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.

Lactic Acid Bacteria Are Prevalent in the Infrabuccal Pockets and Crops of Ants That Prefer Aphid Honeydew

“…Wolbachia was dominant in Formica ants in this study, and its relative abundance exceeded 50% in the midguts and hindguts of workers, larvae, and pupae. Wolbachia has been estimated to infect 34% of ant species (Russell, 2012), which is mainly localized in the germline and various somatic tissues of workers and queens (Andersen et al, 2012;Frost et al, 2014;Zhukova et al, 2017;Ramalho et al, 2018;Zheng et al, 2021). Based on our present results, we hypothesize that Wolbachia is transmitted vertically in Formica ants and restricted in the midguts and hindguts.…”

“…The elaborated proventriculus obstructs not only solid particles but also bacteria harbored in the food flow, resulting in the difference in bacterial communities between the crops and midguts. However, in Ponerinae, the proventriculus is not elaborated and cannot obstruct bacteria flow backward with the food, leading to the similarity of bacterial communities in the crops and midguts, this can be verified in our previous study on two ponerine ants (Zheng et al, 2021).…”

“…The flow of liquid food allows the microbe to pass through the digestive tract and be retained temporarily in the crop, and probably leading to the similarity in bacterial communities in the IBPs and crops. However, a previous study on bacterial communities in O. monticola and E. javanus has shown opposite results, in that the IBPs and crops exhibited different bacterial communities (Zheng et al, 2021). This is mainly due to the structural and functional differences of the IBPs between formicines and prey-feeding ants: the IBP is well-developed in prey-feeding ants (Edwards, 1980) and is more capable of obstructing solid particles and bacteria than in formicines, and thus leading to the differences in bacterial communities in the IBPs and crops of predatory ants.…”

“…Formica ants and L. niger harbor different bacterial communities and occupy different trophic levels compared to the ants studied in previous research (Russell et al, 2009). For instance, predatory ants (Ecitoninae, Dorylinae, Aenictinae and Ponerinae) at a high trophic level possess Entomoplasmatales (Mesoplasma and Spiroplasma) and Wolbachia (Funaro et al, 2011;Zheng et al, 2021). Functionally herbivorous ants (Formicinae and Myrmicinae) at a low trophic level house Blochmannia, Rhizobiales, Pseudomonadales, Xanthomonadales, Opitutals, Flavobacteriales, and Burkholderiales (Russell et al, 2009;Anderson et al, 2012;Poulsen and Sapountzis, 2012).…”

“…A recent study on the bacterial communities of two predatory ants, Odontomachus monticola Forel and Ectomomyrmex javanus Mayr, has shown that although bacterial communities differ significantly between the IBPs and guts of both ant species, they are similar in IBPs of workers and larvae in O. monticola. This provides meaningful information regarding the function of the IBP in ants (Zheng et al, 2021). The IBP can also prevent the invasion and spread of the microbial parasite Escovopsis in the workers of leaf-cutting ants (Little et al, 2003(Little et al, , 2006.…”