Natural insensitivity and the effects of concentration on the repellency and survival of American dog ticks ( Dermacento
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Natural insensitivity and the effects of concentration on the repellency and survival of American dog ticks (Dermacentor variabilis) by DEET Cody W. Koloski1 · Carlyn A. M Duncan1 · Pamela L. Rutherford1 · Bryan J. Cassone1 Received: 21 May 2020 / Accepted: 18 September 2020 © Springer Nature Switzerland AG 2020
Abstract N,N-Diethyl-m-toluamide (DEET) is by far the most used repellent worldwide. When applied topically to the skin, the active ingredient has been shown to provide protection from a variety of hematophagous insects, including mosquitoes and flies. DEET’s effectiveness against ticks is influenced by a variety of factors (e.g., duration and concentration of application, drying time, route of exposure, tick species and developmental stage), and may differ from insects due to their unique chemosensory system that primarily involves the Haller’s organ. We therefore used several approaches to investigate DEET’s efficacy to repel Dermacentor variabilis at different concentrations (5, 30 or 75%), as well as explore its toxicological properties and natural variability in DEET insensitivity across populations from Manitoba, Canada. Climbing bioassays indicated that higher concentrations of DEET were more effective at repelling D. variabilis, and that ticks from some sampling localities were more sensitive to lower concentrations than others. Petri dish arena assays revealed ticks exposed to high concentrations of the repellent lose their ability to discriminate lower concentrations, perhaps due to overstimulation or habituation. Finally, our tactile assays demonstrated reduced tick survival after contact with high DEET concentrations, with mortality occurring more rapidly with increased concentration. Dermacentor variabilis from these tactile assays displayed a multitude of physiological and neurological symptoms, such as ‘hot foot’ and various bodily secretions. Overall, our study shows a strong association between repellency, concentration and the acaricidal effects of DEET on D. variabilis. Keywords Ixodida · Behavior · Laboratory bioassays · Acaricidal effect · Electron microscopy
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s1049 3-020-00550-x) contains supplementary material, which is available to authorized users. * Bryan J. Cassone [email protected] 1
Department of Biology, Brandon University, Brandon, MB R78 6A9, Canada
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Experimental and Applied Acarology
Introduction Developed for use by the USA military nearly 8 decades ago, N,N-diethyl-m-toluamide (DEET) is considered the gold standard in insect repellents (Fradin 1998; Katz et al. 2008; DeGennaro 2015). The oily substance is applied onto the skin and/or clothes to deter/alter/ block feeding behaviors from diverse blood-sucking invertebrates. Despite DEET’s widespread commercial availability, the precise mechanisms underlying the mode of action of its active ingredient remain unclear, and may differ based on strength of concentration (Stanczyk et al. 2010; DeG
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