Farming insects for food and for animal feed is set to take off in the near future, according to the authors of an Opinion piece published today in the journal Trends in Plant Science. The experts point out that the EU has recently authorized the incorporation of insects into pig and poultry feed, and that this will support the newly developing practice of insect farming.
Insects provide an excellent source of readily available protein and, unlike the situation with mammal livestock, the whole insect body is edible. In addition, the farming of insects gives rise to a steady supply of waste products that can be used to fertilize soils and improve crop growth.
In the publication, researchers including Marcel Dicke of Wageningen University discuss the many potential benefits of using the waste from insect production in circular farming practices to promote sustainable agriculture. The authors argue this approach could enhance plant growth, health, pollination, and resilience.
Waste comes in two main forms; there are the exuviae (molted exoskeletons or skins), and the frass, which is insect feces mixed with uneaten food. Both substances are rich in nutrients and could form an important organic fertilizer, especially these days as the use of inorganic fertilizers becomes more and more restricted. Frass is rich in nitrogen, an element that is required for plant growth, but that is often in short supply in the soil. And exuviae contain chitin, an amino-sugar polysaccharide that is indigestible for most animals but can be broken down by bacteria.
“There is a set of bacteria that can metabolize chitin, and those microbes help plants to be more resilient to diseases and pests,” explained Dicke. “When exuviae are added to soil, the populations of those beneficial bacteria increase.”
The scientists propose that by adding waste from insect farming to the soil, the microbial populations in the soil could be enhanced. Microbes are very beneficial for plant growth and modern agricultural practices often include inoculating soils with specific types of soil bacteria that improve crop growth, resistance to disease and herbivory, and tolerance of abiotic conditions. Enhancing soil microbes is seen as an attractive alternative to using agrochemicals.
However, inoculating soil with microbes is not always a successful practice. The authors of the paper suggest, instead, that enriching the soil with organic waste from insect farming will encourage the development of the important microbes anyway. They propose that insect “livestock” could be fed waste from crops, such as offcut leaves and stems. The insects would form food for people or for livestock, such as poultry or pigs, and their waste could be introduced into the soil as an organic fertilizer, to enhance the growth of the crops. This type of circular farming leads to almost no wastage.
Insects are very efficient to farm, especially when compared with more traditional livestock. It takes roughly 25 kilograms of grass to produce one kilogram of beef. The same amount of grass can produce ten times as much edible insect protein. This is because insects are more efficient at converting their food into body mass, and also because up to 90 percent of an insect’s body mass is edible, as opposed to only 40 percent of a cow.
The team’s research showed that beneficial soil bacteria, derived from the enrichment of the soil with insect waste, can boost plant growth and also cause changes in plant physiology, attract mutualistic insects such as pollinators and natural enemies, and suppress insect pests on crop plants. They stress that further studies on the effects of insect waste on plant production are needed because these interactions are complex and dynamic but potentially extremely useful.
Currently, several different species of insects are farmed for use as both human food and livestock feed. These include yellow mealworms (Tenebrio molitor), lesser meal-worms (Alphitobius diaperinus), house crickets (Acheta domesticus), black soldierflies (Hermetiaillucens), and houseflies (Musca domestica).
“I have eaten crickets, mealworms, and locusts,” said 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.”