PRESENCE OF AEDES (STEGOMYIA) USAMBARA MA TTINGLY, 1953 (DIPTERA, CULICIDAE) IN IVORY-COAST, SEASONAL-VARIATIONS AND EPIDEMIOLOGIC POSITION

Every month, studies were carried out in Ivory-Coast to study mosquito -borne diseases. This took place for three years in a semi-deciduous f orest, a local village (called Tanoekro) and nearby bamboo plantations . It was through these investigations that we discovered - for the fir st time in West Africa - specimens of a species called Aedes (Stegomyi a) usambara Mattingly, 1953, or a very similar new one. The females bi te humans and can thus, in theory, transmit the Chikungunya virus whic h they carry. The population of Ae. usambara relies on there being rai n. The females often disappear during the dry season (December, Januar y and February) and then re-appear at the start of the rainy season to achieve a maximum abundance generally in July. The peak corresponds w ith a cumulated rainfall of between 600 and 700 mm. This is the estima ted quantity of water needed to fill larval habitats. There is thus a quantitative relationship between the abundance of females and the rai n. After this peak in July, the population does not develop any furthe r unless there are both rainy and dry periods, each lasting several da ys. The eggs of Ae. usambara, like the other species belonging to the Stegomyia sub-genus, need to be dry before they can hatch. There is th us a qualitative relationship between the abundance of females and the rain.