While insects have been touted as an excellent source of protein in addition to our diets, they may also help plants, says a new study

Even though Marcel Dicke was aware that insects are a great source of protein for humans, he had no idea how beneficial they are to plants.

Opinion paper published in Trends in Plant Science on March 2 by Wageningen University in the Netherlands, Dicke, a researcher, and colleagues highlight the potential of integrating waste from insect-based food and feed production to enhance sustainable crop growth.

This method, according to the authors, could improve plant growth, health, and resilience.

Exuviae, the exoskeletons left behind after molting, and frass, called after the German word for feeding, are the two main types of insect waste. According to Dicke, frass is “basically insect poop and unconsumed food.”

Exuviae and frass, when given to soil, stimulate plant growth and health. Insect feces are high in nitrogen, a chemical that is essential for plant growth but is limited in most soils. As a result, synthetic fertilizer is frequently applied to crops. Chitin, a polymer that is difficult for most organisms to digest, is abundant in insect exoskeletons.

“There is, however, a set of bacteria that can metabolize chitin, and those microbes help plants to be more resilient to diseases and pests,” explains Dicke. “When exuviae are added to soil, the populations of those beneficial bacteria increase.”

Dicke and his colleagues regard the application of insect-rearing leftovers to crops as an innovative step toward a waste-free circular food chain. Insects are fed crop or food production waste streams, and the insects supply food for people. This circle could be closed by repurposing insect waste to boost crop development. Now all he has to do is persuade people to join him.

As Dicke puts it, “mini-livestock” are already more efficient to farm than traditional livestock. One kilogram of beef requires approximately 25 kilos of grass. The same amount of grass can make ten times as much edible insect protein as it did the first time. This is owing to insects’ higher conversion rate and the fact that up to 90% of an insect’s body mass is edible, compared to only 40% of a cow’s.

“I have eaten crickets, mealworms, and locusts,” adds Dicke. “Many people in in our part of the world need to get used to eating insects, but I can tell you that I’ve eaten many other insect species around the globe, and I’ve always had a wonderful meal on them.”

Exuviae’s potential as a pest control will be investigated further by the researchers. Pesticides can be released from a plant’s leaves if it is being attacked by an insect.

“I call it the plant’s cry for help,” says Dicke. “They are recruiting bodyguards.”

Dicke believes that a similar process is taking place in the roots of the plants, and that the bacteria that are digesting the chitin in the insect feces are also protecting the plants by breaking down pathogenic fungus and making them pest-resistant.

“Studies have already shown that microbes associated with the roots help plants by protecting against diseases,” says Dicke. “Now we’re investigating whether plant roots recruit microbes that help them in defending against pests.”

Source: 10.1016/j.tplants.2022.01.007

Image Credit: Getty

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