B. apis is a bacterium found in honeybee hives, especially in nectar and royal jelly stores, and in the little rooms called cells where larvae live. Scientists at Indiana University really love bees, and they are working hard to understand the role of the microbiome of the European honeybee. Earlier work has indicated that the presence of B. apis is correlated with increased resistance to the nasty Nosema fungal infections that have devastated honeybee hives all around the world. This suggests that the bacterium has a protective effect.
In the new study, a team led by Irene Newton showed that B. apis can inhibit the growth of two common fungal pathogens, Beauveria bassiana that infects 70 percent of all known insect species and is actually used as a biological insecticide to kill herbivorous insect pests like mites, and the more relevant pathogen Aspergillus flavus that targets honeybee brood and can also infect crop plants. When B. apis was grown together with either fungus – what microbiologists call co-culturing – the fungi were severely impaired in the ability to form spores. The authors suggest that this not only reduces the occurrence of infection and disease among bees in the hive, but it may also reduce the likelihood that bees who go out foraging could spread the infection to another hive or to other insects.
The protection offered by B. apis to honeybees makes it a solid biocontrol candidate. The population of B. apis within a hive can be increased by delivering more bacterial cells within a sugar solution that bees feed on. Sugar/syrup solutions are used routinely by beekeepers to supplement the diet of bees who struggle to gather enough nectar during winter.