Oviposition and vertical dispersal of Aedes species Meigen 1818 (Diptera: Culicidae) at different heights and seasonal periods in an urban forest fragment in Manaus, Amazonas, Brazil

Abstract

Mosquitoes of the genus Aedes stand out for their high susceptibility to several groups of arboviruses, especially those that cause dengue fever, Zika, and Chikungunya fever. However, aspects related to the vertical distribution of species in large urban centers are still poorly understood, therefore, this study aims to evaluate the dispersal and oviposition of Aedes at different height levels and seasonal periods. The study was developed in a tower with six floors located in an urban forest fragment, measuring 15.13 meters (m) high and 3.20 meters at the base. The following height ranges were considered: ground: 0 m; 1.20 m; 2.50 m; 3.60m; 4.90 m; 6m; 7.30m; 8.40m; 9.70 m; and 10.8 m. Three ovitraps were installed on each floor, separated by a distance of 1.50 m, totaling 30 for each sampling period. The ovitrap positivity index (OPI) and egg density index (EDI) were evaluated in order to monitor Aedes populations in different height ranges and also in different seasonal periods. The data demonstrated that lower heights show a greater abundance of Aedes eggs, however, this variable did not prove to be a limiting factor for mosquito colonization at the other heights evaluated. Furthermore, climatic factors, such as relative humidity have a positive influence (p<0.05) on the average number of eggs in the urban area of Manaus, especially during the dry period. These findings demonstrate that the vertical growth of urban centers can act positively tin increasing the density of Aedes and can influence the incidence of dengue and other arboviruses.