls. I;Ixodes kingi Bishopp, Ixodes minor Neumann, Ixodes muris Bishopp and Smith, bodes pacificus Cooley and Kohls, Ixodes scapularis Say, Ixodes sculptus Neumann, I. spinipalpis Hadwe n and Nuttall. Ixodes texanus Banks, Ixodes uriae White, and bodes woodi Bi shopp. A 900-bp fragment of the ITS-2 was amplified using the polymerase ch ain reaction. This fragment was then digested with the restriction enzymes MspI and CfoI, and the digested fragments were size fractionated on a 2.5% high-resolution agarose gel. A dichotomous key was developed based on diges ted fragment sizes relative to a standard set of size markers. Little intra specific variation in restriction fragment banding patterns was detected.