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Mosquito (Diptera: Culicidae) collections were made on the Pedro Peixoto Colonization Project in the State of Acre, Brazil. Four thousand, five hundred and eighty-eight (4,588) specimens were collected and fifty-three (53) species or group recognised. The occurrence of Anopheles (Nyssorhynchus) oswaldoi is given special emphasis.
Among dipterans of medical and veterinary importance, the mosquitoes (Culicidae) play the most important role both as vectors and nuisance insects. Mass occurrence of floodwater mosquito species in the flooded area in Wrocław district (Lower Silesia, Poland) in 1997 has enhanced the already existed problem of mosquito control. A successful model of control strategy for the city based on the currently recommended integrated methodologies with special emphasis on preventive treatment of aquatic larvae with microbial insecticides has been conducted. Bacillus thuringiensis israelensis-based formulations replaced chemicals to control Culex pipiens and Culiseta annulata--two dominant species out of eight noticed during field study in Wrocław area in the years 1998-2000. Use of Bti larvicide or other biocontrol agent, conserving biodiversity, requires collecting entomological data, mapping and treating all breeding sources as well as the designing appropriate strategies every year.
Newly hatched Toxorhynchites rutilus (Coquillet) were added to experimental populations of Aedes triseriatus (Say) at varying days after prey hatch to test the hypothesis that a developmental asynchrony of Ae. triseriatus and Tx. rutilus leads to escape from predation by Ae. triseriatus in small water bodies. Presence of Tx. rutilus significantly affected prey survivorship. Regression of survivorship [log10 (x + 1) transformed] versus days head start for prey yielded a small, but significant positive slope, indicating that survivorship increased slightly with an increasing number of days head start. For females, mean weight at emergence was not significantly affected by treatments; however, median days to emergence differed significantly between the treatments, with females taking significantly longer to emerge with Tx. rutilus absent than when the predator was present. For males, neither mean mass nor median days to emergence was significantly affected by treatments. Treatments had no significant effect on the frequency of deaths or on mean weight of Tx. rutilus. Thus, a developmental asynchrony between Tx. rutilus and Ae. Triseriatus appears to have no effects on the predator, but does have a weak effect on prey performance at high hatch densities.
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Aedes notoscriptus (Skuse) mosquitoes colonized from Brisbane, Queensland, Australia, were fed on blood suspensions containing either Barmah Forest (BF) virus, dengue virus type 1 (DEN-1), dengue virus type 2 (DEN-2), dengue virus type 3 (DEN-3), or dengue virus type 4 (DEN-4). Ae. notoscriptus was shown to be moderately susceptible to oral infection with BF virus, ID50 = 10(3.3) CCID50 per mosquito, with titers in infected mosquitoes peaking 10 d after infection. BF virus transmission occurred between days 5 and 12, with an average rate of 45% (range, 40-50%). For DEN 1-4, Ae. notoscriptus showed low level susceptibility to oral infection, with maximum head and thorax squash infection rates of 8, 5, 13, and 3%, respectively. Rates of infection were notably higher in a north Queensland strain of Aedes aegypti (L.) used as a positive control, with maximum thorax squash infection rates of 58, 68, 78, and 60% for DEN 1-4, respectively. On the basis of these data, it is concluded that Ae. notoscriptus could act as an efficient vector of BF in urban environments, but it is unlikely to be an important vector of DEN.
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The knockdown resistance (kdr) mutation in the voltage-gated sodium channel gene (VGSCG), an important resistance mechanism against pyrethroids, was studied in Anopheles sacharovi Favre. It was found that the specific primers Agd1 and Agd2 used for polymerase chain reaction (PCR) amplification of Anopheles gambiae Giles VGSCG also amplified this genomic region in An. sacharovi. Comparison of the IIs4-IIs6 domain segments of the gene indicated 70% nucleotides common to both species and a genetic distance of 0.255 between them. Four different samples of pyrethroid-resistant An. sacharovi produced three types of amino acid, serine (TCG),leucine (TTG),and phenylalanine (TTT) at the kdr mutation point, whereas only two kdr mutations, leucine to phenylalanine and leucine to serine, occur in An. gambiae.
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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.
INTRODUCTION: The use of receptacles containing water for the laying of the Culicidae eggs in an anthropogenic area, may indicate a genetic plasticity that leads them evolutionarily towards domiciliation. Thus, the various species of Culicidae which colonize the receptables placed in reparian forest were collected for this study. MATERIAL AND METHODS: The materials used were: Tires, plastic, can and bamboo receptacles, installed in a rural area of a reparian forest along a river in Northern Parana, Brazil. RESULTS: The results were obtained by means of the collection of Cx.grup coronator, Cx. declarator, Cx. laticlasper, Cx. (Melanoconion), Cx. section Spissipes, Cx. mollis, Ae. terrens, Tr. compressum, Tr. pallidiventer, Hg. leucocelaenus, Cx. quinquefasciatus, Li. durhamii and Toxorhynchites sp larvae. The first five species were tire specific, while the two Trichoprosopon species were bamboo specific. Ae. terrens and Cx. mollis were collected both in tires and bamboo, Cx. bigoti was collected in tires, cans and bamboo, while Hg. leucocelaenus could only be found in cans. The last four species were collected in all kinds of receptacles. Cx. quinquefasciatus, Cx. eduardoi and Li. durhamii had significant population fluctuations. DISCUSSION: Tires were characterized as the receptacle most acceptable to the Culicidae. The areas where the forest was the densest and the places where the soil was the most humid were the spots with the highest capture register.
OBJECTIVE: To compare the Culicidae fauna in forest, ecotone and anthropic environments and to analyze their composition according to the number of species and individuals, species richness, diversity, heterogeneity and similarities and to determine species dominance and the relationship between species dominance and climatic factors. METHODS: CO2 -baited CDC light traps were used for mosquito collection twice a month in the Serra da Cantareira State Park from February 2001 to January 2002. CO2 - baited CDC light traps were placed in five different environments. The analyses were carried out using Margalef and Menhinick's diversity indexes. Similarity was calculated using the Sorensen index and species dominance was indicated by the Berger-Parker index. Mosquito heterogeneity was estimated using Simpson and Shannon indexes. The correlation between species dominance and climatic factors was estimated by Spearman's coefficient. RESULTS: There were collected 2,219 Culicidae mosquitoes of 11 genera and 21 species. The forest environment showed the highest species richness (Mg=3.64) and the anthropic environment presented the most dominant species (d=0.85). Temperature showed the greatest positive correlation (Rs=0.747; p<0.0001) when analyzing the relationship between climatic factors and number of individuals caught in the study area. CONCLUSIONS: As the Serra da Cantareira State Park is a forest patch inserted in an urban environment, this may have changed the ecological relationships in the Culicidae breeding sites. The absence of Kerteszia subgenus and Culex quinquefasciatus species, in addiction to the presence of Sabethini Tribe specimens and Cx. (Mel.) vaxus species indicate that the Serra da Cantareira State Park is a forest section with sylvan features but show some anthropic interference.