Entomological survey in the state of Piauí, Northeastern Brazil, reveals intradomiciliary colonization of Triatoma brasiliensis macromelasoma

ABSTRACT This survey aimed to assess the presence of triatomine vectors of Chagas disease within the rural communities of São João do Piauí, Northeast Brazil. Intradomiciliary and peridomiciliary collection strategies were implemented wherein 279 specimens of Triatoma brasiliensis macromelasoma, both nymph and adult were found in 15 (50%) of the studied homes. Of the intradomiciliary insects, 73 (67.6%) were identified as nymph instars (1st instar [N1]= 6, N2= 14, N3= 28, N4= 7 and N5= 18). In the studied communities, a continuous interaction between triatomine bugs and humans could be shown. It is therefore urgent that suitable strategies for the control of the triatomine vector are implemented in this area.

Where do these bugs come from? Phenotypic structure of Triatoma infestans populations after control interventions in the Argentine Chaco

House re-invasion by native triatomines after insecticide-based control campaigns represents a major threat for Chagas disease vector control. We conducted a longitudinal intervention study in a rural section (Area III, 407 houses) of Pampa del Indio, northeastern Argentina, and used wing geometric morphometry to compare pre-spray and post-spray (re-infestant bugs) Triatoma infestans populations. The community-wide spraying with pyrethroids reduced the prevalence of house infestation by T. infestans from 31.9% to < 1% during a four-year follow-up, unlike our previous studies in the neighbouring Area I. Two groups of bug collection sites differing in wing shape variables before interventions (including 221 adults from 11 domiciles) were used as a reference for assigning 44 post-spray adults. Wing shape variables from post-spray, high-density bug colonies and pre-spray groups were significantly different, suggesting that re-infestant insects had an external origin. Insects from one house differed strongly in wing shape variables from all other specimens. A further comparison between insects from both areas supported the existence of independent re-infestation processes within the same district. These results point to local heterogeneities in house re-infestation dynamics and emphasise the need to expand the geographic coverage of vector surveillance and control operations to the affected region.

Revalidation and redescription of Triatoma brasiliensis macromelasoma Galvão, 1956 and an identification key for the Triatoma brasiliensis complex (Hemiptera: Reduviidae: Triatominae)

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.

Triatoma jatai sp. nov. in the state of Tocantins, Brazil (Hemiptera: Reduviidae: Triatominae)

Triatoma jatai sp. nov. is the first new species of triatomine to be described in the state of Tocantins, in the northern region of Brazil. It was caught on rock outcrops in the wild environment and, more recently, invading homes. While T. jatai sp. nov. is morphologically similar to Triatoma costalimai, it is distinguished by its general colouring, differences in the blotches on the connexivum, wing size in females and external structures of the male genitalia. The type series has been deposited in the Entomological Collection and Herman Lent Collection, Oswaldo Cruz Institute-Oswaldo Cruz Foundation, Rio de Janeiro, Brazil.

Potential sources of Triatoma infestans reinfesting peridomiciles identified by morphological characterization in Los Llanos, La Rioja, Argentina

The presence of Triatoma infestans in habitats treated with insecticides constitutes a frequent problem in endemic areas. Basing our study on the hypothesis that descendants of a residual population should be more similar to the pre-treatment population than to any other, we compared the indications of two quantitative morphological approaches. This study seeks to find the origin of 247 T. infestans from three populations found in two chicken coops and a goat corral after treatment with insecticides. The results obtained by quantitative morphology suggest that the T. infestans found between three-34 months after the application of insecticides formed mixed populations with insects derived from residual foci and neighbouring habitats. Our analyses also showed the presence of a phenotype which does not resemble neither the pre-treatment phenotype nor the one from neighbouring populations, suggesting the presence of a particular post-treatment phenotype. The heads size showed some variations in males from different populations and remained unchanged in females, which reinforces the hypothesis of an intraspecific competition for food with priority for females. This article presents, for the first time, the combined analysis of geometric morphometry of heads and antennal phenotypes to identify the composition of reinfesting populations.

Capture of Triatoma arthurneivai (Hemiptera: Reduviidae) using a new luminous trap in Southeast Brazil / Captura de Triatoma arthurneivai (Hemiptera: Reduviidae) por nova armadilha luminosa no sudeste do Brasil

INTRODUÇÃO: As capturas de triatomíneos em meio silvestre são laboriosas e demoradas. Algumas armadilhas podem auxiliar nessa tarefa. Relata-se novo modelo de armadilha e captura de exemplar de espécie de triatomíneo raramente encontrada. MÉTODOS: Duas armadilhas luminosas foram instaladas em Diamantina, Estado de Minas Gerais e acompanhadas, semanalmente, durante um ano. RESULTADOS: Uma fêmea de Triatoma arthurneivai foi capturada além de outros triatomíneos. CONCLUSÕES: Um novo modelo de armadilha poderá ser empregado na captura de triatomíneos principalmente em áreas de baixa densidade. Presume-se que o centro de endemismo de Triatoma arthurneivai seja a Cordilheira do Espinhaço.

INTRODUCTION: Triatomine bug captures in the wild are laborious and time-consuming. Some traps may assist in this task. We report a new trap design and the capture of a specimen of a triatomine rarely found. METHODS: Two luminous traps were installed in the city of Diamantina, State of Minas Gerais, and surveyed weekly for a year. RESULTS: A Triatoma arthurneivai female and other triatomine bugs were caught. CONCLUSIONS: A new trap design may be used in triatomine bugs field captures, mainly in low density areas. We assume the center of endemism of Triatoma arthurneivai is the Espinhaço Mountain range.

Análisis morfológico de huevos de Triatoma barberi Usinger(Hemiptera: Reduviidae) / Morphologic analysis of eggs of Triatoma barberi Usinger (Hemiptera: Reduviidae)

Triatoma barberi Usinger is a widely recognized vector of the protozoa Trypanosoma cruzi. The determination of its presence in the rural houses is made by direct observation of adults, nymphs, exuviae or eggs. For this reason, egg structural characteristics could facilitate the differentiation and identification of species that inhabit such environments. In here, the morphologic characteristics of eggs of T. barberi are described and analyzed with special attention to the anterior pole of the egg. The structural analysis of eggs by scanning electron microscopy (SEM) showed the presence of a wide and rough chorion edge, which contain aeropyles and micropyles. A deep spermatic canal between the endochorion and exochorion, and a trabecular network in the interior were also observed. The operculum showed cells with irregular growth and undefined polygonal shape. Externally, the operculum cells forms two rings of projections that surround a single extension located to the center. The cellular projections resemble respiratory horns, although the presence of aeropyles was not observed. The chorion structural characteristics can help to identify and separate close species in the Triatominae subfamily.

Morphometry and morphology of the antennae of Panstrongylus megistus Burmeister, Rhodnius neglectus Lent, Rhodnius prolixus Stal and Triatoma vitticeps Stal (Hemiptera: Reduviidae)

The length of the four right antennal segments from nymphs and adults of Panstrongylus megistus Burmeister, Rhodnius neglectus Lent, Rhodnius prolixus Stal and Triatoma vitticeps Stal were measured. The length of the antennal segments of the adults of all four species, 4th and 5th instars of P. megistus, and 5th instar of R. neglectus and R. prolixus followed the same pattern: 2nd>3rd>4th>1st. The pattern of 1st and 2nd instars of P. megistus was: 4th>3rd>2nd>1st. For 3rd instars of P. megistus, 1st and 2nd instars of R. neglectus and R. prolixus they were: 3rd>4th>2nd>1st. Third and 4th instars of Rhodnius neglectus and R. prolixus had a pattern of: 3rd>2nd>4th>1st. Only T. vitticeps showed the same pattern (4th>3rd>2nd>1st) for all five instars. The morphological study of the second antennal segment by scanning electron microscopy (SEM) disclosed that the first instars of all four species exhibit type I bristles sensillae and one trichobothrium. Another type III bristle and basiconic, campaniform, coeloconic, trichoid sensillae and type I bristle and trichobothria were noted on their fourth instars and adults. Campaniform sensillae were noted only on T. vitticeps adults. Nodules were observed in the joint between 1st and 2nd antennal segments of adults of P. megistus and T. vitticeps, but not on R. neglectus and R. prolixus.

Morphological study of the eggs and nymphs of Triatoma dimidiata (Latreille, 1811) observed by light and scanning electron microscopy (Hemiptera: Reduviidae: Triatominae)

Eggs and nymphs of Triatoma dimidiata were described using both light and scanning electron microscopy. The egg body and operculum have an exochorion formed by irregular juxtaposed polygonal cells; these cells are without sculpture and the majority of them are hexagonal in shape. The five instars of T. dimidiatacan be distinguished from each other by characteristics of the pre, meso and metanotum. The number of setiferous tubercles increases progressively among instars. The sulcus stridulatorium of 1st instar nymphs is amorphous, showing median parallel grooves; from the 2nd instar on the sulcus is, progressively, elongate, deep and posteriorly pointed with stretched parallel grooves. All instars have a trichobothrium on the apical 1/3 of segment II of the antenna. The opening of the Brindley's gland is on the mesopleura. Fifth instar nymphs have an apical ctenidium on the ventral surface of the fore tibia. Dorsal glabrous patches are found on the lateral 1/3 of abdomen. Bright oval patches are found on the ventral median line of the abdomen, from segment IV-VI; 1st instar nymphs lack these patches. Abdominal dorsal plates are present from the 1st-5th instars; the 1st instar also contains a rectangular plate in segment IX. From the 2nd instar on, variably-shaped plates are present on segments VII to IX. Morphometric data were also obtained and proved to be useful for distinguishing T. dimidiata instars.

Influence of blood meal and mating in reproduction patterns of Triatoma brasiliensis females (Hemiptera: Reduviidae) under laboratory conditions

The influence of blood meal and mating on Triatoma brasiliensis (Neiva) female fecundity, fertility, life-span and the preoviposition period were investigated under laboratory conditions. Nourishment increased fecundity, fertility and adult lifespan, whereas mating increased fecundity, fertility and decreased the preoviposition period. Females also required more than one mating to reach their full reproductive potential. Results indicate that both nourishment and mating are important in T. brasiliensis proliferation. Such information will help towards developing effective control strategies of this vector of Chagas disease.

The metasternal and Brindley's Glands of Triatoma brasiliensis Neiva (Hemiptera: Reduviidae) / Glândulas de Brindley e metasternal de Triatoma brasiliensis Neiva (Hemiptera: Reduviidae)

Triatoma brasiliensis Neiva is the most important vector of the Chagas' disease in the semiarid zones of North-eastern Brazil. Adult bugs have two main pairs of exocrine glands, the metasternal and the Brindley's glands, which release volatiles possibly with defense, alarm and/or mating functions. To date, anatomical and histological studies of the metasternal and the Brindley's glands in the genus Triatoma are scarce and, considering the relevance of these exocrine glands, the present work aimed at studying their morphology in T. brasiliensis. The metasternal and the Brindley's glands of T. brasiliensis consist of glandular units similar to those described for Rhodnius prolixus Stål and Panstrongylus megistus Burmeister, comprising a secretory apparatus, saccule and collector duct.

Triatoma brasiliensis Neiva é o principal inseto vetor da doença de Chagas no Nordeste do Brasil. Os adultos da espécie apresentam dois pares de glândulas exócrinas, as glândulas metasternais e as glândulas de Brindley que liberam compostos voláteis, possivelmente com função de defesa, alarme e/ou acasalamento. O conhecimento anatômico e histológico das glândulas de Brindley e metasternal no gênero Triatoma é escasso e, considerando a relevância dessas glândulas na sua biologia, o objetivo do presente trabalho foi estudar e conhecer a sua morfologia. As glândulas de Brindley e metasternal de T. brasiliensis possuem uma unidade glandular similar àquela descrita para Rhodnius prolixus Stål e Panstrongylus megistus Burmeister, formada principalmente por um aparato secretor, sáculo e ducto coletor.

Population dynamics of Triatoma vitticeps (Stål, 1859) in Itanhomi, Minas Gerais, Brazil

Taxonomic markers (head structure morphometry, isoenzymes and randon amplified polymorphism of DNA - RAPD) were used to understand the population dynamics of Triatoma vitticeps, predominant triatomine species in Itanhomi district, using samples obtained from domestic, peridomiciliary and sylvatic habitats. Morphometric analysis revealed sexual dimorphism within the three samples although specimens could not be separated according to the habitat in which they were captured. Forty-two bands were analyzed from RAPD profiles generated using four primers. A dendrogram constructed from Dice's similarity coefficient values showed that migration of the insects between the habitats has occurred, without structuring of populations. Moreover, the dendrogram obtained from the genetic distance values showed an important gene flow between the sylvatic and domestic habitats. No polymorphism was found in the electrophoretic mobility of proteins for the ten enzymes studied. Our results revealed movement of triatomines between the three habitats, suggesting that the presence of T. vitticeps in houses should not be ignored. As invasion of houses by sylvatic insects is frequent and the natural infection indices of this species are among the highest known, epidemiological vigilance studies may reveal possible changes in T. vitticeps behaviour which could present future risks to public health.

Triatoma tibiamaculata (Pinto, 1926): Tábua de vida das ninfas, duração das formas adultas e postura das fêmeas (Hemiptera - Reduviidae) / Triatoma tibiamaculata (Pinto, 1926): life table for nymphs, duration of adult forms and oviposition of females

Os autores analisaram em condições de laboratório, a taxa de sobrevida das ninfas, duração mínima e máxima de cada estádio, tempo de vida das formas adultas e postura das fêmeas. Foram acompanhados dois grupos de 100 ovos. Lote A, exemplares criados em um único cristalizador. Lote B os exemplares foram mantidos isolados um a um e ao atingir a fase alada formaram 20 casais, possibilitando o controle da postura das fêmeas e o tempo de vida de cada exemplar. O percentual de eclosão dos ovos foi de 96 por cento; a taxa de vida no final da fase ninfal foi de 69,5 por cento no Lote A e de 78,4 por cento no Lote B. A maior freqüência observada no tempo decorrido entre postura e eclosão da ninfa do 1° estádio foi de 28 dias. O tempo de permanência na fase de ninfa foi de 4 a 8 meses e de 5 meses na fase adulta. A postura total (média) no Lote B foi de 181,6 ovos por fêmea.

Under laboratory conditions, the authors analyzed the survival rate of nymphs, the minimum and maximum duration of each stage, the length of life of the winged forms and oviposition of the females. Two groups of 100 eggs each were monitored. In batch A, the specimens were reared in a single glass receptacle. In batch B, the specimens were kept apart, one by one, and when they reached the winged stage, they formed twenty couples, which made it possible to watch over the oviposition of the females and the length of life of each specimen. The egg eclosion rate was 96 percent; the proportion still alive at the end of the nymph phase was 69. 5 percent in batch A and 78. 4 percent in batch B. The most frequent length of time observed between oviposition and eclosion of first-stage nymphs was 28 days. The nymph phase lasted four to eight months and the adult phase five months. The mean total oviposition in batch B was 181. 6 eggs per female.

Morphometric changes of Triatoma flavida Neiva, 1911 (Hemiptera: Triatominae) in the transition from sylvatic to laboratory conditions

The one-generational metric changes occurring in Triatoma flavida (Hemiptera: Triatominae) when carried from its wild habitat (caves) to laboratory, were examined using traditional morphometric techniques. As for other species of Triatoma, Rhodnius or Panstrongylus studied in similar conditions, a significant reduction of head, thorax and wing size was observed. Sexual dimorphism of the wings, while present in the wild sample, was not detected anymore in the laboratory individuals. Biological significance and epidemiological importance are discussed.

Fueron examinados los cambios morfométricos que ocurrieron en la primera generación de Triatoma flavida cuando fueron llevados desde su hábitat selvático (cuevas) al laboratorio, mediante el uso de técnicas morfométricas tradicionales. Se observó una reducción significativa del tamaño de la cabeza, tórax y alas, como ocurre en otras especies de Triatoma, Rhodnius o Panstrongylus estudiados en condiciones similares. El dimorfismo sexual de tamaño en las alas, aunque presente en los individuos selváticos, no se detectó en los de laboratorio. La significación biológica y la importancia epidemiológica son discutidas.

Triatoma juazeirensis sp. nov. from the state of Bahia, Northeastern Brazil (Hemiptera: Reduviidae: Triatominae)

Triatoma juazeirensis, a new triatomine species from the state of Bahia, Northeastern Brazil, is described. The new species is found among rocks in sylvatic environment and in the peridomicile. Type specimens were deposited in the Entomological Collection of Oswaldo Cruz Institute-Fiocruz, Museum of Zoology of University of São Paulo, and Florida Museum of Natural History. T. juazeirensis can be distinguished from the other members of the T. brasiliensis species complex mainly by the overall color of the pronotum, which is dark, and by the entirely dark femora.

Triatoma boliviana sp.n. (hemiptera: reduviidae: triatominae) de los valles subandinos de La Paz-Bolivia, similar a Triatoma nigromaculata Stal, 1859 / Triatoma boliviana sp.n. (hemiptera: reduviidae: triatominae) from sub andean valleys of La Paz-Bolivia, related to triatoma nigromaculata stal,1859

Presentamos la descripción de triatoma boliviana sp. n. en base a caracteres morfológicos externos de 3 machos y 3 hembras siguiendo las claves de Lent y Wygodzinsky (1979) y Carcavallo y col. (1997). La nueva especie es muy similar a triatoma nigromaculata y fue capturada en valles subandinos de la Provincia Muñecas Departamento de La Paz Bolivia.

We present the description of Triatomaboliviana sp. n. based on morphological external characters of 3males and 3 females following the keys of Lent and Wygodzinsky(1979) and Carcavallo et al. (1997). The new species are very similarto Triatoma nigromaculata and was captured in Sub Andean valleysfrom Muñecas Province, Department of La Paz, Bolivia.

Genetic structure of Triatoma venosa (Hemiptera: Reduviidae): molecular and morphometric evidence

Triatoma venosa presents a restricted geographical distribution in America and is considered as a secondary vector of Chagas disease in Colombia and Ecuador. A total of 120 adult insects were collected in domestic and peridomestic habitats in an endemic area of the department of Boyacá, Colombia, in order to determine their genetic structure through morphometric and molecular techniques. The head and wings of each specimen were used for the analyses of size, shape, and sexual dimorphism. A significant sexual dimorphism was found, although no differences in size among the studied groups were detected. Differences were found in the analyzed structures except for male heads. DNA was extracted from the legs in order to carry out the internal transcriber space-2 (ITS-2) amplification and the randon amplified polymorphic DNA (RAPD) analyses. Length polymorphisms were not detected in the ITS-2. Fst and Nm values were estimated (0.047 and 3.4, respectively). The high genetic flow found among the insects captured in the domicile and peridomiciliary environment does not permit a genetic differentiation, thus establishing the peridomicile as an important place for epidemiological surveillance.

Morfologia comparada dos ovos e ninfas de Triatoma vandae Carcavallo, Jurberg, Rocha, Galvão, Noireau & Lent, 2002 e Triatoma williami Galvão, Souza & Lima, 1965 (Hemiptera, Reduviidae, Triatominae) / Comparative morphology of eggs and nymphs of Triatoma vandae Carcavallo, Jurberg, Rocha, Galvão, Noireau & Lent, 2002 and Triatoma williami Galvão, Souza & Lima, 1965

Eggs and all nymphs of these species were studied employing light microscopy (LM) and scanning electron microscopy (SEM). The major differences observed by LM in the eggs were related to the presence and the distribution of pores on the surface of their chorion. Morphological differences among three nymphal stages (1st, 3rd, and 5th) development of each species were observed. The differential characteristics are chromatic and in the shape of connexival spots. The ultrastructure of the ventral region of the head and the IX, X, and XI abdominal segments (anal tube) of the both species were described demonstrating morphological differences that can be used for diagnosis of the species.

Morphometric analysis of Triatoma dimidiata populations (Reduviidae: Triatominae) from Mexico and Northern Guatemala

Triatoma dimidiata is one of the major vectors of Chagas disease in Latin America. Its range includes Mexico, all countries of Central America, Colombia, and Ecuador. In light of recent genetic analysis suggesting that the possible origin of this species is the Yucatan peninsula, we have analyzed populations from the state of Yucatan, San Luis Potosi, and Veracruz in Mexico, and a population from the southern region of the Yucatan peninsula located in Northern Guatemala, the region of El Peten. Classical morphometry including principal component, discriminant, sexual dimorphism, and wing asymmetry was analyzed. San Luis Potosi and Veracruz populations were indistinguishable while clearly separate from Yucatan and Peten populations. Despite important genetic differences, Yucatan and Peten populations were highly similar. Yucatan specimens were the smallest in size, while females were larger than males in all populations. Only head characters were necessary to distinguish population level differences, although wing fluctuating asymmetry was present in all populations. These results are discussed in light of recent findings suggesting genetic polymorphism in most populations of Triatoma dimidiata south of Chiapas to Ecuador.

Triatoma rubrovaria (Blanchard 1843): tábua de vida das ninfas, duração das formas e oviposição das fêmeas / Triatoma rubrovaria (Blanchard 1843): life table of nymphs, duration of the forms and posture of the females

Os autores acompanharam a evolução de 150 ovos de Triatoma rubrovaria o que permitiu a construção de uma tábua de sobrevida das ninfas. A forma alada foi atingida por 94,64 por cento dos exemplares, sendo 79 deles machos e 65 fêmeas. O tempo médio dos alados machos foi de 115 dias e das fêmeas, 99 dias. Parte desses exemplares formaram 30 casais, mantidos isolados, o que possibilitou o levantamento da postura de cada fêmea. Outro lote, também formado por 30 machos e 30 fêmeas, foi mantido em um único cristalizador de vidro, o que permitiu constatar sua maior postura (7.832 ovos) em relação aquela das fêmeas acasaladas por único macho (5.167). O bom desenvolvimento dos exemplares no processo de evolução e de reprodução da espécie, nas condições do experimento, mostrou a boa capacidade de manutenção das colônias do Triatoma rubrovaria, em condições de laboratório.