Bacterial Diversity in Solenopsis invicta and Solenopsis geminata Ant Colonies Characterized by 16S amplicon 454 Pyrosequencing

Abstract

Social insects harbor diverse assemblages of bacterial microbes, which may play a crucial role in the success or failure of biological invasions. The invasive fire ant Solenopsis invicta (Formicidae, Hymenoptera) is a model system for understanding the dynamics of invasive social insects and their biological control. However, little is known about microbes as biotic factors influencing the success or failure of ant invasions. This pilot study is the first attempt to characterize and compare microbial communities associated with the introduced S. invicta and the native Solenopsis geminata in the USA. Using 16S amplicon 454 pyrosequencing, bacterial communities of workers, brood, and soil from nest walls were compared between neighboring S. invicta and S. geminata colonies at Brackenridge Field Laboratory, Austin, Texas, with the aim of identifying potential pathogenic, commensal, or mutualistic microbial associates. Two samples of S. geminata workers showed high counts of Spiroplasma bacteria, a known pathogen or mutualist of other insects. A subsequent analysis using PCR and sequencing confirmed the presence of Spiroplasma in additional colonies of both Solenopsis species. Wolbachia was found in one alate sample of S. geminata, while one brood sample of S. invicta had a high count of Lactococcus. As expected, ant samples from both species showed much lower microbial diversity than the surrounding soil. Both ant species had similar overall bacterial diversities, although little overlap in specific microbes. To properly characterize a single bacterial community associated with a Solenopsis ant sample, rarefaction analyses indicate that it is necessary to obtain 5,000-10,000 sequences. Overall, 16S amplicon 454 pyrosequencing appears to be a cost-effective approach to screen whole microbial diversity associated with invasive ant species.

Bacterial Communities in the Midgut of Ponerine Ants (Hymenoptera: Formicidae: Ponerinae)

“…This characteristic of their colonies could be evolved in the ants to reduce the effects of these bacteria by allowing uninfected queens to maintain the production of males in the nest. However, the opposite was observed to the ant Solenopsis, where Wolbachia infection was prevalent in monogynous colonies (Ishak et al, 2011).…”

“…and are known to be present in a number of ant species (Funaro et al, 2011;Ishak et al, 2011;Sapountzis et al, 2015). However, previous studies (Funaro et al, 2011) have found that these bacteria are not always present in different subcastes within a single ant colony or different colonies from the same population, indicating that these microorganisms are not essential for the development of the host species.…”

“…In O. bauri, neither of the two bacterial genera mentioned above were detected. Ishak et al (2011) explored the microbiome of the ant Solenopsis geminata, which has a more granivorous diet, using a massive parallel sequencing, and they found a high abundance of Spiroplasma in workers and that is why they suggested it to be an important partner for this ant. Therefore, considering that these bacteria infect ants with different diet it is possible to predict that Spiroplasma and Mesoplasma are likely mutualists and have more immunologic instead of nutritional role by inhibiting the occurrence of a greater diversity of bacteria, including potential pathogens, protecting the host ants against massive infection by other prokaryotic microorganisms.…”

“…Nitrogen-fixing bacteria were also observed in a great diversity of ants and it is has been linked with the evolution of herbivory in ants (Russel et al, 2009). In this sense, many researches have attempted to characterize microbial communities associated to ants and their putative role to improve host fitness (Eilmus & Heil, 2009;Ishak et al, 2011;Anderson et al, 2012;He et al, 2014).…”

Hydrocarbon-Degrading Bacteria and the Bacterial Community Response in Gulf of Mexico Beach Sands Impacted by the Deepwater Horizon Oil Spill

“…PCR amplification was performed using the primers Gray28F and Gray519r (Table 1) (31), and sequencing reactions utilized a Roche 454 FLX instrument (Roche, Indianapolis, IN) with Titanium reagents, titanium procedures, a one-step PCR, and a mixture of Hot Start and HotStar high-fidelity Taq polymerases. After sequencing, all failed sequence reads and low-quality sequence ends and tags were removed, and sequences were depleted of any nonbacterial ribosome sequences and chimeras using custom software (21), as has been described previously (1).…”