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Novel technologies for integrated control of slug damage in key horticultural crops

Contract nr: FAIR-CT97-3355
Project nr: 3355
Project type: SC
Starting date: 16/02/1998
Duration: 36 months
Total cost: 1,400,609 EUR
EC Contribution: 830,000 EUR
Scientific Officer: Massimo BURIONI
Research topic: Plant health
Acronym: Novel Slug Control

Slugs are amongst the most harmful pests in key vegetable and soft fruit crops, causing loss in quality. Despite routine repeated applications of chemicals, control in these crops is inadequate and the chemicals in current use also kill non-target organisms and may result in residues in harvested produce. Slugs are likely to increase in importance in conventional crops under the reformed CAP. Slugs are especially troublesome in organic crops where no direct methods of slug control are available. The availability of efficient methods of slug control will encourage the conversion of farms to organic production. This project is timely because of this and the recent discovery of novel methods of slug control, including a nematode biocontrol agent, non-chemical methods and low-toxicity repellent compounds.

To evaluate and deliver to conventional and organic growers integrated packages of novel methods of slug control for key horticultural crops, thereby achieving environmentally benign control of slug damage.

The packages will involve the use of
(1) a novel nematode biocontrol agent, produced by an SME;
(2) novel cultural, mechanical and physical methods of control;
(3) novel low-toxicity feeding deterrents;
(4) novel low-chemical methods against slug eggs.

Work plan:
Task 1: Produce slug-parasitic nematodes for use as biocontrol agents.
Task 2: Quantify effects of environmental conditions on nematode survival in soil and ability to kill slugs; search for warm-adapted strains suitable for use in southern Europe; search for new strains suitable for northern Europe; develop monoclonal antibodies as novel tools to investigate nematode survival in soil; establish relationships between nematode pathogenicity and host-slug body weight.
Task 3: Field experiments in key crops in several countries to establish the principles for safe and effective use of the nematode biocontrol agent.
Task 4: Devise and assess novel crop management techniques for slug control, including mechanical, physical and cultural methods.
Task 5: Evaluate low toxicity compounds, which prevent slugs from feeding or resting on plant tissues.
Task 6: Devise and evaluate low chemical methods of killing slug eggs.
Tasks 7 & 8: Devise and test integrated packages of control measures for key conventionally grown crops (Task 7) and organically grown crops (Task 8).

Industrial context: Involvement of research institutes for field vegetables and organic production, together with two SMEs, will ensure that the results are developed and put to practical use by growers at the earliest possible stage. One SME already produces and markets a product containing the nematode biocontrol agent for use in private gardens in the UK. However, use of the nematode biocontrol agent will need to be integrated with other control measures for effective, economic use in commercial horticulture. The SME does not have sufficient resources to achieve this on its own. The SME will conduct further development work after the end of this pre-competitive project.

Current situation/results:
Tasks 1 & 2 Infective juveniles of the nematode biocontrol agent, Phasmarhabditis hermaphrodita, survived best in moist soil at low temperature, but their ability to cause disease in slugs was little affected by soil temperatures from 5-20oC and by relatively dry soil. The upper temperature limit for survival was 23oC. Monoclonal antibodies putatively diagnostic for P. hermaphrodita have been produced and characterised. In the laboratory, nematodes survived similarly well in sterilised and unsterilised soil. Thirty two new nematode isolates were obtained from slugs in the Netherlands, Spain, Switzerland and UK. Several were P. hermaphrodita, but related species were also found. In bioassays, many were highly pathogenic to Deroceras reticulatum. In the laboratory, Arion lusitanicus was highly susceptible to P. hermaphrodita (commercial strain) immediately after hatching, but not when they reached 1-2 g. By contrast, young A. distinctus were insensitive to nematodes. All size classes of D. reticulatum were susceptible.

Task 3 In field trials in asparagus, Brussels sprouts, Chinese cabbage, courgettes, lettuce, radish and strawberries, nematodes were generally effective, except where Arion species caused most damage.

Task 4 Neither hoeing nor the presence of weeds reduced slug damage. Green and red lettuce cultivars were similarly susceptible to slugs. Molluscicidal compost reduced slug damage. Electrical barriers protected courgette plants from slug damage. Commercially available zinc-coated fences reduced immigration by A. lusitanicus.

Task 5 Carvone acted as a slug repellent in the laboratory but not in the field. Application of common salt to an asparagus crop, alone or with nematodes, significantly reduced slug damage.

Task 6 Microwave energy was not suitable for killing slug eggs in the field. Cupric, aluminium and ferric salts were highly toxic to eggs, but were inactivated in soil. Two herbicides killed slug eggs and were not inactivated by soil. Extracts of two plants killed slug eggs.

Tasks 7 & 8 In one site, A. lusitanicus moved from wildflower strips and caused severe damage up to 4 m into the adjacent crop. Trials have been established to investigate novel combinations of biological, chemical, cultural and mechanical control measures.


David GLEN
University of Bristol
Department of Agricultural Sciences
Long Ashton Research Station - (IACR-Long Ashton)
UK-BS41 9AF Bristol
Tel: +44 1275 54 92 78
Fax: +44 1275 39 42 99


  • Keith DAVIES
    Rothamsted Experimental Station - IACR-Rothamsted
    West Common
    UK-AL5 2JQ Harpenden
    Tel: +44 1582 76 31 33
    Fax: +44 1582 76 09 81

    Universidad de Santiago de Compostela
    Faculty of Biology
    Pazo De San Xerome - Praza Do Obradoiro
    E-15706 Santiago de Compostela
    Tel: +34 98 156 31 00
    Fax: +34 98 159 69 04

  • Bernhard SPEISER
    Research Institute of Organic Agriculture - FIBL (Public funded Research Institute)
    Ackerstrasse Postfach
    CH-5070 Frick
    Tel: +41 62 86 572 43
    Fax: +41 62 86 572 73

  • James COUPLAND
    FarmForest Research (formerly Helix Consulting) - Dr. James Coupland enterprise individual
    Rue de Las Sorbes 152
    F-34000 Montpellier
    Tel: +33 4 67 63 10 14
    Fax: +33 4 67 59 90 40

  • Roman GWYNN
    MicroBio limited
    High Street 17
    UK-CB2 4LT Whittlesford, Cambridge
    Tel: +44 1223 83 08 60
    Fax: +44 1223 83 08 61

  • Albert ESTER
    Research Station for Applied Research for Arable Farming and Field Production of Vegetables - PAV
    Edelhertweg 1
    NL-8200 AK Lelystad
    Tel: +31 320 29 11 11
    Fax: +31 320 23 04 79
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