Triatoma Research Articles

Triatoma yelapensis sp. nov. (Hemiptera: Reduviidae) from Mexico, with a Key of Triatoma Species Recorded in Mexico

Thirty-four species of Triatominae (Hemiptera, Reduviidae) are recorded in Mexico, Triatoma Laporte, 1832 the most speciose genus in this country. Here, we describe Triatoma yelapensis sp. nov. from the Pacific coast of Jalisco (Mexico). The most similar species to T. yelapensis sp. nov. is T. recurva (Stål, 1868), but they differ in head longitude, the proportion of labial segments, coloration pattern of corium and connexivum, spiracles location, and male genitalia. To provide statistical support for the morphological distinctiveness of the new species, we performed a geometric morphometric analysis of T. yelapensis sp. nov., T. dimidiata s.s. (Latreille, 1811), T. gerstaeckeri (Stål, 1859), and T. recurva (Stål, 1868), considering head morphology. We also provide an updated key of the genus Triatoma for species recorded in Mexico.

Do not judge a book by its cover: would Triatoma tibiamaculata (Pinto, 1926) belong to Triatoma Laporte, 1832, or to Panstrongylus Berg, 1879, with misleading homoplasies?

BackgroundTriatoma tibiamaculata is a species distributed in ten Brazilian states which has epidemiological importance as it has already been found infecting household areas. The taxonomy of this triatomine has been quite unstable: it was initially described as Eutriatoma tibiamaculata. Later, the species was transferred from the genus Eutriatoma to Triatoma. Although included in the genus Triatoma, the phylogenetic position of T. tibiamaculata in relation to other species of this genus has always been uncertain once this triatomine was grouped in all phylogenies with the genus Panstrongylus, rescuing T. tibiamaculata and P. megistus as sister species. Thus, we evaluated the generic status of T. tibiamaculata using phylogenetic and chromosomal analysis.MethodsChromosomal (karyotype) and phylogenetic (with mitochondrial and nuclear markers) analyses were performed to assess the relationship between T. tibiamaculata and Panstrongylus spp.ResultsThe chromosomal and phylogenetic relationship of T. tibiamaculata and Panstrongylus spp. confirms the transfer of the species to Panstrongylus with the new combination: Panstrongylus tibiamaculatus.ConclusionsBased on chromosomal and phylogenetic characteristics, we state that P. tibiamaculatus comb. nov. belongs to the genus Panstrongylus and that the morphological features shared with Triatoma spp. represent homoplasies.Graphical

Testing Phylogeographic Hypotheses in Mepraia (Hemiptera: Reduviidae) Suggests a Complex Spatio-Temporal Colonization in the Coastal Atacama Desert

Simple SummaryMepraia is a blood-sucking bug endemic to Chile and a vector of the parasite that causes Chagas disease. Different colonization routes have been suggested for this bug; therefore, we tested different colonization routes using DNA sequences and bioinformatics approaches to select the most probable route. Our results suggest that, after the split of Triatoma, Mepraia divided into two main groups ~2.1 Mya. The northern group would have speciated between 1.7–1.4 Mya, giving rise to M. parapatrica, M. gajardoi and to a new, still undescribed lineage (Mepraia sp.). The southern group formed M. spinolai ~1.68 Mya. We suggest that Mepraia originated from the north-central Andes due to the last Andes uplift and hyperaridity. The hyperarid cycle would have separated the southern and northern groups. Then, within the northern group, colonization would have occurred from the centre to the north and south through corridors influenced by Pleistocene climatic changes. The habitat colonized by the southern clade led to only one species (M. spinolai). Fluctuations in climatic changes probably influenced speciation strongly in this kissing bug in the Atacama Desert.Mepraia is a genus (Triatominae) endemic to Chile and a vector of Trypanosoma cruzi. Alternative phylogeographic hypotheses have been suggested for Mepraia. We tested different colonization routes hypothesized using mitochondrial sequences and phylogeographic approaches to select the best-supported hypothesis. Our results suggest that, after the split from the sister genus Triatoma at ~4.3 Mya, Mepraia formed two main clades at ~2.1 Mya. The northern clade diverged from Mepraia sp. ~1.7 Mya, giving rise to M. parapatrica and M. gajardoi about ~1.4 Mya. The southern clade originated M. spinolai ~1.68 Mya. We suggest that Mepraia had an origin in the north-central Andes along with orogenic processes, reinforced by hyperaridity during the Pliocene. The hyperarid cycle would have separated the southern and northern clades. Then, in the northern clade, dispersal occurred north and south from the centre through corridors during the Pleistocene Climatic Oscillations. Climate changes may have induced a major speciation process in the Atacama Desert, while the more homogeneous habitat colonized by the southern clade led to only one, but structured, species.

Formal Assignation of the Kissing Bug Triatoma lecticularia (Hemiptera: Reduviidae: Triatominae) to the Genus Paratriatoma.

Simple SummaryThe genus Paratriatoma is closely related to the paraphyletic genus Triatoma—the most diverse and relevant in the epidemiology of Chagas disease. Molecular phylogenetic treatments consistently place the species Triatoma lecticularia (Stål, 1859) as a sister to the genus Paratriatoma. To determine its correct taxonomic assignment, we examined the morphology of several specimens, including types, and cytogenetic data for both taxa. The observations clearly support the transfer of Triatoma lecticularia (Stål, 1859) to the genus Paratriatoma, with the resulting new combination: Paratriatoma lecticularia (Stål, 1859) comb. nov. (Hemiptera: Heteroptera: Reduviidae: Triatominae).The subfamily Triatominae (Hemiptera: Reduviidae) comprises hematophagous insects that are vectors of Chagas disease; including species assigned to the genera Triatoma and Paratriatoma. Initial examination of Triatoma lecticularia revealed the hirsuteness covering the entire body—a characteristic and striking feature of members of the genus Paratriatoma—and a systematic study revealed several other morphological characters that are in diagnostic alignment with Paratriatoma. Based on the examination of several specimens (including the lectotype), and with the additional support of molecular and cytogenetic data, we propose the formal transferal of Triatoma lecticularia (Stål, 1859) into the genus Paratriatoma with the resulting new combination: Paratriatoma lecticularia (Stål, 1859) comb. nov. (Hemiptera: Reduviidae: Triatominae).

Triatoma rosai sp. nov. (Hemiptera, Triatominae): A New Species of Argentinian Chagas Disease Vector Described Based on Integrative Taxonomy.

Simple SummaryAlthough all triatomines are potential vectors of Chagas' disease, there are species with greater or lesser vectorial importance. Therefore, the correct identification of triatomines species is essential for the vector control programs. In general, triatomines are identified by external morphological characters. However, some species are very similar or even morphologically identical, being important the use of complementary analyses for the correct identification of species. For this reason, this study focused on the use of morphological, morphometric, molecular data, and experimental crosses to describe Triatoma rosai sp. nov., a new species of Argentinian Chagas disease vector. Significant morphological and morphometric differences, associated with phylogenetic support and high mortality rate of the hybrids made it possible to confirm the specific status of T. rosai sp. nov., emphasizing the importance of integrative analyses for the taxonomy of triatomines.Chagas disease is the most prevalent neglected tropical disease in the Americas and makes an important contribution to morbidity and mortality rates in countries where it is endemic since 30 to 40% of patients develop cardiac diseases, gastrointestinal disorders, or both. In this paper, a new species of the genus Triatoma is described based on specimens collected in the Department San Miguel, Province of Corrientes, Argentina. Triatoma rosai sp. nov. is closely related to T. sordida (Stål, 1859), and was characterized based on integrative taxonomy using morphological, morphometric, molecular data, and experimental crosses. These analyses, combined with data from the literature (cytogenetics, electrophoresis pattern, molecular analyses, cuticular hydrocarbons pattern, geometric morphometry, cycle, and average time of life as well as geographic distribution) confirm the specific status of T. rosai sp. nov. Natural Trypanosoma cruzi infection, coupled with its presence mostly in peridomestic habitats, indicates that this species can be considered as an important Chagas disease vector from Argentina.

Molecular data supports monophyly of Triatoma dispar complex within genus Triatoma

The genus Triatoma contains numerous species, principal or secondary vectors of Chagas disease, which have been included in the three main lineages of Triatomini tribe based on morphological and biogeographical characteristics: North American, South American, and T. dispar complex. The three members of the T. dispar complex are distributed in Ecuador. This complex has been scarcely studied through molecular approaches, and the taxonomic position of this complex is not confirmed. In this study, we explored the phylogenetic relationships within the genus Triatoma, including five species from North and Central America, six from South America, and the three species belonging to the T. dispar complex. Partial sequences of four mitochondrial genes (Cyt b, COII, 16S-rRNA, 12S-rRNA) and two nuclear genes (18S-rRNA, ITS2) were obtained from 74 specimens. Phylogenetic trees were built with concatenated and single sequences through maximum likelihood (ML), maximum parsimony (MP), and Bayesian methods. The trees built using concatenated sequences showed three main branches (clusters) highly supported by significant bootstrap values; the T. dispar complex appeared as a monophyletic group separate from species of North and Central American origin and South American origin. On the contrary, for each gene tree, the three main clusters were not always significantly supported, mostly because genetic information is dramatically reduced when a single gene is considered. Consequently, concatenation of genes gives relevant results and is highly recommended for further in-depth examination of the relationships of several species and complexes of triatomines that remain unresolved. Moreover, our current molecular data fully revealed the division of genus Triatoma into at least three main genetic groups.

Gene expression to contaminated or not contaminated Triatoma dimidiata faeces with Trypanosoma cruzi in vivo and in vitro assay.

Triatoma dimidiata is considered one of the most important vectors in the spread of Chagas disease in Mesoamerica. Hematophagous insects may deposit faeces contaminated or not with Trypanosoma cruzi on the surface of the skin during the feeding process. In endemic areas humans can be in contact several times to this fluid before get infection. Due to limited work on the of immune response to insect's fluids in mammals. In this work, we explored the early response of chemokine and cytokines of skin tissue at the inoculation site against faeces from T. dimidiata contaminated or not with T. cruzi in murine model, also we explored the in vitro response of epitheloid cells line "HeLa cells" to this fluid. Mice were exposed intradermically to faeces free of metacyclic trypomastigotes, oneor multiple times along the experiment before challenged with faeces contaminated with metacyclic trypomastigotes, mimicking natural conditions. In in vitro assay with HeLa cells only one exposure was carried out. It was observed that mice multiexposed to faeces, induced the strong response of TNF-α and CXCL3 expression at the inoculation site; but faeces contaminated with metacyclic trypomastigotes lower the response of TNF-α, and CXCL3. In in vitro assay with HeLa cell line, the faeces induced a strong response of CXCL8 and IL-6, but the presence of faeces contaminated with metacyclic trypomastigotes lower the response of CXCL8. In contrast, to in vivo model null response of TNF α and IL-1-α was observed in HeLa cells. In conclusion, Triatoma dimidiata faeces induces at the inoculation site chemokines that mediate preferentially chemotaxis of neutrophils and macrophages but the presence of metacyclic trypomastigotes moderate their induction. Epithelial cells act as efficient sentinels producing chemokines that may recruit neutrophils and monocytes.

Mitochondrial genomes of three kissing bugs (Reduviidae: Triatominae) and their phylogenetic implications

The reduviid subfamily Triatominae, also called kissing bugs, are vectors of Chagas disease, which is one of the most seriously neglected tropical parasitic diseases. Only three complete mitochondrial genomes of kissing bugs from the genus Triatoma have been sequenced to date. To better understand the diversity of mitochondrial genomes and the evolution of kissing bugs, mitochondrial genomes of three kissing bugs, Triatoma migrans, Panstrongylus rufotuberculatus, and Rhodnius pictipes, were sequenced using next-generation sequencing and a comparative mitochondrial genomic analysis of three genera and two tribes in Triatominae was conducted. Kissing bug mitochondrial genomes shared a similar pattern of nucleotide composition, gene order, and structure of control region. The comparison among orthologous protein-coding genes indicated that different genes had different rates of molecular evolution and six genes (ND1, ND2, ND4L, ND5, ND6, and ATP8) had higher evolutionary rates than other protein-coding genes. Phylogenetic analyses inferred from mitochondrial genome sequences supported a sister relationship between Triatominae and Stenopodainae, and the genus Triatoma was paraphyletic. The present study revealed the high conservation of the mitochondrial genome organization of kissing bugs and highlighted the utility of mitochondrial genomes in the phylogenetic study of Triatominae.

Morphological study of the urotergite I process in ten species of the genus Triatoma (Hemiptera, Reduviidae, Triatominae)

The insects of subfamily Triatominae exhibit many morphological features used for taxonomic identification. In some species, however, these features are very similar. The authors have proposed by first time the description of the structure referred as urotergite I process. The objective of the study was analyse the use of urotergite I process in the species of the genus Triatoma as a taxonomic feature that may contribute to the more precise and correct identification of these Trypanosoma cruzi Chagas, 1909 vectors. Scanning electron microscopy (SEM) was used to describe the structure of urotergite I process in ten Triatoma (Hemiptera, Reduviidae, Triatominae) species: Triatoma brasiliensis Neiva, 1911; Triatoma circummaculata Stål, 1859; Triatoma infestans (Klug, 1834); Triatoma maculata (Erichson, 1848); Triatoma pseudomaculata Corrêa & Espínola, 1964; Triatoma rubrovaria (Blanchard, 1843); Triatoma sordida (Stål, 1859); Triatoma tibiamaculata (Pinto, 1926); Triatoma vitticeps (Stål, 1859) and Triatoma wygodzinskyi Lent, 1951. The morphological description of the urotergite I process reflects the taxonomic value of the structure for separating and identifying species of ten specimens of the genus Triatoma. The morphological pattern of the urotergite I process on these ten species was compared, and interspecific variability was observed. We suggest the use of the urotergite I process as a complementary character to identify insects of the subfamily Triatominae. In the future, the use of the urotergite I process in dichotomic keys to identify triatomines may contribute to the improvement of the entomological surveillance of Chagas' disease.

Second-Best Is Better Than Nothing: Cockroaches as a Viable Food Source for the Kissing Bug Triatoma recurva (Hemiptera: Reduviidae).

Kissing bugs in the genus Triatoma are obligate blood feeders that feed mainly on vertebrate blood and have lost the predatory lifestyle found in other reduviid bugs. They occasionally also feed on the hemolymph of arthropods, especially during the first and second instar stages. The largest kissing bug species in the United States, Triatoma recurva (Stål) (Hemiptera: Reduviidae), is poorly known and was chosen to investigate its ability to feed and develop on a diet of cockroach hemolymph. Molting from first instar individuals to second instars readily occurred at approximately the same rate reported for the species feeding on mammalian blood. Subsequent instars also fed on and survived on cockroach hemolymph with some individuals maturing to adults. In the larger instars, development time and survival rates were reduced relative to the results reported in the literature for mammalian-blood-fed individuals. Two other species of kissing bugs, Triatoma protracta (Uhler) and T. rubida (Uhler) failed to survive on cockroach hemolymph with most individuals failing to molt from the first instar stage. Although T. recurva does not thrive on a diet limited to hemolymph of cockroaches, it appears to be an unusual species in which cockroaches might be a primary source of nutrition for smaller individuals and are a viable exclusive source of nutrition for all immatures. At a minimum during times of limited availability of vertebrate blood sources, the presence of cockroaches enhances survival opportunities. Efforts to control populations of this kissing bug species likely will be improved with additional control of cockroach populations in the environment.

DataTri, a database of American triatomine species occurrence

Trypanosoma cruzi, the causative agent of Chagas disease, is transmitted to mammals - including humans - by insect vectors of the subfamily Triatominae. We present the results of a compilation of triatomine occurrence and complementary ecological data that represents the most complete, integrated and updated database (DataTri) available on triatomine species at a continental scale. This database was assembled by collecting the records of triatomine species published from 1904 to 2017, spanning all American countries with triatomine presence. A total of 21815 georeferenced records were obtained from published literature, personal fieldwork and data provided by colleagues. The data compiled includes 24 American countries, 14 genera and 135 species. From a taxonomic perspective, 67.33% of the records correspond to the genus Triatoma, 20.81% to Panstrongylus, 9.01% to Rhodnius and the remaining 2.85% are distributed among the other 11 triatomine genera. We encourage using DataTri information in various areas, especially to improve knowledge of the geographical distribution of triatomine species and its variations in time.

Blood meal source of specimens of Triatoma sordida in an area with high risk of domiciliation in the Paraguayan Chaco

En el presente estudio evaluamos indicadores entomologicos (indices de infeccion, colonizacion e infeccion natural) de ejemplares de Triatoma sordida capturados en el intra y peridomicilio de viviendas del Chaco Paraguayo en el periodo 2014 al 2016. El objetivo fue comparar con los hallazgos previamente reportados en el periodo 2010 al 2013 en la misma region. Ademas se ha incorporado la deteccion de fuente de alimentacion como complemento para definir el riesgo de domiciliacion de este vector secundario. Se aplicaron tecnicas moleculares asociados a indicadores entomologicos y epidemiologicos a 220 ejemplares de T. sordida capturados en 67 viviendas de 24 localidades del Chaco. Se detecto infestacion y colonizacion por T. sordida en el intradomicilio 13/67 (19%) y 5/13 (38%) y en el peridomicilio 54/67 (81%) y 43/54 (80%), respectivamente. Se detecto infeccion con T. cruzi en un 17,3% de los ejemplares analizados. La fuente de alimentacion pudo detectarse en tan solo 13 de 220 ejemplares (6%), todos resultaron positivos para sangre de gallina y correspondian a captura en el peridomicilio. El indice de infestacion intradomiciliar fue del 19%, superior al de anos anteriores y similar a las zonas historicamente endemicas de la Region Occidental (18%-20%). El riesgo de transmision intradomiciliar sigue siendo elevado porque en 3 de 5 viviendas con ninfas de T. sordida, los ejemplares estaban infectados con T. cruzi. Los indicadores entomologicos obtenidos en el presente estudio concuerdan con resultados previos de nuestro equipo, y confirman la capacidad vectorial de este triatomino secundario en la transmision de la enfermedad de Chagas.

Morphological and morphometric analysis of scutella of six species and two subspecies of Triatoma (Hemiptera: Reduviidae) in Mexico.

Morphological characters can be used to distinguish the vast majority of triatomine species, but the existence of high levels of phenotypic plasticity and recently diverged species can lead to erroneous determinations. To approach this problem, we analyzed the male and female morphologies of the scutella of Triatoma barberi, T. dimidiata, T. lecticularia, T. mexicana, T. recurva, T. rubida, and two sub-species, T. protracta protracta and T. protracta nahuatlae. Scutellum samples were observed by scanning electron microscopy and subjected to morphological analysis and morphometric investigation using a canonical discriminant analysis. The results revealed differences primarily in central depression shape, posterior process, and vestiture. We observed clear dimension-based differences in scutellum morphometry in all the taxa under study, providing sound evidence for species and subspecies differentiation. On the other hand, there is no difference between sexes in T. lecticularia, T. protracta protracta, and T. protracta nahuatlae. Our methodology can be implemented to differentiate species of the genus Triatoma.

Sobre la biología del Telenomus fariai Lima, 1927 (Hymenoptera: Scelionidae), parásito endófago de huevos de algunos Triatominae

A study is presented of the,outstanding aspects of the biology of Central American Telenomus fariai, an endophagolis parasite on eggs or certain Tria­tominae, found on eggs of Triatoma phyllosoma in the laboratory by Dr. Luis M, Penalver of El Salvador. The little wasp was found capable of parasitizing under experimental conditions eggs of T. dimidiata of Costa Rica, of T. phyllosoma of Mexico, of Panstrongylus chinai of Ecuador, and of P. megistus of Brasil. It proved unable to attack eggs of T. infestans of Chile, of Rhodnius prolixus of El Salvador, and of R. pallescens of Panama. The fact that it does not attack eggs of T. infestans is the only difference observed from Telenomus fariai described in Brazil by Costa Lima, other than an apparently inferior capacity for laying and shorter mean duration of life. Infestation may or may not follow the attack on eggs of hemipterae in advanced stages of development; in the negative case, death results occasionally from mechanical injury. Several counts were made of the little wasps developing within the eggs of T. phyllosoma, T. dimidiata, and P. chinai, noting the total number of insects, the number of each sex and the mean number of wasps per egg. The relation­ ship of the latter figures with the size of the host eggs was investigated, and a close relationship was found between the two values: each Telenomus requires from 0.00019 to 0.00025 gm. and from 0.178 to 0.193 mm3. With a variable temperature incubator the influence of temperature on development of Telenomus was demonstrated. At 30° C. complete development was obtained in 19 days on P. chinai and in 20 days in T. phyllosoma. At room temperature development was completed in from 32 to 42 days. Host eggs were dissected just before the parasites left them and groups of females were separated after periods of various length. It was shown that females separated after up to 1 hr. of initial contact with the male gave parth­ enogenetic progeny; fertilization, therefore, occurs after that periodo Measurements were made on females and on both types of males of Telenomus; parthenogenetic males were found to be larger than normal males, and females to be larger than either. Remarks are made on the possibility of biological control of vectors of Chagas disease.

Miocarditis chagásica aguda mortal

1) A fatal case is reported of acute Chagas miocarditis a 17-year-old male, a resident of a suburb of San Jose CR. 2) The etiological diagnosis was not made i n the clinic, nor at the macroscopic autopsy. 3) The principal clinical facts were: an indefinite infectious state of a month's duration, which in the last week changed to a picture of violent cardiac insufficiency, with global cardiomegaly and gallop rhythm, without any sign of valvular disease. The hemogram showed lymphomonocytosis 40%. 4) The anatomopathologic findings included: signs of chronic pulmonary and abdominal visceral stasis; moderate cardiomegaly (360 gr.), parietal throm­bosis in the left ventricle, miocardial flaccidity with dilatation of all the cavities. Acute intense miocarditis; reticular hyperplasia in Peyer's patches, mesenteric ganglia and spleen. 5) Epidemiologic investigation showed 32 out of 116 dwellings of the neigh­borhood where the patient lived, to be infested by triatomids, 30% of which were infested with Trypanosoma cruzi. 6) Domestic carriers of T. cruzi so far reported from Costa Rica are and Rhodnius prolixus. Triatoma dimidiata 7) Up to April 1954, 20 cases have been reported from Costa Rica of Chagas disease, 3 of which have be en fatal.

Relaciones huésped-parásito en Tripanosomiasis Rangeli I. Infección intestinal y hemolinfática comparativa de Rhodnius prolixus y Triatoma infestans

In this initial contribution on host-parasite relationships in Rangeli Trypanosomiasis, the results on the infection of 837 nymphs of Rhodnius prolixus and 827 of Triatoma infestans , by artificial xenodiagnosis, with two different strains of T. rangeli , are discussed. The insects were divided in groups in different experiments and in sorne cases the feces were examined and in others only the hemolymph. R. prolixus gave higher rates of infection, by feces exam· ination, than T. infestans at 15 and 30 days. The Venezuelan strain produced higher rates than the Costa Rican strain in both species. The rates in the two species were even higher when the insects were examined by dissecting the intostine, due to the lack of colonization of the flagellates in the rectum: With the Venezuelan strain T. infestans tended to lose the infection, and the same was true for both species with the Costa Rican strain. In the groups where hemolymph was examined for up to two months, it was shown that the haemocoele is more commonly invaded in Rhodnius, and at a higher rate with Venezuelan strain. With this strain a few T. infestans gave light infections with only a few flagellates present, and the Costa Rican strain gave not a single infection in this species. There was no correlation between the feces and hemolymph since it was possible to find insects positive in the latter and negative in the former or viceversa. The implications of the results as far as the experimental conditions used, the life cycle in the invertebrate, and the influence of the insect and different strains of the flagellate are discussed.

A Sporozoan Parasite of Triatoma rubida uhleri

A sporozoan parasite was observed in 9 of 451 Triatoma rubida uhleri collected near Tucson, Arizona. This organism is believed to correspond to Hepatozoon triatomae (Osimani, 1942 ) Reichenow, 1953.

The incidence of Trypanosoma cruzi in Triatoma of Tucson, Arizona.

Species of Triatoma rubida uhleri and T. protracta were collected and dissected to determine the percentages infected with Trypanosoma cruzi from areas near Tucson, Arizona. Of 657 T. rubida uhleri and T. protracta dissected 65 (9.9 per cent) were infected. When each species was considered separately, a higher infection rate was found in T. protracta than in T. rubida uhler ; (19.5 per cent compared to 7.5 per cent), even though there were a higher number of T. rubida uhleri observed in the field. One area was found with a significantly higher infection rate of 19.2 per cent, compared to 2.9 per cent from all other areas. A seasonal pattern for the occurrence of T. rubida uhleri instars during the year was noted. The adults were found in May and June, 1st, 2nd, 3rd and 4th instars developed through the summer months, and by the end of September the majority of T. rubida uhleri collected were 5th instars. The 5th instars molted in the spring to the adult stage.

Triatoma dimidiata capitata, a natural vector of Trypanosoma rangeli in Colombia.

Triatoma dimidiata capilata were abundant in houses of the village San Joaquin (Dept. Santander), Colombia. Five of these triatomids presented salivary gland infestation with Trypanosoma rangeli . Two showed hemofymph infection and 8 showed intestinal infection with crithidiae of T. rangeli . Mice bitten by naturally infected triatomids became infected with T. rangeli . The flagellates were easy to cultivate in diphasic blood agar media, and able to produce salivary gland infection in Rhodnius prolixtus . An U.S. citizen frequently bitten by the triatomids in San Joaquin presented infection with T. rangeli .

Parámetros biológicos de Meccus phyllosomus phyllosomus (Burmeister) 1835, de Triatoma recurva (Stål) 1868 (Hemiptera, Reduviidae) y de sus híbridos de laboratorio

Introduction: Hybrids from species and subspecies of Mexican triatomines have shown outstanding biological and behavioral characteristics as compared with their parental groups. This could lead to an increasing risk of transmission of Trypanosoma cruzi to human and animal reservoir hosts. Objective: To describe and compare biological parameters related to the life cycle of Triatoma recurva , Meccus phyllosomus phyllosomus and their laboratory hybrids and estimate their risk as transmitters of T. cruzi to humans. Materials and methods: We kept a cohort of each one of the three groups ( T. recurva , M. p. phyllosomus and their hybrids) under similar laboratory conditions and then compared them to record the data related to their life cycles, number of blood meals to molt, mortality rates, egg eclosion rates and female fecundity. Results: The hybrid cohort showed the lowest mean time from first-instar nymph to adult (136.6 ± 17.5 days). The number of blood meals from molt to next instar (13.4 ± 1.7; 15.6 ± 5.2) was higher in the hybrid and T. recurva cohorts. The hybrid cohort showed the lowest mortality rate (29.5%) and the highest rate (70%) of adult females at the end of the biological cycle. Fecundity per day per female (range: 1.1 ± 0.6– 1.6 ± 0.7 eggs) was similar in the three cohorts. Egg hatching rate was higher than 70% in both hybrid and M. p. phyllosomus cohorts. Conclusion: The hybrid cohort showed some outstanding biological characteristics, which would entail a higher risk of transmission of T. cruzi to hosts than their parentals.