Bumble bee populations in the U.S. have declined sharply over the past 20 years, with some species plummeting over 90 percent, according to a new study.
Scientists at the University of Illinois assessed the populations of eight of North America’s 50 species of wild bumble bees. University of Illinois entomology professor and head researcher Sydney Cameron says four of the species “are significantly in trouble.”
“They could potentially recover; some of them might. But we only studied eight. This could be the tip of the iceberg,” Cameron said.
The scientists said the bumble bees exhibit low genetic diversity and are more likely to be infected with Nosema bombi, a parasite that has afflicted European bumble bees. Both of these factors may have contributed to the sudden die-off, which has taken place in the last two decades.
“It’s just an association. There may be other causes,” Cameron said, adding that climate change appears to play a role in the drop-off of bee populations in Europe.
The relative abundance of the four species in question has dropped by as much as 96 percent, and the surveyed geographic ranges of those species have diminished by 23 percent to 87 percent.
The study raises serious concerns because bees are essential for the pollination of crops such as tomatoes, peppers and berries.
“We need to start to develop other bees for pollination beside honey bees, because they are suffering enormously,” he added.
The three-year study was published in the Proceedings of the National Academy of Sciences (PNAS).