title: Evolutionary and dispersal history of Triatoma infestans, main vector of Chagas disease, by chromosomal markers.
abstract: Chagas disease, one of the most important vector-borne diseases in the Americas, is caused by Trypanosoma cruzi and transmitted to humans by insects of the subfamily Triatominae. An effective control of this disease depends on elimination of vectors through spraying with insecticides. Genetic research can help insect control programs by identifying and characterizing vector populations. In southern Latin America, Triatoma infestans is the main vector and presents two distinct lineages, known as Andean and non-Andean chromosomal groups, that are highly differentiated by the amount of heterochromatin and genome size. Analyses with nuclear and mitochondrial sequences are not conclusive about resolving the origin and spread of T. infestans. The present paper includes the analyses of karyotypes, heterochromatin distribution and chromosomal mapping of the major ribosomal cluster (45S rDNA) to specimens throughout the distribution range of this species, including pyrethroid-resistant populations. A total of 417 specimens from seven different countries were analyzed. We show an unusual wide rDNA variability related to number and chromosomal position of the ribosomal genes, never before reported in species with holocentric chromosomes. Considering the chromosomal groups previously described, the ribosomal patterns are associated with a particular geographic distribution. Our results reveal that the differentiation process between both T. infestans chromosomal groups has involved significant genomic reorganization of essential coding sequences, besides the changes in heterochromatin and genomic size previously reported. The chromosomal markers also allowed us to detect the existence of a hybrid zone occupied by individuals derived from crosses between both chromosomal groups. Our genetic studies support the hypothesis of an Andean origin for T. infestans, and suggest that pyrethroid-resistant populations from the Argentinean-Bolivian border are most likely the result of recent secondary contact between both lineages. We suggest that vector control programs should make a greater effort in the entomological surveillance of those regions with both chromosomal groups to avoid rapid emergence of resistant individuals.
authors.affiliation: Sección Genética Evolutiva, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay. Electronic address: fcopanzera@gmail.com.
authors.forename: Francisco
authors.initials: F
authors.lastname: Panzera
authors.affiliation: Sección Genética Evolutiva, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay.
authors.forename: María J
authors.initials: MJ
authors.lastname: Ferreiro
authors.affiliation: Sección Genética Evolutiva, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay.
authors.forename: Sebastián
authors.initials: S
authors.lastname: Pita
authors.affiliation: Sección Genética Evolutiva, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay.
authors.forename: Lucía
authors.initials: L
authors.lastname: Calleros
authors.affiliation: Sección Genética Evolutiva, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay.
authors.forename: Ruben
authors.initials: R
authors.lastname: Pérez
authors.affiliation: Departamento de Parasitología y Medicina, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay.
authors.forename: Yester
authors.initials: Y
authors.lastname: Basmadjián
authors.affiliation: Laboratorio de Citogenética Alberto Tellería Cáceres, Universidad Nacional Mayor de San Marcos, Lima, Peru.
authors.forename: Yenny
authors.initials: Y
authors.lastname: Guevara
authors.affiliation: INTERTRYP (Interactions hôtes-vecteurs-parasites dans les infections par trypanosomatidae), Institut de Recherche pour le Développement (IRD), Montpellier, France.
authors.forename: Simone Frédérique
authors.initials: SF
authors.lastname: Brenière
authors.affiliation: Sección Genética Evolutiva, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay.
authors.forename: Yanina
authors.initials: Y
authors.lastname: Panzera
mesh_terms: D000818:Animals; D001938:Brazil; D014355:Chagas Disease / Q000635:transmission*; D002871:Chromosome Banding; D059006:Chromosomes, Insect; D004275:DNA, Ribosomal / Q000235:genetics; D005260:Female; D005819:Genetic Markers; D005843:Geography; D006801:Humans; D007303:Insect Vectors / Q000235:genetics*; D008297:Male; D012335:RNA, Ribosomal; D014224:Triatoma / Q000235:genetics* / Q000469:parasitology; D014349:Trypanosoma cruzi
chemical_list: D004275:DNA, Ribosomal; D005819:Genetic Markers; D012335:RNA, Ribosomal; C088179:RNA, ribosomal, 45S
keywords: C-heterochromatic polymorphism; Hybrid zone; Hybridization; Pyrethroid resistance; Triatoma infestans; rDNA variability