Gut Bacterial Diversity of Field and Laboratory-Reared Aedes albopictus Populations of Rio de Janeiro, Brazil

Abstract

Background: The mosquito microbiota impacts different parameters in host biology, such as development, metabolism, immune response and vector competence to pathogens. As the environment is an important source of acquisition of host associate microbes, we described the microbiota and the vector competence to Zika virus (ZIKV) of Aedes albopictus from three areas with distinct landscapes.

Methods: Adult females were collected during two different seasons, while eggs were used to rear F1 colonies. Midgut bacterial communities were described in field and F1 mosquitoes as well as in insects from a laboratory colony (>30 generations, LAB) using 16S rRNA gene sequencing. F1 mosquitoes were infected with ZIKV to determine virus infection rates (IRs) and dissemination rates (DRs). Collection season significantly affected the bacterial microbiota diversity and composition, e.g., diversity levels decreased from the wet to the dry season. Field-collected and LAB mosquitoes' microbiota had similar diversity levels, which were higher compared to F1 mosquitoes. However, the gut microbiota composition of field mosquitoes was distinct from that of laboratory-reared mosquitoes (LAB and F1), regardless of the collection season and location. A possible negative correlation was detected between Acetobacteraceae and Wolbachia, with the former dominating the gut microbiota of F1 Ae. albopictus, while the latter was absent/undetectable. Furthermore, we detected significant differences in infection and dissemination rates (but not in the viral load) between the mosquito populations, but it does not seem to be related to gut microbiota composition, as it was similar between F1 mosquitoes regardless of their population.

Conclusions: Our results indicate that the environment and the collection season play a significant role in shaping mosquitoes' bacterial microbiota.

Keywords: 16S RNA gene sequencing; Ae. albopictus; Zika; bacteria; gut microbiota.

Figure 1

Mosquito collection areas. Map built using ArcGIS, sampling areas with different landscapes in Rio de Janeiro and Niterói cities. RPC—Represa dos Ciganos; JDG—Jardim Guanabara; JU—Jurujuba.

Figure 2

Alpha diversity of Aedes albopictus gut microbiota according to origin. (A) Observed ASVs (Kruskal–Wallis: H = 9.73; p-value < 0.001); (B) Faith (Kruskal–Wallis: H = 11.44; p-value < 0.05); (C) Shannon–Weaver (Kruskal–Wallis: H = 7.38; p-value < 0.05). Black lines indicate medians, and black dots indicate outliers. Groups indicated with the same letters are not significantly different (paired Kruskal–Wallis q-value > 0.05) (Table S4).

Figure 3

Alpha diversity of Aedes albopictus gut microbiota according to collection season. (A) Observed ASVs (Kruskal–Wallis: H = 29.60, p-value < 0.001); (B) Faith (Kruskal–Wallis: H = 17.58, p-value < 0.001); (C) Shannon–Weaver (Kruskal–Wallis: H = 21.94, p-value < 0.001); (D) Pielou (Kruskal–Wallis: H = 11.95, p-value < 0.05). Black lines indicate medians, and black dots indicate outliers. Groups indicated with the same letters are not significantly different (paired Kruskal–Wallis q-value > 0.05) (Table S4).

Figure 4

Principal component analysis (PCoA) of the gut microbiota of Aedes albopictus: (A) based on the Bray–Curtis dissimilarity matrix and (B) based on the Weighted Unifrac matrix. Shapes indicate the different populations, while colors show whether mosquitoes were collected during the wet or dry season or were laboratory reared (F1 and LAB). The variation explained by the PCoA axes is shown in parentheses.

Figure 5

Relative abundance of ASVs, classified at the lowest taxonomic level possible according to (A) collection season, (B) origin and (C) collection area, detected in the midgut of mosquitoes from the groups described in Table 2. Legends at the upper right: the remainder belong to bacterial taxa with <3% of abundance (C).

Figure 6

Quantification of ZIKV copies (log10) by RT-qPCR in the body (A for 14 dpi and C for 21 dpi) and head (B for 14 dpi and D for 21 dpi) of Ae. albopictus. The black horizontal line represents the median number of viral copies.