Naturally occurring semiochemicals, that control the behaviour or development of pests and their hosts, can be extracted from cultivated non-food plants and deployed for the protection of larger areas of crop plants. However even where naturally derived, semiochemicals that are applied as “plant protection products”, require registration under EC Directive 91/414. In the United Kingdom, there is considerable demand for use of alternatives in crop protection to synthetic broad-spectrum toxicant pesticides. Since semiochemicals act as signals regulating behaviour or development rather than by toxic or other direct physiological effects, effective pest control methods based on their use may be more acceptable not only over synthetic conventional pesticides but also over botanically-derived toxicants. Semiochemicals are intrinsically expected to be more benign than conventional crop protection methods, but this must be demonstrated objectively in the formal assessment of potential risks made by the Pesticide Safety Directorate based on information contained in the registration package. The developing industry has indicated that data requirements, their presentation and assessment procedures geared to convetional pesticides appear a potential barrier to commercialisation and hence the availability of more desirable control methods. The placement of information arising from pilot registration exercises in to the public domain would assist this emerging industry with development of appropriate registration packages and further exploitation of semiochemicals.
The main objective of this research project will be to take information on three specific examples of semiochemicals and to produce associated packages suitable for registration. The main activities will involve providing data for long term previous and current human contact with the three natural semiochemicals, together with toxicological data as available for each, or for closely related natural products, and any appropriate synthetic analogues. Any further data required will be provided by ongoing research in other projects, with this study concentrating on the compilation of existing data, and those from other sources, and the computation of or extrapolation from these data for the purposes of the registration packages.
In order to conduct the operation in the public domain, a web site incorporating the data relevant to the registration package as it is assembled will be constructed and maintained. Although considerable know-how in the UK has been accrued on the potential and demonstrable use of semiochemicals in crop protection, further ongoing work is essential before semiochemical-based pest control can be exploited widely. However it is now opportune to examine representative examples of natural semiochemicals for use so that the process by which these agents are registered can be formally tested.
Three natural semiochemicals will be chosen and a probative registration package assembled for each, to devise a general framework. These will be:
1. Hop â-acids. This material is derived from brewing hops and acts as an effective antifeedant (a semiochemical interfering with feeding behaviour) against, for example, the two-spotted spider mite, Tetranychus urticae, a pest of high value horticultural crops.
2. Methyl salicylate. This is employed as the major component of a fully definable essential oil (oil of wintergreen) and acts as an indicator of plant stress, and therefore non-host status, thereby reducing aphid colonisation of, for example, cereal crops.
3. cis-Jasmone. This is obtained as the major component of various essential oils and acts as a plant signal, or plant activator, that usefully “switches on” plant defence and reduces thereby, for example, aphid numbers on cereal crops.
Hop â-acids, methyl salicylate and cis-jasmone are found naturally in foods or in food crops and hop â-acids and methyl salicylate are recognised food additives. The packages will be assembled as though for submission to PSD, with the assembly process made publicly transparent via a web site, from work conducted at Rothamsted with consultancy for construction of the packages from JSC International Ltd. The acceptance of the general framework will clear the way for commercial exploitation of natural semiochemicals and the full publication of the work will support subsequent registrations in the private sector.