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10-Minute Presentation

Medical, Urban, and Veterinary Entomology

10-min: MUVE, Ticks and Tick-borne Diseases

The need for standardization of tick mortality using nootkatone as a case study

Wednesday, November 12, 2025
3:18 PM - 3:30 PM Pacific
Location: Oregon Convention Center, B114, OCC
Oral Presentation
Nootkatone, a botanical derived from Alaskan yellow cedar, was EPA registered as a repellent and insecticide in 2020 and has been promoted as a promising alternative to repel and kill ticks and mosquitoes. In prior literature, both repellent and acaricidal activity has been reported against Ixodes scapularis. With the hope of utilizing nootkatone within a future commercial product, we conducted dose-response experiments by placing 10 I. scapularis nymphs on treated filter paper within a sealed petri dish for 24h. At the end of the exposure period mortality was assessed through prodding and breathing on individual ticks. The resulting mortality trends were different than prior literature described, with low mortality even after exposure to high doses. Within the literature there are inconsistencies regarding how mortality is defined, leading to questions about the functionality of nootkatone as an acaricide. For further assessment, life status was assessed using four categories: normal, knocked-down, moribund, or dead. After initial categorization, all ticks were observed and reassessed daily for 7d post-exposure. The majority of knocked-down ticks returned to normal by the end of the 7d observation period and a number of ‘dead’ ticks returned to normal. When testing acaricidal properties of compounds, the ability to accurately assess if subjects have died is crucial but this can be difficult to do and can lead to discrepancies between tests. Some of these differences can, however, be minimized by providing more strict criteria for evaluating life status and standardizing this across tick toxicity tests.