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Molecular survey of pyrethroid resistance mechanisms in Mexican field populations of Rhipicephalus (Boophilus) microplus
- Rosario-Cruz, Rodrigo, Guerrero, Felix D., Miller, Robert J., Rodriguez-Vivas, Roger Ivan, Tijerina, Mary, Dominguez-Garcia, Delia Ines, Hernandez-Ortiz, Ruben, Cornel, Anthony J., McAbee, Rory D., Alonso-Diaz, Miguel Angel
- Parasitology Research 2009 v.105 no.4 pp. 1145
- Boophilus microplus, Rhipicephalus, acaricide resistance, cross resistance, cypermethrin, deltamethrin, enzyme activity, esterases, flumethrin, mutation, polymerase chain reaction, pyrethrins, resistance mechanisms, sodium channels, surveys, ticks, Mexico
- Susceptibility to synthetic pyrethroids (SP´s) and the role of two major resistance mechanisms were evaluated in Mexican Rhipicephalus microplus tick populations. Larval packet test (LPT), knock-down (kdr) PCR allele-specific assay (PASA) and esterase activity assays were conducted in tick populations for cypermethrin, flumethrin and deltamethrin. Esterase activity did not have a significant correlation with SP´s resistance. However a significant correlation (p < 0.01) was found between the presence of the sodium channel mutation, and resistance to SP´s as measured by PASA and LPT respectively. Just over half the populations (16/28) were cross-resistant to flumethrin, deltamethrin and cypermethrine, 21.4% of the samples (6/28) were susceptible to all of the three pyrethroids 10.7 of the samples (3/28) were resistant to flumethrin, 3.4 of the samples (1/28) were resistant to deltamethrin only and 7.1% (2/28) were resistant to flumethrin and deltamethrin. The presence of the kdr mutation correlates with resistance to the SP´s as a class. Target site insensitivity is the major mechanism of resistance to SP´s in Mexican R. microplus field strains, involving the presence of a sodium channel mutation, however, esterase-based, other mutations or combination of mechanisms can also occur.