Molecular and biochemical diagnosis of esterase-mediated pyrethroid resistance in a Mexican strain of Boophilus microplus (Acari: Ixodidae).
We examined pyrethroid resistant Mexican strains of Boophilus microplus using biochemical and molecular tests to determine the mechanisms conferring resistance. Permethrin hydrolysis assays and esterase activity gels indicated enhanced esterase-mediated metabolic detoxification in the Cz strain, while one other pyrethroid resistant strain, SF, and two pyrethroid susceptible strains had lower levels of permethrin hydrolysis. Results from assays using a PCR-based test to detect a pyrethroid target site resistance-associated mutation in the tick sodium channel gene found only low levels of mutations in the Cz strain, while the SF strain had a high level of the mutated sodium channel alleles. A specific esterase, designated CzEst9, believed to be responsible for the esterase-mediated pyrethroid resistance in the Cz strain was purified, and the gene encoding CzEst9 cloned.
USDA-ARS, Knipling-Bushland US Livestock Insects Research Laboratory, 2700 Fredericksburg Rd., Kerrville, TX 78028, USA. felixg@ktc.com
Felix D
FD
Guerrero
John H
JH
Pruett
Andrew Y
AY
Li
D000818:Animals; D004247:DNA / Q000737:chemistry / Q000235:genetics; D004950:Esterases / Q000235:genetics / Q000378:metabolism*; D007305:Insecticide Resistance / Q000235:genetics; D007306:Insecticides; D026863:Ixodidae / Q000201:enzymology / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D008800:Mexico; D026023:Permethrin; D016133:Polymerase Chain Reaction; D015222:Sodium Channels / Q000235:genetics / Q000378:metabolism*
D007306:Insecticides; D015222:Sodium Channels; D026023:Permethrin; D004247:DNA; D004950:Esterases