Wolbachia dominance influences the Culex quinquefasciatus microbiota.

Microorganisms present in mosquitoes and their interactions are key factors affecting insect development. Among them, Wolbachia is closely associated with the host and affects several fitness parameters. In this study, the bacterial and fungal microbiota from two laboratory Culex quinquefasciatus isolines (wild type and tetracycline-cured) were characterized by metagenome amplicon sequencing of the ITS2 and 16S rRNA genes at different developmental stages and feeding conditions. We identified 572 bacterial and 61 fungal OTUs. Both isolines presented variable bacterial communities and different trends in the distribution of diversity among the groups. The lowest bacterial richness was detected in sugar-fed adults of the cured isoline, whereas fungal richness was highly reduced in blood-fed mosquitoes. Beta diversity analysis indicated that isolines are an important factor in the differentiation of mosquito bacterial communities. Considering composition, Penicillium was the dominant fungal genus, whereas Wolbachia dominance was inversely related to that of Enterobacteria (mainly Thorsellia and Serratia). This study provides a more complete overview of the mosquito microbiome, emphasizing specific highly abundant components that should be considered in microorganism manipulation approaches to control vector-borne diseases.

Culex quinquefasciatus Holobiont: A Fungal Metagenomic Approach.

Microorganisms associated with mosquitoes have fundamental roles, not only in their nutrition, but also in physiological and immunological processes, and in their adaptation to the environment as well. Studies on mosquito hologenomes have increased significantly during the last years, achieving important advances in the characterization of the "core bacteriome" of some species of health importance. However, the fungal mycobiome has not been exhaustively researched, especially throughout the life cycle of some hematophagous mosquito species. In this work, the diversity and composition of fungal communities in different developmental stages, sexes, and adult nutrition of Culex quinquefasciatus reared on laboratory conditions were characterized, using internal transcribed spacer high throughput amplicon sequencing. Larvae presented a higher fungal richness, while sucrose-fed males and females showed a similar diversity between them. Blood-fed females presented few operational taxonomic units with an even distribution. Results are consistent with the reduction of larval microbiota after molting, observed for the bacterial microbiome in other mosquito species. The filamentous Ascomycota Penicillium polonicum and Cladosporium sp. were present in all stages of the mosquitoes; in addition, the presence of yeasts in the insects or their subsequent colonization associated with their diet is also discussed. These results suggest that some species of fungi could be essential for the nutrition and development of mosquitoes throughout their life cycle.

Bacillus wiedmannii biovar thuringiensis: A Specialized Mosquitocidal Pathogen with Plasmids from Diverse Origins.

Bacillus cereus sensu lato also known as B. cereus group is composed of an ecologically diverse bacterial group with an increasing number of related species, some of which are medically or agriculturally important. Numerous efforts have been undertaken to allow presumptive differentiation of B. cereus group species from one another. FCC41 is a Bacillus sp. strain toxic against mosquito species like Aedes aegypti, Aedes (Ochlerotatus) albifasciatus, Culex pipiens, Culex quinquefasciatus, and Culex apicinus, some of them responsible for the transmission of vector-borne diseases. Here, we report the complete genome sequence of FCC41 strain, which consists of one circular chromosome and eight circular plasmids ranging in size from 8 to 490 kb. This strain harbors six crystal protein genes, including cry24Ca, two cry4-like and two cry52-like, a cry41-like parasporin gene and multiple virulence factors. The phylogenetic analysis of the whole-genome sequence of this strain with molecular approaches places this strain into the Bacillus wiedmannii cluster. However, according with phenotypical characteristics such as the mosquitocidal activity due to the presence of Cry proteins found in the parasporal body and cry genes encoded in plasmids of different sizes, indicate that this strain could be renamed as B. wiedmannii biovar thuringiensis strain FCC41.