The effects of flumethrin (Bayticol® pour-on) on European ticks exposed to treated hairs of cattle and sheep.

Tick infestations in cattle and sheep pose serious health problems when agents of diseases are transmitted. In addition, blood feeding of ticks induces enormous economic losses due to reduced weight gain of infested animals. The present study was designed to investigate the effects of exposure to hairs clipped from cattle and sheep treated with flumethrin (Bayticol®) on European ticks. The dose used was 10 ml/100 kg body weight for both animal species. At intervals of 7 days (days 7, 14, 21, 28 and 35), hairs were cut off from treated and untreated animals along the backline and from the feet just above the claws. These hairs were mingled with stages of the tick species Ixodes ricinus, Dermacentor reticulatus and Rhipicephalus sanguineus. It was found that in the cases of I. ricinus and D. reticulatus, all specimens died within 5-12 h when coming into contact with cattle hair from the feet or back of animals treated 3 weeks ago and within 6 to 9 h after contact to sheep hair from back or feet. After 4 weeks, the specimens of both tick species that had contact with hair of treated sheep and cattle, independent from the origin backline or feet, were dead after 8 h except for one tick that had contact to hair from feet of cattle. It remained fully motile after a 12-h contact even for the observation time on another 5 days. When having contact to hair of animals treated 5 weeks before, several specimens of Ixodes and Dermacentor survived an exposition of 12 h. There were more survivors in the case of ticks tested on hair of the feet than in the case of contacts with hair of the backline. The exposure of R. sanguineus to hair obtained from animals treated 2 weeks earlier resulted in death in 2-4 h. However, most R. sanguineus ticks when coming in contact with treated hairs (collected from animals treated 3, 4 or 5 weeks earlier) from back or feet survived for atleast 5 days even after exposure for 12 h. These experiments confirmed the positive protection results obtained in former studies with typical cattle ticks in the tropics and/or subtropics. In addition to the killing effects described above, it was noted that flumethrin had a significant repellent effect. If ticks were mingled with treated hair, they tried to flee away and did not seek shelter inside the hair as the controls did in untreated hair.