ABSTRACT
Triatoma brasiliensis macromelasoma occurs in Pernambuco state, Brazil, which is situated between the distribution areas of Triatoma brasiliensis brasiliensis (north) and Triatoma juazeirensis (south). T. b. macromelasoma displays greater variations in its chromatic phenotype than either T. b. brasiliensis or T. juazeirensis, and patterns reminiscent of one or the other. Experimental crosses from each of these members of the T. brasiliensis species complex generated fertile offspring suggesting that viable hybrids could be present in nature, despite their significant genetic distances. Considering the geographical position of occurrence of the T. b. macromelasoma (in Pernambuco) it was proposed to be an area capable of supporting natural hybridization between T. b. brasiliensis and T. juazeirensis. Since phenotypic variability is expected, this study investigated the existence of intermediate chromatic phenotypes for T. b. macromelasoma in various locations in areas between the T. b. brasiliensis and T. juazeirensis occurrences. Thirteen different color patterns were for the first time characterized and nine of those displayed intermediate phenotypes. Molecular analysis performed using ribosomal DNA intergenic region, grouped all within the T. brasiliensis complex. The intermediate chromatic phenotypes, molecular analysis and experimental crosses all support the distinction of a zone of hybridization that gave rise to the T. b. macromelasoma through homoploidal evolution.
Subject(s)
DNA, Ribosomal/genetics , Skin Pigmentation , Triatoma/genetics , Animals , Brazil , Chromatin/genetics , Evolution, Molecular , Phenotype , Phylogeography , Triatoma/classificationABSTRACT
No presente estudo avaliaram-se diferentes parâmetros biológicos de T. sherlocki para inferir sua capacidade vetorial. Para isso, foram efetuadas coletas no ambiente silvestre e domiciliar em 2009, quando foi feita a pesquisa para presença de T. cruzi-like, e em 2010, para o estabelecimento de colônias mantidas em condições controladas de temperatura (24,6 ± 1,3 ºC) e umidade relativa (71,6 porcento ± 6,3) (não controlada). Tais colônias deram suporte aos estudos do ciclo biológico, do comportamento alimentar e de defecação e da resistência ao jejum. A taxa de infecção natural foi obtida pelo exame microscópico de fezes dos triatomíneos. Para o estudo do ciclo biológico e do comportamento alimentar e de defecação, foram selecionados aleatoriamente 123 ovos a partir de trinta casais mantidos juntos. Assim, acompanhou-se o desenvolvimento de ovo-adulto e o seu comportamento de alimentação e de defecação após a alimentação até 10 min. Os insetos foram alimentados semanalmente em camundongos Mus musculus. A resistência ao jejum foi estudada através da seleção aleatória de um grupo de 50 ovos e 50 ninfas de 2º a 5º estádio, perfazendo um total de 350 espécimes, os quais foram alimentados semanalmente em camundongos e observados diariamente para registrar a eclosão ou ecdise...
The insects were fed weekly on mice Mus musculus. The resistance to starvation was studied by randomlyselecting a group of 50 eggs and 50 nymphs of 2nd to 5th instar, which were fed weekly on mice and observed daily to record hatching or moulting. Thereafter, each triatomine wasobserved individually for the record of the period of resistance to starvation unto death. During field sampling, 471 specimens were collected, 170 in 2009 and 301 in 2010. Of the 170 specimens collected in 2009, 145 were examined for the presence of T. cruzi-like, ofwhich 20 percent were positive. Regarding the biological cycle, T. sherlocki showed averagedevelopment time from egg to adult of 325.0 ± 40.0 days, indicating that this species has one generation per year. The number of blood meal ranged from 1 to 11 depending on the instar ofdevelopment. This feature increases the vector-host contact, increasing the likelihood of acquisition or transmission of T. cruzi. The overall mortality rate was low (6.5 percent) compared toother species of triatomines, showing that T. sherlocki has well adapted to laboratory conditions. Among the main results obtained in the study of feeding behavior and defecation highlights the short time interval between feeding and defecation of the early nymphal instarof T. sherlocki, average time of 1.38 minutes for the 1st instar and 2.15 minutes for the 2nd instar, and the 63.2 percent (n = 114) of the 1st nymphal instar and 56.7 percent (n = 60) of the 2nd nymphal instar defecated until 1 minute after the 1st and 2nd feeds, respectively. The nymphs of remaining instars took longer to defecate, but had an average time of defecation afterfeeding up to 10 min lower to 4.00 min...
Subject(s)
Humans , Triatoma/metabolism , Triatoma/pathogenicity , Trypanosoma cruzi/classificationABSTRACT
Triatoma brasiliensis macromelasoma is revalidated based on the results of previous multidisciplinary studies on the Triatoma brasiliensis complex, consisting of crossing experiments and morphological, biological, ecological and molecular analyses. These taxonomic tools showed the closest relationship between T. b. macromelasoma and Triatoma brasiliensis brasiliensis. T. b. macromelasoma is redescribed based on specimens collected in the type locality and specimens from a F1 colony. The complex now comprises T. b. brasiliensis, T. b. macromelasoma, Triatoma melanica, Triatoma juazeirensis and Triatoma sherlocki. An identification key for all members of the complex is presented. This detailed comparative study of the morphological features of T. b. macromelasoma and the remaining members of the complex corroborates results from multidisciplinary analyses, suggesting that the subspecific status is applicable. This subspecies can be distinguished by the following combination of features: a pronotum with 1+1 narrow brownish-yellow stripes on the submedian carinae, not attaining its apex, hemelytra with membrane cells darkened on the central portion and legs with an incomplete brownish-yellow ring on the apical half of the femora. Because the T. brasiliensis complex is of distinct epidemiological importance throughout its geographic distribution, a precise identification of its five members is important for monitoring and controlling actions against Chagas disease transmission.
Subject(s)
Triatoma/classification , Animals , Female , Insect Vectors/anatomy & histology , Insect Vectors/classification , Male , Reduviidae/anatomy & histology , Reduviidae/classification , Triatoma/anatomy & histology , Triatominae/anatomy & histology , Triatominae/classificationABSTRACT
Triatoma brasiliensis macromelasoma is revalidated based on the results of previous multidisciplinary studies on the Triatoma brasiliensis complex, consisting of crossing experiments and morphological, biological, ecological and molecular analyses. These taxonomic tools showed the closest relationship between T. b. macromelasoma and Triatoma brasiliensis brasiliensis. T. b. macromelasoma is redescribed based on specimens collected in the type locality and specimens from a F1 colony. The complex now comprises T. b. brasiliensis, T. b. macromelasoma, Triatoma melanica, Triatoma juazeirensis and Triatoma sherlocki. An identification key for all members of the complex is presented. This detailed comparative study of the morphological features of T. b. macromelasoma and the remaining members of the complex corroborates results from multidisciplinary analyses, suggesting that the subspecific status is applicable. This subspecies can be distinguished by the following combination of features: a pronotum with 1+1 narrow brownish-yellow stripes on the submedian carinae, not attaining its apex, hemelytra with membrane cells darkened on the central portion and legs with an incomplete brownish-yellow ring on the apical half of the femora. Because the T. brasiliensis complex is of distinct epidemiological importance throughout its geographic distribution, a precise identification of its five members is important for monitoring and controlling actions against Chagas disease transmission.
