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Managing biodiversity in field margins to enhance integrated pest control in arable crops (3-D Farming Project)

Project Report No. 356

Managing biodiversity in field margins to enhance integrated pest control in arable crops ('3D Farming' project)

by

W. Powell1, S. A'Hara2, R. Harling2, J.M.Holland3, P.Northing4, C.F.G. Thomas5 and K.F.A. Walters4

1Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ
2SAC, Kings Buildings, West Mains Road, Edinburgh, EH9 3JG
3Game Conservancy Trust, Fordingbridge, Hampshire, SP6 1EF
4Central Science Laboratory, Sand Hutton, York, YO41 1LZ
5Seale-Hayne Faculty of Agriculture, University of Plymouth, Newton Abbotm, Devon, TQ12 6NQ

 

Abstract

Agriculture is undergoing important changes as a result of CAP reform and continuing pressure to improve its environmental profile. Restrictions on pesticide use and the withdrawal of increasing numbers of compounds from the crop protection armoury mean it is essential to develop new, sustainable approaches to pest control. Research is required to further promote the development of such methods and to improve our understanding of, and ability to manage, farmland ecosystems to ensure agriculture retains profitability whilst addressing environmental concerns.

Non-crop habitats constitute one of the most important sources of biodiversity within farmland but their beneficial influence on adjacent crops has not been properly taken into account. In many arable areas, field margins are the only major non-crop habitat, acting as the main source of beneficial species, and it has been recognised for some time that field margins can play an important role in the development of novel manipulation techniques to enhance insect predators and parasitoids. Hoverflies, many of which are important aphid predators, can be increased by encouraging wild flowers in field margins, whilst aphid sex pheromones can be used to increase parasitization rates in the field by encouraging movement of parasitoids between margins and the crop at critical times. It is essential to develop these approaches in a unified way and test them on a commercial field scale. The diversification of field margins through agri-environment schemes, primarily designed to increase farmland biodiversity, offers an ideal opportunity to do this. Field margins are also important habitats for other major predator groups, such as carabid beetles and spiders, and the diversification of margin habitats on farms will also affect these groups. Insect interactions between field margin habitats and the crop and the overall density, diversity and distribution of both pests and beneficials are influenced not only by margin management but also by the crop husbandry practices employed in the field. Recent developments in the statistical analysis of intensive spatial data allow these interactions to be investigated more closely.

The overall aim of the project was to use field margin management techniques to increase the abundance and diversity of beneficial insects and spiders and manipulate their distribution and dispersal on farmland for the control of aphid pests.

The specific objectives were:
1. To provide farmers with advice on field margin management to optimise integrated pest management whilst maintaining biodiversity benefits and profitability.
2. To test and further develop a novel aphid control strategy involving the manipulation of parasitoids using aphid sex pheromones in field margins.
3. To develop and evaluate the use of specific native flowering plants in field margins to enhance the abundance and diversity of aphid-eating hoverflies in adjacent crops.
4. To measure the effects of margin and crop management on aphid and beneficial insect abundance, dispersal and spatial distribution in both the margin and adjacent crops.
5. To measure the spatial and temporal distribution of cereal aphids and the extent to which these are controlled by predatory and parasitic species.
6. To measure the impact of recently introduced field margin management options on the biodiversity of aphids and their natural enemies.

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