HL Deb 26 January 2000 vol 608 c198WA
The Countess of Mar

asked Her Majesty's Government:

Whether there have been reports of resistance of sheep ectoparasites to organophosphate sheep dips (from any part of the United Kingdom). [HL678]

Baroness Hayman

The Veterinary Laboratory Agency has received reports of two confirmed cases of resistance to Psoroptes ovis to organophosphorus sheep dips in the UK. Both were reports of resistance to propetamphos and were in 1995–96.