Diversity of the hematophagous insects fauna in new urbanized areas from Upper Valley of the Tiete River: molecular phylogeny, prevalence and the impact of Wolbachia on host populations

Abstract

Wolbachia (alfa-Proteobacteria; Rickettsiaceae) are strictly intracellular bacteria infecting a number of invertebrates including mites, crustaceans, filarial nematodes, and especially insects. These symbionts are usually transmitted maternally through the cytoplasm of eggs. Wolbachia are distinguished by their ability to modify host reproduction in a variety of ways such as: cytoplasmic incompatibility (IC), feminization of males and parthenogenesis. At presents, there are a lot of interesting questions about the interaction and evolution of the host-symbiont relationship. For example, how many species are infected with Wolbachia? What are the cellular and genetic mechanisms of Wolbachia-induced IC? How do Wolbachia alter host reproduction? What are the evolutionary consequences of Wolbachia infection? Is there any relationship between Wolbachia and speciation in arthropods? These questions have been broadly explored in several hosts. Certain progress has been obtained in the characterization of strains of Wolbachia from specific genes. Among them, various genes, including wsp, ftsZ, 16S rDNA and ANK are commonly used for discriminating Wolbachia strains and have shown advantages in its phylogenetic analysis within the Wolbachia clade. Since it is not yet possible to culture Wolbachia in vitro, crossing experiments are realized between individuals uninfected or that differ in their Wolbachia infection type, which results in complex patterns of bidirectional and unidirectional incompatibility. The reproductive distortions induced by Wolbachia infection are known to result in embryonic death due to modify the activity of cell-cycle regulating proteins during early events of fertilization. Introgression of the infected host genome into a native population (uninfected) has been verified, the relevance of these observations has attracted significant research effort to introduce and express transgenic products as strategies for control of insect populations. The prevalence and diversity of Wolbachia infections in mosquito taxa was investigated in Europe and Asia, but little in known about of distribution of this symbiont among native and invaders arthropods from Brazil. Some studies have reported the infection in a limited number of species. The purpose this study is to estimate the prevalence of Wolbachia infections and the diversity of Wolbachia strains in hematophagous mosquitoes. Such analysis will be realized in populations collected from Upper Valley of the Tiete River localities. This region lies in southeastern São Paulo State which contrasts larges urban areas with islands of natural reserves. Thus, the Epidemiologic Control Service has related risk factors potentially associated with the human exposition to vector insects of arboviruses. The findings of this study will might contribute to better knowledge of diversity of Wolbachia infection in mosquitoes species. In previous study, our laboratory has identified Wolbachia among field populations of Culex, Aedes (Diptera; Culicidae) and Solenopsis, Linepithema, Camponotus (Hymenoptera; Formicidae). The acquired experience with these studies also marked possible collaborations with institutes and groups, Entomological Department of School Public Health at USP and the Epidemiologic Control Service of Mogi das Cruzes city. Beyond the prevalence rates, it is possible that this study may allow the identification of new hosts, strains infecting different hosts and new strains. Thus, our experiments would be very useful not only for attempts to identify new infection but also the results should be useful for applied studies that propose manipulating Wolbachia infections with the goal of suppressing or modifying medically important vector populations. (AU)