Date of Award


Degree Type


Degree Name

Master of Science in Biological and Environmental Sciences (MSBES)


Ecology and Ecosystem Sciences (EES)


Plant Sciences and Entomology

First Advisor

Thomas Mather


I evaluated the knock-down and residual activity of eleven minimal risk natural products (MRNP) against host-seeking nymphal stage blacklegged ticks (Ixodes scapularis Say) using a novel micro-plot product screening system in a landscape setting similar to a wooded residential property. The micro-plot system reduced variability between testing sites typically seen in larger field trials and provided the opportunity to compare results of studies conducted under the same environmental conditions, saving both time and money by confining product application and tick sampling to a 0.3 m diameter arena. By seeding the arenas with a known number of laboratory-raised blacklegged tick nymphs, I was able to further reduce the variability and improve product screening reproducibility across years. The products evaluated included CedarCide PCO Choice, EcoPCO® EC-X, Met52® EC, EcoEXEMPT® IC2, EcoSMART® Organic® Insecticide, Essentria™ IC3, nootkatone, Progaea, Tick Guard, Tick Killz and Tick Stop. Five of the eleven products tested (EcoPCO® EC-X, Met52® EC, EcoEXEMPT® IC2, Essentria™ IC3 and nootkatone) were found to have a statistically significant (P < 0.05) “knockdown” effect (meaning the product was applied while ticks were in the arenas), and only two of them, EcoPCO® EC-X and nootkatone, displayed significant “residual” tick-killing activity after weathering for 2 weeks. I found relatively inconsistent results with botanical oil-based products tested multiple times, indicating batch-to-batch variability, as well as variability between formulations. The results of my study suggest a need for better quality control and/or efficacy testing of botanical oil and other minimal risk natural products. Such MRNP screening can provide consumers with an improved ability to make more informed decisions about the level of tick encounter protection they might expect from products they may be purchasing because they believe them to be environmentally safer.



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