The prevalence of pyrethroid resistance phenotype and genotype in Rhipicephalus (Boophilus) microplus in Yucatan, Mexico
| Autor: | Jane E. Hodgkinson, Alexander J. Trees, Roger Iván Rodríguez-Vivas, Sandra Luz Villegas-Perez, J.A. Rosado-Aguilar |
|---|---|
| Rok vydání: | 2012 |
| Předmět: |
Insecticides
Veterinary medicine Genotype Tick Cypermethrin Insecticide Resistance Lethal Dose 50 Toxicology chemistry.chemical_compound Gene Frequency Pyrethrins parasitic diseases Rhipicephalus Animals Bioassay Allele Mexico Allele frequency Larva General Veterinary biology General Medicine biology.organism_classification Phenotype chemistry Female Parasitology |
| Zdroj: | Veterinary Parasitology. 184:221-229 |
| ISSN: | 0304-4017 |
| DOI: | 10.1016/j.vetpar.2011.09.017 |
| Popis: | A field survey was conducted to evaluate susceptibility of Rhipicephalus (Boophilus) microplus to cypermethrin on 49 farms in three areas of Yucatan, Mexico. The modified larval packet test was used to evaluate larval mortality at different cypermethrin concentrations. Dose-mortality regressions, lethal concentrations (LC(50)-LC(99)), confidence intervals and slope were estimated by probit analysis. Phenotype was defined as susceptible, tolerant or resistant when the resistance factor (RF) derived from both LC(50) and LC(99) determinations were3, 3-5 or5, respectively. An allele specific PCR (AS-PCR) was used to determine the frequency of a sodium channel mutation (F1550I, Phe→Ile) associated with pyrethroid resistance. Overall, 26.5%, 40.8% and 32.6% of tick populations were susceptible, tolerant and resistant to cypermethrin, respectively. A substantial inter-population variation in the level of cypermethrin response was evident (resistance factors ranged from 0.3 to 2599 and from 0.7 to5000 when were indicated by the LC(50) and LC(99), respectively). The F1550I mutation (R allele) in R. microplus was present in all studied areas. The increasing presence of the R allele correlated well with increased levels of response indicated by both the LC(50) (r(2)=0.659, p=0.001) and LC(99) (r(2)=0.688, p=0.001) to cypermethrin. These results indicated that the F1550I mutation is a major common mechanism responsible for pyrethroid resistance in field populations of R. microplus ticks in the Mexican tropics. Both bioassay and AS-PCR showed that the prevalence of cypermethrin-resistant/tolerant R. microplus is high in Yucatan, Mexico and the relationship between the RF and the frequency of the R allele supports the role of F1550I as one of the most important mechanisms conferring pyrethroid resistance in these R. microplus populations. |
| Databáze: | OpenAIRE |
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