Caracterization of anopheline malaria vector (Diptera: Culicidae) breeding sites at the upper Orinoco river, Amazonas, Venezuela

Resumo

Between October 1999 and January 2000, anopheline breeding habitats were identified and characterized in the Ocamo area, municipality Upper Orinoco, Amazonas state, in southern Venezuela. During the study, 46 samples were taken from 4 types of larval habitats: lagoon (37), pond (2), stream (6) and pool (1). A total of 1 304 anopheline larvae were collected belonging to 8 species: Anopheles oswaldoi, A. darlingi, A. triannulatus, A. mattogrossensis, A. punctimacula, A. forattinii, A. braziliensis and A. peryassui. The most abundant and frequent species collected was A. oswaldoi, followed by A. triannulatus and A. darlingi. The remaining species accounted for 11% of the total anophelines identified. Larvae density was higher in the ponds (3.38 larvae/dip) . The analysis of canonIc correspondence (ACC) showed a strong spatial structure in relation to anopheline species and environmental variables. These results were confirmed a posteriori by the Monte Carlo permutation test, p= 0,01. The variables that explained the spatial distribution of A. oswaldoi, A. darlingi and A. mattogrossensis were: detritus (twigs and leafs), pH, water depth and temperature. Anopheles triannulatus preferred lagoons with floating vegetation and tall grasses. Higher density of inmature stages (DEL3, DEL4 and DEP-PA) were associated with shaded lagoons and abundant algae.