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
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
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.
1: Produce slug-parasitic nematodes for use as biocontrol agents.
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.
3: Field experiments in key crops in several countries to establish
the principles for safe and effective use of the nematode biocontrol
4: Devise and assess novel crop management techniques for slug
control, including mechanical, physical and cultural methods.
5: Evaluate low toxicity compounds, which prevent slugs from feeding
or resting on plant tissues.
6: Devise and evaluate low chemical methods of killing slug eggs.
7 & 8: Devise and test integrated packages of control measures
for key conventionally grown crops (Task 7) and organically grown
crops (Task 8).
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
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.
3 In field trials in asparagus, Brussels sprouts, Chinese
cabbage, courgettes, lettuce, radish and strawberries, nematodes
were generally effective, except where Arion species caused
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.
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.
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.
of Agricultural Sciences
Ashton Research Station - (IACR-Long Ashton)
+44 1275 54 92 78
+44 1275 39 42 99
- Keith DAVIES
Rothamsted Experimental Station - IACR-Rothamsted
UK-AL5 2JQ Harpenden
Tel: +44 1582 76 31 33
Fax: +44 1582 76 09 81
- José CASTILLEJO
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
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
Tel: +33 4 67 63 10 14
Fax: +33 4 67 59 90 40
- Roman GWYNN
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
NL-8200 AK Lelystad
Tel: +31 320 29 11 11
Fax: +31 320 23 04 79