Integrated pest management
Integrated Pest Management (IPM) has built on the fundamental idea of ecological engineering (Odum, 1971) over several decades, particularly in developing countries where pesticides and other crop protection technologies have been largely unaffordable to farmers. IPM is a holistic approach, integrating several strategies to reduce pests below economic thresholds while minimising the use of pesticides, particularly those which have adverse effects on non-target organisms like biocontrol agents and pollinators.
The main research areas that feed into practical IPM include plant breeding / genetic engineering for pest resistance, biocontrol, cultural control, conventional pesticide use and habitat management (at field to landscape scales).
Contact: Nick Birch
Examples of the IPM approach at SCRI
- Raspberry as a model ecosystem for IPM studies
- Plant breeding for pest resistance
- Population dynamics of pests and their natural enemies
- Recognition signals and insect lures
Raspberry as a model ecosystem for IPM studies
At SCRI we have a long history of breeding crops with built-in (genetic) resistance to pests and diseases. One of the best known examples involves more than 30 years breeding for durable resistance to the large raspberry aphid, Amphorophora ideai in red raspberries grown throughout the EU. This virus vector aphid has been successfully controlled by sequentially introducing resistance genes from the Rubus gene pool. However, as predicted by co-evolutionary theory, the pest has in turn evolved to overcome single resistance genes, each gene lasting between 10-20 years. Multi-genic resistance has been more durable over time but is less effective, only conferring partial resistance to the pest.
Plant breeding for pest resistance
Plant breeders are now at a pivotal point, where the time taken to breed a new cultivar with genetic resistance to pests like aphids takes longer than the time taken for the aphid to evolve counteracting adaptation (virulence), making the gene ineffective. This means the past successes of durable crop protection via plant breeding is under threat, exacerbated by the withdrawal of many currently used pesticides, due to stricter EU regulations. In addition, the use of polytunnels has rapidly changed the crops’ growing environment, providing an ideal habitat for insects almost all year round.
Figure: Sexual reproduction enables spread of R-breaking genes in UK. A1 R gene now 100 per cent ineffective in the UK. A10 R gene now breaking England.
Population dynamics of pests and their natural enemies
New research on raspberry agroecosystems in open field and polytunnel crops is showing that the durability of genetic resistance to aphids is being affected by both macro- (major differences in temperature, light and humidity) and micro-climate (more subtle differences, seen within the crop canopy).
These SCRI studies show that both ‘bottom up’ (genetic resistance to pests) and ‘top down’ pressures have major impacts on the population dynamics of pests and their key natural enemies (predators, parasitoids and pathogens attacking pest insects) in the complex but different food webs found in open fields versus covered crops.
Through understanding these complex food web interactions we are devising IPM systems which enhance positive interactions between pest resistance genes and natural enemies. This has the dual benefit of a) extending the durable lifetime of a resistance gene b) optimising the efficacy of biocontrol agents.
Chemical ecology: Host recognition signals and insect lures
Besides deploying pest-resistant cultivars as the foundation of SCRI’s IPM, we are also developing traps and lures for key pests, based on understanding the key host recognition signals that insects use to find specific plant species for egg laying or feeding.
Using raspberry as a model, SCRI has used a multi-disciplinary approach involving chemists and entomologists to identify the key host attractants for raspberry beetle and raspberry cane midge. By studying insect behaviour, using video cameras linked to specialised computer software, we have identified specific plant signals (plant volatiles and surface chemicals) which pest insects use to select suitable host plants. New techniques, using selective microfibres to trap plant volatiles, have enabled SCRI to narrow down the bioactive chemicals from the complex suite of aromas emitted from plants.
The next stage of identification involves the use of electrophysiology to record signals from the insect’s antenna while individual plant volatile compounds, separated on a gas chromatogram (GC), are passed over the insect’s head.This approach has led to the successful development of a trap for raspberry beetle using raspberry flower volatiles and another for cane midge females, using cane wound volatiles (with EMR and NRI). The SCRI traps and lures are delivered to raspberry growers in the UK, France, Switzerland and Norway via funding from hortLINK and Bioforsk. These traps enable growers to reduce pesticide inputs based on weekly trap catches and action thresholds for spraying only when the pest population increases to a level likely to cause economic damage.
Figure: Picture of SCRI's electro-antennogram (EAG), used to record signals from insect's antennae to identify the key plant chemical signals responsible for host recognition. The EAG is linked to a gas chromatogram mass spectrometer (GC-MS) to identify the bioactive plant chemicals for use as attractants and repellents.
Papers and reports
Bjorkmam, M., Klingen, I., Birch, A.N.E., Bones, A.M., Bruce, J.A., Johansen, T.J., Meadow, R., Molman, J., Seljasen R., Smart, L.E., Stewart, D. 2011. Phytochemicals of Brassicaceae in plant protection and human health – Influences of climate, environment and agronomic practice. Phytochemistry (in press).
Birch, A.N.E., Begg, G.S., Squire, G.R. 2011. How agro-ecological research helps to address food security under new IPM and pesticide reduction policies for global production systems. Journal of Experimental Botany (in press).
Birch, A.N.E. and Begg, G.S. 2010. The future central role of EU crop protection: How can ecological research be put into practice? Proceedings Crop Protection in Northern Britain 23-24 February 2010, 9-20.
Birch, A.N.E., Gordon S.C., Mitchell, C., Johnson S.N. Gordon, S.C., Birch, A.N.E. and Hubbard, S.F. 2010. Combining plant resistance and a natural enemy to control Amphorophora idaei. BioControl 55, 321-327.
Birch, A.N.E., S.C., Brennan, R.M., Jennings, S.N. and Mitchell, C. 2007. Breeding for durable resistance to the large raspberry aphid, Amphorophora ideai, in field and protected raspberry plantations: Co-evolution and IPM. IOBC Working Group: Integrated Plant Protection in Fruit Crops, subgroup, 'Soft Fruits', East Malling Research, 24-25 September 2007.
Birch, A.N.E., Gordon, S.C., Mitchell, C., Shepherd, T., Griffiths, D.W., Robertson, G. and Brennan, R. 2007. Development of semiochemical attractants, lures and traps for raspberry beetle, Byturus tomentosus at SCRI; from fundamental chemical ecology to testing IPM tools with growers. IOBC Bulletin, Lund, Sweden, September 2007.
Birch, A.N.E., Griffiths, B.S., Caul, S., Thompson, J., Heckmann, L.H., Krogh, P.H. and Cortet, J. 2007. The role of laboratory, glasshouse and field scale experiments in understanding the interactions between genetically modified crops and soil ecosystems: A review of the ECOGEN project. Pedobiologia 51, 251-260.
Jones, A.T., MCGavin, W.J. and Birch, A.N.E. 2000. Effectiveness of resistance genes to the large raspberry aphid, Amphorophora idaei Börner, in different raspberry (Rubus idaeus L.) genotypes and under different environmental conditions. Annals of Applied Biology 136, 107-113.
Odum, H.T. 1971. Environment, power and society. John Wiley and Sons, New York. 336 pages.
Applications
A Defra funded Hortlink project has developed a trap and lure for raspberry beetle. This IPM-based system has already been successfully trialled in UK, Norway, France and Switzerland and will be commercialised in the UK and EU via a commercial partner in 2009. Raspberry growers can use the trap and lure to monitor when this pest is active and rationally decide if it is necessary to apply any pesticides. This reduces pesticide use on high value raspberry crops and so also helps to promote biodiversiy (predators, parasitoids) needed for biocontrol of other pests, including aphids.
Read the Agrisense press release about the raspberry beetle trap (pdf file).
Expertise in IPM at SCRI is applied in studies on the impacts of pest-resistant GM crops in the EU FP6 ECOGEN project on Bt maize and in developing countries through the ERA IOBC project.
A ‘funnel approach’ (see PDF file diagram 3.57 KB) is used to rank pest-natural enemy importance in each agroecosystem so that the key food web interactions can be prioritised for investigation and delivery as part of a durable crop protection strategy. This research is delivered to end users via Workpackage 1.3 funded by the Scottish Government.
