Susceptibility of Rhipicephalus (Boophilus) microplus to ivermectin (200, 500 and 630 μg/kg) in field studies in Brazil

Autor: Gilson Pereira de Oliveira, Willian Giquelin Maciel, Marcos Henrique Alcantara Colli, Breno Cayeiro Cruz, Gustavo Felippelli, Weslen Fabricio Pires Teixeira, Rafael Silveira Carvalho, Welber Daniel Zanetti Lopes, Alvimar José da Costa, Flávia Carolina Fávero, Claudio Alessandro Massamitsu Sakamoto, Maycon Araújo Ruivo
Přispěvatelé: Universidade Estadual Paulista (Unesp), Universidade Federal de Goiás (UFG), Universidade Estadual de Maringá (UEM)
Rok vydání: 2014
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Zdroj: Web of Science
Repositório Institucional da UNESP
Universidade Estadual Paulista (UNESP)
instacron:UNESP
ISSN: 1873-2550
Popis: Made available in DSpace on 2015-10-22T06:19:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-01-30 The present study aimed to determine the susceptibility of 17 Rhipicephalus (Boophilus) microplus populations, originating in the Southeast and Southern regions of Brazil, to different ivermectin concentrations (200, 500 and 630 mu g/kg), administered through subcutaneous or topical (pour-on) routes. R. (B.) microplus populations from the states of Minas Gerais (seven populations), Sao Paulo (seven populations) and Parana (three populations) were chosen for the tests. The selected cattle were allocated to treatment groups on day 0, and block formation was based on the arithmetic mean of female ticks (4.5-8.0 mm long) counted on three consecutive days (-3, -2 and -1). To evaluate the therapeutic and residual efficacies of these formulations, tick counts (females ranging from 4.5 to 8.0 mm long) were performed on days 3,7 and 14 post-treatment, and continued on a weekly basis thereafter until the end of each experiment. The results obtained throughout this study, utilizing field efficacy studies, allowed us to conclude that the resistance of R. (B.) microplus against 200 and 500 mu g/kg ivermectin is widely disseminated because all tick populations that had contact with these specific concentrations were diagnosed as resistant. However, it is possible to infer that R. (B.) microplus resistance against 630 mu g/kg ivermectin was also widespread, diagnosed at six of ten analyzed properties. Resistance of these ectoparasites to 630 mu g/kg ivermectin is most likely emerging in three other populations of R. (B.) microplus. Strategies of resistance management need to be quickly determined to keep the selection pressure at a minimum level in Brazil. (C) 2014 Elsevier B.V. All rights reserved. Universidade Estadual Paulista (UNESP) - Faculdade de Ciências Agrárias e Veterinárias, Centro de Pesquisa de Saúde Animal, Campus de Jaboticabal, Jaboticabal, São Paulo, Brasil Universidade Federal de Goiás, Parque Industrial Jataí, Goiás, Brasil Universidade Estadual de Maringá, Campus Regional de Umuarama, Paraná, Brasil Universidade Estadual Paulista (UNESP) - Faculdade de Ciências Agrárias e Veterinárias, Centro de Pesquisa de Saúde Animal, Campus de Jaboticabal, Jaboticabal, São Paulo, Brasil
Databáze: OpenAIRE
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