Urban rain pools: seasonal dynamics and entomofauna in a park of Buenos Aires

We describe the seasonal variations of the insect community of the rain poo ls in a park of Buenos Aires during a 1-year period, based on a weekly samp ling programme. We also analyse the relationships between the observed biot ic patterns and some physical and meteorological variables. Four periods, f airly coincident with the seasons of the year, were graphically identified as functions of temperature, rainfall, flooded area, number of rain pools, depth and taxonomic richness. A total of 45 insect taxa was identified: 18 Coleoptera, 15 Diptera, 9 Heteroptera, 1 Ephemeroptera and 2 Odonata. Culic idae represented 76% of the pooled abundance of insects, probably related t o their rapid development before the pools dry up. Taxonomic richness was m aximum at the end of the summer (32), in coincidence with maximum rainfalls and temperatures. Inversely, the minimum richness (2) was recorded during the spring drought. Richness was positively correlated to the flooded area and to the number of pools on each sampling date. The species recorded thro ughout the study period were: Aedes albifasciatus, Culex eduardoi, Culex pi piens, Liodessus sp., Rhantus signatus signatus, Tropisternus setiger, Trop isternus lateralis limbatus and Sigara platensis. Some of the species recor ded are considered pioneer in temporary habitats. Both coleopterans and het eropterans are likely to persist in the park through repeated colonisation from more permanent habitats. Habitat duration and flooded area were positi vely correlated to richness in each one of the rain pools.