Christy Bell, a researcher from University of Wyoming, searched Wyoming for four years looking for western bumble bees, furry black and yellow insects with distinctive white tails.
She concentrated on areas where the western bumble bee was historically recorded as residing. She set colorful traps that looked like flowers. She was one of the first researchers to quest for the western bumble bee in Wyoming and she didn’t find many. Her data shows that western bumble bee habitat has declined by almost 70% statewide.
In a study that was published in June 2020, Bell and several co-authors revealed that in the rest of the West, where these other researchers have much data, the facts are disturbing. Populations of this once common bee with a wide-ranging habitat have shrunk by a shocking 93% in little over 20 years.
The situation is dire enough that the US Fish and Wildlife Service is researching whether the western bumble bee should be added to the endangered species list. Another bee that is being considered for listing is the cuckoo bee or Suckley’s bee, a native to Wyoming. The strange twist is that the Suckley’s bee survives by preying on western bumble bee hives.
This 0:30-seconds video by Earth Rangers features the western bumble bee:
The role of bees in pollination and food production is essential. Without them, we won’t have food for ourselves or for many other wildlife. Most plants need bees in order to reproduce.
Lusha Tronstad, an invertebrate zoologist at the Wyoming Natural Diversity Database, who also studies western bumble bees, reminds us that bumble bees are generalist pollinators, which means they are not loyal to any one type of flower. They pollinate many different flowers.
We know very little about the western bumble bee. One thing that scientists have discovered is that a wide range of insects have plummeting populations. A recent special issue of the journal Proceedings of the National Academy of Sciences indicates that the number of insects around the world is declining by 1% to 2% every year due to pesticides, climate change and pollution as well as commercialized agriculture. That is alarming news for the future.
Bell believes that one of the most likely stressors in Wyoming is parasites.
Bumblebees are pros at pollinating tomatoes, cranberries, and blueberries, due to the “buzz pollination” technique they have mastered. When the bumblebee lands on a flower, it vibrates its flight muscles and shakes the flower until pollen falls out. If you get a chance to see this you will be captivated by the high-pitched buzz and the bees are adorable.
This 1:39-minute video by Smithsonian Channel shows bumble bees performing buzz pollination:
At one time both western and eastern (US) bumble bees were sent to Britain for breeding and pollination. When they returned to the US, they carried higher loads of parasites than they could fight. Researchers don’t understand why the eastern bumble bee survives with the load, while the western bumble bee is faltering.
In summer 2020, UW undergraduate researcher Maxwell Packebush focused on this. He collected bees around the southeastern corner of Wyoming, dissected 75 bumblebees and analyzed DNA samples of the organisms found in their guts. All of them had some sorts of parasites, but experts don’t know which parasites are deadly, and why. Those questions just scratch the surface on western bumble bees.
The US Fish and Wildlife Service plans to have a draft status assessment of the western bumble bee complete by Spring 2022. The agency is reviewing the best available science to better understand if a listing is warranted. Doug Keinath is recovery coordinator with the service’s Wyoming field office. He believes a listing might stimulate habitat improvement projects in the state.
If the bee is listed, this comes with protections that wouldn’t affect most people. Just like you can’t shoot a grizzly bear if you find one on your land, you couldn’t gas or poison a bumble bee colony if you saw one on your land.
Conservationists recently petitioned for the Suckley’s bee to be listed. It is a parasite because it survives by invading a bumble bee nest, killing the queen, and forcing the workers to raise its young. It is not doing well.
Keinath wonders how it works when a petition is made to list both predator and its prey simultaneously.
Wyoming has 25 native bumble bee species, and experts remind people to help these native bees. They all can benefit from less pesticide use, more native plants and gardens that are a little messy in winter.
Queen bees nest underground or in dead and decaying leaves. Letting these stay on the ground and waiting until after April to dig up the ground means more queens will survive into summer and reproduce.
Honeybees are not native to the US. They carry parasites that can be fatal to native bees and compete with them for food.
People can be citizen scientists and report bee sightings on apps like iNaturalist or Bumble Bee Watch. This helps track verified insect locations. The more data experts have, the more efficient conservation becomes.