The tropical cattle tick, Rhipicephalus microplus, is one of the most damaging parasites that affects cattle in tropical and subtropical regions in the world. Tick resistance to acaricides is dispersed worldwide and a number of associated mutations in target site genes have been described. Phenylpyrazole (e.g. fipronil) and cyclodiene (e.g. lindane, dieldrin) insecticides both have the same mode of action blocking the GABA-gated chloride channel encoded by the GABA-Cl gene. A conserved mutation, rdl (resistance to dieldrin) is found across a number of arthropods resistant to cyclodienes and phenylpyrazoles. In ticks, the mutation T290 L, was identified in the second transmembrane (TM2) domain of the GABA-gated chloride channel of Australian cattle tick populations that are resistant to dieldrin. Recently, cross-resistance between fipronil and lindane was reported in R. microplus populations obtained from Uruguay and Brazil. The objective of the present study was to identify mutations in the GABA-Cl gene associated with fipronil resistance. Genomic DNA was obtained from engorged females from fipronil-susceptible and resistant populations sampled from Uruguay and Brazil (n = 166). Initially, it was searched the T290 L mutation described in Australia; however, this mutation was not detected in individuals from resistant populations from either country. The sequencing of a fragment of the GABA-Cl gene revealed nucleotide polymorphisms in fipronil- and lindane-resistant ticks in two populations from Uruguay and five from Brazil. Five amino acid substitutions were present in the resistant strains. Two different substitutions were found in an alanine residue (A286S and A286 L) that is homolog to rdl mutations in fipronil-resistant individuals of other arthropod species. Four other amino acid substitutions (S281 T, V317I, T328 A and A329S) were present in some resistant strains, always with the mutation A286S. This is the first documentation of mutations in the GABA-Cl gene associated with fipronil-resistant in R. microplus.
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http://dx.doi.org/10.1016/j.ttbdis.2019.03.009 | DOI Listing |
Ticks Tick Borne Dis
July 2024
Pathogen and Microbiome Institute, Northern Arizona University, PO Box 4073, Flagstaff, AZ 86011, United States. Electronic address:
Ticks Tick Borne Dis
November 2022
Instituto de Investigación de la Cadena Láctea (IdICaL) (INTA-CONICET), Instituto Nacional de Tecnología Agropecuaria, Estación Experimental Agropecuaria Rafaela (INTA E.E.A. Rafaela), CP 2300 Rafaela, Santa Fe, Argentina.
This study aimed to evaluate the sequence variations of the GABA-Cl gene of Rhipicephalus (Boophilus) microplus ticks from Argentina with different resistance levels to fipronil. Genomic DNA was obtained from engorged females (n = 50) of fipronil-susceptible and resistant tick field populations from five localities in northern Argentina. Tick populations were tested for fipronil resistance by in vitro larval packet test.
View Article and Find Full Text PDFTicks Tick Borne Dis
September 2021
Departamento de Patobiología, Unidad de Enfermedades Parasitarias, Facultad de Veterinaria, UDELAR. Av. Lasplaces 1620, CP 11600 Montevideo, Uruguay.
The resistance of Rhipicephalus microplus to acaricides is a serious control problem, so its early diagnosis by a molecular technique is important. This study aims to develop a multiplex allele-specific polymerase chain reaction (PCR) for single-nucleotide polymorphisms (SNPs) in the para-sodium channel gene and in the GABA-Cl gene, associated with pyrethroids (cypermethrin and flumethrin) and fipronil resistance, respectively. We used 22 tick field isolates from farms with tick control problems (sampling convenience).
View Article and Find Full Text PDFVet Parasitol
April 2021
Departamento de Patobiología, Unidad Enfermedades Parasitarias, Facultad de Veterinaria, UDELAR- Av. Lasplaces 1620, CP.11600, Montevideo, Uruguay.
The resistance of Rhipicephalus microplus to pyrethroids is widely dispersed worldwide and has been associated with several nucleotide substitutions in its target site, the para-sodium ion channel (Na-channel) gene. The resistance of the tick to fipronil has been increasing in South America, and mutations in the GABA-gated chloride channel (GABA-Cl) have been described in fipronil-resistant tick strains. We developed a multiplex allele-specific PCR (mAS-PCR) to screen for single-nucleotide polymorphisms (SNPs) associated with the resistance to pyrethroids (knockdown resistance or kdr) and fipronil (resistance to dieldrin or rdl) in susceptible tick populations from Uruguay (n = 11) and the Rio Grande do Sul state in Southern Brazil (n = 15).
View Article and Find Full Text PDFTicks Tick Borne Dis
June 2019
Department of Parasitology, Instituto de Ciências Biomédicas-USP, Av. Prof. Lineu Prestes 1374, Cidade Universitária, CEP. 05508-000, São Paulo, SP, Brazil.
The tropical cattle tick, Rhipicephalus microplus, is one of the most damaging parasites that affects cattle in tropical and subtropical regions in the world. Tick resistance to acaricides is dispersed worldwide and a number of associated mutations in target site genes have been described. Phenylpyrazole (e.
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