DRUG-RESISTANT FLEA POPULATIONS AND PROBL EMS WITH THERAPY

A flea strain was isolated from a cat breeding colony in Berlin. This strain had been imported accidently with a tomcat from Florida and was therapy resistant since June 1991. The strain was isolated, named ''C ottontail'' and tested against the common insecticides. It showed to b e resistant against HCH, carbamates, organophosphates, rotenon, pyreth rine, pyrethroids, iveimectin and lufenuron (in the claimed dosages) and partially resistant against fipronil. It was sensible to methopren e, triflumuron, imidacloprid and pyriproxyfen. A cat flea laboratory s train sewed as control and it was sensible against all tested actives. The difficulty in treatment of therapy resistant flea strains and the problems of treatment mistakes are discussed.