Researchers funded by the UK Biotechnology and Biological Sciences Research Council and the French Institut National de la Recherche Agronomique (INRA) have found that ground beetles reduce the amount of weed seeds in the soil. Weeds reduce crop yields and these findings support the need to conserve farmland biodiversity as it plays an important supporting role to herbicides in controlling weeds and improving food security.

The new study, to be published in the August edition of the Journal of Applied Ecology, is the first to show that ground beetles can reduce the amount of weed seeds in the seedbank.

Reducing competition from weeds increases agricultural production, therefore these findings support the need to conserve farmland biodiversity.

This research confirms a long-held belief by scientists that ground beetles play a role in weed control. Dr David Bohan, Rothamsted Research, who led the research, said "seed predation by naturally occurring beetles in farmland does have a beneficial effect, reducing weed numbers in fields and potentially improving agricultural productivity".

Throughout the UK, 257 conventionally managed fields of sugar beet, maize, and spring and winter oilseed rape were examined to investigate the changes ground beetles cause in the amount of weed seeds in the seedbank. All weeds were reduced in fields of spring maize and winter oilseed rape, which the scientists attribute to the different communities of weeds and insects in these crops. In the other crops, grass weeds were reduced, even when broadleaved weeds were more common.

Many UK farms have severe problems with grass weeds, and some species are increasingly resistant to herbicides. These weeds have a major impact on productivity as they compete with the crop for resources, leading to lower yields. Policy-driven reduction in herbicide use could lead to higher numbers of weeds in fields, so alternatives to herbicides have the potential for significant impact.

The ground beetles studied appear to eat a significant proportion of the weed seeds that would otherwise go into the seedbank. Within a careful pest management strategy beetles could be used alongside and in place of some herbicide applications to significantly reduce weed populations, improve yields and help ensure future food security. 'Beetle banks', which involve leaving an area of a field as a wildlife habitat, are already supported under the Environmental Stewardship schemes available to farmers.

Professor Douglas Kell, Chief Executive, BBSRC said "We have a challenge to feed 9 billion people by 2050 and to do so we must engage in research now that will underpin improvements in yield and sustainability of farming in the future. By studying whole biological systems such as farm ecosystems we can spot the various contributions made by different aspects of a system, including these beetles. This project shows that the balance of farm ecosystems can be vital to ensuring sustainability in farming in the future. It also makes the link between biodiversity and food security very clear".