Controlling Ectoparasites on Welsh Organic Sheep Farms

Summary

1. Organophosphate (OP) based dips offer a broad spectrum control against all major ectoparasites in the UK. However, there is continuing controversy over the safety to dip operators and the environment. The use of OPs is prohibited by organic standards, primarily because of concerns about mammalian toxicity.
2. Organic farmers are permitted to use synthetic pyrethroids (SPs)(dip products and pour-on products) and/or macrocyclic lactones (injectable products) to treat/control ectoparasites providing a derogation has been obtained from the certifying body.
3. SPs have been shown to be considerably more toxic to aquatic organisms than OPs. The environmental impact of SPs is not limited to levels in dip but also to residues in sheep fleeces. SPs may be removed from the wool by climatic conditions and then deposited in the local environment.
4. The Environment Agency have indicated that the majority of sheep dip pollution incidents involve SP dips. Concerns have been raised that as organic farmers can only use SP based dips they may be contributing to the higher levels of SP based pollution incidents.
5. There is little information as to current practices amongst organic sheep farmers to control/treat ectoparasites or on how these farmers dispose of the spent dip. In order to address this lack of information a survey was carried out by ADAS Pwllpeiran to investigate current practices amongst sheep farmers in Wales. For comparison purposes both conventional and organic farmers were included in the survey.
6. In total, 134 questionnaires were completed with 96 completed by conventional sheep farmers and the remaining 38 being completed by either in-conversion organic farmers or fully registered organic farmers.
7. Results showed that 58% of organic farmers surveyed treated their flocks for ectoparasites compared to 67% of conventional farmers.
8. Of the organic farmers surveyed, 52.6% listed flystrike as a parasite for which they treated their flocks. This was comparable to conventional farmers where 58.3% listed flystrike. Only 21.1% of organic farmers surveyed listed scab compared to 61.5% of conventional farmers. Less than 10% of both conventional and organic farmers surveyed treated for other ectoparasites. Those who did listed lice and ticks as the main ectoparasites.
9. Despite a large percentage of conventional farmers listing scab as an ectoparasite to be treated, only 11.5% of those surveyed treated for ‘scab only’ compared to 51.0% who treated for scab in combination with other ectoparasite control. A similar pattern was seen amongst organic farmers surveyed, where only 2.6% treated for ‘scab only’ whereas 18.4% treated for scab in combination with other ectoparasite control.
10. Of the organic farmers surveyed, 36.8% treated for ‘flystrike only’ compared to 7.3% of conventional farmers.
11. Despite other ectoparasites such as lice and ticks being listed by both conventional and organic farmers neither of these two parasites were treated singly but were always treated in combination with other ectoparasites.
12. Of conventional farmers surveyed who treated for ectoparasite control, 76.1% listed plunge dipping as the preferred dipping method compared to only 22.7% of the organic farmers surveyed who treated for ectoparasites.
13. The use of pour-on products was higher amongst organic farmers with 54.5% using pour-ons as a treatment method compared to 16.5% of conventional farmers.
14. Less than 5% of the organic farmers who treated for ectoparasites used a combination of treatments compared to 19% of conventional farmers who treated for ectoparasites.
15. When asked how often they treated for ectoparasites, 54% of organic farmers treated once a year compared to 42% of conventional farmers. 27% of organic farmers treated twice a year whereas 52% of conventional farmers treated twice a year. 14% of organic farmers treated three or more times a year compared to 7% of conventional farmers.
16. All organic farmers who carried out plunge dipping operations used a SP based product however of the conventional farmers who carried out plunge dipping, 39% used an SP based product. Overall, 16% of organic farmers surveyed used an SP based dip product compared to 24% of conventional farmers surveyed. Of all conventional farmers surveyed 38% used an OP based dip product.
17. Where farmers carried out plunge dipping, 53% of conventional farmers diluted spent dip before spreading to land compared to 83% of organic farmers who carried out plunge dipping operations. Of all the farmers surveyed who carried out plunge dipping only 1 treated dip with slaked lime before spreading.
18. Of all organic farmers surveyed, 5% used a mobile dipping contractor compared to 23% of conventional farmers surveyed.
19. Where contractors were used on organic holdings they were also responsible for the disposal of spent dip. The contractor was responsible for the disposal of dip on 74% of conventional holdings using contractors for dipping.
20. On 42% of the holdings using contractors, the spent dip was removed from the farm whereas on 32% of holdings the spent dip was spread on the farm land. 26% of farmers using contractors in this survey did not know how the contractor disposed of spent dip.
21. The percentage of farmers treating their flocks for ectoparasite infestations is similar for organic (58%) and conventional (69%) sheep farmers however there is a marked difference in the species of ectoparasites treated.
22. Of the conventional farmers who treated their flocks for ectoparasites, 86% listed scab as a major parasite compared to only 36% of organic farmers who also treated their flocks for ectoparasites.
23. Overall, only 3% of the organic farmers surveyed treated their sheep specifically for scab, compared to 11% of conventional farmers surveyed.
24. Of organic farmers surveyed, 37% treated their flocks specifically for blowfly strike compared to only 7% of conventional farmers surveyed.
25. Of the conventional farmers surveyed, 51% treated their flocks for more than one ectoparasite infestations compared to 18% of organic farmers surveyed.
26. From the evidence of several of the completed survey forms some farmers appeared to be using incorrect treatment methods and some were using multiple treatment methods to treat ectoparasite infestations. The use of incorrect treatments or multiple treatments is largely a reflection of the plethora of products available and suggests a lack of understanding as to which products are appropriate and licensed for the treatment of specific ectoparasites.
27. The survey found that fewer organic sheep farmers use SP dips than conventional sheep farmers do. As there are fewer organic sheep farmers overall, there is little evidence that organic sheep farmers contribute disproportionately to the level of SP based pollution incidents.
28. Summary of Recommendations:
A. A further in-depth survey would be valuable to elucidate the extent of the scab problem in the national organic flock.
B. Both organic and conventional farmers have difficulty in selecting the best/ most appropriate treatment for their flocks. An educational campaign would help to remedy this problem.
C. Annual training courses for certifying bodies and advisors to keep up to date with developments in research and products are recommended.
D. Given the potential for SP dips to cause major environmental damage if disposed of incorrectly it is a mandatory requirement that organic farmers are licensed by EA to dispose of spent dip. Inspectors should ensure cross compliance where organic farmers are using dip.
E. Certifying bodies need to consider all the available evidence as to what chemicals should be permitted to treat scab and other ectoparasites and where appropriate make alterations to the standards.
F. Inspection of dips facilities and EA licence should be part of the annual inspection procedures.
G. Certification bodies should collate information on dipping practices and dip disposal.
H. Where a pollution incident occurs on an organic holding this should be reported to the relevant certifying body.
I. Development and evaluation of IPM programmes should be assessed as a management tool to reduce use of chemical treatments whilst promoting good animal husbandry and management. IPM programmes should be incorporated with animal health plans.