by Shelby Wyzykowski with scientific information provided by Dr. Ainsley Seago, Associate Curator of Invertebrate Zoology.
What could be more thrilling than a summer weekend trip to explore one of the most exciting metropolises in the world, New York City. It has so much to offer, way too much to experience in a mere two or three days. There’s the sights…the Statue of Liberty, the Empire State Building, and Broadway. There’s the sounds…the beeping horns of taxi cabs and the noisy, bustling, crowded sidewalks. And there’s the smells…the sweet fragrances that drift from stalls in the Flower District, the tantalizing aromas wafting from street-side food carts, and the unmistakable odor of sixty thousand hot dogs sitting under the noon day sun in Times Square. Sixty thousand hot dogs? Really?! Well, no, not really, at least not literally. But the city that never sleeps is a city that loves to eat. And with the number of people that live, work, and visit this town, enormous amounts of food can litter the streets at any given time. The battle to keep public spaces free of food waste is daunting, but humans do have some unlikely tiny allies in this unending garbage war…insects. These crews of itsy-bitsy street cleaners, along with other arthropods like spiders and millipedes, are surprisingly efficient scavengers. We undoubtedly know this thanks to the work of researchers at North Carolina State University. Their entomologists, or insect scientists, studied these mini trash disposals at work in the urban ecosystem of New York. They found that pavement ants, cockroaches, and other hungry foragers can eat 2,100 pounds of food refuse (the equivalent of 60,000 hot dogs) in one year. Now in the grand scheme of things, a ton of food is not a lot, but researchers have still taken notice. They know that diverting food waste from landfills benefits our planet. And they are experimenting to try and find innovative ways to use insects to transform edible trash into eco-friendly treasure.
Entomologists at Louisiana State University are also doing their part to make their Baton Rouge campus more environmentally responsible. They’ve collaborated with the nearby Fluker Farms, a pet supply business that sells insects as reptile food. Together they’re taking food bound for a landfill and transforming it into animal feed. But there is also a third indispensable partner in this entomological endeavor. It’s the black soldier fly, an insect that is common in the Southern United States. The larvae of the black soldier fly do one thing exceptionally well…eat. A black soldier fly larva can eat twice its own body weight in one day! During their larval stage, they consume all the food that they’ll need for the rest of their lives. The fly’s feeding frenzy results in rapid growth. They’ll grow 300% in size during their two-week larval stage. But, after these two weeks, they’ll never eat again. It would be impossible, because an adult black soldier fly has no mouth!
Before the larvae can chow down on the leftovers from the campus’s dining halls, the food scraps have to be blended into a slurry. Then the ravenous little larvae get two weeks to eat to their heart’s content. They are then sifted out of the remaining slurry. Some larvae are sold as Fluker Farms reptile food while the others return to the colony to become adults. The leftover slurry/compost mixture is then spread on the flower beds that decorate the university’s campus. In 2019 alone, 15 tons of food waste was processed this way! The joint effort between LSU’s Entomology department and Fluker Farms is helping the university to reach its goal to reduce the amount of waste the campus sends to landfills by three quarters by the year 2030.
But the LSU scientists have an even grander vision for their larvae farm and other farms like it. Black soldier fly larvae can also take the place of soy and fish meal as feed for livestock, and this helps to take the pressure off the world fisheries. With an ever-increasing world population, perhaps larvae may even become a food staple for humans someday. Food scientists at Stellenbosch University in South Africa are already using black soldier fly larvae to produce dairy-free ice cream and Vienna-style sausage. Imagine, someday, sitting down to enjoy a full seven-course dinner with larvae as a key ingredient!
Fly larvae are not the only insects that are being utilized as animal feed. Cockroaches, which are actually very fastidious, well-groomed insects, are great little amateur recyclers. They can chew down almost anything, but they can live without food for up to one month if they need to. Luckily, the roaches at the Shadong Agricultural Technology Company in Jinan, China never need to worry about going hungry. The food waste recycling plant works on a much larger scale than LSU, housing a billion cockroaches that are fed fifty tons of kitchen scraps each day. That’s the equivalent of seven adult bull elephants! The cockroaches are allowed to live out their natural lifespan. Then they are steamed, cleaned, and processed into a protein-rich, antibiotic-free livestock feed that, like larvae, can take the place of fish meal. This profitable food waste plant, as well as others like it in other Chinese cities, undoubtedly proves that insect farms can help to solve our landfill problems.
With the success of these promising initiatives, scientists are taking things a step further and applying insects to the problem of plastic waste. It’s no secret that the many types of plastic that we use in our everyday lives are polluting the planet. Marine ecologists have even found plastic microfibers in sea ice samples from Antarctica! Some researchers, in their quest to try and help to solve our plastic problem, have made a surprising discovery; some insects are plastivores, meaning they can eat plastic! A March 2020 project at Brandon University in Canada studied the larvae of the Greater Wax Moth (a regular beehive pest) and their ability to consume LDPE, or low-density polyethylene. This type of soft plastic, which is used to make grocery bags, is one of the leading contributors to non-biodegradable waste. It can be recycled, but much of it ends up in the trash. At the landfill, LDPE breaks down and releases dangerous greenhouse gases, including methane. This is cause for concern, since greenhouse gases contribute to climate change. Brandon University researchers have been trying to figure out the exact way that these caterpillar larvae are able to digest this troublesome plastic. Their goal was to isolate and identify the specific chemical that the caterpillar uses to break down LDPE, and they got off to a promising start. The scientists found that the amount of the larvae’s gut microbes (bacteria and fungi) actually increased when fed LDPE. Their intestinal biome actually preferred it over the caterpillar’s regular natural diet of honeycomb. The larvae thrived on plastic! And they seemed to love it because LDPE has the same chemical structure (specifically, a long, open-chain hydrocarbon) as beeswax! Further research revealed that the caterpillar’s breakdown of LDPE is a complicated process that has to happen in vivo (inside their bodies). One of the waste products that the caterpillars produce when they digest LDPE is called glycol. Glycol is toxic to humans, but, fortuitously, it can be biodegraded by several common, naturally occurring bacteria. For now, recycling LDPE is still the best option. But further research into the Greater Wax Moth larva’s in vivo process of digesting plastic may prove to be fruitful.
This summer, even if you’re not able to escape for a weekend getaway to the Big Apple, you are still likely to get the opportunity to enjoy a Sunday stroll along the sidewalks of your own hometown. And if, by chance, you look down and see a line of ants diligently portioning out and carrying away a cast-off crust of bread, take a moment to stop and watch them hard at work. You can maybe even silently thank them for their Herculean efforts. If it weren’t for their help, food waste would be an environmental hazard, a threat to public health, and an additional financial burden to your city. It’s a dirty job, but somebody’s got to do it. Fortunately for us, our voracious, multi-legged little friends are ready and willing to take on the task.
Shelby Wyzykowski is a Gallery Experience Presenter in CMNH’s Life Long Learning Department. Museum staff, volunteers, and interns are encouraged to blog about their unique experiences and knowledge gained from working at the museum.
Carnegie Museum of Natural History Blog Citation InformationBlog author: Wyzykowski, Shelby
Publication date: May 20, 2021