February 12, 2014
Plastic Waste Being Utilized As Nesting Material By Canada’s Urban Bees
April Flowers for redOrbit.com - Your Universe Online
Canada's bee population will be back hard at work pollinating, making honey and keeping busy doing bee things once the snows melt. A new study from the University of Guelph reveals that for two urban bee species, those "bee things" include making nests out of plastic waste.The findings, published in the journal Ecosphere, show that some bees use bits of plastic bags and plastic building materials to construct their nests. The researchers say that this is an important discovery because it shows the resourcefulness and flexibility of the bees' in adapting to a human-dominated world.
“Plastic waste pervades the global landscape,” said Scott MacIvor, a doctoral student at York University and a 2008 U of G graduate. Although prior studies have shown adverse impacts of plastic on species and the ecosystem, few scientists have observed insects adapting to a plastic-rich environment.
“We found two solitary bee species using plastic in place of natural nest building materials, which suggests innovative use of common urban materials."
Some detective work was needed to figure out that the bees were using plastics in place of natural material. That was the job of Andrew Moore, U of G's supervisor of analytical microscopy at Laboratory Services.
McIvor discovered a grey "goo" in the nests of one kind of bee, Megachile campanulae, that uses plant resins to build its nests. Moore then analyzed the goo.
“Scott thought it might be chewing gum originally,” Moore said. The goo was analyzed with a scanning electron microscope, which took highly detailed pictures of items. X-ray microanalysis was used by the researchers to determine the elements in the sample, as well as infrared microscopy to identify polymers. These methods can distinguish the finest detail on the surface of an animal hair.
The goo in M. campanulae's nest turned out the be polyurethane-based exterior building sealant, such as caulking. The researchers found that the bees' were occasionally replacing the plant resins in the brood cells, which are created in a nest to rear the larva.
Another species of bee, Megachile rotundata, an alfalfa leafcutter, was also found to be using pieces of polyurethane-based plastic bags to construct its brood cells. The researchers found that nearly one-quarter of the cut leaves normally used to build each cell had been replaced.
The research team discovered markings that revealed that the bees chewed the plastic differently than they did leaves. This suggests that the insects had not incidentally collected plastic, nor were leaves hard to find for the bees in the study area.
"The plastic materials had been gathered by the bees, and then worked – chewed up and spit out like gum – to form something new that they could use,” Moore said.
For both species of bees, larvae successfully developed from the plastic-lined nests. The researchers found that the larvae were parasite-free, suggesting that the plastic nests may physically impede parasites.
The nests that contained plastic were among 2,000 artificial nest boxes monitored by MacIvor in a large-scale project involving numerous citizen scientists investigating the ecology of urban bees and wasps. The boxes are located in the Toronto area in backyards, community gardens, parks and green roofs, and are used by a variety of bees.
“The novel use of plastics in the nests of bees could reflect the ecologically adaptive traits necessary for survival in an increasingly human-dominated environment,” MacIvor said.