Munching Mealworms Just Part of the Solution to Plastics Pollution

Mealworms tend to prefer the dark. Lately, however, the tiny insects have been thrust into the limelight after two studies revealed their propensity for munching on Styrofoam.

In the world of trash, news that microorganisms in a mealworm’s gut can biodegrade all types of polystyrene has been lauded by the hopeful who see endless opportunities and criticized by skeptics who fear it will be viewed as a panacea on a planet littered with plastics.

None of that is lost on Wei-Min Wu, co-author of the pair of companion papers published recently in the journal Environmental Science and Technology. He is a senior research engineer with Stanford University’s Civil and Environmental Engineering Department.

“Our findings have opened a new door for remediation technology because most plastic wastes have been considered non-biodegradable,” Wu tells Waste360 in an interview from Lansing, Mich., where he was on a break with his family. But even with this discovery, he cautions, “we should still reduce plastic waste as much as possible and focus on more green products.”

Thus far, his research is confined to the lab. There, the Styrofoam-chomping mealworms—which are actually the larvae form of the darkling beetle—leave behind miniature yellowish-white feces. Large-scale, in-the-field testing of the mealworms’ capabilities might prove difficult because they are an appealing dinner for the birds, rats and other creatures that frequent landfills and trash bins, he says.

The brown waste excreted by mealworms on a more conventional diet of grains, vegetables and fruits is used as an agricultural fertilizer and even as chicken food in China, Wu says. He adds that while the waste from Styrofoam-fed worms is likely not poisonous because they are able to complete their normal larvae-pupae-beetle lifecycle, more study of its biodegradability and potential health effects is needed.

Wu shuttled between Palo Alto, Calif., and Beijing, China, to conduct his mealworm research after his colleague Jun Yang, a professor at Beihang University, invited him aboard as a collaborator five years ago.

Yang’s curiosity had been piqued when he observed waxworms—larvae of the Indian meal moth, a pest found in kitchens galore—chewing holes in a polyethylene bag containing millet. That launched his studies of biodegradation of plastic by an array of pest worms.

Spokespeople from the Washington, D.C.-based Association of Postconsumer Plastic Recyclers did not return several requests for comment from Waste 360 on the mealworm studies.

Styrofoam is the bane of Julie Lawson’s existence. As the director of Trash Free Maryland, an alliance of 60-plus like-minded organizations, she recently coordinated successful campaigns to ban the sale and use of disposable polystyrene foam products in the nation’s capital and two adjacent counties.

She’s worried that Wu’s research will allow an easy way out. If mealworms can devour plastic, people can continue using disposable, overpackaged stuff without the guilt of damaging the planet.

“I’m urging caution,” Lawson says. “Expecting another organism to tackle the ever-increasing amount of disposable plastics we humans consume doesn’t seem sustainable or immune from unintended consequences.”

Wu is mindful of her apprehension. He doesn’t want the hype to get ahead of the science.

“Mealworms are not the final solution for plastics,” he says, adding that pollution caused by plastics has been a global environmental concern for upward of 50 years. “There’s a lot more we can do.”

Concentrating on four specific strategies could solve the problem with plastics, Wu says. Those efforts include recycling; managing plastic waste to significantly reduce what is dumped in the environment; developing cost-effective, biodegradable materials from biomass and other green resources; and remediating plastic waste by deploying technology or other approaches, such as mealworms.

He and other Stanford researchers also are working on developing non-petroleum-based plastic materials that biodegrade rapidly.

While Wu and his colleagues are focused on studying the microbiology of the plastic-digesting bacteria in a mealworm’s gut, they are hoping those basics offer insight about how to tackle monumental challenges such as the tons of plastic debris floating in the ocean.

Some of that plastic bobs into the ocean via the Anacostia River. Its remarkably vast watershed encompasses 176 square miles in Washington, D.C. and Prince George’s and Montgomery counties in Maryland. The 8.5-mile waterway merges with the Potomac River at Hains Point in Southwest Washington.

What frustrates Lawson is that 25 percent to 40 percent of the watershed’s litter by volume is foam, local surveys show. It’s almost impossible to remove it because it breaks into tiny pieces that take hundreds of years to biodegrade. Those tidbits, which are prone to absorbing petrochemicals in waterways, enter the food chain as an enticing but hazardous snack for fish and other wildlife.

Might there be a freshwater or marine equivalent of the mealworm?

“This is an interesting question,” Wu says. “I hope that some marine animals may have a similar plastic-degrading capability. More investigation is needed.”