Detailed assessment of microhabitat suitability for Aedes aegypti (Diptera: Culicidae) in Buenos Aires, Argentina.

Little information is available on the ecology of Aedes aegypti Linnaeus at the southern extreme of its distribution (Buenos Aires, Argentina), particularly on microhabitat suitability. The aim of our study was to identify at a detailed scale, microhabitat factors that correlate with the presence of preimaginal stages of the mosquito. In March 2001, we performed a spatial census of all containers located in a 1 ha patch within a cemetery in Buenos Aires City. On a reference map (1:700) we plotted the position of graves and surrounding corridors, the location of containers, the shade projected by each plant between 10:00 and 16:00 h and vegetation cover. We classified vegetation by height, substrate by composition and shadow by level of exposure to sunlight. We performed univariate and multivariate logistic regression analyses with nine constructed independent variables, some of them at scales of 0.5, 1, 2, 3, and 10 m. Of 850 receptacles examined, 101 contained preimaginal stages of Ae. aegypti. Level of exposure to sunlight, type of substratum, vegetation height and distance of containers to vegetation were significantly associated with the presence of breeding sites at the studied scales. Final multivariate models were significant at scales of 2 m (chi(3)2=25.693, p<0.001) and 3m (chi(3)2=26.440, p<0.001), and 65.9 and 66.8% of our data were correctly classified, respectively, for each scale. Our results suggest that sites less exposed to sunlight, with taller and closer vegetation, and in shaded and vegetated neighbourhoods were the most favourable microhabitats for Ae. aegypti breeding.