Overlapping and specific bacterial communities in the gut and reproductive system of Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) adults

Abstract

Background: Different insect tissues represent heterogeneous niches with distinct physiological and biochemical characteristics, and therefore host different bacterial communities.

Methods: In this study, those overlapping and specific bacterial communities in the female gut (fG), male gut (mG), female reproductive system (fR), and male reproductive system (mR) of Bactrocera dorsalis (Hendel) adults were determined by high-throughput sequencing targeting 16S rRNA gene.

Results: The richness of bacterial taxa based on OTU was higher in fR compared to the other three tissues. Among the 29 identified bacterial phyla, Pseudomonadota, Bacillota, and Bacteroidota were predominant, while among the 48 identified genera, Enterobacter, Kluyvera, Asticcacaulis, Mesorhizobium, and Serratia were common in the four tissues. fG harbored specific bacterial genus Morganella, mG harbored specific bacterial genera Vagococcus, Lactobacillus, Lactococcus, Lactobacillales, and Bacilli, fR harbored specific bacterial genera Blastomonas, Ralstonia and Providencia, and mR harbored specific bacterial genera Sphingobacteriia, Asticcacaulis, Caulobacter, Caulobacterales, Bradyrhizobium, and Luteimonas. In the 35 annotated KEGG pathways, high-abundance bacterial taxa were mainly enriched in these pathways of membrane transport, carbohydrate metabolism, amino acid metabolism, replication and repair, and energy metabolism, while low-abundance bacterial taxa were involved in these pathways of cardiovascular diseases, circulatory system, and excretory system. The abundances of the 5 pathways associated with cardiovascular diseases, circulatory system, excretory system, membrane transport, and polysaccharide biosynthesis and metabolism exhibited greater variations among fG, mG, fR, and mR. Among them, the two pathways abundances of cardiovascular disease and circulatory system were higher in the reproductive system, whereas the other three pathways abundances were higher in the female gut.

Conclusion: Our study revealed the abundance, composition and function of overlapping and specific bacterial communities in the gut and reproductive system of B. dorsalis, providing valuable information for inhibiting the occurrence of B. dorsalis by interfering with these functional bacterial communities in tissues.

Keywords: Bactrocera dorsalis; bacterial diversity; function annotation; gut; reproductive system; specific bacterial communities.

FIGURE 1

Comparisons of bacterial community based on the OTUs in the fG, mG, fR, and mR of B. dorsalis. (A) OTU number in each tissue. (B) Venn diagram shows those shared and specific OTUs among the four tissues. OTUs were defined based on 3% sequence divergence.

FIGURE 2

Principal co-ordinates analysis (PCoA) illustrating differences in the taxonomic composition of bacterial communities among independent replicates of four tissue samples (fG, mG, fR, and mR). Dissimilarity in bacterial community composition is based on the weighted UniFrac distance metrics. Percentage of variation explained by each principle component is indicated on axis.

FIGURE 3

Taxonomic classification of bacterial communities associated with the different tissues of B. dorsalis adults. (A) Relative abundance of bacteria at phylum level. (B) Relative abundance of top 49 bacteria at genus level. The term “other” includes all un-annotated bacterial communities.

FIGURE 4

Diagram of specific and dominant bacterial taxa based on LEfSe analysis. (A) Circular cladogram starting from the innermost circle: phylum, class, order, family and genus. Each node represents a taxa and the larger the node, the higher the abundance of that taxa. Yellow nodes represent those bacterial taxa that there are no significant differences among different tissues. The other color nodes, such as red nodes, represent those bacterial taxa that there are significant differences among different tissues. Names of specific bacterial taxa are showed in the legend on the left. (B) Bar chart created based on the LDA score. Four colors (purple, blue, green and red) in this chart are used to distinguish those bacterial taxa in fG, mG, fR, and mR, respectively. The larger the LDA score, the greater the difference, indicating that the abundance in this bacterial taxon is higher than those in other bacterial taxa.

FIGURE 5

Function classification and annotation of bacterial communities from the fG, mG, fR, and mR of B. dorsalis based on KEGG pathway analysis.

FIGURE 6

Comparisons of KEGG pathway absolute abundance among the fG, mG, fR, and mR of B. dorsalis. Values are means ± standard error (SE). Different letters (a or b) above the different column denote significant differences on KEGG pathway abundance.