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Further development of a framework for the practical application of semiochemicals in field crops - PS2113

The main objective of this project is to develop a framework for the practical control of insect pests by means of semiochemicals. These are non-toxic, insect-produced (pheromones) or plant-derived chemicals that act as signals between organisms to cause natural behavioural or developmental changes in the recipient. As such, they can be used to manipulate populations of both pest and beneficial species and are perceived as a means of answering the demand for the reduction of intrinsically toxic materials in the environment.
The semiochemical signals used will include attractants, identified either from the pest or from its host plant, and also semiochemicals that mask the attractiveness of the host plant, odours or extracts from non-host plants and chemicals that are repellent to the pest. Compounds will be sourced from behaviourally active semiochemicals identified and synthesised/extracted in other previous and current research projects, principally PS2101 `Identification and provision of potential semiochemical tools for use in integrated crop management systems` and PS2105 `Delivery of semiochemicals within plant-pest-natural enemy systems`.
Since semiochemicals seldom act alone and are often synergised by others, particularly those from the host plant, this project will largely concentrate on the use of plant- derived compounds, with selected use of pheromones where there is a clear advantage in their use over compounds released by plants. Due to their non-toxic modes of action, the deployment of semiochemicals for future alternative plant protection technologies requires some form of combined pest control strategy such as the “push-pull” or habitat management strategy. For example, alarm/spacing pheromones, masking/repellent cues, including plant-derived antifeedants and plant activators can be used to deter or direct pests away from the main crop (the ‘push component’) whilst attractive host plant volatiles, sex/aggregation pheromones attract them to areas or “trap crops” (the ‘pull component’) where they can be maintained or selectively controlled by natural agents, e.g. pathogens, parasitoids and predators.
The semiochemicals will be delivered by novel approaches suitable for use in field crops. Delivery will not only be by direct application, but also by use of plant activators that switch on the plant’s own natural defence mechanisms causing crop plants themselves to release strategically required semiochemicals. Ultimately, this project aims to develop pest management strategies, on a realistic agricultural scale, for representative pest/crop interactions, including beetle pests of oilseed rape, aphids on cereals and weevils and aphids on legumes, used in conventional UK arable crop rotation.
The project will also define and quantify the effects of the pest management strategies on non-target species, with emphasis on natural enemies and other beneficial insects. The natural enemies will be exploited in the push-pull system, both by using appropriate semiochemical signals and by habitat management to enhance their survival. A key aspect of this work is that the control strategies will define and utilise semiochemical interactions relating to the complete plant/pest/natural enemy complex for each crop.
This project will clearly demonstrate the circumstances under which semiochemicals can be deployed on a realistic agricultural scale as a component of integrated pest management. This will provide the first evidence of the opportunities for full scale push-pull based crop protection systems in the UK. The intrinsically benign nature of the semiochemicals selected (e.g. plant essential oils and pheromones) and exploited in this work is highly relevant to the Government and Defra policies of minimising usage of conventional pesticides. This research is a necessary first step in encouraging further commercial development e.g. through Defra LINK and larger scale investigation e.g. through the joint Research Council funded landscape scale studies in the RELU (Rural Economy and Land Use) programme, Re-bugging the system – Promoting Adoption of Alternative Pest Management Strategies in Field Crop Systems. The results will assist a wider move towards alternatives to broad-spectrum pesticides and will inform the regulatory processes needed for semiochemical agents, particularly new plant activators.
This project exploits the discoveries made in the more strategic previous and ongoing projects PS2101 and PS2105, and aims to promote the development and uptake of alternatives to broad-spectrum eradicant pesticides, based on semiochemicals that have non-toxic modes of action. The project will develop and demonstrate, on a realistic field scale, a push-pull strategy for the key combinable crops used in conventional UK arable rotation i.e. cereals, oilseed rape and legumes.
Although the objective is to target the major crop/pest complex for each crop i.e. cereals/aphids, oilseed rape/Coleoptera and legumes, both aphids and Coleoptera, collateral effects of the strategy on other pests (e.g. cereals/gout fly, wheat blossom midge) and the potential impact on non-target organisms, particularly beneficials, will also be investigated.
Because of the practical fieldwork constraints on this project, the overall objective is divided into two main sub-objectives. One will focus on demonstrating, the push-pull control strategy on a representative brassica crop, spring oilseed rape (SOSR) using a turnip rape trap crop. The other will develop this approach for cropping systems involving cereals and legumes utilising Defra-recommended field margin mixtures. These mixtures are being promoted in current agri-environment schemes, but mechanisms to maximise and utilize the resulting biodiversity still need to be practically determined. This work will provide generic information and technologies for this and other crop rotations specifically associated with winter wheat (e.g. 2 x wheat; 1 x OSR; 2 x wheat).

1. Devise and test a semiochemical based management strategy for pests of oilseed rape.
Devise and test, on a realistic agricultural scale, a semiochemical based strategy for the pests of the representative brassica crop SOSR. The effects of the strategy on non-target species, particularly natural enemies and other beneficial insects will be defined and quantified. Spring rape will be targeted initially to build on previous experience and maximise natural occurrence of coleopterous pests of the inflorescence stage, but the study will extend to winter rape in the autumn of year 1.

2. Devise and test a semiochemical based management strategy for pests of cereal and legume crops in a conventional arable rotation.
Use plant-derived and other semiochemical stimuli that provide enhanced attractant and non-host/masking/repellent cues under field conditions for target pests and their natural enemies, to formulate an integrated crop protection strategy for the other combinable crops used in conventional arable rotation i.e. cereals (winter wheat chosen to utilise best existing knowledge of predatory and parasitic insects) and legumes (chosen to target both coleopterous and aphid pests). Define and quantify the effects of the strategy on non-target species, particularly natural enemies and other beneficial insects.
Project Documents
• Final Report : A framework for the practical application of semiochemicals in field crops   (884k)
Time-Scale and Cost
From: 2006

To: 2010

Cost: £430,938
Contractor / Funded Organisations
Rothamsted Research (BBSRC)
Crop Pests              
Pest and Weed Control              
Pest Control              
Pesticide use              
Plants and Animals              
Fields of Study
Pesticide Safety