A new study by a Canadian scientist reports two species of urban wild bees using plastic to build their nests.
Scott MacIvor, a researcher at Toronto’s York University has recently reported the surprising discovery of two species of urban wild bees building their nests with plastic. Not only and exclusively plastic, obviously, but still as part of their normal construction materials along with organic materials. Unlike honey bees, wild bee species are mostly solitary creatures. The females build individual small nests in which to lay their eggs. These nests are mostly found on the ground or in hollows in tree trunks or walls. To learn more about these fascinating creatures and protect them, Toronto city council has set up more than 200 nest boxes.
In the nests of one species - Megachile campanulae - the researcher found a greyish, chewing gum-like substance which analysis showed to be mainly composed of polyurethane. This grey goo was being used instead of plant resin like pine sap as a sealing material for the brood cells, where the larvae grow.
Nests of the other species, Megachile rotundata, however seemed to have been built directly with bits of plastic. This species, also known as the leaf-cutter bee, normally builds its nests by cutting leaves and bonding them together in a cigar shape. Here, some bits of leaves were replaced by bits of plastic bags. Why they have turned to plastic is not clear. Scott MacIvor’s observations suggest that the use of new materials seems not to interfere with larval development. But the researcher sees no ready explanation as to why bees use plastic to construct their nests where leaves and tree sap are widely available. One theory is that bees are opportunistic, so females may simply use the closest suitable material for building their nest in order to spend less time away from it and cut down on the risks it faces while they are out on a mission.