Evaluation of methods for collecting diurnal Culicidae (Diptera) in canopy and soil strata of the Atlantic Forest biome

Abstract

Purpose: The aerial net is the standard method for capturing wild arbovirus vector mosquitoes, in which the human presence acts as an attractant. However, biases related to the collectors’ abilities to attract and collect the insects, in addition to the occupational risk, are important limitations to be considered in the obtained result. Chemical attractants and automatic traps could be alternatives to resolve these limitations. In Brazil, few studies have employed this approach in the wild and during the daytime; therefore, this study sought to collect diurnal mosquitoes in two forest strata: the ground and canopy, to compare aerial nets and electric traps (CDC) that were associated with two different kairomones Methods & Materials: The studied area lies in the green belt of the metropolitan region of the city of São Paulo, Brazil, within to the Atlantic Forest biome. Electrical traps associated with kairomones: CO2 and BG-Lure®, were used. These were compared to the standard aerial net technique. The collections with the different techniques were carried out from 9:00 to 16:00 on the ground and in the canopy. For comparison between the methods, diversity and abundance index and cluster analysis were used.. Results: In the 18 collections conducted, 3570 specimens were obtained, distributed in 52 different taxa. The most frequent species in the ground stratum were Wyeomyia confusa (53.1%) and Limatus durhamii (30.9%), while Sabethes albiprivus (14.5%), Sabethes purpureus (13.1%), and Haemagogus leucocelaenus (11.3%) were the most frequent in the canopy. The net method resulted in the greatest richness and abundance of species in both strata, followed by the trap containing CO2. The yield did not improve when CO2 traps included BG-Lure®. The use of BG-Lure® alone resulted in a restricted number of species and low abundance. Conclusion: Our results demonstrate that the association of traps with CO2 can complement collections with aerial nets; however, for species with epidemiological interest, such as those in the genera Haemagogus and Sabethes, especially in the canopy, the aerial net is still the method of choice. Further studies are needed with other attractions to replace human presence