Antimicrobial activity of gland secretions of the Asian needle ant, Brachyponera chinensis (Hymenoptera: Formicidae)

Ant glandular secretions and venoms are well known for having antimicrobial activity. The Asian needle ant, Brachyponera chinensis (formerly Pachycondyla) chinensis (Emery) is an invasive ant originally introduced in Georgia in the 1930s, but officially recognized as a pest since 2006. Since its introduction, it has become of increasing concern both for its competition with and displacement of native seed-dispersing ants, but also the allergic effect its venom has on humans. It has previously been shown that B. chinensis produces and uses antimicrobials to increase survival against bacterial infection, and that a closely related ant has venom with antibacterial properties. But less is known about the amount of microbes from the environment they carry on their cuticles, their survival against entomopathogens, and whether any of those secretions are incorporated into their nest environment. This study examined the antimicrobial activity of the metapleural gland secretions and venom of B. chinensis against gram-positive and gram-negative bacteria, and an entomopathogenic fungus known to exist in their soil environment, as well as their ability to survive exposure to these same entomopathogens. During survival trials, ant secretions were extracted from the filter paper of the Petri dishes they inhabited, tested for antimicrobial activity, and compared to the extractions from the ants themselves to determine which secretions are incorporated into their environment. Identification and quantification of these secretions from the nest material of B. chinensis could have important implications for their success as an invasive species, as well as for their Reticulitermes prey they cohabitate with.