ECTOPARASITE CONTROL ON SHEEP FARMS IN ENGLAND AND WALES - THE METHOD, TYPE AND TIMING OF INSECTICIDAL TREATMENT

The chemical control of sheep ectoparasites raises important environme ntal, health and welfare issues. There is increasing concern about the possible harmful effects of pesticides on human health and the role o f dipping in the contamination of natural watercourses. A longitudinal survey was conducted in 1991, the last year of compulsory dipping for the control of sheep scab, to obtain information about the chemical c ontrol of ectoparasites on 485 farms in England and Wales. Organophosp hate insecticides were the most commonly used for both summer and comp ulsory dipping and for spraying sheep, although many of the products u sed for spraying sheep were not licensed for this purpose. The early p attern of dipping and spraying appeared to follow the pattern of incid ence of blowfly strike although more than 40 per cent of sheep were di pped during the first two weeks of the compulsory dipping period. Comp ulsory dipping for the control of sheep scab was reduced from two dips to one dip between 1988 and 1989 and removed altogether in 1999. The results from the survey were compared with the results of a previous s urvey and showed an apparent decline in the use of dipping and an incr ease in the use of alternative methods of control between 1988 and 199 1.