Mealworms ate and digested nearly half the plastic fed to them at a laboratory in Vancouver, B.C., in what scientists are describing as one of the first “ecologically realistic” experiments showing how insects can consume microplastics.
The research, published in the journal Biology Letters this week, involved grinding up medical face masks and mixing them with wheat bran and gelatine, said Michelle Tseng, the study's senior author and an assistant professor at the University of British Columbia’s Department of Botany and Zoology.
“Basically, we made plastic granola,” said Tseng. “We wanted to see if they could break plastic down in these household items.”
The experiment ran into some basic problems at first. It turns out medical face masks are incredibly hard to grind up. Tseng discovered the best way to turn a face mask into a powder was to first melt it into a puck in the oven.
“I don’t recommend doing it at home. My kids were like, ‘What are you baking?’” Tseng said. “We were kind of flying by the seat of our pants.”
In the lab, research assistant Shim Gicole would mix up the plastic-laced food and feed about 20 starved worms. Once the worms finished digesting and pooping, the researchers would dissolve the feces and measure how much plastic had made it through their digestive system.
“I was very nervous. It was just very new to me,” Gicole said. “I wasn’t even aware before this that they ate plastic."
What began as a kind of bug “cooking show” ended up becoming the first step on the way to a job at a bio-tech company.
“It was just a confirmation that I was capable,” said the UBC alum. “It had a huge impact.”
The results came back showing the mealworms ate about half the plastic given to them. Each worm was found to eat about 150 particles of the ground-up face mask, while excreting between four to six particles.
Digesting the vast amount of the plastic they ate and transforming it into its elemental parts did not appear to impact the worms’ health or growth.
The research comes as many researchers around the world are attempting to understand the impact microplastics are having on Earth’s oceans and lands, and increasingly, human health.
Last week, a report found Canadians doing their laundry are responsible for releasing 1,465 tonnes of microplastic fibres into the environment.
Attempts to negotiate a global plastics treaty aimed at curbing plastic pollution wrapped up in Busan, South Korea, over the weekend without a deal in place.
The problem, say experts, is besides stopping the flow of plastics at the source, there are few measures to clean up the tiny pollution — a mix of plastic granules, pellets, flakes, beads and fibres.
For Tseng, the UBC experiment is vindication for the lowly mealworm, a species she said nobody cares about unless they are feeding them to their reptiles.
“There’s just things in nature that are kind of unexpected. We shouldn’t take for granted our little friends in nature,” added Gicole.
Don’t expect mealworms to solve the world’s plastic problems any time soon. By their calculations, Tseng said it would take 100 mealworms almost five months to eat and digest one face mask.
“I don’t think we can fill the world with mealworms,” she said.
What the worms can do is inspire Tseng's colleagues in the fields of chemistry and microbiology to extract or synthesize the microbes and enzymes produced by plastic-digesting bugs. Maybe someday, that will lead to a real-world solution, Tseng said.
“These enzymes definitely exist and they’re out there in nature. We just need to find them,” she said.
