Another bee, the Canadian native Megachile campanulae, normally collects sticky resins and sap from trees. However, the ecologists discovered polyurethane sealant incorporated into two out of seven of the insect's brooding chambers.
Although the collection may have been accidental, the ecologists said the bees' innovative use could be a useful adaptation to a human-dominated ecosystem, since the plastic may supplement scarce supplies of leaves. However, this didn't seem to be the case, they noted, since several nests contained only leaves and the nests with the plastic also incorporated leaves after the plastic had been glued into place. The bees simply may have used the plastic because of its structural similarity to the materials they naturally use.
Are People Worried About the Wrong Bees?
Plastic could have pros and cons for the bees. The plastic bags didn't stick together like leaves, which the bees chew into a natural glue. The bag-built nests crumbled easily.
On the positive side, the bag-nested bees didn't suffer attacks from parasites, although the polyurethane-using bees did. Research from the 70s found that when leafcutters nested inside plastic straws, they were safe from parasites, but died from mold because the polymers didn't let moisture escape.