Taxocenose e morfologia de mosquitos (Diptera: Culicidae) com ênfase na tribo Mansoniini em áreas de aproveitamento hidrelétrico na Amazônia, Estado de Rondônia - Brasil

Abstract

Mosquitoes are the group with the highest vectorial capacity for pathogens among hematophagous arthropods. Among those of medical importance, Mansonia spp. and Coquillettidia spp. demonstrate to be potential vectors of several arboviruses associated with human diseases in several regions of the world. This thesis is structured in five chapters and aimed to study the bioecology and morphology of mosquitoes with emphasis on the Mansoniini tribe in areas of hydroelectric development in the Amazon - UHE - JIRAU, in the state of Rondônia, Brazil. To capture the Culicidae adults, we used Castro traps, battery-powered vacuum cleaners, CDC-type light traps and Shannon light traps. The captures were carried out during the months of May, July, October and December 2018 and in the months of April, July, September and November 2019. Immature collections were carried out through active search in aquatic macrophyte banks from February 2016 to December 2018. We captured a total of 46,564 adult mosquitoes represented by 32 species, being the genus Mansonia spp. responsible for 96% of the total number of individuals collected during the study period. The temperature and the precipitation concentrated in the two weeks that preceded the samplings, were decisive on the mosquito populations and affected the pattern of the composition of the fauna. We obtained a total of 31,287 immature specimens belonging to the genus Mansonia spp. The immatures were more commonly found in Eichhornia crassipes, this plant accounted for an average of 96.2% of all specimens, with a percentage that varies between 58.2% and 77.1% in the different breeding sites. The number of specimens collected was positively correlated with temperature, pH and conductivity. These correlations showed a marked increase in the rainy season and allowed us to establish preliminary parameters of how environmental changes influence the ecology of this important mosquito genus. We evaluated the degree of active dispersal of females of Mansonia spp. around the Jirau hydroelectric plant using mark-release-recapture techniques. A total of 38,113 females of Mansonia spp. were captured, of which 26,677 were marked and released. During the periods of drought, rain and transition between these two periods, in the years 2018 and 2019, a total of 169 recaptured specimens were recorded. The flight behavior of recaptured specimens was summarized with a set of average and maximum distances traveled. Ma. amazonensis during 2018 and Ma. humeralis during 2019 covered maximum distances of 2,000 m from the release point. A total of 181 wings of Ma. amazonensis were analyzed using morphological methods and morphometric characters. The wing size of Ma. amazonensis increases following a relatively gradual trend, being smaller during the dry season and larger in the rainy season. This is the first study of Ma. amazonensis that shows phenotypic variability, both in conformation and in wing size, associated with seasonality, using geometric morphometry. We examined the ultrastructural features of the Cq. venezuelensis eggs with the aid of scanning electron microscopy. The length, width and index of eggs of Cq. venezuelensis are distinct from those of Cq. juxtamansonia, Cq. albifera and Cq. Shannoni.