Transferência do Hepatozoon tupinambis, parasita do lagarto Tupinambis teguixin, para a serpente cascavel (Crotalus durissus terrificus), por intermédio do mosquito Culex fatigans

Os autores obtiveram a transferência do Hepatozoon tupinambis (Laveran e Salibeni, 1909) parasita do lagarto Teiidae, Tupinambis teguixin, L., para a serpente cascavel, Crotalus durissus terrificus (Laur.), alimentando-a com mosquitos experimentalmente infectados. o parasita mantém os seus caracteres morfológicos no animal receptor, nos limites do tempo observado (cerca de 100 dias). O ofídio receptor apresentou cistos esquizogônicos do fígado.

Development of Hepatozoon caimani (Carini, 1909) Pessôa, De Biasi & De Souza, 1972 in the Caiman Caiman c. crocodilus, the frog Rana catesbeiana and the mosquito Culex fatigans

The sporogony of Hepatozoon caimani has been studied, by light microscopy, in the mosquito Culex fatigans fed on specimens of the caiman Caiman c. crocodilus showing gametocytes in their peripheral blood. Sporonts iniciate development in the space between the epithelium of the insect gut and the elastic membrane covering the haemocoele surface of the stomach. Sporulating oocysts are clustered on the gut, still invested by the gut surface membrane. Fully mature oocysts were first seen 21 days after the blood-meal. No sporogonic stages were found in some unidentified leeches fed on an infected caiman, up to 30 days following the blood-meal. When mosquitoes containing mature oocysts were fed to frogs (Leptodactylus fuscus and Rana catesbeiana), cysts containing cystozoites developed in the internal organs, principally the liver. Feeding these frogs to farm-bred caimans resulted in the appearance of gametocytes in their peripheral blood at some time between 59 and 79 days later, and the development of tissue cysts in the liver, spleen, lungs and kidneys. Transmission of the parasite was also obtained by feeding young caimans with infected mosquitoes and it is suggested that both methods occur in nature. The finding of similar cysts containing cystozoites in the semi-aquatic lizard Neusticurus bicarinatus, experimentally fed with infected C. fatigans, suggests that other secondary hosts may be involved.

Caso de um mosquito intensamente parasitado por larvas de ácaros aquáticos

One female of Culex fatigans Wied., 1828, was collected in a light trap at CENA-ESA«LQ»-USP, Piracicaba, at about 500 meters off the Piracicaba River banks. This mosquito exhibited 15 partially engorged pionid larvae of water mites (Prostigmata, Hydrachnellae) of the genus Arrenurus, attached to the articular membranes of the abdominal segments; no mites were found on the thorax or coxae. The larva is drawn, dorsad and ventrad. Since species cannot be identified from larvae, no specific name is given.

O virus do mixoma no coelho do mato (Sylvilagus minenses), sua transmissão pelos Aedes scapularis e aegypti

The brazilian wild rabbit (Sylvilagus minensis) is sensible to the virus of the mixomatosis but the desease takes on it a mild character, lasts for long time and generally do not kill the animal. The tumors are generally smaller and less numerous than those of the domestic rabbit, but sometimes there were noted large and flat lesions (fig. 3). The natural infection of the wild rabbit may be quite common not only because many rabbits caught in the country were found to be immune as also because it was found among the animals caught in the country near Rio, one that was infected with mixomatosis. The experimental infection of the Sylvilagus may be easily obtained by cutan, subcutan or conjuntival way and also when a health wild rabbit is placed in the same cage with a sick domestic animal. It is also possible to obtain the infection of the wild and domestic rabbits by the bite of infected blood sucking insects as fleas and mosquitoes. The infected mosquito can transmit the disease 2 or 3 times til 17 days after an infective meal on a sick rabbit. The transmission is a mecanical one and only the proboscis of the insect contains the virus as it was shown by the inoculation of emulsions of the proboscis, thorax and abdomen of the mosquito. Though mecanical this kind of transmission acts as an important epidemiological mean of dissemination of the deseasse and splains the suddendly outbreaks of mixomatosis in rabbits breedings where no new rabbits were introduced since very long time. The transmition of mixomatosis by fleas (Slenopsylla) was at first demonstrated by us, then S. Torres pointed out the capacity of Culex fatigans to transmit the desease and now we have proved that Aedes scapularis and Aedes aegypti were also able to transmit it (Foto 1 and 2). The virus of the mixomatosis (Chlamidozoon mixoma) is seen on the smeavs of the tumors of the wild reabbit with the same morphology, as in the material of the domestic animal.

Observações sobre os mosquitos Culex da cidade de São Paulo, Brasil

São apresentados os resultados obtidos na coleta de mosquitos do gênero Culex na área urbana da cidade de São Paulo, Brasil. Foram empregadas armadilhas luminosas automáticas tipo "New Jersey 50". Os resultados revelaram a presença de outras populações representadas principalmente por Culex chidesteri, C. dolosus e C. bidens as quais, em conjunto, chegaram algumas vezes a sobrepujar a de Culex pipiens fatigans. O maior rendimento foi obtido em áreas com abastecimento de água mas sem rede de esgotos. As coletas intradomiciliares revelaram franca predominância de C. pipiens fatigans.

Density and survival rate of Culex quinquefasciatus at Parque Ecologico do Tiete, Sao Paulo, Brazil

Parity rate, gonotrophic cycle length, and density of a Culex quinquefasciatus female population was estimated at the Parque Ecologico do Tiete (PET), Sao Paulo, Brazil. Adult Cx. quinquefasciatus females were collected from vegetation along the edges of a polluted drainage canal with the use of a battery-powered backpack aspirator from September to November 2005 and from February to April 2006. We examined 255 Cx. quinquefasciatus ovaries to establish the parity rate of 0.22 and determined the gonotrophic cycle length under laboratory conditions to be 3 and 4 days. From these data, we calculated the Cx. quinquefasciatus survival rate to be 0.60 and 0.68 per day. Density of the Cx. quinquefasciatus female (5.71 females per m(2)) was estimated based on a population size of 28,810 individuals divided by the sampled area of 5,040 m(2). Results of all experiments indicate medium survivorship and high density of the Cx. quinquefasciatus female population. This species is epidemiologically relevant in the PET area and should be a target of the vector control program of Sao Paulo municipality.

Culex quinquefasciatus vitellogenesis: morphological and biochemical aspects

The vitellogenic process in Culex quinquefasciatus, which is triggered by a blood meal, involves the synthesis, distribution and storage of the nutrients necessary for embryo development. The fat body of an adult female Cx. quinquefasciatus revealed two cell types: large trophocytes and small, eosinophilic, "oenocyte-like" cells, which show no morphological changes throughout the gonotrophic cycle. Trophocytes, which only begin to synthesise vitellogenin (Vg) 12 h post-blood meal (PBM), undergo a series of morphological changes following engorgement. These changes include the expansion of the rough endoplasmic reticulum (RER) and Golgi complex, which are later destroyed by autophagosomes. At 84 h PBM, trophocytes return to their pre-engorgement morphology. The ovarian follicles of non-blood-fed Cx. quinquefasciatus contain a cluster of eight undifferentiated cells surrounded by follicular epithelium. After engorgement, the oocyte membrane facing the perioocytic space increases its absorptive surface by microvilli development; large amounts of Vg and lipids are stored between 24 and 48 h PBM. Along with yolk storage in the oocyte, follicular cells exhibit the development of RER cisternae and electron-dense granules begin to fill the perioocytic space, possibly giving rise to endochorion. Later in the gonotrophic cycle, electron-dense vesicles, which are possible exochorion precursors, fuse at the apical membrane of follicular cells. This fusion is followed by follicular cell degeneration.

Wing diagnostic characters for Culex quinquefasciatus and Culex nigripalpus (Diptera, Culicidae)

Wing diagnostic characters for Culex quinquefasciatus and Culex nigripalpus (Diptera, Culicidae). Culex quinquefasciatus and Culex nigripalpus are mosquitoes of public health interest, which can occur sympatrically in urban and semi-urban localities. Morphological identification of these species may be difficult when specimens are not perfectly preserved. In order to suggest an alternative taxonomical diagnosis, wings of these species were comparatively characterized using geometric morphometrics. Both species could be distinguished by wing shape with accuracy rates ranging from 85-100%. Present results indicate that one can identify these species relying only on wing characters when traditional taxonomical characters are not visible.

Culex nigripalpus Theobald (Diptera, Culicidae) feeding habit at the Parque Ecológico do Tietê, São Paulo, Brazil

The blood feeding of a population of Cx. nigripalpus from Parque Ecológico do Tietê (PET) was investigated using an indirect ELISA protocol. Mosquitoes were captured outside houses. Five hundred sixteen engorged females collected in a reforested area and 25 in an open area were tested. Rodents and dogs were the most common blood sources, accounting for approximately 65.3% of blood meals. Human blood was detected in 10.9%, dog blood in 26.1%, chicken blood in 2.4%, and rodent blood in 39.2% of the 541 insects tested. ELISA failed in identifying the blood sources of 233 engorged females, indicating that the mosquitoes may have fed on a host which was not tested. One hundred six individuals were positive for more than one host. The unweighted human blood index was 0.14 and the rodent/human, human/chicken, and dog/rodent feeding index values were 2.70, 1.51, and 1.33, respectively. Furthermore, rodents are defensive hosts for this haematophagous insect which looks for another host to complete blood-feeding. Considering that rodents are potential reservoirs for Mucambo virus and Saint Louis encephalitis virus and that Cx. nigripalpus feed on the blood of those mammals, we hypothesize that mosquito population in PET could participate in the transmission cycle of those arboviruses. Additionally, this species might be involved in the transmission of Dirofilaria immitis to dogs at this area.

First Record of Culex (Culex) brethesi (Dyar) (Diptera: Culicidae) in Rio Grande do Sul State, Brazil

This is the first record of Culex (Culex) brethesi (Dyar) in Rio Grande do Sul state, Brazil. The species was identified from specimens collected in a sand bar vegetation with the aid of a Nasci's trap, during an expedition for surveillance of the West Nile Virus in July of 2006, in the city of Mostardas, Rio Grande do Sul, Brazil.

Density and survival rate of Culex quinquefasciatus at Parque Ecológico do Tietê, São Paulo, Brazil

Parity rate, gonotrophic cycle length, and density of a Culex quinquefasciatus female population was estimated at the Parque Ecológico do Tietê (PET), São Paulo, Brazil. Adult Cx. quinquefasciatus females were collected from vegetation along the edges of a polluted drainage canal with the use of a battery-powered backpack aspirator from September to November 2005 and from February to April 2006. We examined 255 Cx. quinquefasciatus ovaries to establish the parity rate of 0.22 and determined the gonotrophic cycle length under laboratory conditions to be 3 and 4 days. From these data, we calculated the Cx. quinquefasciatus survival rate to be 0.60 and 0.68 per day. Density of the Cx. quinquefasciatus female (5.71 females per m2) was estimated based on a population size of 28,810 individuals divided by the sampled area of 5,040 m2. Results of all experiments indicate medium survivorship and high density of the Cx. quinquefasciatus female population. This species is epidemiologically relevant in the PET area and should be a target of the vector control program of São Paulo municipality

Redescription of Culex (Culex) dolosus (Lynch Arribálzaga)(Diptera: Culicidae), based on specimens from Pico do Itapeva, Serra da Mantiqueira, São Paulo, Brazil

Culex (Culex) dolosus (Lych Arribálzaga, 1891) is re-described and compared with Cx. eduardoi Casal & Garcia (1968) based on morphological characteristics. Both species are morphologically similar, and they have been largely misidentified throughout Brazil. Adult male and female, fourth instar larvae, and pupae of Cx. dolosus were examined, based on specimens from Pico do Itapeva, Pindamonhangaba Municipality, Serra da Mantiqueira, São Paulo State, southern Brazil. Male genitalia, larvae and pupae are illustrated. Geographical distribution is summarized from published records, and information on bionomics is based on literature and field data

Genetic-morphometric variation in Culex quinquefasciatus from Brazil and La Plata, Argentina

Variation among natural populations of Culex (Culex) quinquefasciatus Say is associated with different vectorial capacities. The species Cx. quinquefasciatus is present in the equatorial, tropical and subtropical zones in the Brazilian territory, with intermediate forms between Cx. quinquefasciatus and Culex pipiens occurring in regions of latitudes around 33°-35°S. Herein, we studied geographically distinct populations of Cx. quinquefasciatus by genetic characterization and analysis of intra-specific wing morphometrics. After morphological analysis, molecular characterization of Cx. quinquefasciatus and intermediate forms was performed by polymerase chain reaction of the polymorphic nuclear region of the second intron of the acetylcholinesterase locus. Additionally, the morphology of adult female wings collected from six locations was analyzed. Wing centroid sizes were significantly different between some geographical pairs. Mean values of R2/R2+3 differed significantly after pairwise comparisons. The overall wing shape represented by morphometric characters could be divided into two main groupings. Our data suggest that Brazilian samples are morphologically and genetically distinct from the Argentinean samples and also indicated a morphological distinction between northern and southern populations of Brazilian Cx. quinquefasciatus. We suggest that wing morphology may be used for preliminary assessment of population structure of Cx. quinquefasciatusin Brazil