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First record of Triatoma barberi Usinger, 1939 (Hemiptera: Reduviidae) in northern State of Mexico, Mexico

2018; Wiley; Volume: 43; Issue: 2 Linguagem: Inglês

10.1111/jvec.12319

1948-7134

Nancy Rivas, Saúl González‐Guzmán, Ricardo Alejandre‐Aguilar,

Hemiptera Insect Studies

Triatomines, also known as kissing bugs, are blood-feeding insects in the subfamily Triatominae. They are important natural vectors of Trypanosoma cruzi, the parasite that causes Chagas disease (Lent and Wygodzinsky 1979). A total of 151 species has been described in the world and assigned to fifteen genera (Justi and Galvão 2017). In Mexico, there are 32 triatomine species grouped into eight genera. Triatoma is the most abundant (19 species), followed by Meccus (6), Belminus (1), Dipetalogaster (1), Eratyrus (1), Paratriatoma (1), Panstrongylus (2), and Rhodnius (1) (Galvão et al. 2003, Schofield and Galvão 2009). Most of these species have been found naturally infected with T. cruzi (Ramsey et al. 2015). The State of Mexico is not considered a Chagas endemic area; however, researchers have reported the occurrence of two species of triatomines, Triatoma dimidiata and Meccus pallidipennis, which have been reported only in southern municipalities, and the authors reported the active transmission of T. cruzi, which is found in domestic reservoirs and in humans infected with the parasite (Estrada-Franco et al. 2006, Barbabosa-Pliego et al. 2011, Quijano-Hernandez, et al. 2012). A recent study showed the seroprevalence of T. cruzi to be 9.1% in populations of the Hueypoxtla and Tequixquiac municipalities (Estado de Mexico), suggesting the possible presence of the vector in the area (González-Guzmán et al. 2017). Triatoma barberi was described in 1939 by Usinger and is an endemic species of Mexico, where it has been reported in Colima, Hidalgo, Jalisco, Mexico City, Michoacán, Morelos, Oaxaca, Puebla, Guerrero, Tlaxcala, Guanajuato, Querétaro and Veracruz (Galvão et al. 2003, Ramsey et al. 2015). It is considered to be the most important vector in Mexico due to the presence of domestic and peri-domestic habitats, its ability to live until 2,400 m above sea level, and its especially extensive geographical distribution and high infection rate in this country (Guzmán-Bracho 2011, Cruz-Reyes and Pickering-Lopez 2006, Salazar-Schettino et al. 2010, Evangelista-Martínez et al. 2010). The present study reports for the first time the presence of T. barberi in Hueypoxtla Municipality in the northern State of Mexico, Mexico. Twenty-three samples of vectors were collected in three different localities in the Hueypoxtla municipality, and two samples were collected in San Buenaventura, located in Huehuetoca municipality. In total, triatomines were found in six homes distributed in the four localities (Figure 1). The active search was carried on overnight in four houses, while the San Buenaventura collections were made by the inhabitants. The triatomines were collected manually, employing one person-hour of capture effort per house. Each collected sample was placed into a plastic container labeled for transportation. Table 1 shows the number of samples, developmental stage, location, geographical coordinates, and altitude for each collection site. The presence of nymphs in two locations should be noted, with a greater number of samples collected (20) compared with adults (5). Location Nymphs Adults Exochorion Exuvia Positive to T. cruzi Coordinates Altitude m.a.s.l. Latitude Longitude Hueypoxtla 8 0 0 0 6 19°54′23″N 99°04′36″O 2,335 Santa Maria Ajoloapan 0 1♀ 0 0 ND 19°58′37″N 99°02′41″O 2,360 Tezontlalpan de Zapata 12 1♀/1♂/ 1* 12 1 12 20°01′17″N 98°59′45″O 2,433 San Buenaventura 0 1♀/1♂ 0 0 0 19°54´19´´N 99°20´30´´O 2,181 Total 20 5 12 1 18 The identification of the specimens as Triatominae was carried out in the Laboratory of Entomology, ENCB, Instituto Politecnico Nacional, Mexico City, according to the keys of Lent and Wygodzinsky (1979). All the triatomines collected were T. barberi. Feces from each sample were obtained by spontaneous defecation after feeding on rabbit, and these fecal samples were mixed with saline solution and examined for the presence of T. cruzi by direct optical microscopic observation (400X). Eighteen samples were positive for infection with T. cruzi (18/25), representing an infection rate of 72% (Table 1). The specimens were incorporated into the insectary and were maintained at 28 ± 1° C and 60% RH. Each week, they were allowed to feed on New Zealand variety rabbits. Triatoma barberi (Figure 2) has a length of up to 20 mm, color from piceous to black, with red-yellowish markings on the connexivum. Head is distinctly convex. Anteocular region is twice as long as the postocular. The first antennal segment is very short, attaining only two-thirds of the distance between the base and level of apex of clypeus. Pronotum is completely dark and trapezoidal. A scutellum with a roughened surface is marked by the presence of grooves on the first half of the central depression. The depression edges are thick and the posterior process is short and conical. It should be noted that all the specimens were captured in houses and inside barns and cellars that were built with masonry. The area from which the specimens were collected is semi-urban. The climate in this region is temperate and semi-dry with annual rainfall between 600 mm (Hueypoxtla) and 704 mm (Huehuetoca) in summer and an annual average temperature of 16° C. The average altitudes are 2,327 m above sea level, with San Buenaventura at the lower altitude of 2,181 m.a.s.l. and Tezontlalpan with the highest altitude of 2,433 m.a.s.l. The presence of T. barberi colonizing barns located less than 20 m from dwellings in a semi-urban area in which seropositive patients have been reported showed active transmission in the region. The presence of nymphs, exuvia, and exochorion indicate the process of triatomine colonization, which generates a major problem for vector control and disease transmission in the population. The knowledge of the geographical distribution of the different species of triatomines is extremely important to better understand the epidemiology of the disease, the transmission of the T. cruzi parasite, and the behavior of vectors. We thank the people of Hueypoxtla for allowing us to search for triatomines in their homes.