Many studies have shown that planting strips of wildflowers amidst croplands can help replace some of the biodiversity that is lost in the quest to feed a growing, global population. More recently, studies have demonstrated that the increased biodiversity found in these strips includes species of insects and birds that act as an all-natural pest control, reducing or eliminating the need for pesticides.

How these strips affect crop yields, however, has been largely unexplored. That’s the topic researchers tackled in a study published recently in the journal Agriculture, Ecosystems and Environment. They found that the presence of nearby perennial, species-rich wildflower strips increased winter wheat production by 10 percent as compared to control fields.

“Farmers care about biodiversity and they likely also know about the importance of natural enemies of crop pests,” said lead author Matthias Tschumi. “But what is mostly decisive for the farmer is what he gets in terms of yield at the end of the day.”

Scientists from Agroscope, the governmental Swiss Centre of Excellence for Agricultural Research, conducted the research on Swiss winter wheat fields, which are often plagued by the cereal leaf beetle—a major pest in Europe, Asia, and parts of North America. They took advantage of the many farms that have implemented wildflower strips as part of a government subsidy program that aims to boost biodiversity on farm lands.

The researchers selected ten pairs of fields that were similar in terms of their landscape and how they are managed. In each pair, however, one field was adjacent to a previously established wildflower strip and the other to a crop field. (Pesticides were not used on any of the fields.) Over the course of a few months, they measured cereal leaf beetle eggs and larvae, crop damage and crop yields, at 5 meters and 10 meters from the border of the wildflower strip. They found a 44 percent reduction in beetle eggs, putting it under the threshold for pesticide application, a 66 percent reduction in larvae, and 40 percent reduction in crop damage, all at 5 meters. Crop yields, however, increased at both the 5 and 10 meter marks.

The wildlife strips provide habitat for natural predators of other known wheat pests, so reductions in pests other than the cereal leaf beetle—not measured in this study—may have contributed to the increased yields, Tschumi said.

While Tschumi said he was surprised at how big of an effect they found on crop yields, the paper did not take into account any losses in yields that farmers would incur if they set aside arable lands for wildflower strips. He also cautioned that while the range of effect of 10 meters is significant for the scale of Swiss farms, it may be “rather ridiculous” for the scale of many American farms. That said, some of the natural predators present in the wildflower strips are highly mobile, he said, and effects may well extend to greater distances and should be assessed in future studies.

Even still, Tschumi hopes that the findings in this study, which constitute a win-win for biodiversity and farming, will sway more farmers to incorporate wildflower strips into their farmlands. —Catherine Elton | 12 February 2016

Source: Tschumi, M. et al. (2016) Perennial, species-rich wildflower strips enhance pest control and crop yield. Agriculture, Ecosystems and Environment (220) DOI: doi:10.1016/j.agee.2016.01.001

Header image ©Matthias Tschumi