Bacterial Composition and Diversity of the Digestive Tract of Odontomachus monticola Emery and Ectomomyrmex javanus Mayr

Abstract

Ponerine ants are generalist predators feeding on a variety of small arthropods, annelids, and isopods; however, knowledge of their bacterial communities is rather limited. This study investigated the bacterial composition and diversity in the digestive tract (different gut sections and the infrabuccal pockets (IBPs)) of two ponerine ant species (Odontomachus monticola Emery and Ectomomyrmex javanus Mayr) distributed in northwestern China using high-throughput sequencing. We found that several dominant bacteria that exist in other predatory ants were also detected in these two ponerine ant species, including Wolbachia, Mesoplasma, and Spiroplasma. Bacterial communities of these two ant species were differed significantly from each other, and significant differences were also observed across their colonies, showing distinctive inter-colony characteristics. Moreover, bacterial communities between the gut sections (crops, midguts, and hindguts) of workers were highly similar within colony, but they were clearly different from those in IBPs. Further, bacterial communities in the larvae of O. monticola were similar to those in the IBPs of workers, but significantly different from those in gut sections. We presume that the bacterial composition and diversity in ponerine ants are related to their social behavior and feeding habits, and bacterial communities in the IBPs may play a potential role in their social life.

Keywords: bacterial communities; guts; high-throughput sequencing; infrabuccal pockets; ponerine ants; social insects.

Figure 1

Bacterial communities of two ponerine ant species and their colonies at the phylum level. O1, O2, and O3, three colonies of Odontomachus monticola; E1 and E2, two colonies of Ectomomyrmex javanus. WI, the infrabuccal pockets of workers; WC, the crop of workers; WM, the midguts of workers; WH, the hindguts of workers; L, larvae. Sample names are listed in Table 1.

Figure 2

Bacterial communities of two ponerine ant species and their colonies at the genus level. O1, O2, and O3, three colonies of O. monticola; E1 and E2, two colonies of E. javanus. WI, the infrabuccal pockets of workers; WC, the crop of workers; WM, the midguts of workers; WH, the hindguts of workers; L, larvae. Sample names are listed in Table 1.

Figure 3

Principal coordinate analysis (PCoA) of bacterial community composition and abundance among different groups. (a) Bray–Curtis distance matrix for samples from O. monticola and E. javanus. (b) Bray–Curtis distance matrix for samples from different colonies of each ant species. (c) Bray–Curtis distance matrix for samples from infrabuccal pockets, gut sections (crops, midguts, and hindguts) of workers and larvae of O. monticola and E. javanus. Dots in different color represented different groups. PERMANOVA tests showed statistical analysis between groups. O1, O2, and O3, three colonies of O. monticola; E1 and E2, two colonies of E. javanus. WI, the infrabuccal pockets of workers; WC, the crop of workers; WM, the midguts of workers; WH, the hindguts of workers; L, larvae. Sample names are listed in Table 1.

Figure 4

ANOSIM analysis presenting the similarity of bacterial communities among different groups. (a) Similarities of bacterial communities between O. monticola and E. javanus. (b) Similarities of bacterial communities across three colonies (O1, O2, and O3) of O. monticola. (c) Similarities of bacterial communities between two colonies (E1 and E2) of E. javanus.

Figure 5

Bacterial genera that significantly differ (FDR adjusted p-value < 0.05) in abundance among different groups. (a) Bacterial genera that significantly differ between O. monticola and E. javanus. (b) Bacterial genera that significantly differ across three colonies (O1, O2, and O3) of O. monticola and two colonies (E1 and E2) of E. javanus. (c) Bacterial genus that significantly differ between samples within colony O1. (d) Bacterial genera that significantly differ between samples within colony E2. WI, the infrabuccal pockets of workers; WC, the crop of workers; WM, the midguts of workers; WH, the hindguts of workers; L, larvae. Significant bacterial genera were ranked in decreasing order based on their LDA score (x axis). The mini heatmap to the right of the plot indicated whether the relative abundance of bacterial genera were higher (red) or lower (blue) in each group.