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One of the most charismatic faces of the climate crisis and our changing world is the humble honey bee. According to the USDA, honey bees are responsible for every one in three bites of food we eat, and without them, it has been estimated that yields on more than 30% of agricultural land worldwide would decrease. But heavy colony losses, linked to environmental factors such as pesticide use, viral infections, and extreme weather, are a problem faced by many beekeepers. Researchers like Audrey Parish, a graduate student from Indiana University, are looking into ways to help the bees; in Audrey’s case, looking to bolster honey bees against viral disease by studying their microbiome. As research suggests, microbiomes are extremely complicated and can have wide-ranging, if poorly understood, effects on health. The human gut microbiome is famously intricate, with humans being estimated to host somewhere in the range of one thousand different species within our gut. Honey bee adults, by comparison, only host five to ten species in their gut microbiome, with honey bee larvae hosting even fewer. However, as Audrey hypothesizes, even a single microbe can play a critical role in their health.

What appears to be a critical player in the larval bee’s microbiome is a bacterium called Bombella apis, which has so far been the only bacterium isolated that is able to survive within royal jelly, a strongly antimicrobial food source provided to honey bee larvae during their development. Because of this, B. apis has also been one of the few microbes isolated from the gut of larval bees, along with a few Fructobacillus and Lactobacillus species. Audrey set out to determine what specific role B. apis had in larval development.  When she performed a chemical analysis on a synthetic larval diet containing about 50% royal jelly with and without B. apis, she found that the presence of the bacterium significantly altered the amino acid concentration of the diet, showing a decrease in non-essential amino acids observed alongside an increase in essential amino acids. To explore this further, Audrey raised bees in the lab under poor or rich diet conditions, and then provided them with B. apis or a saline control. She found that bees with a poor diet but that had B. apis were not much smaller than bees with rich diets without the bacterium. From her results, it was clear that B. apis helps to buffer the nutrition of growing bees. Audrey decided to take this one step further and look at potential interactions between B. apis, diet, and viral infections. It is known that bees with poor diets are more likely to succumb to viral infections. Would the presence of B. apis help protect bees against viral infection? To answer this question, Audrey collaborated with Dr. Adam Dolezal at the University of Illinois Urbana-Champaign, to investigate larval viral infection. Using a fatal larval virus called sacbrood virus, Audrey found that if B. apis is present throughout larval development, larvae challenged with sacbrood virus had a 25% better chance of survival than larvae without the bacterium. This summer, Audrey plans to return to UIUC to continue her collaboration and scale up these experiments to also consider the compounding effects of poor diet. 

Identifying factors which help to buffer bees against changing conditions such as low nutrition and viral infections could be key to protecting the honey bee species. And because honey bee health is so intricately connected to human health, efforts to safeguard the bees are also directly safeguarding our own futures in the face of a rapidly changing environment.

This summary was written by Sierra Bedwell, Graduate Student, University of Illinois Urbana-Champaign.