Professor Rachel Vannette: 'Ski With a Scientist'

Ski with a scientist?

Yes! That’s what occurred when community ecologist (and veteran skier) Rachel Vannette, professor and vice chair of the UC Davis Department of Entomology and Nematology, led a program on “Bees in Winter Survival Mode” in a Ski with a Scientist scientific event hosted by the UC Davis Tahoe Environmental Research Center (TERC).

The attendees--all on skis or snowboards--learned “where bees go in the winter” and “how they survive” during the 90-minute afternoon program, held Feb. 28 at the Palisades Alpine Meadows,  located at Alpine Meadows, Calif., on the north shore of Lake Tahoe.

The event, with limited enrollment and a waiting list, drew the maximum 15 attendees, plus several TERC educators and mountain hosts from Palisades Tahoe Alpine Ski Resort. 

“I talked about the different strategies that bees use to survive the winter, contrasting honey bees, bumble bees and solitary bees,” said Vannette, a TERC research affiliate. She discussed how young digger bees (genus  Anthophora), which overwinter in brood cells in underground burrows or tree holes, are susceptible to mold and fungi. “Fungal pathogens are a main source of mortality for many bee species,” Vannette told the attendees. “In some populations, that’s responsible for over 70 percent of young bee deaths.” 

TERC educators also shared information on the geology of the region, reforestation in the Tahoe basin following fire, and how the snowpack season is changing. 

The attendees, all in ski attire, including googles, maintained their balance with ski poles planted firmly in the snow, as they gathered around the professor to learn about bumble bees (genus Bombus) and digger bees. They skiied or snowboarded with the professor to multiple locations. 

It was Vannette’s first Ski with a Scientist event, which is patterned after “Ski with a Ranger,” a free conservation program hosted by the Heavenly Mountain Resort and the USDA Forest Service. 

Skiing was no challenge for the UC Davis professor. "My parents put me on skis before I turned 2."  

Ski with a Scientist takes place every Friday at 1 p.m. through March 28 at the Palisades Tahoe Alpine Ski Resort.   Like Ski with a Ranger, it is free and family friendly.

Vannette, an international leader in microbial ecology, studies interactions between plants, insects and microbes, focusing her research on the chemical and microbial ecology of plant-pollinator interactions and how microbes influence plant defense and resistance against insect pests. A member of the UC Davis Entomology and Nematology Department  since 2015, she  was named a five-year Chancellor’s Fellow in 2023 and a Hellman Fellow in 2018. She holds a doctorate in ecology and evolutionary biology (2011) from the University of Michigan.

The Vannette lab is a team of entomologists, microbiologists, chemical ecologists, and community ecologists trying to understand how microbial communities affect plants and insects.

“Much of the work in my lab focuses on how microorganisms affect plant defense against herbivores and plant attraction to pollinators,” Vannette related. “For example, we are interested in understanding the microbial drivers of soil health, which can influence plant attractiveness to herbivores and the plant's ability to tolerate or defend against damage by herbivores. In addition, we are working to examine how microorganisms modify flower attractiveness to pollinators. This may have relevance in agricultural systems to improve plant and pollinator health.”

TERC, dedicated to interdisciplinary research and education, seeks to “advance the knowledge of aquatic and terrestrial ecosystems and their interactions within natural and developed Earth systems, and to communicate science-informed solutions worldwide,” according to its website.

Its vision is three-fold:

1. To achieve healthy aquatic and terrestrial ecosystems through scientific understanding and education for the benefit of communities locally and globally.
2. To guide the preservation of a resilient and sustainable ecosystem at Lake Tahoe for generations to come. 
3. To provide objective scientific knowledge to the public, school children, private industry, government agencies, and elected officials.

Reporter Eli Ramos of the Tahoe Daily Tribune covered Vannette’s talk on bees and published the piece, titled “Tahoe’s Bees May Use Fermentation and Bacteria to Survive the Winter,” in the March 4th issue.

“On the whole, insects can’t tolerate freezing weather, so adult bees have a variety of strategies to survive,” Ramos wrote. “Some bumble bees create hibernacula: refuges from cold temperatures, often in plant material like pine duff, that keep them just above lethal temperatures. Others drink up sugar alcohols before the season starts, which essentially act as antifreeze in their systems, keeping their body functioning.”

“However, some bees spend the winter as larvae, laid on top of food stores that they eat during the season, until they emerge as adults in spring,” Ramos continued. “Here in the Tahoe area, chimney bees, leafcutter bees, and some bees in the genus Anthophora face the snow as newly hatched young.”

When fungi feed on the food stores meant for bees, Ramos described it as an image “straight out of a horror movie…to avoid this, bees have developed a strategy to preserve this food. One method is through fermentation.”

 “It’s kind of like making kimchi or kombucha—they ferment their provision with the lactobacillus bacteria, which acidifies the food and makes it more stable,” Vannette said.

“Lactobacillus can be found in fermented food like kimchi, sauerkraut, and yogurt, but bees are likely deriving it from the flowers that they consume,” Ramos wrote. “Vannette’s lab is currently researching what plants can create or host the bacteria.”

“Even more unusual is that some bees have created a new, unique strain of Streptomyces that acts as an anti-fungal for their brood cells,” Ramos pointed out. “Streptomyces is the largest source of antibiotics that humans use—this new strain could help researchers develop new drugs and medication; especially as antibiotic resistance is on the rise. Now, Vannette’s lab is studying where the strain originated and how it was passed down.”

Vannette told the reporter: “I’ve always been interested in the natural world and studying it, pursuing scientific knowledge. And this application to other fields, such as food preservation and medical use really excites me. By looking to the natural world, especially to insects that are so threatened by fungal pathogens, we can find new applications of chemistry and biology that can expand our understanding.”