Microbiomes of harvester ants - Do ants use biological control to protect their seed deposits?

Harvester ants (genus Pogonomyrmex) collect seeds and store them for food in subterranean chambers called granaries. These ants are important seed dispersers in native deserts, prairies and grasslands, such as prairies and Post Oak Savannahs of North and East Texas. Nothing so far is known about the mechanisms these ants use to prevent their stored seeds from spoilage. One possibility is that microorganisms secrete secondary metabolites that are in effect seed coatings that protect the seed from pathogens.
Using next-generation sequencing methods we investigate bacterial and fungal microbiomes associated with harvester ants and their stored seeds. Samples of ants, seeds, and chamber and outside soils as negative controls were collected near Tallahassee, Florida, from Pogonomyrmex badius. Bacterial and fungal DNA was extracted and the 16s rDNA and ITS was Illumina-sequenced to identify bacteria and fungus associated with ants, their seeds and the chamber soils.
Preliminary data shows that, while absent from surrounding soils, microbiomes of seeds are dominated by Actinobacteria, a group of bacteria often cultured by other insects as a form of biological control used to protect against pathogenic bacteria and fungi.  While we could not detect Actinobacteria on the ants, more in depth analyses and larger sample sizes will investigate the source of Actinobacteria and the bioactive substances they produce that the ants use to prevent seed spoilage.