Wild bees, nesting in Argentinian crop fields, were recently found constructing nests entirely made of the flimsy plastic packaging material left on farms.
From 2017 to 2018, researchers at Argentina's National Agricultural Technology Institute crafted wooden, artificial nests for wild bees. Unlike bee species that have a large hive with queens and workers, wild bees burrow into nests to individually lay larvae. The constructed nests fit together like long rectangles with a narrow, hollow opening that allowed wild bees to crawl inside and fill it with cut leaves, twigs, and mud.
Sixty-three wooden nests were constructed, and three were found lined entirely with plastic. Similar in size and shape to a fingernail, the bits of plastic had been carefully cut by bees and arranged in an overlapping pattern in their nests. Based on the material, researchers think the plastic may have come from a plastic bag or film, which has a similar texture to the leaves bees typically use to line their nests.
Of the three plastic nests, one had not been finished, meaning the bee did not use it to lay her larvae, Science Alert reports. In the remaining two, one larva died and the other was not found, leading the researchers to believe it survived.
What does it mean for bees?
This new research, published in the journal Apidologie, documents the first time bees have been seen making nests only out of plastic, but for years scientists have known bees were incorporating plastic into their building materials.
In 2013, a paper published in Ecosphere outlined how bees were using plastic films and foams to line nests in urban areas throughout Toronto, Canada. Similar to the bees in Argentina, the wild bees observed in Canada cut pieces of plastic that resembled the leaves they commonly use.
Notably, the Canadian study found it wasn't just flaps of plastic bags the bees were using. Plant resins, which can be fashioned into anything from gum to latex, often bind a bee's building materials together. But some individuals, they observed, were hauling a plastic-based caulk back to their nests to use instead.
Both studies noted that more research needs to be done before scientists can outline the potential impact plastic might have on bees, but the nest building shows that bees are highly adaptive to changing environments. In both places, leaves were readily available as a building material.
“It would demonstrate the adaptive flexibility that certain species of bees would have in the face of changes in environmental conditions,” the study’s lead author Mariana Allasino wrote in a press release translated from Spanish.
Hollis Woodard, an entomologist who studies bees at the University of California Riversides Woodard Lab, isn’t surprised to see bees hauling plastic to their nests.
“I think it’s really sad,” she says. “It’s another example of the rampant use of materials that end up in places we don’t intend them to.”
Plastic often presents a threat to wildlife in the form of microplastics, the incredibly tiny bits of plastic that form as larger plastic trash breaks down. Microplastics are a danger to the animals that mistake them for food, which many do, especially in marine environments. No study, however, indicates that bees might be consuming plastic.
Among the dangers that bees face are pesticides, habitat destruction, and exposure to viruses or parasites.
Researchers have speculated that plastic may form a barrier against common nest issues like mold and parasites.
If the bees are in fact choosing plastic over natural materials, it wouldn't be the first time animals have used trash to their advantage.
Sparrows and finches line their nests with cigarette butts to ward off parasitic mites, and black kites in the Italian Alps collect bright strips of plastic to decorate their nests and attract mates.
“It would take a lot more research to know what this means for the bees themselves,” says Woodard. “Sure it’s possible it might afford some benefits, but that hasn’t been shown yet. I think it’s equally likely to have things that are harmful.”