HL0192 - Perennial field margins with combined agronomical and ecological benefits for vegetable rotation schemes
Aim of Initiative To develop species compositions for perennial field margins across a horticultural rotation that provide reliable and cost-effective pest control while maintaining crop yield and quality, combined with benefits in terms of biodiversity and conservation. The final output will include recommendations for use and management of these field margins with a proposed goal of their inclusion in future Environmental Stewardship Options. A database will be set up to collate experience and knowledge from this and related functional biodiversity projects in order to make this information accessible to end-users.
Commercial and Technical Background The horticultural industry faces a range of issues linked to crop protection. These include a reduction in the available products approved for use; the potential for increasing resistance in the target organisms; increasing pressures from consumers and retailers for residue-free produce; and a need to comply with legislation and industry initiatives (e.g. Water Framework and Voluntary Initiative). These pressures lead to a need for a more rational approach to pesticide use and for the full exploitation of the range of methods available for maintaining pest populations below the economic damage thresholds.
The development of stewardship schemes that encourage the management of the farmed environment in a way that increases levels of biodiversity, provides an opportunity to combine the current conservation objectives with the benefit of enhanced pest control (either through conservation biological control or through trap cropping). Current stewardship options include pollen and nectar mixes targeting bees and butterflies, and margins to encourage farmland birds. In our previous work we developed the concept of designing flowering field margins for the specific purpose of optimizing pest control. The current project seeks to combine biodiversity and pest-control benefits, providing growers with a direct economic benefit in addition to the subsidies from stewardship schemes.
The Problem/OpportunityNon-crop vegetation in agricultural landscapes can provide a range of important ecological services, including conservation of native flora/fauna and the enhancement of pollination efficacy and biological pest control. A broad range of biological control agents depend on flowering vegetation as a source of nectar and pollen. The scarcity of floral resources in modern horticulture severely constrains predator survival, limiting the effectiveness of biological pest control (Heimpel and Jervis, 2005). In addition, flowering field margins can also be a crucial element in the divertion or interception of pest insects (trap crops) (Wäckers et al., 2007). However, the effectiveness of field margins in boosting pest control strongly depends on their botanical composition (Wäckers, 2005). Currently, non-crop elements are typically designed for wildlife conservation, often rendering them unsuitable in supporting biological control (Olsen & Wäckers 2007). As an alternative, we propose a multifunctional focus in composing field margins, allowing joint optimization of pest control-, pollination-, and conservation-benefits. To achieve such additionality in benefits we intend to chose non-crop vegetation based on the ecological requirements of a range of target species including biological control agents, key pest species, pollinators and farmland birds.By combining the leading UK expertise on the use of non-crop elements for the conservation of birds and pollinators with our international experience in the use of field margins for conservation biological control, this project will be leading the way in this increasingly important area.
Scientific Background Previous LINK projects have looked at the use of field margins to provide conservation biological control in cereal crops using natural predators (LK0915: 3D Farming) and entomopathogenic fungi (LK0908) and to provide increased biodiversity to help farmland birds (LK0926: SAFFIE). The PI has worked since 1989 in the area of agro-biodiversity in the US, Switzerland and the Netherlands, pioneering the informed design of agro-ecosystems and landscape structure to enhance conservation biological control. His group is currently involved in several international agro-biodiversity projects, including a large scale (540 km2) horticultural project in the Netherlands (Functional AgroBiodiversity, FAB) involving brassicas, potatoes and wheat. While the proposed project builds on previous and ongoing projects, it is unique in addressing the use of field margins in terms of joint agronomical and environmental benefits and in developing a specific seed mixture to optimize perennial field margins across a wide horticultural rotation. It brings together and develops knowledge on how field margins provide for specific requirements (nectar, prey, overwintering needs) of biological control agents. It is also novel in using field margins as part of a trap crop approach for the control of carrot fly and cabbage root fly and in developing the use of field margins to monitor levels of biological control agents.
Scientific Approach It is widely recognized that the ecological impact of biodiversity elements depends on the botanical composition of these elements. We propose an approach in which we compose perennial field margins to support pest control in a combination of crops within a horticultural rotation. This involves specific selection of plants that suit the ecological requirements of the most important biological control agents, farmland birds and pollinators, whilst helping trap nectar feeding pests such as the carrot fly and the cabbage root fly in designated border rows where they can be controlled by targeted insecticide sprays or other control methods.