Patterns of cuticular hydrocarbon variation and genetic similarity between natural populations of Amblyomma cajennense (Acari: Ixodidae).

Gas chromatography has been used to analyze the variation in cuticular hydrocarbon patterns between several populations of Amblyomma cajennense. 88 compounds were detected and these could be divided into 17 groups of hydrocarbons. Heterozygosis in the populations ranges from 0% to 25.84%. Isomers for pentacosane, heptacosane and nonatriacontane are the most variable, with 13, 10 and 11 variants, respectively. Nei's genetic identity and genetic distance show that populations may be considered as regional variants of only one species: the results do not indicate the presence of sibling species. However, a relatively high genetic distance has been observed between several Cuban and continental populations, suggesting a long reproductive isolation. Gas chromatography of cuticular hydrocarbons is a good alternative to isozyme analysis for population studies, when collecting conditions do not allow the use of live ticks and only alcohol-preserved collections are available. The high number of compounds available for genetic studies will provide excellent markers for evaluating the extent of gene flow and migration of tick species.