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Research Project: Year 2 Cattle Fever Tick Eradication Program Funding - Susceptibility of Rhipicephalus microplus to Nootkatone

Location: Cattle Fever Tick Research

Project Number: 3094-32000-042-039-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Jul 15, 2019
End Date: Apr 30, 2022

Nootkatone is a naturally occurring compound that is found in the Alaska yellow cedar tree and citrus fruits and is a common additive to food, cosmetics and pharmaceuticals. Nootkatone has been shown to be an effective control measure against numerous tick and mosquito species of public health importance. The objectives of this research are to: 1) determine the susceptibility of R. microplus and R. annulatus to nootkatone, 2) design field-based experiments to assess the effectiveness of environmental spraying as a means by which to control fever ticks under natural conditions, and 3) to determine the mode of action for nootkatone in Rhipicephalus using a transcriptomic approach.

To determine susceptibility of fever ticks to nootkatone, bioassays will be completed to calculate the lethal concentrations (LC) required to kill 50% (LC50) and 90% (LC90) of ticks. Bioassays will be conducted using vials coated with various concentrations of nootkatone and tick mortality will be recorded. Should nootkatone result in fever tick mortality in vitro, the product will be assessed for efficacy against the different developmental stages of fever ticks on an artificially infested bovine host stanchioned in a research barn. The mode of action in R. microplus and R. annulatus will be evaluated by identifying transcripts that are differentially expressed between unexposed, exposed-dead, and exposed-alive ticks.