Natural Enemies for Enhanced Bio-control of cereal
Project Code: AR0301
Funded By Department for Environment, Food and Rural Affairs
Lead Research Centre
Horticulture Research International
Abstract of Research Proposal
The overall aim of the project is to understand the mechanisms whereby biocontrol of cereal pests can be successfully enhanced by augmenting the abundance and diversity of generalist predators within the crop. Increasing the abundance and diversity of prey for these predators is likely to, in turn, increase the abundance and diversity of predators, but this needs to be tested and quantified. There is a danger that generalist predators, given a wide choice of prey types, will reduce their per capita feeding rate on pests, if pests are less-preferred foods. It is also possible that increase in the diversity of predators will result in a top predator killing aphid predators (intraguild predation) which would destabilise biological control of aphids. These topics require careful investigation by experimentation in the field, to guide the future effective use of the generalist predator component in ICM systems.
Obtaining an energy and nutrient subsidy from the detrital food chain is chosen as an experimental system for diversifying the trophic components of the habitat. This can be achieved by addition of organic material to the soil surface (which may also have direct application in ICM systems) and this will also achieve some structural diversification. Organic material will be added to the soil surface of a cereal field in small replicated and randomised patches. Thereafter the abundance and diversity of non-pest detritivores (flies and mites etc, that feed on the organic material) and generalist predators will be monitored in these treated patches and in an equal number of untreated patches. Some of the patches will be caged to create mesocosms into which assay plants bearing aphids will be introduced in order to quantify the effect of the diversification on the efficiency of aphid biocontrol. In a separate experiment top predators (that are known to kill other predators) will be added to the mesocosms to determine the extent to which they interfere with successful biocontrol by killing aphid predators. By investigating the principles underlying successful biological control, this project addresses the policy problem of the need to reduce pesticide inputs whilst also maintaining the profitability of farming and the supply of affordable and wholesome food to the public. The information gained will be useful to the scientific community in promoting a greater understanding of the ecology of generalist predators and of the ecological complexities of biological control in arable crops. The results will be of value to applied scientists and technologists engaged in the development of robust ICM programmes, and to MAFF in guiding policy decisions that relate to biological control issues and the conservation of biodiversity in the UK countryside. The findings of this project, after appropriate downstream development and integration with outputs from other projects, will be of value to the industry and consumer by contributing to the development of efficient, profitable, predictable yet environmentally sustainable farming.
Summary of Objectives
The overall aim of the project is to understand the mechanisms whereby biocontrol of cereal pests can be successfully enhanced by augmenting the abundance and diversity of generalist predators within the crop. Addition of organic material to the soil surface is chosen as a tractable experimental system (which may Laos have direct application in ICM systems) for diversifying the structural and tropic components of the habitat. The specific objectives are:
01 Determine the effect of soil-surface organic additives on the detritivore and generalist predator communities in winter wheat
02 Determine the impact of soil-surface organic additives on the biocontrol of cereal aphids, as mediated by the enhancement of generalist predators
03 Determine how intraguild predation, arising from enhancement of generalist predators, may reduce the efficiency of aphid biocontrol
Executive Summary of Final Report
Project not completed.
Start date: 01/04/00
Completion date: 31/03/04