Mosquito communities in Nova Iguaçu Natural Park, Rio de Janeiro, Brazil

ABSTRACT. In order to gather information on the culicid fauna of Nova Iguaçu Municipal Park, Rio de Janeiro, Brazil, adult and immature stages were collected with the Centers for Disease Control and Prevention miniature light traps, and dippers and suction tubes, respectively. In all, 828 adult and 990 immature specimens were collected belonging to 12 genera. Among the species collected were Aedes aegypti, Ae. albopictus, Ae. fluviatilis, Ae. scapularis, Haemagogus leucocelaenus, and Psorophora ferox that are considered of potential medical importance. Culicids used a variety of larval habitats and bred under diverse ecological conditions, mostly in natural water containers formed by bamboo, bromeliad, ground depression, rock pool, stream, tree hole, and in artificial containers such as abandoned bathtub, car carcass, abandoned sink, plastic cup, waste tire, and water tank. Species richness and diversity increased from lower to higher forest cover and was highest in sites with highest diversity and high number of larval habitats.

Immature mosquitoes (Diptera: Culicidae) in a eutrophic landfill tank from State of Rio de Janeiro, Brazil

INTRODUCTION

To determine the faunal composition of immature culicids inhabiting a percolation tank in the landfill of Sapucaia, State of Rio de Janeiro, Brazil, immature mosquitoes were collected over a two-day period during the third weeks of April, August and October 2011.

RESULTS

The species found were Culex usquatus, Lutzia bigoti, Anopheles argyritarsis and Limatus durhamii. This study is the first to report the colonization of eutrophic breeding sites by these species.

CONCLUSIONS

The oviposition behavior observed in this study suggests a secondary adaptation or change in habit to select eutrophic environments during the developmental stages of the observed species.

Scanning electron microscopy of eggs of Georgecraigius fluviatilis (Lutz) (Diptera: Culicidae, Aedini)

Scanning Electron Microscopy was used to describe the eggs of Georgecraigius fluviatilis (Lutz). Length is 722.8±39.6 µm and width is 177.1±9.8 µm. Diameter of the micropylar disk, surrounded by an irregular flattened collar, is 28 µm. The outer chorionic sculpture consists of cells of irregular shapes, containing tubercles with pitted surface. In the ventral region, tubercles of several diameters are irregularly distributed in chorionic cells, while in the dorsal region one larger tubercle is surrounded by several smaller ones. The eggs appear to lack structures for adhesion, certainly unnecessary due to the habit of laying eggs separately on water surfaces.

A comparative study of the effect of multiple immersions on Aedini (Diptera: Culicidae) mosquito eggs with emphasis on sylvan vectors of yellow fever virus

The effect of multiple immersions on Haemagogus janthinomys , Haemagogus leucocelaenus , Aedes albopictus and Ochlerotatus terrens eggs was studied. Eggs were collected in April, June, October and December of 2011 in Minas Gerais, Brazil. Most of the Aedes and Ochlerotatus eggs hatched upon the first immersion, while Haemagogus eggs showed a varied instalment hatching response. The number of immersions required for hatching increased for eggs collected closer to the dry winter season.

Flight height preference for oviposition of mosquito (Diptera: Culicidae) vectors of sylvatic yellow fever virus near the hydroelectric reservoir of Simplício, Minas Gerais, Brazil

In this study, the oviposition behavior of mosquito species exhibiting acrodendrophilic habits was investigated. The study was conducted near the Simplicio Hydroelectic Reservoir (SHR) located on the border of the states of Minas Gerais and Rio de Janeiro, Brazil. Samples were collected using oviposition traps installed in forest vegetation cover between 1.70 and 4.30 m above ground level during the months of April, June, August, October, and December of 2011. Haemagogus janthinomys (Dyar), Haemagogus leucocelaenus (Dyar and Shannon), Aedes albopictus (Skuse), and Aedes terrens (Walker) specimens were present among the collected samples, the first two of which being proven vectors of sylvatic yellow fever (SYF) in Brazil and the latter is a vector of dengue in mainland Asia. As the data set was zero-inflated, a specific Poisson-based model was used for the statistical analysis. When all four species were considered in the model, only heights used for egg laying and months of sampling were explaining the distribution. However, grouping the species under the genera Haemagogus Williston and Aedes Meigen showed a significant preference for higher traps of the former. Considering the local working population of SHR is very large, fluctuating, and potentially exposed to SYF, and that this virus occurs in almost all Brazilian states, monitoring of Culicidae in Brazil is essential for assessing the risk of transmission of this arbovirus.

Serological detection of West Nile virus in horses and chicken from Pantanal, Brazil

In an effort to detect West Nile virus (WNV) in Brazil, we sampled serum from horses and chickens from the Pantanal region of the state of Mato Grosso and tested for flavivirus-reactive antibodies by blocking ELISA. The positive samples were further confirmed for serological evidence of WNV infection in three (8%) of the 38 horses and one (3.2%) of the 31 chickens using an 80% plaque-reduction neutralisation test (PRNT80). These results provide evidence of the circulation of WNV in chickens and horses in Pantanal.

Scanning electron microscopy of eggs of Sabethes cyaneus

Mosquitoes of the Neotropical genus Sabethes, some species of which are yellow fever vectors, most often develop through the immature stages in tree holes. Sabethes eggs have not been previously characterized using scanning electron microscopy. Eggs of Sabethes cyaneus (length: 349.6 +/- 2.7 microm; width: 172.6 +/- 1.14 microm; n = 10) are almost biconical when examined from the top. From a lateral perspective 2 surfaces can be seen. One surface is smooth and more convex, whereas the other is less convex and partially covered by a network from which many fungiform tubercles arise. The micropyle is situated on the smooth surface of the pointed anterior tip and is surrounded by an irregular row of tubercles, some of which are leaf shaped. No structures possibly involved in adhesion to surfaces are visible. When hatching, the egg splits dorsoventrally approximately two-thirds of the length from the anterior end. The tubercles appear to be water repellent, and the more convex/smoother surface is downturned, and this position on water was confirmed by direct observation. The eggs float free on the water surface.

Feeding patterns of Culex quinquefasciatus (Diptera: Culicidae) from eastern Santa Catarina state, Brazil

Blood-feeding sources of Culex quinquefasciatus Say (Diptera: Culicidae) collected in the eastern region of the Brazilian state of Santa Catarina were analyzed by precipitin technique. One hundred fifty-four female mosquitoes collected by CDC traps in the Navegantes municipality 13-15 February 2005 reacted to one or more of eight antisera, including chicken, dog, goat, sheep, horse, opossum, human and rodent antisera. One hundred thirty-seven specimens (89%) reacted to only one source, and 17 (11%) specimens reacted to two sources. Among the 137 specimens reacting to only one source, reactions to rodent (50.4%), sheep (5.8%), chicken (5.1%), goat (5.1%), dog (2.2%), horse (3.6%), and human (3.6%) antisera were observed. The analyzed species demonstrated a high degree of opportunistic feeding behavior in relation to host preference. Results are compared with results from similar studies, and the low proportion of reactions to human antisera is discussed.

Evaluation of mosquito (Diptera: Culicidae) species richness using two sampling methods in the hydroelectric reservoir of Simplício, Minas Gerais, Brazil

We compared two types of light traps used for monitoring mosquito abundance in the hydroelectric reservoir of Simplício, Além Paraíba - Minas Gerais. Mosquitoes were captured bimonthly using automatic CDC and Shannon traps before the filling of the hydroelectric plant reservoir from December 2008 to December 2009. In total, 1474 specimens from 13 genera were captured. Among the captured specimens, several species known to be vectors of disease-causing agents for humans and/or animals were identified, including Anopheles aquasalis, Aedes albopictus, Coquillettidia venezuelensis, Haemagogus leucocelaenus, and Aedes scapularis. Sampling efficacy between the four capture sites was not found to be significantly different, irrespective of species captured or type of trap used. Poor correlation (r (x, y) = -0.0444) between the number of mosquito species and capture site was observed when not influenced by the type of trap used. Among the installation sites of the CDC and Shannon traps in the areas investigated, CDC traps fixed in livestock shelters obtained an overall higher abundance of species captured.

New report on the bionomics of Coquillettidia venezuelensis in temporary breeding sites (Diptera: Culicidae)

INTRODUCTION: Findings of immature forms of Coquillettidia venezuelensis in temporary breeding sites, without the presence of aquatic plants or other submerged plant tissue are reported. METHODS: A systematic scooping technique to collect specimens was used at the breeding site. RESULTS: Immature forms of Coquillettidia venezuelensis, Anopheles rangeli, An. evansae and Culex sp. were collected from areas of the hydroelectric power station of São Salvador, State of Goiás. CONCLUSIONS This is a novel finding relating to the bioecology of Cq. venezuelensis, a species of medical interest that has been found naturally infected with arboviruses, including Oropouche and West Nile virus.

Biodiversity and times of activity of mosquitoes (Diptera: Culicidae) in the biome of the Atlantic Forest in the State of Rio de Janeiro, Brazil

A temporal observational study on culicid entomofauna was conducted in a region characterized as a fragment of the Atlantic Forest that forms the Tinguá Biological Reserve in the State of Rio de Janeiro. This investigation was performed with the aim of analyzing the influence of climatic factors (temperature and relative air humidity) on the activity levels at different times of the day among mosquito species within the ecosystems that form the Tinguá Biological Reserve. The abundance index and dominance coefficient were calculated in relation to 61 mosquito species that were caught at four sampling sites, in the mornings, afternoons, and evenings. The results revealed that culicid species were distributed with greater incidence during the two diurnal periods and that their preference for times of the day was directly influenced by the climatic variables analyzed. The latter acted as limiting factors for occurrences of mosquito species.

Immature mosquitoes of Serra do Mar park, Sao Paulo State, Brazil

With the objective of providing knowledge about the natural habitat of mosquito larvae, we conducted a study on the culicid fauna and identified larval habitat types at 3 different locations in the Serra do Mar State Park, Brazil, over the 12 months of 1991. We collected 1,425 larvae belonging to 23 species, of which the most frequent were Culex iridescens, Culex spp., Limatus durhami, and Trichoprosopon pallidiventer. The mosquito larval habitats presenting the greatest densities of specimens were bamboo, bromeliads, rubber boots, and streams. We observed that the culicids used a variety of containers as larval habitats and bred under a diversity of ecological conditions. Most of the habitats were natural, formed by bamboo, bromeliads, streams, and depressions in the ground and in rocks, along with artificial habitats consisting of rubber boots and abandoned metal cans. Seven species occurred preferentially in the internodes of closed bamboo stems, 6 in internodes of open stems, and 4 in bromeliads.

Biodiversity and influence of climatic factors on mosquitoes (Diptera: Culicidae) around the Peixe Angical hydroelectric scheme in the state of Tocantins, Brazil

The influence of climatic factors on the seasonal frequency of mosquitoes (Diptera: Culicidae) at the Peixe Angical hydroelectric scheme (Tocantins, Brazil) was evaluated in the present paper. Mosquito surveys were conducted in the municipality of Peixe and in areas surrounding the reservoir in the municipalities of Paranã and São Salvador do Tocantins during two daytime periods (10 am-12 noon and 2 pm-4 pm) and two night-time periods (6 pm-8 pm and 6 pm-10 am) over 14 months. In total, 10,840 specimens from 42 species were captured, 84.5% of which belonged to the Culcinae. The most common species were Anopheles darlingi, Psorophora albipes and Sabethes chloropterus. The number of Culicidae specimens was higher in months with higher rainfall and air humidity than during the drier months. The large population of Ps. albipes and the presence of both An. darlingi (primary vector for human malaria parasites) and Haemagogus janthinomys (primary vector for yellow fever virus) are highlighted.

Preliminary investigation of Culicidae species in South Pantanal, Brazil and their potential importance in arbovirus transmission

In view of the high circulation of migratory birds and the environmental and climatic conditions which favor the proliferation of arthropods, the Brazilian Pantanal is susceptible to circulation of arboviruses. However, the amount of data concerning arbovirus vectors in this area is scarce; therefore the aim of this study was to conduct a preliminary investigation of Culicidae species in the Nhecolândia Sub-region of South Pantanal, Brazil and their potential importance in the arbovirus transmission. A total of 3684 specimens of mosquitoes were captured, 1689 of which caught in the rainy season of 2007, were divided into 78 pools and submitted to viral isolation, Semi-Nested RT-PCR and Nested RT-PCR, with a view to identifying the most important arboviruses in Brazil. Simultaneously, 70 specimens of ticks found blood-feeding on horses were also submitted to the same virological assays. No virus was isolated and viral nucleic-acid detection by RT-PCR was also negative. Nevertheless, a total of 22 Culicidae species were identified, ten of which had previously been reported as vectors of important arboviruses. The diversity of species found blood-feeding on human and horse hosts together with the arboviruses circulation previously reported suggest that the Nhecolândia Sub-region of South Pantanal is an important area for arbovirus surveillance in Brazil.

Blood meal identification of selected mosquitoes in Rio de Janeiro, Brazil

ABSTRACT. The blood meal sources of 5 species (Mansonia titillans, Aedes scapularis, Culex quinquefasciatus, Coquillettidia shannoni, and Anopheles peryassui) collected in Conceição do Macacu, in the southeastern Brazilian state of Rio de Janeiro, were examined with the precipitin test. Of the 1,128 mosquitoes collected, 907 (80.4%) reacted to some antisera. Although all 5 species were eclectic in their feeding habits, Ma. titillans and Ae. scapularis fed mostly on birds, while Cx. quinquefasciatus, Cq. shannoni, and An. peryassui fed mostly on bovines. Proportions of mosquitoes feeding on 1 source varied from 60.0% (Ae. scapularis) to 87.7% (Ma. titillans), while that of mosquitoes feeding on > 1 source varied from 12.2% (Ma. titillans) to 34.4% (Ae. scapularis). Epidemiological implications of the feeding and their potential involvements in the transmission of arboviruses are commented upon.

Estudo comparativo entre larvitrampas e ovitrampas para avaliação da presença de Aedes aegypti (Diptera: Culicidae) em Campo Grande, Estado do Rio de Janeiro

Objetivando-se avaliar a eficiência de armadilhas no monitoramento de vetores de dengue e febre amarela no Rio de Janeiro, foram utilizadas simultaneamente, 12 larvitrampas e 12 ovitrampas ao longo de 13 semanas. Resultados mostraram que as larvitrampas apresentam maior capacidade de positivar, destacando-se como importante ferramenta no monitoramento de vigilância vetorial.

Scanning electron microscopy of the egg of Ochlerotatus albifasciatus (Diptera: Culicidae)

Ochlerotatus albifasciatus (Macquart) (Diptera: Culicidae) is a mosquito species of medical and veterinary importance, usually associated with temporary groundwater habitats. Eggs obtained from females collected in Córdoba city, in the center of Argentina, were studied using scanning electron microscopy. The eggs are elliptical in outline, measuring approximately 615.7 +/- 37.24 microm in length (1) and 180.7 +/- 22.87 microm in width (w), with an egg index (l/w ratio) of 2.9-3.7. The outer chorionic sculpture has racquet-shaped and wristwatch-shaped cells consisting of a small central tubercle surrounded by larger tubercles and followed by a row of smaller tubercles on one or both sides, respectively, although variations between regions of the egg were observed. The micropylar apparatus has a collar with evident molding and edges of determined length, albeit irregular, with defined margins for the transition area and a thickness of approximately 10.7 microm. The margins of the micropylar disc are raised and the disc measures approximately 21.1 microm in diameter. The micropyle is distinct.

Multivariate discrimination between two cryptic Haemagogus species associated with the transmission of yellow fever virus in the Americas

Mosquitoes of the genus Haemagogus are important vectors of yellow fever virus and other arboviruses and are the principal reservoirs of these viruses in nature. Haemagogus capricornii and Haemagogus janthinomys are closely related species between which females are morphologically cryptic. A morphometric study of these species was performed on male and female specimens from 14 municipalities in Brazil. Morphometric analyses were able to distinguish females. Multivariate morphometrics may be a useful tool for taxonomic studies of cryptic species in this group.

Feeding patterns of Haemagogus capricornii and Haemagogus leucocelaenus (Diptera: Culicidae) in two Brazilian states (Rio de Janeiro and Goiás)

We present the identification of bloodfeeding sources of Haemagogus (Haemagogus) capricornii Lutz and Haemagogus (Conopostegus) leucocelaenus (Dyar & Shannon) (Diptera: Culicidae) from different regions of Brazil, as analyzed by precipitin tests. Anti-sera for bird, bovine, equine, human, opossum, and rodent were used. Two hundred one mosquitoes were examined (147 Hg. leucocelaenus and 54 Hg. capricornii), of which 177 reacted for some anti-serum. For Hg. leucocelaenus, 86 (68.3%) reacted to one blood source, 38 (30.2%) to two sources, and two (1.6%) to three sources; the combinations of bird + human (18.4%), bird + rodent (15.8%), and bird + marsupial (15.8%) were the most frequent. For Hg. capricornii, 34 (66.7%) reacted to one blood source; combinations bird + rodent (37.5%) and bird + marsupial (25%) were the most frequent combinations. Mosquito preference for bloodfeeding sources was different in these areas, possibly because of the availability of sources. This diversity of sources can have important epidemiological implications.

Encontro de larvas de Anopheles (Nyssorhynchus) argyritarsis em criadouros artificiais no Estado de Mato Grosso

Cita-se o encontro de formas imaturas de culicídeos em caixas d’água colocadas no nível do solo. Foram encontradas larvas de Anopheles argyritarsis e Aedes albopictus no município de Várzea Grande (MT). Considera-se que estes recipientes artificiais possam constituir locais adicionais utilizáveis como criadouros de anofelinos.

[Occurrence of Aedes (Stegomyia) albopictus (Skuse) in urban area of Tocantins state, Brazil]

This is the first report of the presence of Aedes albopictus (Skuse) in the Tocantins State, Brazil, in urban area of the Mateiros city. Immature specimens (aquatic stages) of this vector were collected in water reservoirs, treeholes, old tires and others. The existence of Ae. albopictus in the metropolitan area poses a potential risk for the interaction of this mosquito species with the urban human population.

Scanning electron microscopy of the egg of Haemagogus tropicalis

Haemagogus tropicalis is strictly a forest-dwelling species from the fertile valley area of the Amazônia forest. It is a diurnal mosquito, and the oviposition sites for the species include tree holes. The eggs of Hg. tropicalis used in this study were from females captured on Combú Island, situated across from the city of Belém, Guajará Bay, state of Pará, at 1 degrees 25'S latitude and 48 degrees 25'W longitude. The eggs are elliptical and approximately 575 microm long with a width of approximately 144 microm. The ventral surface of the chorionic reticulum has regular chorionic cells with hexagonal and sometimes pentagonal ornamentation. Each chorionic cell has a thick external chorionic reticulum with regular borders. The interior of the chorionic cells have small, evenly distributed tubercles, and the dorsal external chorionic reticulum appears porous. The micropylar apparatus, located on the anterior area of the egg, was formed by a collar with a well-developed frame. Centrally, the micropylar disc had a diameter of approximately 20 microm and the micropylar orifice is 2.1 microm in diameter. These data may enable construction of taxonomic keys for identifying eggs of Haemagogus species.

Description of three practical and inexpensive devices for the collection of mosquitoes and other small insects

Three new devices for collecting and maintaining mosquitoes and other small insects are described. A suction tube, composed of two pieces of plastic transparent tube, the narrower fitted in the wider, with the mouth protected by the use of voile, is cheap and practical and can be transported around the neck. A 900-ml plastic transparent box is utilized for the restraint of sucked insects and, with the adaptation of two pieces of plastic tube, as a suction chamber.

Diversidade de criadouros e tipos de imóveis freqüentados por Aedes albopictus e Aedes aegypti

OBJETIVOS: Verificar a diversidade de criadouros e tipos de imóveis freqüentados por fêmeas de Aedes albopictus e Aedes aegypti. MÉTODOS: O estudo foi realizado nos anos de 2002 e 2003 no bairro de Campo Grande, Rio de Janeiro, RJ. Realizou-se pesquisa larvária em diferentes tipos de imóveis. As larvas encontradas foram identificadas em laboratório. A freqüência de larvas dessas duas espécies foi computada nos diversos criadouros disponíveis. Foram calculados os índices de infestação predial e de Breteau, as diferenças foram testadas pelo qui-quadrado. RESULTADOS: Os tipos de imóveis positivos para os aedinos foram: residências (83,9% do total); igrejas, escolas, clubes (6,8%); terrenos baldios (6,4%); e comércios (2,8%). Das 9.153 larvas, 12,0% eram de Aedes albopictus e 88,0% de Aedes aegypti. Para aquela espécie, os recipientes onde foram mais encontradas foram ralos (25,4%), latas, garrafas, vasilhames (23,9%) e vasos com plantas (16,2%). Aedes aegypti mostrou-se mais freqüente nos criadouros que Aedes albopictus (chi2=145,067, p<0,001). Também ocorreu diferença significante na freqüência dessas espécies em criadouros artificiais do que em naturais (chi2=31,46; p<0,001). O índice de infestação predial e índice de Breteau para Aedes albopictus foram respectivamente em 2002 (0,3%; 0,28), em 2003 (0,4%; 0,5); para Aedes aegypti, em 2002 (1,0%;1,16) e 2003 (3,5%; 4,35). CONCLUSÕES: Verificou-se a freqüência das fêmeas de Aedes albopictus e Ae. aegypti em variados tipos de criadouros e tipos de imóveis para postura. A oferta abundante de recipientes artificiais inservíveis nas residências, associada à capacidade de Ae. albopictus de freqüentar também os criadouros naturais, contribui sobremaneira para sua adaptação gradativa ao meio antrópico.

Scanning electron microscopy of eggs of Ochlerotatus (Protomacleaya) terrens Walker

Observations on the morphological ultrastructure of eggs of Ochlerotatus (Protomacleaya) terrens (Diptera: Culicidae) were conducted by using scanning electron microscopy. Morphometry of the principal structures was obtained with the aid of Semafore analysis software. Eggs of Oc. terrens from females caught in the Biological Reserve of Tinguá, State of Rio de Janeiro, Brazil, were utilized. The eggs presented elliptical outlines, with a length of approximately 649.0 microm and width of 168.7 microm. The egg index (length to width ratio) was 3.85 microm. The exochorion had hexagonal and sometimes pentagonal ornamentation. Inside the chorionic cells were small, well-distributed tubercles with a large range of sizes. The micropylar apparatus, located in the anterior region of the egg, presented a collar with a poorly visible frame, with borders of indeterminate extent and margins without a defined transition area, and a thickness of approximately 1.8 microm. The micropyle was plugged.

Feeding patterns of Haemagogus janthinomys (Diptera: Culicidae) in different regions of Brazil

New data on the feeding patterns of Haemagogus (Haemagogus) janthinomys Dyar from different geographical regions of Brazil, by using the precipitin test as the bloodmeal-identifying tool, are presented. The following antisera were used: bird, dog, human, rodent, cattle, horse, and opossum. The origins of 287 bloodmeals were identified, whereas 33 specimens were negative to the antiserums tested. Among the reactive specimens, 174 (60.6%) fed on only one food source, of which 35.1% originated from birds, 19.5% from rodents, 12.6% from humans, 10.3% from cattle, 10.3% from opossums, 7.5% from dogs, and 4.6% from horses. One hundred six (37.0%) mosquitoes fed on two sources, of which the most common combinations were bird + rodent (16.0%), bird + human (10.4%), and horse + human (9.4%). Seven (2.4%) mosquitoes fed on three different hosts. Our results suggest that Hg. janthinomys is more eclectic and opportunist than previously known in relation to its hosts and that such patterns are probably highly adaptive to a temporally and spatially variable environment.

Scanning electron microscopy study of the egg of Haemagogus (Haemagogus) capricornii Lutz, 1904 (Diptera: Culicidae)

Morphological details are provided for the dorsal and ventral surfaces of both extremities and the micropylar area of eggs of Haemagogus (Haemagogus) capricornii Lutz, captured in the Biological Reserve of Tinguá, State of Rio de Janeiro, Brazil. The eggs were observed by scanning electron microscopy with a morphometrical analysis of the main structures. The outer chorionic cells on the ventral surface were extremely regular, such as those observed in Hg. equinus and Hg. janthinomys. The tubercles present differences in form, size, and distribution. Filaments to attach to the substrate were observed in this species.

Ecology of Anopheline (Diptera, Culicidae), malaria vectors around the Serra da Mesa Reservoir, State of Goiás, Brazil: 1 - Frequency and climatic factors

The ecology of anopheline species (Diptera, Culicidae) was studied in the vicinity of the Serra da Mesa Reservoir, State of Goiás, Brazil. Climatic factors and frequency of anopheline populations were analyzed. Bimonthly human-bait and Shannon trap captures were conducted for 36 consecutive months (January 1997 through December 1999). A total of 5,205 adult anophelines belonging to five species were collected. Anopheles darlingi was the most frequently collected anopheline (61.4%), followed by An. albitarsis s.l. (35.4%), An. triannulatus. (2.5%), An. oswaldoi (0.4%), and An. evansae (0.2%). The water level and vegetation along the banks of the reservoir were crucial to the frequency of the various anopheline species. Climatic factors had a secondary influence. The reservoir's water-level stability, increased frequency of An. darlingi, and the arrival of gold prospectors were responsible for the increase in malaria cases.

Microscopia eletrônica de varredura de ovos de Haemagogus leucocelaenus (Diptera: Culicidae)

OBJETIVO: Observar detalhes morfológicos de ovos de Haemagogus leucocelaenus visualizados pela primeira vez por microscopia eletrônica de varredura (MEV) e realizar morfometria das principais estruturas. MÉTODOS: Foram utilizados ovos de Hg. leucocelaenus provenientes de fêmeas capturadas na Reserva Biológica do Tinguá, RJ, sendo parte destinada à eclosão e outra ao processamento de MEV, dos quais três foram submetidos à análise morfométrica. O material foi fixado em glutaraldeído 2,5% e pós-fixado em tetróxido de ósmio 1%, ambos em tampão cacodilato de sódio 0.1M, pH 7.2, processado e observado ao MEV Jeol 5310. Medições foram realizadas com o auxílio do software de análise Semafore. RESULTADOS: Os ovos apresentaram contorno elíptico com aproximadamente 574 µm de comprimento e 169 µm de largura, sendo o índice do ovo (l/wratio) 3,39 µm. O exocório é extremamente regular, possuindo ornamentação hexagonal e algumas vezes pentagonal. Nas células coriônicas, observaram-se tubérculos simetricamente dispostos com relação ao eixo longitudinal, e, no interior delas, tubérculos menores, individualizados, dispostos na periferia, e poucos agrupados no centro. A superfície do retículo coriônico não apresentou rugosidades. O aparelho micropilar apresenta colar proeminente, contínuo, com disco micropilar bem evidente. CONCLUSÕES: A ornamentação do exocório apresenta diferenças em relação aos tubérculos das células coriônicas e ao retículo coriônico externo entre os ovos de Hg. leucocelaenus comparados aos ovos de Hg. janthinomys e Hg. equinus, bem como com relação aos de Aedes aegypti, Ae. albopictus e Ae bahamensis.

[Mosquito (Diptera, Culicidae) ecology in the Iguaçu National Park, Brazil: 1 Habitat distribution]

A study of the mosquito fauna in the Iguaçu National Park focused on population behavior in four biotopes with different types of plant cover inside the Park. Systematic bimonthly diurnal and nocturnal human bait and Shannon trap captures were conducted in both forest and domiciliary environments over the course of 24 months. A total of 20,273 adult mosquito specimens belonging to 44 species were collected: Ochlerotatus serratus (10.3%), Haemagogus leucocelaenus (9.7%), Mansonia titillans (9.6%), and Chagasia fajardoi (8.8%) were the most frequently captured mosquitoes. Anopheles cruzii, Runchomyia theobaldi, Wyeomyia aporonoma, and Wy. confusa were captured almost exclusively in well-preserved areas with dense forest cover. Culex nigripalpus, Oc. pennai, Oc. serratus, Sabethes purpureus, and Sa. albiprivus were captured in three essentially sylvatic biotopes. Species captured in the forest areas around a dam were: An. albitarsis s.l., An. galvaoi, An. evansae, An. fluminensis, Coquillettidia venezuelensis, Cq. juxtamansonia, Wy. quasilongirostris, and Onirion personatum, Ch. fajardoi, Cq. fasciolata, Cq nitens, and Ma. titillans were the most frequently captured species in a residential area.

[Prevalence of Anophelines (Diptera: Culicidae) during sunset in areas of the Itaipu Hydroelectric plant in Guaíra county, state of Paraná, Brazil]

Systematic collections of anophelines were conducted from November 1994 to August 1995 from 18:00 to 20:00 hr using Shannon traps and human-bait along the lake margin which forms the Itaipu Hydroelectric reservoir, State of Paraná, Brazil. Species prevalence was studied at 15 min intervals. Anopheles albitarsis sensu latu and An. galvaoi, were the most frequently collected mosquitoes. All Anopheles species populations peaked between 18:45 and 19:30 hr. The observations illustrate the existence of a haematophagic activity cycle during the early evening hours: exogenous stimulus (the beginning of sunset)-->Shannon trap (light attraction)-->human bait (haematophagy)-->rest and digestion-->exogenous stimulus-->Shannon trap or surrounding vegetation. The greater abundance of An. albitarsis collected in human-bait and Shannon trap suggests it may be a potential malaria vector in the region.