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United States Department of Agriculture

Agricultural Research Service

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Research Project: ASSESSMENT OF THE LARVAL TARSAL TEST AND SEARCH FOR SINGLE NUCLEOTIDE MUTATIONS IN PYRETHROID-RESISTANT RHIPICEPHALUS MICROPLUS

Location: Tick and Biting Fly Research

Project Number: 6205-32000-034-25
Project Type: Nonfunded Cooperative Agreement

Start Date: Sep 05, 2011
End Date: Sep 05, 2013

Objective:
Evaluate the resistance profile of cattle tick strains, and identify the presence of point mutations (PM) in cattle tick larvae.

Approach:
Perform in vitro bioassays to determine susceptibility of four laboratory strains to ten acaricidal compounds with the Larval Tarsal Test (LTT); susceptibility to ivermectin of an ivermectin-resistant strain and susceptibility to fipronil of a fipronil-resistant strain using the Larval Packet Test (LPT); and susceptibility to ivermectin of an ivermectin-resistant strain using the Klafke Larvel Immersion Test (LIT). LC50s will be calculated from which resistance ratios will be estimated based on the comparison with a susceptible reference strain (Munoz). Molecular bioassays will be either run individually or investigated through a multiplex PCR newly developed in the CFTRL. Thirty larvae per population will be analyzed individually. The presence and frequency of the point mutation in these field strains will be compared with in vitro results on their resistance status previously assessed with the LTT. For some of the strains, if the presence of a point mutation is identified, there will be the possibility to investigate the frequency of the mutation among larvae having survived or died at a specific dose of flumethrin and cypermethrin.

Last Modified: 9/23/2014
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