Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 8, 2002
Publication Date: July 15, 2002
Citation: PRUETT JR, J.H., GUERRERO, F., HERNANDEZ, R. ISOLATION AND IDENTIFICATION OF AN ESTERASE FROM A MEXICAN STRAIN OF BOOPHILUS MICROPLUS (ACARI: IXODIDAE) (ENTERING MODIFIED TITLE). JOURNAL OF ECONOMIC ENTOMOLOGY. 2002. v. 95. p. 1001-1007. Interpretive Summary: The southern cattle fever tick, Boophilus microplus, is a significant vector of bovine babesiosis. Both the tick and disease are found in northern Mexico. Reintroduction of the tick, and disease, into the United States is prevented by a vigilant quarantine and inspection program at import stations along the south Texas border with Mexico. All imported cattle must be dipped in vats containing acaricides. Thus, acaricide effectiveness is essential to the eradication program. Reports of acaricide resistance within tick populations threatens the eradication program. In order to monitor and mitigate the effects of acaricide resistance knowledge of those resistance mechanisms is required. In this study we isolated a protein from a Mexican tick strain that we believe is responsible for the metabolic breakdown of the acaricide permethrin. The presence of this protein within this strain of tick confers resistance to permethrin. By isolation of this protein and determination of internal amino acid sequences we now have isolated the gene as well. This knowledge allows us to develop diagnostic tests to determine the extent of this resistant mechanism in the tick population. Diagnostic tools should allow us to mitigate the effects of resistance development, prolonging the effective life of available acaricides and the control program that prevents reentry of the tick into the United States.
Technical Abstract: A strain of Mexican B. microplus (Cz) collected near Coatzacoalcos, Veracruz, Mexico, exhibits a moderate, but significant, level of permethrin resistance. Unlike other highly permethrin resistant strains, the Cz strain does not have a mutation within the sodium channel gene that results in target-site insensitivity. However, the Cz strain possesses a substantial increase in general and permethrin esterase activity relative to highly permethrin resistant and control strains suggesting the involvement of a metabolic esterase(s) in the expression of permethrin resistance. We report the isolation of a 62.8 kDa protein from Cz strain larvae that we think is the esterase previously reported as Cz EST9. In addition, internal amino acid sequence data obtained from the 62.8 kDa protein suggest that it is the gene product of a previously reported B. microplus carboxylesterase cDNA. We propose that the 62.8 kDa protein (Cz EST9) has permethrin hydrolytic activity and as a result plays an importan role in Cz strain resistance to permethrin.