Award details

Dynamic responses of predators to biodiversity in sustainable agriculture: spatial and molecular analyses

Reference	BB/D001188/1
Principal Investigator / Supervisor	Professor William Symondson
Co-Investigators / Co-Supervisors	Dr David Bohan
Institution	Cardiff University
Department	School of Biosciences
Funding type	Research
Value (£)	358,499
Status	Completed
Type	Research Grant
Start date	01/09/2005
End date	31/03/2009
Duration	43 months

Abstract

Dynamic and complex interactions between generalist predators and their different prey (pest and non-pest) contribute to the natural regulation of crop pests and may be an essential component of sustainable agriculture. We will study the spatio-temporal responses of generalist predators to prey diversity and the effects of such diversity on pest suppression and crop yield. We will reveal the fundamental mechanisms governing predator responses to diversity using a unique combination of gut content analysis using a novel molecular approach (multiplex PCR), spatial analysis by distance indices (SADIE) and behavioural bioassays. We will track spatial patterns and associations between predators, pests, predation on pests and alternative prey, prey abundance and diversity (in the field and in predator guts) over space and time. Using carabid beetles as model generalist predators we will test the hypotheses that the predators respond spatially to prey diversity and not simply to prey abundance; that the predators respond spatially to prey biomass when prey density is suboptimal but to prey diversity when there is an excess of prey; that when the predators encounter greater diversity they respond by eating a greater range of prey rather than simply being more selective; that increased alternative prey diversity and/or abundance leads to reduced pest density (both spatially and temporally; that increased alternative prey diversity and/or abundance leads to increased crop yield; and that predators change their prey choices in response to previous feeding history. The answers to these questions should allow us to evaluate the benefits of maintaining high numbers and diversity of the alternative prey species exploited by generalist predators, and thus encourage the development of improved farming systems that maximise the sustainability and resilience of arable farming to pest attack.

Summary

Generalist predators are common in most arable crops, feed on a wide variety of prey and contribute to pest suppression. We propose to ask fundamental questions regarding the spatial and temporal responses of such predators to prey biodiversity and the effects of that diversity on pest control. Using the common ground beetle Pterostichus melanarius as a model we will map the distributions of predators and prey, then analyse associations between them over space and time. Prey DNA will be identified within the guts of the predators to confirm predatory events using a new technique developed by us in Cardiff. The beetles are known to survive and reproduce better on a diverse diet incorporating a variety of prey species. Thus, using a unique combination of spatially structured field sampling, novel molecular biology approaches and mathematical modelling, we ask what would happen when many prey species are abundant in the field: do the predators aggregate to particular prey, to the highest number/biomass of prey overall or to the greatest diversity of prey species? Do the predators respond to prey number when prey availability is low but to diversity when prey are numerous? Where prey are diverse, do the predators eat a diverse diet or are they simply more selective, consuming the nutritionally most beneficial species? And how does all this affect the control of important pests, like slugs and aphids, and crop yields? This will be the first such research to directly assess the effects of biodiversity on crop yields, using approaches that will reveal the biological and ecological mechanisms and processes involved. The answers to these questions will help us to evaluate the benefits of maintaining high numbers and diversity of predators and alternative prey species within arable lands, and thus improve the sustainability and resilience of arable farming to pest attack.

Committee	Closed Committee - Agri-food (AF)
Research Topics	Crop Science, Plant Science
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

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