Assessment of the correlation between wing size and body weight in captive Culex quinquefasciatus

Introduction: Mass production of mosquitoes under laboratory conditions allows implementing methods to control vector mosquitoes. Colony development depends on mosquito size and weight. Body size can be estimated from its correlation with wing size, whereas weight is more difficult to determine. Our goal was to test whether wing size can predict the weight. Methods: We compared dry weight and wing centroid size of Culex quinquefasciatus reared at different temperatures and four diets. Results: Weight and wing size were strongly correlated. The diets did not influence wing size. Conclusions: Wing centroid size is a good predictor of Cx. quinquefasciatus body weight

First Record of Anopheles oryzalimnetes, Anopheles argyritarsis, and Anopheles sawyeri (Diptera: Culicidae) in the Caatinga Biome, Semiarid Scrubland of Sergipe State, Brazil.

Caatinga is one of the least known biomes of Brazil in relation to biodiversity. The dry condition of semiarid areas has been associated in the past with low richness of fauna and flora, not encouraging studies in this region. There is a lack of mosquito records including anophelines. Thus, to investigate the biodiversity of Anopheles mosquitoes in the Caatinga biome, we collected immature mosquitoes in aquatic habitats in a conservation reserve located in the northwestern portion of Sergipe state. The captured specimens were initially identified as Anopheles albitarsis l.s. and Anopheles argyritarsis l.s. To confirm the morphological identification, sequences were generated by cytochrome oxidase subunit I mitocondrial gene. The results showed that the specimens belong to the species Anopheles oryzalimnetes, An. argyritarsis, and Anopheles sawyeri. These are the first records of these species in this region. The presence of Anopheles in the Caatinga biome, which is characterized by arid and semiarid climatic conditions, encourages the interest in the study of biological, physiological, and behavioral adaptations, selected over time, which allow these mosquito populations to survive through the long periods of drought that is characteristic of this region.

Comparative Study of Distribution of Anopheline Vectors (Diptera: Culicidae) in Areas with and Without Malaria Transmission in the Highlands of an Extra-Amazonian Region in Brazil

This study compares the distribution of anopheline mosquitoes in a malaria-endemic municipality (MAL) and a malaria-free municipality (FREE) in an area of the Atlantic Forest in Brazil. Simultaneous quarterly nightly captures were made in three locations in each municipality. One Shannon light trap (Shannon light traps were home made according to specifications published in Am. J. Trop. Med. 1939; 19: 131–140) (SLT) and five CDC light traps (a kind of automatic trap fed by batteries of 12 V and 7 amp/h, with dry ice as a source of CO2; John W. Hock Company, Gainesville, FL) (CLT) (two in the canopy and three at ground level) were operated from 6:00 p.m. to 6:00 a.m. More specimens were captured in MAL (362 in SLTs and 126 in CLTs) than in FREE (66 in SLTs and 59 in CLTs). For the SLTs, Simpson's dominance index was similar in MAL and FREE (D = 0.15 versus D = 0.203, P > 0.7), but Shannon's diversity index was higher for MAL (H = 1.969 versus H = 1.641, P < 0.01)...

Effects of Artificial Flooding for Hydroelectric Development on the Population of Mansonia humeralis (Diptera: Culicidae) in the Paraná River, São Paulo, Brazil

The closure of two phases of the dam at the Porto Primavera Hydroelectric Plant on the Paraná River flooded a flawed system located in the Municipality of Presidente Epitácio, São Paulo state, favoring the proliferation of aquatic weeds. This study aimedto observe the population of Mansonia humeralis in the area, monitoring the richness, diversity, and dominance of this species both before and during different phases of reservoir flooding as well as evaluate its possible consequences concerning human and animal contact. Adult mosquitoes were collected monthly in the following periods: at the original level, after the first flood, and after the maximum level had been reached between 1997 and 2002. Collection methods used were an aspirator, a Shannontrap, and the Human Attractive Technique. A total of 30,723 mosquitoes were collected, Ma. humeralis accounting for 3.1% in the preflood phase, 59.6% in the intermediate, and 53.8% at maximum level. This species is relevant to public health, since the prospect of continued contact between Ma. humeralis and the human population enhances the dam’s importance in the production of nuisance mosquitoes, possibly facilitating the transmission of arboviruses. Local authorities should continue to monitor culicidactivity through sustainable entomological surveillance...

Survival, population size, and gonotrophic cycle duration of Nyssomyia neivai (Diptera: Psychodidae) at an endemic area of American cutaneous leishmaniasis in southeastern Brazil.

The survival, absolute population size, gonotrophic cycle duration, and temporal and spatial abundance of Nyssomyia neivai (Pinto) were studied in a rural area endemic for American cutaneous leishmaniasis (ACL) in Conchal, São Paulo State, southeastern Brazil, using mark-release-recapture techniques and by monitoring population fluctuation. The monthly abundance exhibited a unimodal pattern, with forest and domicile habitats having the highest relative abundances. A total of 1,873 males and 3,557 females were marked and released during the six experiments, of which 4.1-13.0% of males and 4.1-11.8% of females were recaptured. Daily survivorship estimated from the decline in recaptures per day was 0.681 for males and 0.667 for females. Gonotrophic cycle duration was estimated to be 4.0 d. Absolute population size was calculated using the Lincoln Index and ranged from 861 to 4,612 males and from 2,187 to 19,739 females. The low proportion of females that reach the age when they are potentially infective suggests that N. neivai has a low biological capacity to serve as a vector and that factors such as high biting rates and opportunistic feeding behavior would be needed to enable Leishmania (Viannia) braziliensis Vianna transmission. This agreed with the epidemiological pattern of ACL in southeastern Brazil that is characterized by low incidence, with isolated cases acquired principally within domiciliary habitats.

Survival, Population Size, and Gonotrophic Cycle Duration of Nyssomyia neivai (Diptera: Psychodidae) at an Endemic Area of American Cutaneous Leishmaniasis in Southeastern Brazil

The survival, absolute population size, gonotrophic cycle duration, and temporal and spatial abundance of Nyssomyia neivai (Pinto) were studied in a rural area endemic for American cutaneous leishmaniasis (ACL) in Conchal, Sõo Paulo State, southeastern Brazil, using mark-release-recapture techniques and by monitoring population fluctuation. The monthly abundance exhibited a unimodal pattern, with forest and domicile habitats having the highest relative abundances. A total of 1,873 males and 3,557 females were marked and released during the six experiments, of which 4.1–13.0% of males and 4.1–11.8% of females were recaptured. Daily survivorship estimated from the decline in recaptures per day was 0.681 for males and 0.667 for females. Gonotrophic cycle duration was estimated to be 4.0 d. Absolute population size was calculated using the Lincoln Index and ranged from 861 to 4,612 males and from 2,187 to 19,739 females. The low proportion of females that reach the age when they are potentially infective suggests that N. neivai has a low biological capacity to serve as a vector and that factors such as high biting rates and opportunistic feeding behavior would be needed to enable Leishmania (Viannia) braziliensis Vianna transmission. This agreed with the epidemiological pattern of ACL in southeastern Brazil that is characterized by low incidence, with isolated cases acquired principally within domiciliary habitats...

[Immature mosquitoes (Diptera: Culicidae) in a public city park]. / Imaturos de mosquitos (Diptera: Culicidae) em parque de área metropolitana aberto à visitação pública.

OBJECTIVE: To identify and compare the immature Culicidae population and their predators in different breeding places in a public city park. METHODS: The study was carried out in an ecological park situated in the outskirts of the city of São Paulo, Brazil. Four Culicidae breeding places were selected: one semi-permanent, two permanent and one polluted brook. Throughout a year, at monthly intervals, systematic and standardized collections of Culicidae and their predators were undertaken to assess mosquito frequency, and estimate the index of abundance and predatory potential of the associated fauna. RESULTS: A total of 9,065 Culicidae were collected at the four breeding places studied. Twenty-two species or groups were obtained, generally at low frequencies, except for Culex quinquefasciatus, the only species at the polluted breeding place seen highly frequent. This was the most abundant species in this study, followed by others of the Culex genus. CONCLUSIONS: It was found an imbalance in the polluted breeding place as a result of a high concentration of pollutants and absence of predators, which leads to an intense proliferation of only one species. At the other breeding places, there is evidence that the associated fauna promotes a natural biological balance.

[Aedes aegypti (l.) population in an endemic area of dengue in Southeast Brazil]. / População de Aedes aegypti (l.) em área endêmica de dengue, Sudeste do Brasil.

OBJECTIVE: A Aedes aegypti population from an area of dengue transmission was studied to determine mosquito's frequency, spatial distribution, parity, its ovarian development and midgut contents. METHODS: The study carried out in São José do Rio Preto country, São Paulo, SP, Brazil. Low and intermediate socioeconomic level regions were chosen to the study, which was carried out 1996 and 1997. Using a manual electric aspirator, captures were performed inside and outside the houses. Dissections were conducted to allow classify female mosquitoes according to their physiologic state. RESULTS: One hundred and eighty-eight males and 189 females were captured in both regions. A general index of 0.46 Ae. aegypti females per house was determined. Of the total sample, 82.4% of males and 87.3% of females were collected indoors. Greater proportions of females were found in the region of low socioeconomic level, and higher population density. One hundred and forty-eight female mosquitoes were analyzed: 27.0% were nulliparous and 10.1% parous. The rest were classified as Christophers and Mer's (C & M) phases III to V, 28.0% of which had red blood in their midgut. Of the total female population, 87.9% had bloodmeals. CONCLUSIONS: The mosquito species revealed a high degree of endophily. There was a higher proportion of nulliparous mosquitoes, although the majority of the females were classified as C & M's phases III to V. These results highlight both the great number of females who had had bloodmeals, and the lack of gonotrophic concordance.

[Aedes albopictus in rural zone of Brazil and its implication in the wild yellow fever transmission]. / Aedes albopictus em área rural do Brasil e implicações na transmissão de febre amarela silvestre.

Larvae and adult forms of Aedes albopictus were found during ecological study of anopheline mosquitos in the rural zone of the state of Mato Grosso do Sul in Brazil. This occurrence was registered, for the first time in Brazil, in an enzoootic area if sylvatic yellow fever virus. This implies a potential risk of the transfer of this virus to an urban area infested with Aedes aegypti.

[Geographical distribution of dengue and socioeconomic factors in an urban locality in southeastern Brazil]. / Distribuição espacial da dengue e determinantes socioeconômicos em localidade urbana no Sudeste do Brasil.

INTRODUCTION: The incidence of dengue (serum type I) in the city of S. José do Rio Preto during an epidemic which occurred in the first semester of 1995 is analyzed in terms of geographical areas defined by socioeconomic variables. MATERIAL AND METHOD: The epidemiological method of analysis is the "ecological study" type. To calculate the coefficient of incidence of dengue, all cases both confirmed and reported between January and July, 1995 are considered. The environmental units are defined according to socioeconomic variables based on the IBGE (Brazilian Institute of Geography and Statistics) Census of 1991, through cluster analysis. The linear correlation coefficient between coefficient of incidence and environmental variables is also calculated. RESULTS AND DISCUSSION: Three distinct environmental units are identified and described on the basis of both economic and educational level. The coefficient of incidence of dengue varied in accordance with the environmental unit: in the unit of low standard the coefficient was 2.7 times greater than that of the unit of highest standard, showing that in these units the determining factors of dengue have a differentiating effect. The roles of some of the determining factors such as population density, basic sanitary services and vector density are discussed. The importance of this study for the control of dengue is also emphasized.

Correlation between positive serology for Plasmodium vivax-like/Plasmodium simiovale malaria parasites in the human and anopheline populations in the State of Acre, Brazil.

Antibodies against the Plasmodium vivax-like/P. simiovale malaria parasite circumsporozoite repeat peptide (APGANQEGGAA)3 were determined by enzyme-linked immunosorbent assay (ELISA) in 120 sera randomly collected in 1994 from adults in 3 localities of the malaria endemic area in the State of Acre, Brazil; antibody was detected in 18 (15%). A 'sandwich' ELISA using monoclonal antibody (mab) Pam 172, directed against the same peptide, was carried out on 1207 Anopheles oswaldoi, 12 of which (1.0%) were positive, and 168 A. deaneorum, 2 of which (1.2%) were positive. This is the first report of serological detection of the P. vivax-like parasite in anophelines and the first report linking anopheline to human serology for this parasite in the same geographical area. It is an additional indication that A. oswaldoi is a malaria vector in Acre.

[Aedes (Stegomyia) albopictus (Skuse) breeding in Bromeliaceae in the outskirts of an urban area of the city of São Paulo, Brazil]. / Encontro de Aedes (Stegomyia) albopictus (Skuse) em Bromeliaceae na periferia de São Paulo, SP, Brasil.

Larvae of Aedes albopictus from a plant of the Bromeliaceae family on the outskirts of S. Paulo, SP, Brazil, were collected. This occurrence sheds new light on the attempt to determine the potential of this plants as a breeding site for this mosquito in Brazil.

[Infection of Anopheles (Kerteszia) cruzii by Plasmodium vivax and Plasmodium vivax variant VK247 in the municipalities of São Vicente and Juquitiba, São Paulo]. / Infecção do Anopheles (Kerteszia) cruzii por Plasmodium vivax e Plasmodium vivax variante VK247 nos Municípios de São Vicente e Juquitiba, São Paulo.

Sporadic cases of autochthonous malaria have been recorded in São Paulo State, located in the Southeast region of Brazil. These cases are characterized by their benign course, low parasitemia, and mild symptomatology and have been identified as vivax malaria. Little is known about the symptoms and immune response elicited in humans by the variants Plasmodium vivax VK247 and P. vivax-like human malaria parasites. These variants are transmitted by Anopheles (Kerteszia) cruzii, one of the most common species of mosquitoes in the Southeast of Brazil. The objective of the study described in this paper was to investigate infection in anophelines using ELISA immunoenzymatic assay with specific monoclonal antibodies directed against the repetitive regions of the circumsporozoite protein in classic P. vivax, P. brasilianum/P. malariae, and P. vivax VK247. Between 1991 and 1993, mosquitoes were collected in São Vicente and Juquitiba, municipalites located in a remnant of the Brazilian Atlantic forest in São Paulo State, an ecosystem rich in plants of the Bromeliaceae family. These plants function as nurseries for immature forms of anophelines of the subgenus Kerteszia. Of 1,117 An. (Ker.) cruzii captured in São Vicente, 0.179% were positive for classic P. vivax. In Juquitiba, of 1,161 An. (Ker.) cruzii, 0.086% were positive for P. vivax VK247, confirming the presence of this variant in the region. Although the infection rate is low, the high density of these mosquitoes and their voracity (they exhibit 24-h biting activity) could compensate for the low percentage of infected specimens.

Anophelines in the state of Acre, Brazil, infected with Plasmodium falciparum, P. vivax, the variant P. vivax VK247 and P. malariae.

Anophelines collected indoors and in the peri-domiciliary area in 3 localities in the Amazon region, state of Acre, Brazil, from August 1990 to January 1991 were examined by enzyme-linked immunosorbent assay (ELISA) using specific monoclonal antibodies directed against the repeats of the circumsporozoite proteins of Plasmodium falciparum, P. vivax, P. vivax V247, and P. malariae. Of the 3056 specimens collected, 2610 were Anopheles oswaldoi, 362 A. deaneorum, 60 A. triannulatus and 24 were A. darlingi. The infection rates of A. oswaldoi were 3.41% for P. falciparum, 2.26% for P. vivax, 1.22 for P. vivax VK247, and 0.42% for P. malariae. For A. deaneorum, the infection rates were 2.76% for P. falciparum, 0.55% for P. vivax, and 0.82% for P. vivax VK247. All samples of the other 2 species collected (A. triannulatus and A. darlingi) were negative in the ELISA. There were certain differences in the anopheline distribution and infection rates between these localities, and in one only A. oswaldoi was found to be infected. These results strongly point to A. oswaldoi as the main malaria vector in the region. No difference was found between the potential vectors of P. vivax and P. vivax VK247. The significance of these findings for malaria control is discussed.