Microbial Ecologist Danielle Rutkowski Receives Early Career Award

Microbial ecologist Danielle Rutkowski has just received a Royal Entomological Society Early Career Entomology Award, “Highly Commended,” for her research piece, “Bee-Associated Fungi Mediate Effects of Fungicides on Bumble Bees,” published in Ecological Entomology in February 2022.  

Rutkowski, a National Science Foundation Postdoctoral Fellow in Biology at Iowa State University, received her doctorate in 2024, working with major professors Rachel Vannette and Richard “Rick” Karban, now UC Davis distingushed professor emeritus.

Vannette, associate professor and vice chair of the UC Davis Department of Entomology and Nematology, is a co-author of the paper, along with then UC Davis students Eliza Litsey and Isabelle Maalouf. Litsey went on to receive her master’s degree in entomology in 2024. Maalouf received her bachelor’s degree in 2019.

The article announcing winners is posted on this site,  RES Journal Early Career Entomologist Awards 2021-2023 - Royal Entomological Society. Rutkowski's paper is in a Virtual Issue.

The abstract: 

1. Bumble bees are important pollinators that face threats from multiple sources, including agrochemical application. Declining bumble bee populations have been linked to fungicide application, which could directly affect the fungi often found in the stored food and gastrointestinal (GI) tract of healthy bumble bees.
2. We test the hypothesis that fungicides impact bee health by disrupting bee–fungi interactions. We examined the interactive effects of the fungicide propiconazole and fungal supplementation on the survival, reproduction and microbiome composition of microcolonies (queenless colonies) using two species, Bombus vosnesenskii and B. impatiens.
3. We found that in B. vosnesenskii, fungicide exposure decreased survival, while fungal supplementation mitigated fungicide effects. For B. impatiens, fungicide application had no effect, but fungal supplementation improved survival and offspring production.
4. Fungicides reduced fungal abundance in B. vosnesenskii microcolonies, but not in B. impatiens, where instead fungal addition decreased fungal abundance (ITS copy number). Fungal composition varied between treatments but differently between bee species. In B. impatiens, fungal addition increased microbiome diversity. In B. vosnesenskii, the abundance of the pathogen Ascosphaera was negatively associated with survival, while the yeast Zygosaccharomyces was positively associated with survival.
5. Our results highlight that bumble bee species differ in response to fungicides and in the nature of bee-fungi associations. Fungicides can alter bee–fungi interactions with consequences for bee survival and reproduction, and exploring the mechanisms of such interactions, including interactions among fungi in the bee GI tract, may offer insights into bumble bee biology and conservation strategies.

"Through Danielle's rigorous initial dissertation chapter and presentations at national meetings, her work has changed the dialogue in the field, emphasizing the potential effects of fungi on bee ecology and evolution," Vannette said. "Whereas previously the insect microbiome was primarily characterized by describing bacteria, Danielle’s work--along with others--shows that fungi can be important mutualists to important groups of insects and may mediate effects of agrochemicals on pollinators. I have already seen this new perspective being reflected in recently published papers and projects of new graduate students studying bee microbiomes."

While at UC Davis, Rutkowski mentored five undergraduate students, all of whom are co-authors on at least one paper, Vannette said, and nearly all have pursued graduate work in entomology or a related field.  Rutkowski is also an artist and includes her graphics of bumble bees on her website, https://beefungi.wordpress.com/.

In 2023, Rutkowski’s paper,  “Bees Just Wanna Have Fungi: A Review of Bee Associations with Non-Pathogenic Fungi,”  won an Editor’s Choice Award from the Federation of European Microbiological Societies (FEMS). The paper, co-authored by Vannette and then undergraduate student Makena Weston in the Vannette lab, appeared in the August 2023 issue of FEMS Microbiology Ecology.  (Access the link)

The abstract:

"Bee–fungus associations are common, and while most studies focus on entomopathogens, emerging evidence suggests that bees associate with a variety of symbiotic fungi that can influence bee behavior and health. Here, we review nonpathogenic fungal taxa associated with different bee species and bee-related habitats. We synthesize results of studies examining fungal effects on bee behavior, development, survival, and fitness. We find that fungal communities differ across habitats, with some groups restricted mostly to flowers (Metschnikowia), while others are present almost exclusively in stored provisions (Zygosaccharomyces). Starmerella yeasts are found in multiple habitats in association with many bee species. Bee species differ widely in the abundance and identity of fungi hosted. Functional studies suggest that yeasts affect bee foraging, development, and pathogen interactions, though few bee and fungal taxa have been examined in this context. Rarely, fungi are obligately beneficial symbionts of bees, whereas most are facultative bee associates with unknown or ecologically contextual effects. Fungicides can reduce fungal abundance and alter fungal communities associated with bees, potentially disrupting bee–fungi associations. We recommend that future study focus on fungi associated with non-honeybee species and examine multiple bee life stages to document fungal composition, abundance, and mechanistic effects on bees."

Rutkowski,  a member of the Amber Crowley-Gall lab at Iowa State University, writes on her website that  she is "interested in the interactions between social bees and their nest microbiomes, especially symbiotic yeasts. I am currently studying the chemical ecology bee-yeast interactions, and how these microbes can influence bee behavior and bee health through suppression of bee antagonists and alteration of nest microbial communities."

Resources:

• Danielle Rutkowski: Symbiotic Fungi Associated with Social Bees, Bug Squad blog, May 16, 2024
• Behind the Scenes: Danielle Rutkowski Coordinating Picnic Day Activities at Briggs Hall, UC Davis Department of Entomology and Nematology, April 20, 2022