Davey R B, Ahrens E H, George J E, Hunter J S, Jeannin P
USDA, ARS, Cattle Fever Tick Research Lab., Mission, TX 78572, USA.
Vet Parasitol. 1998 Jan 31;74(2-4):261-76. doi: 10.1016/s0304-4017(97)00152-0.
Cattle infested with all parasitic life-stages of Boophilus microplus (Canestrini) were treated once with a pour-on formulation of fipronil at 0.25, 0.5, or 1.0% active ingredient (AI) to determine the therapeutic efficacy. Additionally, cattle were infested at weekly intervals for 13 consecutive weeks after treatment to determine the persistent effectiveness of the three concentrations. Results of therapeutic efficacy of fipronil showed that with each increase in concentration there was a corresponding and often significant (P < 0.05) decrease in the numbers, fecundity and fertility of engorged females. The overall control of the Index of Reproduction (IR) achieved at 0.25 and 0.5% AI was 86.2 and 94.3%, respectively, while the control of the IR at the 1.0% AI concentration was 99.7%. The persistent efficacy of fipronil, like the therapeutic efficacy, was also dose related. The 0.25% AI treatment failed to provide complete protection (100%) against larval reinfestation, although control of the IR remained high (> 95%) for the first 6 weeks after treatment. In contrast, at 0.5% AI the control of the IR remained at 100% for the first 4 weeks after treatment, and was > 90% for an additional 2 weeks (6 weeks posttreatment). The 1.0% AI concentration afforded the longest residual activity, providing virtually 100% protection against larval reinfestation for 8 weeks after treatment was applied. Based on the results, neither the 0.25 or 0.5% AI concentration completely eliminated the immature stages of the tick (nymphs and larvae) on the host at the time of treatment (therapeutic efficacy), and the residual activity (persistent efficacy) did not prevent reinfestation by larvae for long periods after treatment. While the 1.0% AI concentration provided both therapeutic and residual efficacy that would be suitable for use in the eradication program, caution is still warranted because a few engorged females detached for up to 25 days after treatment, although none reproduced after the 6th day.
用含0.25%、0.5%或1.0%有效成分（AI）的氟虫腈浇泼剂对感染微小牛蜱（Canestrini）所有寄生阶段的牛进行一次治疗，以确定其治疗效果。此外，在治疗后连续13周每周对牛进行一次感染，以确定这三种浓度的持续有效性。氟虫腈治疗效果的结果表明，随着浓度的每一次增加，饱血雌蜱的数量、繁殖力和生育力相应减少，且通常具有显著差异（P < 0.05）。在0.25%和0.5% AI浓度下，繁殖指数（IR）的总体控制率分别为86.2%和94.3%，而在1.0% AI浓度下，IR的控制率为99.7%。氟虫腈的持续有效性与治疗效果一样，也与剂量有关。0.25% AI处理未能提供针对幼虫再次感染的完全保护（100%），尽管在治疗后的前6周，IR的控制率仍然很高（> 95%）。相比之下，在0.5% AI浓度下，治疗后的前4周IR的控制率保持在100%，在接下来的2周（治疗后6周）内> 90%。1.0% AI浓度提供了最长的残留活性，在施用治疗后8周内几乎提供了100%的针对幼虫再次感染的保护。基于这些结果，在治疗时（治疗效果），0.25%或0.5% AI浓度均未完全消除宿主上蜱的未成熟阶段（若虫和幼虫），并且残留活性（持续有效性）在治疗后很长一段时间内并不能防止幼虫再次感染。虽然1.0% AI浓度提供了适用于根除计划的治疗和残留效果，但仍需谨慎，因为治疗后有少数饱血雌蜱在长达25天的时间内脱落，尽管在第6天后没有一只产卵。
