Molecular survey of pyrethroid resistance mechanisms in Mexican field populations of Rhipicephalus (Boophilus) microplus.
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.
Rosario-Cruz
Rodrigo
R
Centro Nacional de Investigacion Disciplinaria en Parasitologia Veterinaria, Carr. Fed. Cuernavaca-Cuautla # 8534. Col. Progreso, Jiutepec C.P. 62550, Morelos, Mexico. rockdrig@yahoo.com.mx
Guerrero
Felix D
FD
Miller
Robert J
RJ
Rodriguez-Vivas
Roger Ivan
RI
Tijerina
Mary
M
Dominguez-Garcia
Delia Ines
DI
Hernandez-Ortiz
Ruben
R
Cornel
Anthony J
AJ
McAbee
Rory D
RD
Alonso-Diaz
Miguel Angel
MA
D000818:Animals; D002417:Cattle; D004351:Drug Resistance; D004950:Esterases / Q000378:metabolism; D005260:Female; D055785:Gene Knockdown Techniques; D007306:Insecticides / Q000494:pharmacology*; D007814:Larva / Q000187:drug effects; D008800:Mexico; D020125:Mutation, Missense; D011722:Pyrethrins / Q000494:pharmacology*; D048494:Rhipicephalus / Q000187:drug effects* / Q000235:genetics*; D015222:Sodium Channels / Q000235:genetics; D016019:Survival Analysis
D007306:Insecticides; D011722:Pyrethrins; D015222:Sodium Channels; D004950:Esterases