title: Eprinomectin pour-on for control of Boophilus microplus (Canestrini) ticks (Acari: Ixodidae) on cattle.
abstract: The efficacy of a commercial pour-on formulation of eprinomectin, a macrocyclic lactone, against experimental infestations of Boophilus microplus (Canestrini) ticks was evaluated in two trials involving 27 Bos taurus calves. The first trial was designed to evaluate the effects of a single treatment at a dose of 0.5 mg/kg of body weight against standard size B. microplus females (4.5-8.0 mm long). A significant reduction in tick numbers (P<0.05, Wilcoxon test) was observed between treated calves as compared to untreated ones from Day 3 (44% efficacy) after treatment to the end of the trial on Day 28 (96.9%), with a peak efficacy of 97.1% on Day 21. In the second trial the effect of eprinomectin on standard size tick numbers, engorgement weight and fertility of female ticks from calves with a single treatment dose of 1 mg/kg on Day 0 and calves treated twice at a dose of 0.5 mg/kg on Days 0 and 4 was evaluated. An efficacy >93% was obtained from Day 2 to Day 28 after treatment in calves treated twice at 0.5 mg/kg, and to the end of the trial (Day 35) in calves treated once with 1 mg/kg. The 1mg/kg treatment provided >98% residual efficacy for at least 7 days. During the first part of the second trial the efficacy of eprinomectin resulted from a dramatic adverse effect on engorgement weight and fertility of female ticks, with 100% control on Day 5 (dosage of 1 mg/kg) and on Days 6 and 7 (two doses of 0.5 mg/kg). Following Day 7, most of the effect was due to reduction in the number of standard size female ticks.
authors.affiliation: Instituto Nacional de Tecnología Agropecuaria, Estación Experimental Agropecuaria Salta, CP 4400 Salta, Argentina. daguirre@correo.inta.gov.ar
authors.forename: D H
authors.initials: DH
authors.lastname: Aguirre
authors.forename: A B
authors.initials: AB
authors.lastname: Gaido
authors.forename: M M
authors.initials: MM
authors.lastname: Cafrune
authors.forename: M E
authors.initials: ME
authors.lastname: Castelli
authors.forename: A J
authors.initials: AJ
authors.lastname: Mangold
authors.forename: A A
authors.initials: AA
authors.lastname: Guglielmone
mesh_terms: D000287:Administration, Topical; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000188:drug therapy* / Q000469:parasitology; D004305:Dose-Response Relationship, Drug; D005260:Female; D007306:Insecticides / Q000008:administration & dosage*; D007559:Ivermectin / Q000008:administration & dosage* / Q000031:analogs & derivatives*; D026863:Ixodidae / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology; D012098:Reproduction / Q000187:drug effects; D013983:Tick Control / Q000379:methods*; D013984:Tick Infestations / Q000188:drug therapy / Q000662:veterinary*; D016896:Treatment Outcome
chemical_list: D007306:Insecticides; D007559:Ivermectin; C101434:eprinomectin