Observations on mosquito activity in residual forest in the Ribeira Valley, S. Paulo, Brazil

Abstract

The results of fortnightly 25-hour catches of Culicidae mosquitoes carried out at ground level with human bait in a residual forest area of the Ribeira Valley, S. Paulo, Brazil, are presented and discussed. Besides this, regular simultaneous catches with Shannon traps were made within and outside the forest environment. Daily biting cycles showed diurnal and nocturnal behaviour patterns which distinguished the nine most frequent species. Even through Ae. scapularis and Ae. serratus show a clear diurnal pattern they sustain moderate activity at night. Ae. scapularis also presents a clear peak of biting activity during the sunset-crepuscular period (corresponding to crep. 0.5 -1.0) and sustain their activity outside the forest at an equivalent density to that inside it. The monthly pattern throughout the year showed the constant presence of both mosquitoes, with a June predominance of Ae. scapularis. These data enable one to admit that this mosquito has greater opportunities of contact with the human population and thus relatively greater probability of transmitting arboviruses such as those of encephalitis.