Evaluating pesticide sensitivity of the honey bee (Apis mellifera L.) microbiome

Microflora were isolated from Apis mellifera L. digestive tracts, bee bread, and pollen. A diverse set of culturable fungi, yeasts, and bacteria were found and maintained on Potato Dextrose Agar or Nutrient Agar.

An antagonism test between eight of the fungal isolates against the chalk brood pathogen, Ascosphaera apis, showed that each asymptomatic fungus significantly (P<0.05) inhibited the pathogen’s growth. Measurements of the radial growth of A. apis in vitro toward and away from each microbe were compared and analyzed using a 2-Sample T-test.

Asymptomatic fungal isolates were genetically identified by sequencing of the internal transcriber spacer regions 1 and 4.  Sensitivity of these isolates to important fungicides was also measured and analyzed.

This research suggests that asymptomatic honey bee microflora may play a role in the prevention of some fungal pathogens in the hive. Fungicides, while not directly affecting the honey bee, may affect the functional role of these microbes thus indirectly affecting the health or behavior of the honey bee.