Exploring the effects of the fungal symbiont Kodamaea ohmeri on Aethina tumida

Small hive beetles (SHBs; Aethina tumida) are an important European honey bee (Apis mellifera) pests that damage hive products and brood. Despite its impact on affected hives and apiaries, little is known about the basic biology of SHBs. A particularly important aspect of A. tumida biology that likely contributes to its success, is the fungal symbiont Kodamaea ohmeri. This fungus is present internally and externally during each A. tumida life stage. Kodamaea ohmeri produces attractive volatiles through the fermentation of waste and hive products, resulting in increased adult SHB presence in the apiary. We hypothesize that reducing the internal presence K. ohmeri could disrupt this facultative relationship, and  negatively affect A. tumida success as a pest. We have developed and are refining an oral exposure bioassay that delivers the fungicide amphotericin B to SHB larvae. Feeding bioassays are performed using agarose pellets containing carbohydrate and protein sources, along with amphotericin B. Surface sterilized A. tumida fed amphotericin B (1 ppm) resulted in fewer colony forming units (CFUs) when extracts were plated on chloramphenicol-treated Saurbaroud’s dextrose agar plates. This indicates that we can diminish the internal presence of K. ohmeri. Disrupting this microbe-insect interaction could be an approach to affect growth and lead to the development of selective A. tumida management tools.