Bacterial symbionts protect honey bees from fungal pathogens
Contributed by: Irene Garcia Newton and William Harcombe
Agriculture, Animals, Bacteria, Competition, Conservation, Ecology, Environmental change, Experimental, First-generation, Fundamental research, Fungi, Immune System, Lab, Latino/a/x, Mutualism, North America, Organismal biology, Protection from Symbionts, Terrestrial, Woman
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Miller, D. L., Smith, E. A., & Newton, I. L. G. (2021). A bacterial symbiont protects honey bees from fungal disease. mBio, 12(3), e00503-21. link
Slide 1: Researcher’s Background
Dr. Newton is a microbiologist at Indiana University and she studies functional and evolutionary genomics of symbiotic microbes.
PB: Why did you become a biologist?
IGN: Because I had a great mentor as an undergraduate researcher who convinced me that I could do it and made it exciting to me.
PB: What is your favorite part about your job?
IGN: Teaching others about what I find fascinating.
PB: What obstacles have you overcome to get where you are?
IGN: My mother and father came to the U.S. as undereducated immigrants and my siblings and I were the first to go to college. It was difficult to navigate academia when you don’t have a guide to tell you what’s what.
PB: What advice do you have for aspiring biologists?
IGN: Keep your eyes open and be a good “naturalist”, even in molecular biology – observations are critical to making new discoveries.
PB: Do you feel that any dimension of your identity is invisible or under-represented/marginalized in STEM?
IGN: I am a latina but I have never felt marginalized in STEM. I have felt that women, and people of color, do the majority of the service work – the unpaid labor – of academia, and this can be a heavy emotional burden.
Slide 2: Research Overview
Take home message of study
Honey bees (Apis mellifera) have a symbiotic relationship with Bombella apis – bacteria that block the growth of the fungal pathogen Aspergillus flavus on honey bee larvae. It appears that the bacteria secrete an antifungal metabolite.
At Indiana University, we maintain our own honey bee colonies for our research. Most of the time we perform experiments in a controlled laboratory environment, which means moving larvae into the lab. Studying honey bee larvae in the Newton lab means rearing them by hand! Each of these larvae are hand-fed royal jelly and sugars daily for experiments in which we modulate their microbiome.
Slide 3: Key Research Points
a. Forty-five honey bee larvae collected from the apiary were reared on sterile larval diet, some with and some without the bacterial symbiont, B. apis. After pupation, each honey bee was inoculated with 103 spores of the fungus with or without the bacterial symbiont.
b. Of the pupae inoculated with the fungus A. flavus, those without the bacterial symbiont B. apis all showed signs of infection within 48 hours.
c. and d. Whereas 66% of those with B. apis never developed infections.
e. Pupae with B. apis that did become infected had lower intensity infections, with fewer spores being produced by A. flavus than those without the symbiont.
Fungi are the leading cause of insect disease, contributing to the decline of wild and managed populations. For ecologically and economically critical species, such as the European honey bee (Apis mellifera), the presence and prevalence of fungal pathogens can have far-reaching consequences, endangering other species and threatening food security. Our ability to address fungal epidemics and opportunistic infections is currently hampered by the limited number of antifungal therapies.