As pollinators, honeybees are important part of the Earth’s ecosystem. Populations of the insect have been on the decline, causing concern about crops, and highway traffic may be a contributing factor.
A study published this week in the Sustainable Environment journal indicates that millions of bees are hit and killed daily by cars. To study bee mortality linked to traffic, researchers from Utah State University use affixed sticky traps to car bumpers across nearly 30 trips from 2019 to 2021.
“We found that on a sticky trap of 0.0186 m in size, we consistently recorded at least one bee per trip. Even trips of very short duration… or trips travelled at low speeds… resulted in bee mortality,” said the study authors. They noted that the shortest trip was 20 miles and the slowest average speed was 40 mph.
According to Penn State, “beekeepers across the globe have observed massive declines in managed honey bee populations,” as well as wild bee populations over the past decade.
In the U.S. alone, these bees contribute $20 billion each to agriculture and industries that depend on agriculture. As bee populations decline, there is an increased risk of small harvests and decreased food supply, which in turn could make food more expensive.
“Understanding what is driving these declines is a vital question for researchers, beekeepers, growers, and the public. Several factors are being investigated, including habitat loss, climate change, disease, and pesticide use,” said the university.
Other studies have shown how climate change has impacted bees. Authors of the recent study also noted that habitat modification, complete habitat loss and habitat fragmentation have impacted bees. In efforts to increase habitat areas for bees, roadside vegetation has been identified as a potential population supporter.
Data about bee mortality linked to traffic complicates that approach to supporting bee populations, the authors explained.
“Though roadsides be good bee habitat because they either 1) open up the dense forest canopy in mesic landscapes or 2) include more flowering plants because of increased runoff in arid landscapes, there may also be detriments,” they said. “Most importantly, bees that forage or nest near roads may be more likely to be hit by moving vehicles.”
Since the numbers included in the study rely on several assumptions, and the actual number of bees impacted may be higher or lower. Still, it is clear that cars are contributing to bee deaths.
“The consequences of their frequent collisions with vehicles extend well beyond a minor travel inconvenience,” said Utah State University researcher and study author Joseph Wilson. “In fact, the impacts of bee deaths, occurring minute-by-minute each day, may have a greater negative impact than we realized.”
Wilson said more research is needed to better understand how roadway design, roadway maintenance and vehicle design could be tweaked to decrease pollinator deaths.