Insects are not only very healthy for humans, but also for plants

Insect leftovers after we have feasted on them can serve very well as a nutrient source and soil improver for plants. So two birds with one stone.

Many scientists are in complete agreement: insects are the food of the future. They are healthy and, compared to traditional livestock, better for the environment because they emit far less greenhouse gases and are a lot more economical with water. Also according to plant ecologist Marcel Dicke, affiliated with Wageningen University, we should eat more insects instead of meat. And then use the residual flow from insect farming to grow crops sustainably, he adds.

Plants

As mentioned, insects are very healthy for humans. They are an important source of protein and contain vitamins and the good amino acids. Moreover, insects are better for the environment than traditional livestock (see box). “We know that insects are excellent substitutes for meat,” Dicke says in conversation with Scientias.nl† “They are much more sustainable to produce, soymeal or fishmeal is no longer needed and they emit much less greenhouse gases.”

What Dicke did not expect, however, was that insects would also have such a positive influence on plants. In an opinion piece, Dicke and his colleagues from Wageningen University and the Netherlands Institute of Ecology discuss the benefits of using the residual flow from ‘insect-food-and-feed production’ (in fact the ‘insect leftovers’) to promote sustainable crop production. . The authors argue that this approach can improve plant growth, health, pollination and resilience.

What’s up with that?

How exactly can insect leftovers serve as a food source and soil improver for plants? “When you grow insects for food or animal feed, there is residual material left over,” explains Dicke when asked. “Think of the molting skins, unconsumed food of insects and their excrement. If you put the skins in the soil, you stimulate the micro-organisms that can use the skins as ‘food’ because they have enzymes that can break down, for example, chitin (a polymer that is difficult for most organisms to digest, ed.). . These microbes help plants to be more resistant to diseases and pests, just as we also benefit from certain micro-organisms in our gut. So when we add the molting skins of insects to the soil, the populations of those beneficial bacteria increase.”

Nitrogen

In addition, molting skins – as well as insect droppings – are rich in nitrogen: an important fertilizer for plants. However, nitrogen is normally quite scarce in the soil, so it is still often added to crops through synthetic fertilizers. But insect cliques can also offer a solution here.

Healthy for people and plants

It means that insects are not only healthy for humans, but also for plants. When we add insect leftovers to the soil, this can contribute to the growth, health and resilience of the plant. At the same time, this can help to reduce chemical crop protection and fertilizers.

Little waste

Dicke sees the application of insect farming by-products to crops as another step towards a circular food system in which there is very little waste. The insects are fed with waste streams from arable farming or food production, after which the insects provide humans with food. Using the remnants of insect production to stimulate crop growth could close this loop. “Insects as a protein source are an important element of circular agriculture,” says Dicke. “The use of the residual material further increases that aspect because this residual material can also be given a meaningful destination in this way.”

Insect remains in a circular food system. Image: WUR

Food

It sounds like a good idea. But then more people would have to be willing to eat insects. Incidentally, this is already normal in various parts of the world. In the Netherlands we are still somewhat reserved in that regard. In any case, Dicke doesn’t shy away from it. “I’ve eaten crickets, mealworms, and grasshoppers,” he says. “Many people in our part of the world have to get used to eating insects. But I can tell you that I have eaten many insect species all over the world and have always loved them.” To what extent the Dutch will tack? “It depends on how you use the insects: in a burger or some kind of tofu, as insect meal in pasta or in pasta sauce, or as whole insects,” Dicke says. “The processed shapes will be more accepted, but the whole insects will appeal to a different audience.”

We already eat them

If you still shudder a bit, just think about this: there is a good chance that you too have already eaten a lot of insects. “Everyone already eats insects because all processed products contain insects,” Dicke says. “Think applesauce, orange juice, peanut butter, chocolate, bread, coffee, etc.” In the production of these foods, it may well be that there are some apples that have just crawled into a fruit fly. And this is how finely ground insects end up in the apple juice and applesauce, as you can read in it The Insect Cookbook† The same goes for tomatoes and ketchup, for grain and flour for bread, for coffee beans and coffee, etc. It has been calculated that, without our knowledge, we get behind about 500 grams of insects per year.

All in all, Dicke and his colleagues in the opinion article see that insects can be of great value to plants and circular agriculture. In addition, insects may have even more beneficial properties for plants. So it could just be that they also have certain ‘pest control gifts’. The researchers are going to study it all further. “We are conducting research in Wageningen to understand exactly what the effects are,” he says. “Because then we can make a maximum contribution to circular agriculture and thus link sustainable protein production to sustainable production of vegetables.”