The Cosmic Watchdog

Insects rank high among humankind’s go-to creatures for strangeness: Think movie monster inspirations or extreme biophysics (SN: 11/7/22). So of course scientists have already started testing insect willingness and ability to eat, of all things, plastic.

A new experiment sprinkles a dose of reality on just how effective this strategy might be in preventing the planet from drowning in plastics. It would take 100 mealworms 138 days, or about 4.5 months, to eat just one disposable COVID-era face mask, ecologist Michelle Tseng and colleagues calculate December 4 in Biology Letters. 

When it comes to plastic, bits smaller than 5 millimeters are especially worrisome. Researchers have linked these microplastics to higher risks of heart attacks and strokes, for instance (SN: 4/2/24). Earlier experiments showed that several species of insects could eat and degrade the stuff. Plump, hungry beetle larvae called superworms (Zophobas atratus) and yellow mealworms (Tenebrio molitor), sold in pet stores as food for other animals, will consume tidbits of polypropylene, polyurethane and three more kinds of plastic.

Tseng, of the University of British Columbia in Vancouver, wanted more realistic tests of insect plastic-eating. Almost all earlier research used powdered plastic or a brick of it; her team instead turned to the iconic, rectangular, tissue-y face masks. Some were made using classic polypropylene, others the plant-based plastic polylactic acid. The masks would give insects not just the basic polymer, but real-world additives from the manufacturer.

The team melted the mask plastic and abused it into microbits. And for more realistic dining, wheat bran was mixed in. “They started eating the face-mask granola pretty much right away,” Tseng says.

Eating plastic did not noticeably shorten the insects’ life span, she says. What ingesting all that microplastic does to their own edibility raises questions about fitting the insects into some sustainable food chain. Would they now be suitable to feed chickens? “Probably not,” Tseng says.

The bigger problem with saving the world from microplastics by deploying giant masses of hungry insect larvae is the pace. In intense COVID-19 times, the researchers point out, Asia alone used 2 billion medical face masks per day — an unimaginable endless buffet even for the relentless nibblers. 

A better way to use mealworms or other eaters of microplastics is for inspiration — exploring body chemistry and especially their inner microbial partners. That could lead to useful waste-breakdown hacks. Even with better chemistry, the researchers say the bigger point is this: Use less plastic.