Increasing prices: Experts urge farmers to use nature's own methods to bring beneficial insects back

What do the skylark and the iconic jaguar have in common?

Both species are now considered 'near threatened' due to human activities.

Here at home, intensified agriculture has led to larger fields with monoculture and the use of pesticides, causing the skylark to lose habitats and food sources. Although the species is widespread globally, it is retreating here at home and has gone from being 'vital' in 2010 to 'near threatened' on The Danish Red List just a decade later.

The jaguar also loses its habitats. This happens, among other reasons, because the rainforest is being felled to make room for more agriculture. After decades of decline, the IUCN assesses it as 'near threatened' globally.

Species in this category are not yet officially threatened, but they are close to meeting the criteria for it, or it is likely they will do so in the near future if the development continues.

"Several farmland birds, which almost everyone knows, have declined markedly in Denmark by between 60 and 80 percent in population size since the 1970s and 1980s," says Julie Marie Søby, a biologist and consultant at the Innovation Center for Organic Farming.

The problem is intensification of agriculture

She also mentions the lapwing and the yellowhammer. Two common Danish birds, which used to be easy to spot in the agricultural landscape. Now, the question is whether the next generations will even see them if the development continues.

Both the lapwing and the yellowhammer are now considered 'vulnerable'. Species in this category typically have small populations or suffer from relatively large declines, and there is a high risk they will go extinct in the wild.

"When the Danish Red List was published in 2010, all three birds were in the category 'vital'. There was no concern about the development of their populations, even though it was already on the decline. But when the next Red List was published in 2019, they had all moved into worse threat categories," she explains.

The problem is especially the intensification of agriculture, including large, uniform farmland and the use of pesticides, which leave almost no habitats or food sources for birds and beneficial insects.

This is where Julie Marie Søby and the project 'Landscape and Beneficial Insects' come into the picture.

For birds and other small creatures living in and from the agricultural landscape, it is crucial that there are food and habitats available. Therefore, farmers should consider how they arrange their fields — in return, they get help from beneficial insects that can protect crops from, for example, aphids.

Limited range

Julie Marie Søby begins to draw on a whiteboard to explain.

"Beneficial insects that can only move about 75 to 100 meters will only come here," she says, drawing arrows showing how far into the field their natural enemies of pests move from a planted hedge at the edge.

If the field is too large and the distance between the hedges too great, beneficial insects cannot cover the entire field, and pests have free rein to ravage the crops.

"Therefore, it is advisable to divide your field so that beneficial insects can move between habitats and the field. Without these divisions, a rather large area of the field is never reached by beneficial insects. This also applies to pollinators, which do not fly as far," she explains as she continues drawing.

Nature elements clustered next to a large field have far less beneficial effect on production than if the same elements are divided around and within the fields.

"Connected natural areas are still very important for biodiversity," she emphasizes;

"But nature elements in the agricultural landscape create corridors and can provide resources for beneficial insects that benefit production."

And here, flower strips alone are not enough.

"There are needs and requirements that must be met for animals to be present and reproduce. They need water and moisture, warmth and breeding opportunities, overwintering sites, and of course food. When trying to do good for beneficial insects, many think that just having some flower strips is enough. But that’s not enough. All these elements must be gathered and available at the right times to support the beneficial insects' life cycle in the landscape," she explains.

Project shows the effects

The same is indicated by the project's calculations. The partners of the Innovation Center at Aarhus University’s section for agricultural biodiversity have created computer simulations of different agricultural landscapes, showing how the development among ground beetles and other beneficial insects will be, depending on how the landscape is arranged.

For example, they can see that the placement of various landscape elements like flower strips and hedges affects the number of ground beetles. Many divisions in the field, narrow fields, and closer placement of landscape elements simply result in more beneficial insects, the simulations in the project show.

This aligns perfectly with what a meta-study from 2019 has shown. It included 49 studies over 1,515 landscapes and found that many pollinators and beneficial insects had higher occurrence in landscapes with high edge density, leading to better pollination and pest control.

"We have intensified production and the agricultural landscape to the point where we almost only have huge fields — and at the same time, we have major problems with pests. It’s simply because such a simple landscape is extremely poorly equipped to handle disturbances, like pests. If, on the other hand, we create resilient landscapes where beneficial insects are already present, they are ready to fight as soon as pests appear," she explains.

Hoping for a successor

Next year, she hopes to start a follow-up to the project. The grant application has not yet been approved, but the plan is clear: to develop a model that can specifically calculate how good conditions for beneficial insects can mitigate crop damage and thus be measured in the farmer’s bottom line.

"That’s a convincing argument because it makes good economic sense. Some farmers just like to do something for nature, but we also need to reach those who focus more on the bottom line," she explains.

Could the different nature elements be disruptive to the field operations, thus hindering production more than the higher biodiversity benefits it?

"Many farmers believe that, and that’s why some do not divide their fields. They think it’s a hassle, but we’ve just made a video showing how the field can be arranged," she says.

Julie Marie Søby picks up the marker again and begins to draw. She shows how to design it so that nature elements are planted close enough together but still at a distance that considers field operations and machinery size, so they can drive and turn in the field.

With more nature in the field, there will be space for fewer crops. Do you still find that the higher biodiversity increases productivity enough to compensate for slightly fewer crops?

"That’s exactly what we aim to demonstrate with the new project. I just spoke with a farmer who has a small forest farm, and he says he experiences higher yields in his crop just because of some small strips of trees. He can see that the effects beneficial insects have on his field make it all worthwhile for him."

The article was written as part of the project 'Landscape and Beneficial Insects'