Aedes albifasciatus (Diptera: Culicidae) in ephemeral rain pools of Buenos Aires city Infestation levels and breeding success in relation to some environmental variables

SYLVIA FISCHER; MARÍA CRISTINA MARINONE; NICOLÁS SCHWEIGMANN

Barcelona-España

Congreso; 3rd International Congress of Vector Ecology; 2001

Society of Vector Ecology

Aedes albifasciatus is a floodwater mosquito widely distributed in Argentina. It is the primary species to be incriminated as Western Equine Encephalitis virus vector in South America. It breeds in shallow, temporary waters of variable size, vegetation and sunlight exposition. The present study aims at evaluating for the first time the infestation level of ephemeral rain pools in relation to some relevant environmental variables. Ninety-one rain pools were monitored on a weekly basis during 14 months in a 9-ha park of Buenos Aires City. The occurrence and breeding success of 23 consecutive cohorts of Ae. albifasciatus were evaluated in each pool. The proportions of infested and successful breeding pools (those where the aquatic phase of the life cycle could be completed) were compared for different categories of surface area, depth, substrate vegetation, and insolation. Considering our data as a whole, we detected immature stages of Ae. albifasciatus in pools of all of the categories of the above mentioned environmental variables. The proportions of infested sites and successful pools were positively and significantly related to surface, depth and substrate vegetation. On the other hand, at an intermediate insolation degree, infestation levels were higher. These trends were consistent throughout the different seasons. However, on a seasonal basis, infestation level and cohort success were positively related to surface and depth during the autumn-spring period, to substrate vegetation during the summer-winter period, and to insolation degree during the summer. These results, together with the low infestation and breeding success observed during the summer, suggest that the high temperatures of the warm season in Buenos Aires City are unfavourable for the development of the immature stages of Ae. albifasciatus. The direct relationship between pool size (surface and depth) and the proportion of infested pools, may reflect differences in the opportunity and/or probability of habitat colonization.