The abundance and diversity of cuticular microbes differ on arboreal and terrestrial tropical ants

Ants’ foraging behaviors expose them to a range of microorganisms. Formicidae defenses such as use of the metapleural gland and grooming limit the microbes found on the cuticle; however, environmental conditions may still impact microbial loads. We sampled the cuticular microbes on arboreal and terrestrial foragers from sixteen genera of ants found in tropical rainforests of Panama. The number of colony forming units (CFUs) of bacteria and fungi from cuticular washes were quantified, and diversity was further determined based on morphological characteristics. Overall, 11 bacterial morphotypes and 56 fungal morphotypes were cultured. Arboreal foragers relative to terrestrial foragers exhibited lower bacterial CFUs, yet greater bacterial diversity per individual. No significant difference in the number of fungal CFUs was found between the two groups, yet terrestrial individuals demonstrated greater fungal diversity per individual. The overall bacterial and fungal load varied by ant genera. Thirty-six percent of bacterial morphotypes and 29% of fungal morphotypes were found to be unique to either arboreal or terrestrial foragers. Nesting and foraging behaviors as well as ant defenses characteristic of the different genera likely influenced cuticular microbes.