Waxworms make Holey Shopping Bags

A shameless boast, I take fewer than a dozen plastic shopping bags home from the grocery store each year (a trillion are manufactured). Discarded in garbage for burial in landfill, this non-compostable stuff awaits a post-Homo sapiens archeologist who learns how Anthropocene people trashed their planet. But beekeepers have another option for disposing of polyethylene. A dead hive. Not really practicable, but the idea connects with a new channel for Earth care.

When a bee colony deserted the hive, I saved the frames containing honey, boarded the entrance, and didn’t return to clean the interior for several weeks.

I was gobsmacked when I opened the boxes. The combs eaten to shreds were festooned in silken threads. Wax moths had snuck inside.

Galleria mellonella
One hungry waxworm (Pixabay)

Greater wax moths (Galleria mellonella), originating in Asia and now worldwide, depend on beehives to reproduce. Their eggs turn into plumptious caterpillars gorging on beeswax, and only a strong colony can beat back the invaders. Along with mites and hive beetles, wax moths are the bane of beekeepers.

A few years ago, biologists noticed holes appearing in plastic bags used to collect waxworms. Trained to be inquisitive, they set up an experiment, finding the plastic was eaten at a rate of 2 holes per worm-hour. Their results were published and another paper appeared in Current Biology.

They spun some in a blender to test the effects of caterpillar mush on plastic. It degraded. So, the plastic was digested, not just chewed. It is likely that bacteria in their gut were responsible, and the process probably benefited them by generating energy for metabolism. The long chains of hydrocarbon that make polyethylene turned into ethylene glycol, a substance used as an antifreeze in automobile radiators that is rather toxic to us, although it degrades quickly in soil.

There are unrelated bacteria that digest plastic, albeit slowly. Neither they nor waxworms can consume the mountains of plastic we generate, but that a synthetic compound formerly thought to be stable for eons is biodegradable gives hope that genetic engineering will develop a more efficient agent. Perhaps that can soften absolutist objections some people have toward GMOs.

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