A hybridization model for Rhipicephalus appendiculatus and R. zambeziensis (Acarina: Ixodidae) using glucose-6-phosphate-isomerase isoenzymes.

In the Eastern Province of Zambia, Rhipicephalus appendiculatus (Neumann) and R. zambeziensis (Walker) are sympatric. Intermediate forms as well as typical specimens are found. No morphological criteria could detect cross-breeding between these species in the field. Hybrids between R. appendiculatus and R. zambeziensis were produced and glucose-phosphate-isomerase (EC 5.3.1.9.; GPI) isoenzymes resolved by agarose electrophoresis. Phenotyping hybrids in the F1 and F2 generations was explained by the autosomal transmission of two loci of GPI-genes. Identification of some hybrid phenotypes offers the possibility of showing presently undetected hybridization in the field. A genetic model is proposed to explain the patterns.