We need to stop pests eating our food. Richard Pywell and Ben Woodcock argue that supporting native wildlife on farms is part of the answer.
Farmers have always been in a running battle with pests. We estimate using Defra statistics that in 2010, UK crops worth £715M were lost to insect pests. Chemical pesticides are crucial to controlling them, but the development of pest resistance, and key products being withdrawn amid fears about human and environmental health mean that alternative methods are increasingly important.
One solution is to promote native biodiversity that will kill pests within crops. Many native species have the potential to increase crop yields, so supporting biodiversity on farmland has more to offer than simply beautifying the countryside. For example, bees pollinate crops and predatory beetles eat pest aphids. In any case, the UK has signed the Convention on Biological Diversity, which requires that “by 2020 areas under agriculture, aquaculture and forestry are managed sustainably, ensuring conservation of biodiversity”.
So-called ‘natural pest control’, also called biological control, can cut crop losses by 65%, and is worth an estimated £1.3Bn a year to UK farmers (derived from Defra stats and Losey et al. 2006, links above). £432M of this comes from invertebrates like parasitic wasps or predatory ground beetles. These invertebrate communities are diverse in the UK – we have identified nearly 60 species of predatory ground beetles that feed on pests in wheat, barley and oilseed rape.
A flower-rich field margin. The flowers provide food and shelter for pest-controlling invertebrates. Image: Marek Nowakowski
Yet for biodiversity to benefit agriculture, our native plants and animals need careful husbandry within farmed landscapes. Most invertebrates that help control pests cannot remain in fields throughout the year because ploughing and harvesting will kill them, so we need to sow new habitats where they can shelter before moving back into the crops.
One of the best ways of doing this involves sowing seed mixtures in thin strips around the field edges that provide crucial habitats for pest-eating invertebrates. For example, sowing tussock-forming grasses like cocksfoot will benefit beetles and spiders that hide and overwinter in them. Creating these habitats is an important part of European agri-environmental schemes, of which field margins represent one of the most widely-implemented approaches.
A helping hand
Insects play other roles in food production by pollinating flowering crops like oilseed rape and soft fruits. In the UK this is worth an estimated £400M per year and worldwide its value could be as high as £150Bn.
Yet we know very little about the role our native bee species play in this pollination. In recent surveys we were surprised to find that as well as the well-known honeybee (Apis mellifera), more than 30 species of native bees were pollinating oilseed rape crops. Native bees can account for at least as many flower visits as honeybees, so they are crucial in crop pollination, particularly if there are no longer enough honeybee hives, for example as a result of colony collapse.
A solitary bee covered with oilseed rape pollen that will increase pollination and crop yield. Image: Mike Edwards
And our observations suggest that native solitary bees may be particularly efficient in pollinating crops because they don’t clean pollen off their bodies to the same extent that bumblebees and honeybees do. By being messy eaters, the solitary bees are more likely to transfer pollen to the female reproductive part of the flower.
It is by gaining a more detailed understanding of which insects are pollinating crops that we can map their UK distribution. Using data collected by the volunteers of the Bees, Wasps and Ants Recording Scheme and the Biological Records Centre, we identified crop-growing regions that support limited numbers of native bee species.
It’s the kind of information likely to be increasingly important in the future for policy-makers to target land management that promotes beneficial insect pollinators. For example, a partnership with the agro-chemical company Syngenta helped create wide-reaching benefits for bees under the ‘Operation Pollinator‘ programme by planting field margins rich in flowers.
Future increases in crop yields will almost certainly not be achieved in isolation from the role played by ‘ecosystem services’ like pollination that are provided by native biodiversity. Farm-management techniques that enhance biodiversity need to develop in a way that is compatible with real-world agriculture, and must deliver a wide range of benefits including pollination, pest control, water protection and even locking up greenhouse gases in the soil.
This means management that promotes biodiversity to benefit crop production will be vital to the UK’s long-term food security, and the most successful approaches rely on communication between scientists, farmers, the agricultural industry and the government.
An earlier version of this article originally appeared in Planet Earth Online.
About Richard Pywell
Professor Richard Pywell is a programme leader for research on biodiversity and ecosystem services across the Natural Environment Research Council’s Centre for Ecology and Hydrology (CEH) at Wallingford. He is a leading expert on the restoration and management of biodiversity within intensively managed ecosystems with over 60 peer-reviewed publications.
About Ben Woodstock
Dr Ben Woodcock is an Ecological Entomologist at CEH. He is involved in research that develops applied management solutions to enhancing ecosystems service delivery and biodiversity within arable and grassland ecosystems and has 45 peer-reviewed publications.
Dr Mike Edwards of the Bees, Wasps and Ants Recording Scheme and Dr Marek Nowakowski of the Wildlife Farming Company also contributed to this article.