TRAVERSE CITY — Michigan is home to about 465 bee species, according to a first-ever census that scientists hope will provide information helpful for conserving the insects, which perform the vital chore of pollinating crops and wild plants.
The number might surprise people who can tell the difference between a honeybee and a bumblebee but not much else, scientists said. In fact, there are about 4,000 bee species in the U.S., and some Western states have at least twice as many as Michigan does.
Yet Michigan's total is a bit higher than those recorded in some neighboring Great Lakes states such as New York (447), Indiana (420), Wisconsin (391) and Pennsylvania (371).
“They're mostly species that people wouldn't know about, or maybe they've seen them on flowers in their garden and didn't even realize they're bees,” said Rufus Isaacs, a Michigan State University entomology professor and co-author of a paper about the recently completed Michigan tally.
One reason for their obscurity is that roughly 70 percent of bee species nest underground, laying eggs and delivering pollen from flowers to feed their young. Others find refuge in secluded places such as tree cavities.
Keeping track of bees is taking on new urgency amid reports of sharp population declines in much of the world. More than 40 percent of invertebrate pollinator species, primarily bees and butterflies, are in danger of extinction, said a 2016 report by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. Among likely causes are pesticides, habitat loss, diseases and climate change, it said.
The report said 75 percent of the world's food crops depend at least partly on pollination, as do nearly 90 percent of wild flowering plants.
Studies in North America have been hampered by inadequate samples and lack of other information, Isaacs and colleagues said in their Michigan paper, published recently in the journal Zootaxa. They said their census should provide a baseline that future researchers can use to measure population trends in the state.
"Unfortunately, we don't have a lot of consistently sampled areas where we can go back and say, 'This was the bee community 50 years ago and this is the bee community today' and measure whether we see any change," Isaacs said.
Led by Jason Gibbs, formerly with Michigan State and now an assistant professor at the University of Manitoba in Canada, the scientists built their list from published literature, museum specimens, database records and field observations. Gibbs made the first recorded observations of some types in Michigan State's campus horticultural gardens. "Citizen scientists" provided photos of others.
While 465 are included, evidence for more than a dozen is poor and there may be others yet to be discovered, the paper said.
It's likely that most species identified in older records still exist in Michigan, although a few may have died out, Gibbs said. The rusty patched bumblebee, which this year was listed as endangered in the continental U.S., hasn't been spotted in the state since around 2000.