Experts say it’s the oldest fertilizer available and can be found in nearly every ecosystem — so why aren’t we spooning more insect poop onto our home gardens and greenhouse crops?
Insect poop — also known as "frass" — contains all the regular nutrients you’d expect from a good manure, including nitrogen, phosphorus and potassium, and just a tiny bit of it goes a long way when compared to conventional fertilizers.
Frass also has applications when it comes to climate change. A
2019 study published in the journal Applied Soil Ecology suggests that frass produced by mealworms on low-fat, low-starch diets could help protect plants from climate change events.
“One effect of climate change is increased temperature, and that can lead to drought or even flooding,” said Louise Hénault-Ethier, director of the Eau Terre Environnement Research Centre in Quebec City. “Mealworm frass can help plants tolerate these abiotic or non-living stressors.”
What makes this cocktail of undigested bits a standout fertilizer is a key ingredient that fertilizers produced by mammals don’t naturally contain: chitin. Chitin is an abundant natural polymer and structural component that builds up fungi cell walls and the exoskeletons of arthropods like insects and spiders.
When a plant is exposed to chitin, its immune system flags the polymer as a marker of a threatening fungus or insect. While the chitin doesn’t actually harm the plant, it triggers an immune response that benefits plant health.
“Although chitin isn’t injected into plants, it kind of works like a vaccine,” said Hénault-Ethier. “You're not going to produce the antibodies against COVID if you haven't been exposed to COVID, but if you receive a vaccine, then you're going to start to produce the elements that are going to help protect you.”
Hénault-Ethier says frass is being studied as a potential organic replacement for toxic pesticides. Amid the current drive to raise insects as a new protein source, she says their frass may be as valuable as the insects themselves — if not more.
“Insect farmers are first and foremost frass producers, because they can produce two to three times more frass than they do insects,” said Hénault-Ethier, who is also an associate professor with Quebec’s Institut national de la recherche scientifique (INRS).
While the lab data looks promising, frass can’t be marketed as a pesticide yet because pesticides need to be registered with the Canadian Food Inspection Agency, which requires extensive safety testing and demonstration of a substance’s capacity to manage pests.
Frass is also facing some regulatory hurdles, because manure is defined in Canada as a product that comes from mammals or birds.
“Right now, the insect farmers in Canada run [small-scale] operations,” said Hénault-Ethier. “So they don’t have the financial means to pay hundreds of thousands of dollars to register their products with the Canadian government. It would kill the market.”
Even so, the market is expanding. Last year, insect agriculture company Aspire Food Group announced plans to build a 150,000-square-foot cricket-rearing plant in London, Ont.
Construction on that project is more than halfway done and the facility will start production early next year. But in Texas, where the company is headquartered, Aspire is already selling its own cricket frass as a soil supplement and plant protector.
“The vast majority of our business is actually going to come from the pet food market and the fertilizer or soil amendment market,” said Aspire co-founder and CEO Mohammed Ashour. “Because for every pound of crickets, we generate approximately one pound of frass.”
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Jade Prévost-Manuel
