Applicability of in vitro bioassays for the diagnosis of ivermectin resistance in Rhipicephalus microplus (Acari: Ixodidae)

Autor(es)

Klafke, G. M. ^[1] ; Castro-Janer, E. ^{[1, 2]} ; Mendes, M. C. ^[3] ; Namindome, A. ^[1] ; Schumaker, T. T. S. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Dept Parasitol, Inst Ciencias Biomed, BR-05508900 Sao Paulo - Brazil

^[2] Univ Republica, Dept Parasitol, Fac Vet, Montevideo - Uruguay

^[3] Ctr Pesquisa & Desenvolvimento Sanidade Anim, Inst Biol, BR-0414002 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Veterinary Parasitology; v. 184, n. 2-4, p. 212-220, MAR 23 2012.
• Citações Web of Science: 24

Resumo

The applicability of laboratory bioassays to diagnose ivermectin (IVM) resistance in Rhipicephalus microplus was evaluated. Adult immersion tests (AITs), larval immersion tests (LITs) and larval packet tests (LPTs) were performed to characterise the effects of ivermectin toxicity on adults and larvae of a susceptible reference strain. The AIT was determined to be a reasonable assay but requires a large number of individuals to attain interpretable results. The LIT and LPT were validated with an IVM resistant strain, revealing resistance ratios (RRs) of 6.73 and 1.49, respectively. In a field survey, nine different populations of cattle tick from the states of Sao Paulo and Mato Grosso do Sul, Brazil, were analysed with the LIT. Populations without previous exposure to ivermectin exhibited RRs between 0.87 and 1.01. Populations previously exposed to IVM showed RRs between 1.83 and 4.62. The LIT was more effective at discriminating between resistant and susceptible populations than the LPT. The use of the LIT is recommended for the diagnosis of ivermectin resistance in R microplus. (C) 2011 Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 07/56082-4 - Diagnostico de resistencia de rhipicephalus (boophilus) microplus (acari: ixodidae) ao fipronil e ivermectina e estudos sobre possiveis mecanismos metabolicos envolvidos.
• Beneficiário: Teresinha Tizu Sato Schumaker
• Modalidade de apoio: Auxílio à Pesquisa - Regular