Reduction in tick numbers (Haemaphysalis longicornis), mortality and incidence of Theileria sergenti infection in field-grazed calves treated with flumethrin pour-on

The effectiveness of the pour-on formulation of flumethrin was tested on gr azing cattle, Flumethrin was applied once a month from April to October fro m 1990 to 1995 to cattle grazing in the Aso area of Kumamoto Prefecture in Japan, Bath the number of ticks in the field and the number of ticks feedin g on cattle decreased remarkably in relation to the number of years flumeth rin was applied. Ticks in the field were not detected in 1994 and 1995, and ticks feeding on cattle decreased to 4% in 1995. Mortality due to Theileri a sergenti infection also decreased significantly after more than 3 years o f flumethrin pour-on application, although overall mortality did not change . At the end of the trial the incidence of T. sergenti had decreased to one -fifth of the pretrial value, although total incidence of disease had not c hanged. These results indicated that multiple-year seasonal application of flumethrin pour-on to grazing cattle effectively decreased the number of ti cks and decreased both mortality and incidence of T. sergenti. (C) 2000 Els evier Science B.V. All rights reserved.