Ochlerotatus albifasciatus in rain pools of Buenos Aires: seasonal dynamics and relation to environmental variables

SYLVIA FISCHER; MARÍA CRISTINA MARINONE; NICOLÁS SCHWEIGMANN

MEMóRIAS DO INSTITUTO OSWALDO CRUZ.

Instituto Oswaldo Cruz

Lugar: Rio de Janeiro; Año: 2002 vol. 97 p. 767 - 773

0074-0276

The immature stages of Ochlerotatus albifasciatus develop in temporary pools. The present study aims at evaluating the seasonal dynamics of the aquatic stages of this mosquito, also analysing the relationship among their presence and breeding success to some relevant climatic and environmental variables in the ephemeral rain pools of a urban park. Nineteen cohorts of O. albifasciatus that developed synchronically after rain events were recorded in all seasons. The proportion of infested pools was significantly higher during the fall-winter period than in the spring-summer months (p<0.001). The number of infested pools was positively correlated to the amount of rain (p<0.001) and to the total number of rain pools (p<0.005), whereas negatively correlated to temperature (p<0.005). The distribution of the number of cohorts recorded in each pool showed a grouped pattern (variance/mean: 3.96). The Immature stages of O. albifasciatus were detected in pools belonging to all of the categories of surface area, depth, duration, vegetation cover, and insolation. However, the proportion of infested pools was positively and significantly related to surface, depth, duration, and vegetation cover. On the other hand, infestation levels were higher at an intermediate insolation degree. Our results suggest that although immature stages were present in all seasons, high temperatures may be unfavourable to larval development, and the substrate vegetation may regulate water temperature. The positive relationship between infestation and pool size and duration might reflect a strategy to accomplish immature development.