Population structure and genetic diversity of Triatoma longipennis (Usinger, 1939) (Heteroptera: Reduviidae: Triatominae) in Mexico.

Abstract

Triatoma longipennis (Usinger) is an important vector of Trypanosoma cruzi in western, central and northern Mexico, due to its wide distribution, high infection rates, and epidemiological indices. However, its population genetics has not been completely characterized. In this study, the intra-specific relationships between different T. longipennis populations were analyzed from seven states in Mexico using mitochondrial cyt B as a marker. Our results show that the population of Jalisco was the most diverse, with the highest genetic and haplotypic variation (Hd=0.978, π=0.099 and θ=0.079), even 25 times higher than some other populations analyzed. Heterogeneous migration and gene flow were observed without relation to their geographical distribution, that is, nearby populations may present high values of gene flow with low migration. In contrast, remote populations have low gene flow values with high migration. Genetic isolation was apparently present in the Guanajuato population, however, Mantel's analyzes to determine when an isolation by distance is present did not show correlation between genetic (FST) and geographic (Km) distances (P=0.064). The STRUCTURE analyzes showed that populations such as Chihuahua, Jalisco, Nayarit and Michoacán appear to show a similar population structure, suggesting a common ancestor. Our results suggest two routes of diversification of T. longipennis highly influenced by anthropogenic effects. Elucidation of the population genetic structure of T. longipennis will help to better understand the role of gene flow and migration in the dispersal of this important Chagas disease vector.