15 years of bee sampling reveals the effects of extreme weather

Michigan is home to 465 bee species and each one plays a role in the states’ ecosystems. During a 15-year study of wild bees visiting blueberry fields during their blooming season, researchers caught an unexpected glimpse of how extreme weather events can impact bee populations highlighting the need for more long-term studies, says a Michigan State University researcher.

“There are few bee studies in the U.S. that have sampled bees for many years at the same location,” said Rufus Isaacs, a professor in the Department of Entomology and the Ecology, Evolution, and Behavior Program, “There are even fewer that use the same methods over more than a decade.”

The research was published May 8 in the journal Agriculture, Ecosystems and Environment.

Isaacs worked with Kelsey Graham, a former postdoctoral researcher who is now with the U.S. Department of Agriculture-Agricultural Research Service. Graham collected bees during the last sampling period and combined data from two former MSU students into the analysis.

During the study, bees were sampled during three separate periods in May and June during 2004-2006, 2013-2014 and 2017-2018. The bees were collected using brightly colored bowls full of soapy water located at 15 farms across southwest Michigan. Different bee species are active at different times of the year, nest in different places (in the ground or in the stems of plants) and have different host plants.

 Capturing bees. Photo courtesy of Emily May.

This study looked at a specific slice of the bees who were active during May-June and visited blueberry bushes while they were blooming. To the researchers' surprise, the very warm spring and hot summer of 2012 provided a unique opportunity to see how bee populations responded and recovered to the extreme weather event in subsequent years.  

“The very advanced spring in 2012 was so unique, and flowers were open when the frosts came in April and May" Isaacs said. “This wasn’t what we were trying to study but this helps explain the patterns we found.”

Read more at MSU Today.