Deer Tick Nymphs & Repellents
Parasites Vectors (Burtis, J.C., et al.) 7.10.23, published “Comparison of in vitro and in vivo repellency bioassay methods for Ixodes scapularis nymphs.” In vitro bioassay methods are most commonly used for the testing of new potential unregistered active ingredients. This study aimed to compare both in vitro (use of artificial containers) and in vivo (human subject) methods.
No marked difference showed between the four tested bioassay methods, even comparisons of those equipped with the stimulus of human skin against those that did not. Also, the tick colony source can influence the results of repellency bioassays due to variances in movement rapidity. DEET efficiently repelled nymphs for the full 6-hour duration. Peppermint oil showed comparable repellent efficacy to DEET during the first hour, then decreased sharply. Rosemary had no efficacy across any study time points.
The outcome highlights the necessity to contemplate the geographic origin of ticks used in repellency bioassays as well as species and life stage. The limited efficacy of the two essential oils tested indicates need for additional studies on repellency duration for similar botanically derived active ingredients as well as formulated products.
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