Occurrence and distribution of Panstrongylus megistus (Burmeister, 1835) (Hemiptera, Reduviidae) in a metropolitan area of Southern Brazil

ABSTRACT Two triatomine genera (Panstrongylus and Triatoma) have essentially been recorded in Rio Grande do Sul State, Brazil. Panstrongylus megistus should be highlighted since this species is one of the main vectors of Trypanosoma cruzi in Brazil, due to its wide geographical distribution and the high susceptibility to this protozoan. This study aimed to present not only the occurrence and distribution of P. megistus in the Porto Alegre city's metropolitan area (PAMA), Rio Grande do Sul State, Brazil, but also the rates of T. cruzi infection, from 2009 to 2020. The PAMA, which comprises 34 cities and 4.4 million habitants, extends across the transition area in two biomes - Pampa and Mata Atlantica - found in the state. Results showed that P. megistus was recorded in 76.5% of cities (i.e., 26 out of 34), mainly in Porto Alegre city, where the vector was found in 11 out of the 12 years that were monitored. Three hundred and nineteen specimens were captured. Two hundred and sixty-seven specimens (83.7%) were located intradomicile (p < 0.0001), while 52.3% positivity for T. cruzi was found. Thus, P. megistus is important in the PAMA, because it invades and colonizes the households. Moreover, the high rates of T. cruzi infection have drawn attention.

Triatoma rubrovaria (Hemiptera, Reduviidae, Triatominae) in the Pampa biome, Brazil: a retrospective study of its occurrence and abundance

ABSTRACT Triatoma rubrovaria has been captured in some areas of Rio Grande do Sul State (RS), Brazil, as this species can be found in the Pampa biome. Its distribution across this biome should be described in detail to verify the potential of this vector to transmit Trypanosoma cruzi. This study aimed to investigate the occurrence of T. rubrovaria in the Pampa biome and transitional areas of RS. The collected information resulted from the analysis of secondary data provided by the Centro Estadual de Vigilancia em Saude (CEVS - State's Center of Health Surveillance). The following aspects were taken into consideration: the year in which the insect was captured, the city, the number of specimens captured, invasion or domiciliation, the notification in the household, surroundings or both, and T. cruzi infection. The data comprised the period from 2009 to 2020, in 109 cities located in the Pampa biome and 98 located in transitional areas. The Pampa biome exhibited 85% of the occurrences of T. rubrovaria, while 1.2% of specimens were T. cruzi-like positive. Both the first and second biennia concentrated 64.6% of captures. Alegrete city, Cangucu city and Piratini city were the locations in the Pampa where the largest numbers of specimens were found. Regarding the transitional areas, Roque Gonzales city, Santiago city and Santana da Boa Vista city exhibited the largest numbers. Most insects were adults, which were found in households. Even though positivity for T. cruzi-like was low, the species still has epidemiological importance in the region.

Residual foci of Triatoma infestans infestation: Surveillance and control in Rio Grande do Sul, Brazil, 2001-2018

Abstract INTRODUCTION: This retrospective study conducted from 2001 to 2018 investigated the residual foci of Triatoma infestans infestation in Rio Grande do Sul, Brazil. METHODS: The data were obtained via entomological surveillance and the distribution of vector occurrence. The coverage of active research was mapped. RESULTS: The largest coverage rate for active research was observed in the northwest region of the total of 515,081 domiciles researched. Most T. infestans specimens were captured in the peridomicile. CONCLUSIONS: Infestation has decreased significantly since 2008, and T. infestans has not been captured since 2015.

Morphological and morphometric analysis of skeletal muscle between male and female young adult Colossoma macropomum (Characiformes: Serrasalmidae)

This study aimed to evaluate muscle organization in tambaqui in order to describe the muscle growth process. We analyzed the morphometric pattern of fibers from white muscle of young-adults (300 days) by smaller diameter. The organization of white muscle exhibited a typical morphological pattern found in other fish species. Heavier animals showed higher frequency of larger diameter fibers (>50 m ) and smaller animals had higher frequency of smaller diameter fibers ( 20 m ) (P =0.005). However, both animals showed the same frequency of intermediate diameter fibers (20-50 m ). Body weight showed a positive correlation with muscle diameter fiber (r=0.45), being 20-50 m the diameters that contributed the most to animal weight (P 0.0001). A weak correlation between fiber diameter and animal sex was observed (r=0.2). Females showed higher frequency of large fiber diameters (>50 m ) than males. However, there was no difference between body weight and sex (P =0.8). Our results suggest that muscle growth is by hypertrophy and hyperplasia due to a mosaic appearance from different diameters fibers, which is characteristic of large size fish species.

O objetivo deste trabalho foi avaliar a organização muscular em tambaqui, a fim de descrever o processo de crescimento muscular. Foi analisado o padrão morfométrico das fibras do músculo branco de animais com 300 dias de idade usando o método de diâmetro menor. O músculo branco apresentou uma organização morfológica padrão encontrado em peixes. Animais de maior peso apresentaram maior frequência de fibras de maior diâmetro (> 50 m ) e os animais de menor peso apresentaram maior frequência de fibras de menor diâmetro ( 20 m ) (P = 0,005). Entretanto, ambos os animais, com maior e menor peso, apresentaram frequências semelhantes de fibras de diâmetro intermediário (20-50 m ). O parâmetro peso corporal mostrou correlação positiva com o diâmetro da fibra muscular (r = 0,45), sendo as fibras de diâmetro intermediários (20-50 m ) que mais contribuíram para o peso do animal (P 0,0001). Fêmeas apresentaram maior frequência de fibras de maior diâmetro (>50 m ) que machos. Observou-se uma fraca correlação entre o diâmetro da fibra e o sexo dos animais (r = 0,2). Apesar de fraca, a correlação estimada é corroborada pela fibras de grandes diâmetros (> 50 m ) serem mais frequente nas fêmeas que nos machos. No entanto, não houve diferença entre o peso corporal dos animais aos 300 dias de idade e sexo (P = 0,8). Os resultados encontrados sugerem que o crescimento muscular ocorre por hipertrofia e hiperplasia, caracterizado pela aparência em mosaico de fibras de diferentes diâmetros, característico de peixes de grande tamanho.

Susceptibility characterization of residual Brazilian populations of Triatoma infestans Klug, 1834 (Hemiptera: Reduviidae) to deltamethrin pyrethroid

INTRODUCTION: Despite years of efforts towards the elimination of Triatoma infestans in Brazil, residual foci still persist in some areas of the States of Bahia and Rio Grande do Sul. The persistence of these T. infestans populations in the country has two different origins of equal concern: operational failures or insecticide resistance. Thus, the objective of this study was to characterize the susceptibility profile of the residual Brazilian populations of T. infestans to deltamethrin. METHODS: The susceptibility reference lineage was derived from Cipein/Argentina. The populations studied were manually collected using a dislodging agent in peridomiciles in the States of Bahia (Novo Horizonte) and of Rio Grande do Sul (Santa Rosa and Doutor Maurício Cardoso). Serial dilutions of deltamethrin were prepared and applied at the dorsal abdomen of first instar nymphs. The control group received only pure acetone. Mortality was evaluated after 72h. Qualitative tests assessed the mortality of a diagnostic dose of 1xLD99 (2.76ng a.i./nymph) determined for the susceptibility reference lineage. RESULTS: The susceptibility profile characterization of the T. infestans populations revealed an RR50 ranging from 1.73 to 3.26. The mortality percentage in response to a diagnostic dose was 100%. The results obtained in the quantitative and qualitative assays corresponded for all populations. CONCLUSIONS: The results of this study indicate that the persistence of residual foci of T. infestans in Bahia and Rio Grande do Sul is not related to insecticide resistance but may be associated with operational failures. In Rio Grande do Sul, we must consider the possibility of continuous reinfestation by Argentinian individuals, which justifies active and efficient epidemiological surveillance. .

Aspectos da vigilância entomológica da doença de chagas no sul do Rio Grande do Sul, Brasil / Aspects of Entomological Surveillance of Chagas disease in southern Rio Grande do Sul, Brazil

Este trabalho teve como objetivo descrever as espécies de triatomíneos presentes na região de abrangência da 3ª Coordenadoria Regional de Saúde do Rio Grande do Sul (3ª CRS) e avaliar aspectos da vigilância entomológica da doença de Chagas desencadeada a partir da notificação de insetos pela população. Para tanto, fez-se o acompanhamento das atividades desenvolvidas pelos agentes no período proposto, sendo também realizadas entrevistas com estes agentes para a identificação das principais dificuldades encontradas durante o andamento das ações do programa. No biênio 2010-2011, foram capturados 295 triatomíneos em nove municípios, todos eles provenientes de capturas realizadas pela população (notificação) e entregues em Postos de Informação de Triatomíneos. Dentre os municípios que obtiveram maior número de capturas, destacaram-se Canguçu (37,8 porcento) e Piratini (28,8 porcento). As espécies com mais exemplares capturados foram Triatoma rubrovaria (93,9 porcento) e Panstrongylus tupynambai (5,1 porcento). As capturas dos insetos ocorreram, predominantemente, no intradomicílio e nos meses de temperatura mais elevada. Quanto aos agentes, 95,2 porcento relataram alguma dificuldade no exercício do ofício, destacando-se as inadequações do transporte e a escassez de material educativo para distribuição pública como principais elementos dificultadores. Concluiu-se que alguns municípios apresentam risco permanente de invasão domiciliar por triatomíneos, especialmente T. rubrovaria. Em razão disso, ficou evidenciada a importância da manutenção das atividades de vigilância e de maior assistência ao trabalho dos agentes que atuam no programa...

The objective of this study was to describe the triatomine species present in the region covered by the 3rd Regional Health Coordination of Rio Grande do Sul (3rd CRS) and evaluate aspects of entomological surveillance of Chagas disease from the notification of insects by the population. For this, the agents’ activities over this period were monitored and they were interviewed to ascertain the main difficulties encountered in the activities of the program. Over this period, 295 triatomines were caught in nine municipalities. All of them were caught by members of the public (notifications) and were handed in at triatomine information centers. Among the municipalities in which larger numbers of specimens were caught, Canguçu (37.8 percent) and Piratini (28.8 percent) were prominent. The species for which the largest numbers of specimens were caught were Triatoma rubrovaria (93.9 percent) and Panstrongylus tupynambai (5.1 percent). The insects were predominantly caught inside homes and during the hotter months. Regarding the agents, 95.2 percent reported that they had some difficulties in carrying out their duties. Inadequacies of transportation and scarcity of educational material for public distribution were cited as the main factors that caused difficulties. It was concluded that some municipalities present an ongoing risk of triatomine invasion in homes, especially regarding T. rubrovaria; maintenance of surveillance activities is of fundamental importance, and greater assistance for the work of agents acting within the program is needed...