The influence of accumulated rainfall and its pattern on mosquito (Diptera) populations in Brazil.

Weekly catches of five species of mosquitoes over nearly two years at Belem, Brazil, were plotted against accumulated rainfall during the four weeks before catching. Rain-pool-breeding species ( Aedes serratus (Theo.), A. scapularis (Rond.), Psorophora ferox (Humb.)) show a marked peak in catch size (population density) at 100–180 mm accumulated rainfall; one swamp-breeding species ( Culex portesi Senevet & Abonnenc) shows no relation to rainfall while another ( C. taeniopus D. & K.) reaches a plateau at 180 mm. A more detailed analysis of catches in relation to rainfall distribution showed that maximal populations of A. serratus appear 16 days after 39.7–87.9 mm of rainfall has accumulated over 14 consecutive days, which should include 3–7 dry days; P. ferox requires 55.2–99.4 mm rainfall in the same period; and A. scapularis requires 26.5–114.9 mm rainfall, with a marked alternation of wet and dry days.