11 February 2014

Bees using scavenged plastic to build hives

by Will Parker

The scientists who discovered that urban bees are using plastic bags and building sealant to construct hives say it demonstrates bees' resourcefulness and flexibility in adapting to a human-dominated world.

The study, published in the journal Ecosphere, was carried out by University of Guelph researchers Scott MacIvor and Andrew Moore. MacIvor says it's an important discovery because; "although researchers have shown adverse impacts of the material on species and the ecosystem, few scientists have observed insects adapting to a plastic-rich environment."

Figuring out that the bees were using plastics in place of natural materials took some detective work. It all began when Moore analyzed a grey "goo" that MacIvor had discovered in the nests of one kind of bee, Megachile campanulae, which normally uses plant resins to build its nests. "Scott thought it might be chewing gum originally," Moore said.

The team used a scanning electron microscope and X-ray microanalysis to determine the elements in the sample and infrared microscopy to identify polymers.

They found that the bees were replacing plant resins with polyurethane-based exterior building sealant in their brood cells (created to rear larva).

The researchers also discovered another kind of bee, Megachile rotundata, an alfalfa leafcutter, using pieces of polyethylene-based plastic bags to construct its brood cells. The glossy plastic replaced almost one-quarter of the cut leaves normally used to build each cell.

Further analysis showed that the bees chewed the plastic differently than they did leaves, suggesting that the insects had not mistakenly collected the plastic. "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.

The study notes that in both cases, larvae successfully developed from the plastic-lined nests. Interestingly, the young bees emerged parasite-free, suggesting plastic nests may benefit bees by impeding parasites.

The nests containing plastic were part of a large-scale investigation of the ecology of urban bees and wasps, a project involving numerous citizen scientists. The nest boxes are located in Toronto and the surrounding region in backyards, community gardens and parks and on green roofs. They are used by a variety of bee species.

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Source: University of Guelph