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Mosquitoes in the tribe Mansoniini are distributed into two genera: Mansonia Blanchard (27 spp.) and Coquillettidia Dyar (57 spp.). Adults are large, aggressive biters and mostly zoophilic, but opportunistic in their preferences (Consoli and Lourenço- de-Oliveira 1994). Eggs are usually adhered to aquatic plants and larvae get air from them (Forattini 1965). Some species have been incriminated as vectors of arboviruses (Forattini 1965, Hervé et al. 1986). Microfilariae of Wuchereria bancrofti were found in the proboscis of experimentally infected Cq. juxtamansonia (Chagas, 1907) (Davis 1935).
Eggs of 19 species of Coquillettidia have been described (Reinert 2010), all of them only by optical microscopy. Adequate differentiation of eggs is useful for correct identification in their breeding places and possibly for the study of connection among species in larger groups. A description and morphometric study of Coquillettidia juxtamansonia (Chagas) eggs by Scanning Electron Microscopy is developed.
Five blood fed females of Cq. juxtamansonia were obtained from Reserva Ecológica do Guapiaçu (REGUA), in Municipality of Cachoeiras de Macacu, in the Brazilian state of Rio de Janeiro (22o25'23.9'' S 42o44'30.0'' W). Mosquitoes were identified by keys provided by Consoli and Lourenço-de-Oliveira (1994) and Forattini (2002). From 30 eggs obtained, 11 were utilized for this study. The females were fed during the collection, utilizing suction tubes (Marcondes et al. 2007) and individually maintained in glass tubes 25 mm wide and 50 mm high, having wet cotton covered by a filter paper, in the bottom, for egg-laying (Bates and Roca-Garcia 1945).
Eggs were fixed in 2.5% glutaraldehyde and post-fixed in 1% osmium tetroxide, both buffered with 0.1M sodium cacodylate at pH 7.2. After washing in the same buffer, the eggs were dehydrated in a series of increasing concentrations of ethanol and subjected to the critical-point drying method using superdry CO2 in a Balzers apparatus. The eggs were then mounted on metal supports, gold plated and observed and photographed in a JEOL JSM 6390LV scanning electron microscope (Akishima, Tokyo, Japan), at magnifications of 200 to 5,000 times. Measurements were made directly on the images obtained, with the aid of the Semafore digital slow scan image recording system, version 3.1© (Insinooritoi misto J. Rimppi Oy, Finland) and analyzed using a SEM Control User Interface version 8.24© (JEOL TECHNICHS LTD), coupled to...