Biology of Psorophora albigenu Under Laboratory Conditions.

The present study investigates the effect of multiple immersions on Psorophora albigenu eggs and their development cycle under laboratory conditions. Engorged Ps. albigenu specimens were captured in January 2011 around the Transpantaneira Park Road, Mato Grosso, Brazil, using CO2-baited Centers for Disease Control and Prevention light traps. Psorophora albigenu eggs (n = 1274) were subjected to immersion, with a hatching rate between 49% and 73%. The Williams average showed a peak of 29% hatched eggs in the 3rd immersion; after 4-5 immersions, the effect of additional immersions was generally negligible. The average cycle for both males and females was 5.68 ± 1.00 days. This short development time from the egg stage to adult emergence followed the pattern seen in other species of the genus Psorophora.

Feeding Patterns of Mosquitoes (Diptera: Culicidae) in the Atlantic Forest, Rio de Janeiro, Brazil.

The stomach contents of culicids from the Atlantic Forest in Rio de Janeiro state, Brazil, were analyzed using the precipitin technique to evaluate the feeding patterns of the species. Sampling was performed from February 2012 to December 2013, using CO2-baited Centers for Disease Control and Prevention traps to catch mosquitoes from 15 00 to 07 00 hours. The following antisera were used: bird, rodent, opossum, human, horse, capybara, lizard, and frog. Of the 325 adult bloodfed females caught and analyzed, 273 (84.0%) reacted in the precipitin test. The percentage of specimens with a positive reaction to a single antiserum included bird (39.2%), rodent (22.5%), opossum (13.2%), capybara (6.6%), horse (5.7%), frog (6.2%), human (4.0%), and lizard (2.6%). The specimens that reacted positively against more than one blood source (46) most frequently presented the following combinations: bird + rodent and bird + frog (17.4%), followed by bird + human (13.0%). The predominance of positive results for birds suggested that the avian-rich environment might have influenced the feeding behavior of the culicids.

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.

Sand fly population dynamics in areas of American cutaneous leishmaniasis, Municipality of Paraty, Rio de Janeiro, Brazil.

The present study is the second and last part of the study that investigated the fauna and behavior of sand flies in areas prone to cutaneous leishmaniasis outbreaks, in the State of Rio de Janeiro, in the municipality of Paraty. To collect the sand flies, CDC and Shannon light traps were used, installed in the peridomiciliary and forest areas, and manual suction tubes on the walls of the home and in the animal shelters. A total of 102,937 sand flies, belonging to nine genera and 23 species were captured from October 2009 to September 2012. Regarding the monthly frequency of sand flies, the period of highest density was from November to March, with a maximum peak in January. The lowest density was observed in June and July. In the studied area, the species of epidemiological importance, Nyssomyia intermedia, Pintomyia fischeri, Migonemyia migonei and Nyssomyia whitmani, were found in all months of the year, a period in which residents may be in contact with these vectors of the etiological agent of cutaneous leishmaniasis.

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.

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.

Spatial distribution and interactions between mosquitoes (Diptera: Culicidae) and climatic factors in the Amazon, with emphasis on the tribe Mansoniini.

This work aimed to evaluate the spatial distribution of mosquitoes in different seasonal periods and the interaction between climatic factors and the abundance of mosquitoes, especially those belonging to the tribe Mansoniini in the area surrounding the Amazon hydroelectric production region (Jirau-HP) of Rondônia state, Brazil. Mosquito specimens were collected in May, July, October, and December 2018, and April, July, September, and November 2019, over periods of three alternating days during the hours of 6:00 p.m. to 8:00 p.m. Mosquito sampling was performed using automatic CDC and Shannon light traps. Canonical correspondence analysis (CCA), combined with Monte Carlo permutations, was used to evaluate the correlation between climatic variables and species distribution. In addition, non-metric multidimensional scaling (NMDS) was used to verify the similarity among the sampled communities from the different collections. After analyzing the total mosquito fauna at all sampling points, 46,564 specimens were identified, with Mansonia dyari showing the highest relative abundance in 2018 (35.9%). In contrast, Mansonia titillans had the highest relative abundance in 2019 (25.34%), followed by Mansonia iguassuensis (24.26%). The CCA showed that maximum temperature significantly influenced the distribution of mosquito populations in the study area (p = 0.0406). The NMDS showed that sampling carried out in the rainy and dry seasons formed two distinct groups. There was a significant correlation between species richness and cumulative precipitation 15 days before the sampling period (R2 = 58.39%; p = 0.0272). Thus, both temperature and precipitation affected mosquito population dynamics. The effect of rainfall on mosquito communities may be due to variations in habitat availability for immature forms.

Biodiversity assessment of Phlebotomine (Diptera: Psychodidae) in an environmental impacted area in Rio de Janeiro State, Brazil.

From October 1994 to September 1996, in the municipality of Mangaratiba, Rio de Janeiro State, phlebotomines were captured on the walls of the houses by means of a manual suction tube and light traps, in the household, the peridomicile and in the forest. As it is an area undergoing a real expansion and an increment in the local tourism, with the purpose of assessing changes in the phlebotomine fauna caused by environmental changes in the region, new captures were made in the same location from October 2015 to September 2016, this time using only light traps. In the two phases of the study, a total of 6,681 phlebotomines were captured. The results indicated that Ny. intermedia and Mg. migonei are fully adapted to this anthropic environment, while Pi. fischeri was more abundant and eclectic, and was probably attracted to exercise hematophagy. Nyssomyia intermedia can be suggested as the main vector of the etiological agent of the American Tegumentary Leishmaniasis in the studied areas. Pintomyia fischeri can also transmit Leishmania braziliensis, both in the environment altered by human action, and in the wild environment. Phlebotomines were captured in greater numbers between 6 and 8 pm in the peridomicile and between 9 and 11 pm in the household. The highest densities of phlebotomines were recorded in December, January and February. Despite almost 20 years between the two studies in the municipality of Mangaratiba, there was no change in the profile of the phlebotomine fauna in general; however, there was a greater density of species of medical importance in areas that suffered environmental impacts.

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.

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.

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.

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.

Taxonomic history of species without subgeneric placement in the genus Wyeomyia Theobald (Diptera: Culicidae) and recognition of Wy. compta Senevet amp; Abonnenc as a junior synonym of Wy. argenteorostris (Bonne-Wepster amp; Bonne).

The mosquito genus Wyeomyia (Diptera: Culicidae) includes 17 subgenera and 140 species, 30 of which are without subgeneric placement. The taxonomic history of the unplaced species is summarized and the validity of Wy. compta Senevet Abonnenc is discussed based on examination of the type material. It is clear that the description of Wy. compta was based on specimens belonging to two different species. The holotype adult female is identical to Wy. argenteorostris (Bonne-Wepster Bonne) whereas the characters described from a larval exuviae mounted on the same slide with the holotype of Wy. albocaerulea Senevet Abonnenc coincide with those which characterize the subgenus Dodecamyia. Since the larval exuviae cannot be definitely associated with the holotype female and it belongs to either Wy. aphobema Dyar or another species of the subgenus Dodecamyia, it cannot be afforded type status. Therefore, Wy. compta is synonymized with Wy. argenteorostris.

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.

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.

[Anopheles (Nyssorhynchus) argyritarsis larvae found in artificial breeding sites in the State of Mato Grosso]. / Encontro de larvas de Anopheles (Nyssorhynchus) argyritarsis em criadouros artificiais no Estado de Mato Grosso.

The finding of immature forms of culicid mosquitoes in water tanks at ground level is reported. Anopheles argyritarsis and Aedes albopictus were found in the municipality of Várzea Grande (MT). It is considered that these artificial containers may constitute additional locations that anophelines can use as breeding sites.

Influence of Climatic Factors On Psorophora (Janthinosoma) Albigenu In Pantanal Landscape, Mato Grosso State, Brazil.

In order to assess the influence of climatic variations in temperature, relative humidity, and rainfall upon the population density of Psorophora albigenu (Peryassú, 1908) in its natural habitat, samplings were carried out at different times of the year in Mato Grosso, Brazil. Mosquitoes were captured with the use of suction tubes and Shannon traps during 2 different periods of the day and 1 at night. A total of 2,637 Ps. albigenu specimens were captured, including 497 (18.8%) in March 2009, 1,240 (47.0%) in January 2010, and 484 (18.4%) in January 2011. These months represented 84.2% of this species occurrence during the collection period. November was the month of the lowest occurrence of the species, with only 10 (0.4%) specimens collected in 2009 and 8 (0.3%) specimens in 2010. The climatological variable that presented a linear correlation coefficient within the 95% confidence interval was rainfall, with a linear correlation indicator of 0.793, above the relevance factor of 0.708, showing a relationship between the frequency of Ps. albigenu and rainfall of the region.

Distribution of Haemagogus and Sabethes Species in Relation to Forest Cover and Climatic Factors in the Chapada Dos Guimarães National Park, State of Mato Grosso, Brazil.

Members of the genera Haemagogus and Sabethes are the most important biological vectors of the wild yellow fever virus (WYF) in the forested areas of the Americas. The ecologies of Haemagogus janthinomys, Hg. leucocelaenus, Sabethes chloropterus, and Sa. glaucodaemon were studied in a forest of the Chapada dos Guimarães National Park, state of Mato Grosso, Brazil, to evaluate the influence of climatic factors (temperature and relative humidity [RH]) on their abundance. We also examined the association of climate with landscape structure on species distribution patterns throughout the seasons of the year. Multiple stepwise regressions showed that RH was most likely to influence the density of mosquito populations. A multidimensional scaling (MDS) was used to evaluate the effects of forest cover on the composition of mosquito populations at different radii (100-, 250-, and 1,000-m-radius buffer areas). The MDS provided 2 dimensions with values that indicated a higher similarity in the composition of culicid populations between sites 1 and 3, while site 2 was separate from the others in the ordination space. Site 2 had a much higher forest cover ratio at 100-m radius compared with sites 1 and 3. We found a possible relationship between the forest cover and the composition of the mosquito populations only in the 100-m radius. These results enabled us to infer that RH directly favored the activity of mosquito populations and that the forest cover located closest to the sampling site may influence the species composition. Since mosquito abundance was higher in the sites with lower local forest cover, forest fragmentation may be a key factor on the presence of WYF vector.

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.