Aedine mosquitoes of Manitoba : egg identification

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Kalpage, Kingsley Samuel Perera
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The mosquito fauna in Manitoba is composed of six genera, of which the genus Aedes is the most predominant. As Aedes species spend the majority of their life cycle in the egg stage, a key to the identification of the aedine eggs of Manitoba would undoubtedly be useful. Sanitarians could use the information obtained from the eggs of Aedine species in planning their abatement operations, and ecologists could use a knowledge of egg indentification in population survey studies. Eggs for the present studies were obtained generally from wild caught females from ten locations, extending as far north as Baker Lake in the North West Territories. The adult females were given blood, then placed in individual cages for oviposition. Eggs were conditioned by incubating them first at 20*C for three months and then placing the embryonated eggs in a constant cold temperature (4*C) incubator for four months. Hatching of the conditioned eggs was most satisfactory when eggs were placed directly from the cold into the hatching medium at 65*F (15*C). Larvae were reared in alternating temperature incubators to the fourth instar stage, and then preserved for identification. After the species was known, similar eggs were grouped. In order to study the egg characteristics the whole eggs were examined above a black background in intense reflected white light. ... Aedine eggs show a variation in shape, size, colour and chorionic sculpturing according to species. The present study also shows that eggs possess characteristics indicating certain phylogenetic relationships. Four species had two or more significantly different sizes and/or shapes within the species. This may be an indication of sub-speciation. Twenty-seven species are reported as having been found in Manitoba, four of which are reported for the first time as being present in the Province.