Systematic review on the biology, ecology, genetic diversity and parasite transmission potential of Panstrongylus geniculatus (Latreille 1811) in Latin America

Panstrongylus geniculatus (Latreille, 1811) is the triatomine with the largest geographic distribution in Latin America. It has been reported in 18 countries from southern Mexico to northern Argentina, including the Caribbean islands. Although most reports indicate that P. geniculatus has wild habitats, this species has intrusive habits regarding human dwellings mainly located in intermediate deforested areas. It is attracted by artificial light from urban and rural buildings, raising the risk of transmission of Trypanosoma cruzi. Despite the wide body of published information on P. geniculatus, many knowledge gaps exist about its biology and epidemiological potential. For this reason, we analysed the literature for P. geniculatus in Scopus, PubMed, Scielo, Google Scholar and the BibTriv3.0 databases to update existing knowledge and provide better information on its geographic distribution, life cycle, genetic diversity, evidence of intrusion and domiciliation, vector-related circulating discrete taxonomic units, possible role in oral T. cruzi transmission, and the effect of climate change on its biology and epidemiology.

The development of Panstrongylus herreri under fluctuating environmental conditions

Abstract: INTRODUCTION: Panstrongylus herreri is a main Chagas disease vector, and its success as a vector stems from its ability to establish domiciliated colonies; we aimed to explore its biology and reproduction. METHODS: The average amount of blood ingested and the time from the beginning of a blood meal to the production of feces were recorded. RESULTS: Females exhibited a higher blood ingestion rate than males, but similar defecation times and frequencies were observed. CONCLUSIONS: Despite the detected decrease in oviposition rates, P. herreri's potential as a Chagas disease vector in environments other than the Amazon forest cannot be discounted.

Evaluation of natural foci of Panstrongylus megistus in a forest fragment in Porto Alegre, State of Rio Grande do Sul, Brazil

Introduction Panstrongylus megistus is commonly found in wild environments of the State of Rio Grande do Sul, Brazil. The aim of this study was to characterize the network of refuges used by triatomine in a forest fragment of Porto Alegre and to identify Trypanosoma cruzi infection, associated hosts and the epidemiological importance of both hosts and triatomines. Methods Techniques including the spool-and-line method and active searching (transects) were used to identify natural foci. Results The food source for each triatomine was determined using the precipitin test, and the infection of marsupials was determined by xenodiagnosis. A total of 33 adults (domestic environment) and 27 nymphs (wild environment) of P. megistus were found in addition to 43 Didelphis albiventris specimens. The infection rates of triatomine adults, triatomine nymphs and opossums with T. cruzi I were 64%, 73% and 69%, respectively. Birds, rodents and opossums were the main resources used by triatomine. Conclusions This work presents the first characterization of a natural focus of P. megistus in Rio Grande do Sul. The natural characteristics of this focus and its implication in the transmission of T. cruzi are discussed. .

Análise da fonte alimentar de Panstrongylus megistus (Hemiptera, Reduviidae, Triatominae) e sua atual importância como vetor do Trypanosoma cruzi, no Estado de Minas Gerais / Analysis on the food source of Panstrongylus megistus (Hemiptera, Reduviidae, Triatominae) and its present importance as a vector for Trypanosoma cruzi, in the State of Minas Gerais

INTRODUÇÃO: A pesquisa da fonte alimentar dos triatomíneos auxilia no conhecimento sobre a biologia destes insetos, inclusive para inferir-se a importância dos mesmos como transmissores do Trypanosoma cruzi ao homem. MÉTODOS: O presente estudo objetivou registrar, através da reação de precipitina, a fonte alimentar de triatomíneos provenientes de 54 municípios da região centro-oeste de Minas Gerais, assim como a infecção natural destes para flagelados semelhantes ao Trypanosoma cruzi. RESULTADOS: De julho de 2003 até março de 2007, foram avaliados 416 insetos, todos da espécie Panstrongylus megistus. Somando-se as ocorrências, as aves (70 por cento) e os humanos (22,5 por cento) constituíram as principais fontes sanguíneas. Encontrou-se 16 (3,8 por cento) insetos positivos para flagelados semelhantes ao Trypanosoma cruzi sendo que oito realizaram hematofagia no homem. CONCLUSÕES: Os resultados demonstram necessidade de acentuar a vigilância entomológica na região, visto que foi detectada a possibilidade de ocorrência de novos casos da doença de Chagas através da transmissão vetorial.

INTRODUCTION: Investigation of the food source of triatomines helps in understanding the biology of these insects, and also helps to infer their importance in transmitting Trypanosoma cruzi to humans. METHODS: The present study aimed to use the precipitin reaction to record the food source of triatomines from 54 municipalities in the central-western region of the State of Minas Gerais, as well as their natural infection by flagellates similar to Trypanosoma cruzi. RESULTS: From July 2003 to March 2007, 416 insects were evaluated, all from the species Panstrongylus megistus. Among all these occurrences, birds (70 percent) and humans (22.5 percent) were the major blood sources. Sixteen (3.8 percent) of the insects were found to be positive for flagellates similar to Trypanosoma cruzi, and eight performed hematophagia on humans. CONCLUSIONS: The results show the need to increase the entomological surveillance in this region, given that the possibility of new cases of Chagas disease occurring through vector transmission was detected.

Triatomines (Hemiptera, Reduviidae) prevalent in the northwest of Peru: species with epidemiological vectorial capacity

The development of strategies for the adequate control of the vector transmission of Chagas disease depends on the availability of updated data on the triatomine species present in each region, their geographical distribution, natural infections by Trypanosoma cruzi and/or T. rangeli, eco-biological characteristics and synanthropic behavioral tendencies. This paper summarizes and updates current information, available in previously published reports and obtained by the authors our own field and laboratory studies, mainly in northwest of Peru. Three triatomine species exhibit a strong synanthropic behavior and vector capacity, being present in domestic and peridomestic environments, sometimes showing high infestation rates: Rhodnius ecuadoriensis, Panstrongylus herreri and Triatoma carrioni The three species should be given continuous attention by Peruvian public health authorities. P. chinai and P. rufotuberculatus are bugs with increasing potential in their role as vectors according to their demonstrated synanthropic tendency, wide distribution and trophic eclecticism. Thus far we do not have a scientific explanation for the apparent absence ofT. dimidiata from previously reported geographic distributions in Peru. It is recommended, in the Peruvian northeastern Amazon region, the development of field studies on species of the genus Rhodnius, as well as of other triatominae, to evaluate their present Trypanosomatidae vector capacity.

El desarrollo de estrategias adecuadas para el control de la transmisión vectorial de la Enfermedad de Chagas depende: de la disponibilidad de datos actualizados de las especies de triatominos presentes en cada región, de su distribución geográfica, infección natural por Trypanosoma cruzi ylo T. rangeli, características eco-biológicas y tendencias de comportamiento sinantrópico. Este trabajo resume y actualiza la información disponible en la literatura y aquella obtenida en nuestros estudios de campo y de laboratorio desarrollados en los últimos años por los autores, predominantemente, en la región Nor-Occidental del Perú. El resultado de esas observaciones es la detección de que, tres especies de triatominos presentan un importante comportamiento sinantrópico y capacidad vectorial, ocupando ambientes intradomiciliares y peridomiciliares: Rhodnius ecuadoriensis, Panstrongylus herreri y Triatoma carrioni. Las tres especies deben recibir constante atención por parte de las autoridades de Salud Pública Peruana. P. chinai y P rufotuberculatus tienen potencial creciente en su papel de vectores, por la comprobada tendencia sinantrópica, distribución geográfica y eclecticismo trófico. Se desconocen las causas de la aparente ausencia actual de Triatoma dimidiata, dada su presencia constatada anteriormente en el Perú. Se recomienda que en la región Nor-Oriental Amazónica Peruana se realicen en forma urgente estudios sobre las especies del genero Rhodnius y de otros triatominos que permitan evaluar la real capacidad vectorial de los Trypano-somatideos.

Estudo das fontes alimentares de Panstrongylus lutzi (Neiva & Pinto, 1923) (Hemiptera: Reduviidae: Triatominae) no Estado do Ceará / Feeding sources evaluation of Panstrongylus lutzi (Neiva & Pinto, 1923) (Hemiptera: Reduviidae: Triatominae) in the State of Ceará

Os autores utilizaram a técnica de precipitina para identificar as fontes alimentares de Panstrongylus lutzi (Neiva & Pinto, 1923) em 20 municípios do Estado do Ceará, Brasil. Os resultados detectaram a presença de sangue de oito diferentes fontes sanguíneas e alimentações mistas, demonstrando que Panstrongylus lutzi é uma espécie eclética. Altas taxas de infecção por tripanosomatídeos foram detectadas.

The authors used precipitin technique to detect the feeding sources of Panstrongylus lutzi (Neiva & Pinto, 1923) in 20 municipalities of Ceará State, Brazil. The results detected the presence of blood from eight different blood sources and mixed feedings, demonstrating that Panstrongylus lutzi is an eclectic species. High infection rates for Trypanosoma like-cruzi were detected.

Stridulatory sound emission of Panstrongylus rufotuberculatus Champion, 1899, (Hemiptera: Reduviidae: Triatominae)

Este estudo contém o primeiro reporte da estridulação observada em Panstrongylus rufotuberculatus Champion, 1899, e um novo registro desta espécie na Venezuela. Descrevem-se as condições em que ocorre a estridulação, como também as características gerais das localidades onde foi capturado. Este triatomino só emite som em condições de extrema provocação.

Triatomíneos rupestres infectados por Trypanosomatidae, coletados em Quaraí, Rio Grande do Sul, 2003 / Rupestrian triatomines infected by Trypanosomatidae, collected in Quaraí, Rio Grande do Sul, 2003

Foram capturados triatomíneos rupestres em seis localidades do município de Quaraí-RS, com o intuito de verificar o índice de infeccão por Trypanosomatidae, bem como o animal reservatório. A captura ocorreu no ambiente silvestre, sendo coletados 453 exemplares, os quais foram identificados e separados por estádio ninfal. Coletaram-se 421 (92,9 por cento) exemplares de Triatoma rubrovaria, 26 (5,7 por cento) de Triatoma circummaculata e 6 (1,3 por cento) de Panstrongylus tupynambai. Dentre as três espécies coletadas, somente Triatoma rubrovaria mostrou-se positivo para Trypanosomatidae, num total de 13 (4,2 por cento) exemplares. Após a inoculacão em camundongos e meio de cultura LIT, isolaram-se cinco cepas de Trypanosoma cruzi. Dos triatomíneos infectados com Trypanosomatidae, 4 (30,8 por cento) tiveram a reacão de precipitina não reagente para os anti-soros testados, 4 (30,8 por cento) positivos para anti-soro de roedor, 4 (30,8 por cento) para anti-soro de cabra e 1 (7,7 por cento) para anti-soro de porco e humano.

Experimental evidence for a demographic cline in Panstrongylus megistus populations

The population biology of three populations of Panstrongylus megistus was compared to determine possible influence on the behaviour and epidemiological importance of this species. The results demonstrated differences in terms of egg eclosion time, nymphal mortality and development rates, and feeding and defaecation rates. These differences appeared to follow a geographical cline, primarily reflecting different degrees of adaptation to domestic habitats

Changes in nuclear phenotypes following cold shock in Panstrongylus megistus (Burmeister)

The nuclear phenotypes of Malpighian tubule epithelial cells of 5th instar male nymphs of the blood-sucking insect Panstrongylus megistus were studied immediately after a short (1 h) cold shock at 0o.C, and 10 and 30 days later. The objective was to compare the responses to a cold shock with those known to occur after hyperthermia in order to provide insight into the cellular effect of cold in this species. Nuclei which usually exhibited a conspicuous Y chromosome chromocenter were the most frequent phenotype in control and treated specimens. Phenotypes in which the heterochromatin was unravelled, or in which there was nuclear fusion or cell death were more abundant in the shocked specimens. Most of the changes detected have also been found in heat-shocked nymphs, except for nuclear fusion which generates giant nuclei and which appeared to be less effective or necessary than that elicited after heat shock. Since other studies showed that a short cold shock does not affect the survival of more than 14 percent of 5th instar nymphs of P. megistus with domestic habit and can induce tolerance to a prolonged cold shock, heat shock proteins proteins are probably the best candidates for effective protection of the cells and the insects from drastic damage caused by low temperature shocks

Vetores selváticos de doença de Chagas na área urbana de Manaus (AM): atividade de vôo nas estaçoes secas e chuvosas / Wild vectors of Chagas' disease in an urban area of Manaus (AM): flying activity during dry and rainy seasons

Adultos de Rhodnius prolixus, R. pictipes e Panstrongylus geniculatus encontrados em casas em Manaus apresentam altas taxas de infecção por Trypanosoma cruzi. Rhodnius spp não apresentavam sazonalidade acentuada, porém os encontros de machos de P. geniculatus eram muito mais freqüentes na estação seca.

Adults of Rhodnius prolixus, R. pictipes and Panstrongylus geniculatus found in houses in Manaus have high rates of Trypanosoma cruzi infection. Rhodnius spp. were found throughout the year, but males of P. geniculatus were significantly more frequent in the dry season.

Possible absence of attraction to odor in Panstrongylus megistus (Hemiptera: Reduviidae) under laboratory conditions

We tested the attraction of Panstrongylus megistus odor under laboratory conditons, between males and females of this species and by individuals of each sex on recently fed virgin couples. We employed a system of choice boxes both with or without aeration over the stimuli in the tested situations. We also observed a clear trend among the insects to remain in the central box where they had been placed in the beginning of the tests.

Juvenile hormone III and nutrition effects on spermatogenesis in the 4th instar nymphs of Panstrongylus megistus (Hemiptera: Reduviidae)

When 4th instar nymphs of Panstrongylus megistus are fed eith a saturant blood meal, there is an intense proliferation of the spermatogonia. At the end of the intermoult, the older spermatogonial cysts differentiate into 1st primary spermatocyte cysts. In the nymphs deprived of the blood meal this evolution is not observed, but a small growth of the testicular follicles occurs, due to a few mitotic divisions. This growth is observed at least, until 25 days after ecdysis. Since day 15, an autolytic process starts in the older spermatogonial cysts. The presence of exogenous juvenile hormone III (JH III) does not promote the development of the germ cells in the fasting insects. There is only a small growth of the testicular follicles and the autolytic process is also observed. In the precocious adults obtained by allatectomy or prcocene II treatment, germ cells are observed in all development stages, except packed and elongated spermatozoa bundels

Ciclo de vida de Panstrongylus humeralis Usinger 1939, bajo condiciones de laboratorio (Reduviiae Triatominae) / Life cycle of Panstrougylus humeralis Usinger 1939 (Reduviidae Triatominae) under laboratory conditions

Panstrongylus humeralis, vector potencial de la enfermedad de Chagas, se ha reportado solamente en la República de Panamá, específicamente en la isla de Barro Colorado, áreas aledañas al Canal de Panamá y en Bayano. En el laboratorio con temperatura de 27-C y humedad relativa (HR) de 100%, se dió seguimiento al desarrollo embrionario de 680 huevos de Panstrongylus humeralis. El desarrollo de los huevos bajo estas condiciones fue de 13 a 23 días con un promedio de 18.8 días y 100% de eclosión. Los estadios ninfales y adultos obtenidos fueron alimentados semanalmente sobre Columba livia (paloma castilla) y mantenidos a HR entre 70 y 80%. El ciclo completo de huevo a adulto demoró un promedio de 149 días bajo estas condiciones. Las ninfas de primero a quinto estadio, tuvieron una duración promedio de 17.9, 16.6, 21.6, 30.9 y 43.6 días respectivamente, estableciéndose una diferencia de 5.4 días adicionales en las ninfas de quinto estadio que evolucionaron a hembra, comparada con la duración del quinto estadio ninfal y la evolución de los machos, lo que no representó una diferencia significativa

Aspectos do ciclo evolutivo do Panstrogylus tupinambar Lent, 1942 (Hemiptera, Triatominae) em laboratório / Evolutive cycle of panstrongylus tupinambai Lent, 1942 (Hemiptera, Triatominae) in laboratory

Säo apresentados dados preliminares do ciclo evolutivo de Panstrongylus tupynambai, Lent 1942 em laboratório. Destaca-se o largo período de evoluçäo de ovo a adulto (425 dias); o que, considerado ao lado de suas características biológicas observadas em campo, pode explicar os hábitos exclusivamente silvestres, da espécie