Evidence of Permethrin Resistance and Fipronil Tolerance in<i>Rhipicephalus sanguineus</i>s.l. (Acari: Ixodidae) Populations From Florida and California

Tian, Yuexun; Taylor, Caitlin; Lord, Cynthia C.; Kaufman, Phillip E.

doi:10.1093/jme/tjac185

Cited by 9 publications

(10 citation statements)

References 23 publications

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“…Spatial repellency is likely less relevant for most tick species than for mosquitoes, yet the high spatial repellency of TCA may provide significant benefit to certain tick species, such as the Brown dog tick ( Rhipicephalus sanguineus ), which are associated with dog kennels and places where dogs reside. The translation of TCA activity to R. sanguineus is also significant as TCA was shown to be equally repellent to pyrethroid-resistant mosquitoes carrying kdr mutations compared to pyrethroid-susceptible mosquitoes [ 38 ], which is relevant because of multiple reports of high pyrethroid resistance in this species [ 63 , 64 ].…”

Section: Discussionmentioning

confidence: 99%

Repellent activity of essential oils to the Lone Star tick, Amblyomma americanum

Le Mauff,

Norris,

et al. 2024

Parasites Vectors

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Background The Lone Star tick, Amblyomma americanum is important to human health because of a variety of pathogenic organisms transmitted to humans during feeding events, which underscores the need to identify novel approaches to prevent tick bites. Thus, the goal of this study was to test natural and synthetic molecules for repellent activity against ticks in spatial, contact and human fingertip bioassays. Methods The efficacy of essential oils and naturally derived compounds as repellents to Am. americanum nymphs was compared in three different bioassays: contact, spatial and fingertip repellent bioassays. Results Concentration response curves after contact exposure to 1R-trans-chrysanthemic acid (TCA) indicated a 5.6 μg/cm2 concentration required to repel 50% of ticks (RC50), which was five- and sevenfold more active than DEET and nootkatone, respectively. For contact repellency, the rank order of repellency at 50 μg/cm2 for natural oils was clove > geranium > oregano > cedarwood > thyme > amyris > patchouli > citronella > juniper berry > peppermint > cassia. For spatial bioassays, TCA was approximately twofold more active than DEET and nootkatone at 50 μg/cm2 but was not significantly different at 10 μg/cm2. In spatial assays, thyme and cassia were the most active compounds tested with 100% and 80% ticks repelled within 15 min of exposure respectively and was approximately twofold more effective than DEET at the same concentration. To translate these non-host assays to efficacy when used on the human host, we quantified repellency using a finger-climbing assay. TCA, nootkatone and DEET were equally effective in the fingertip assay, and patchouli oil was the only natural oil that significantly repelled ticks. Conclusions The differences in repellent potency based on the assay type suggests that the ability to discover active tick repellents suitable for development may be more complicated than with other arthropod species; furthermore, the field delivery mechanism must be considered early in development to ensure translation to field efficacy. TCA, which is naturally derived, is a promising candidate for a tick repellent that has comparable repellency to commercialized tick repellents. Graphical Abstract

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Section: Discussionmentioning

confidence: 99%

Repellent activity of essential oils to the Lone Star tick, Amblyomma americanum

Le Mauff,

Norris,

et al. 2024

Parasites Vectors

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“…The minimal application rates and application frequency should reduce the risk of resistance that can result through the process of selection pressure (Nauen 2007) and previous studies indicate that fipronil can be applied at concentrations 100 to 200 times less than other candidate pesticides (Norelius and Lockwood, 1999). It is encouraging that there remains little evidence of direct resistance to fipronil (Rust et al 2015) and that fipronil resistance had not been detected in surveyed tick species ( Rhipicephalus sanguineus ) in the U.S. (Tian et al 2023). However, research from Brazil involving R. sanguineus suggests the potential for resistant populations (Becker et al 2019).…”

Section: Discussionmentioning

confidence: 99%

Development of a low-dose fipronil deer feed: Bait-screening and range-finding to determine the optimal formulation to control blacklegged ticks (Ixodes scapularis) feeding on white-tailed deer (Odocoileus virginianus)

Poché,

Wagner,

Hawthorne

et al. 2023

Journal of Vector Ecology

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Lyme disease is the most prevalent vector-borne disease in the U.S., and acaricidal feeds administered to whitetailed deer (Odocoileus virginianus) have potential to disrupt blood feeding by the blacklegged tick, Ixodes scapularis. Two studies were conducted with the aim of determining an ideal formulation to deliver oral acaricides to white-tailed deer and finding the lowest fipronil dose level to effectively control I. scapularis. During formulation screening, various commercial attractants (baits) were presented to deer in large paddocks under semi-field conditions and motion-sensitive cameras were used to monitor consumption by deer and non-target species. During dose range-finding, deer were housed individually and presented a fipronil feed at one of five dose levels for 48 h (two deer untreated). At 24 h post-exposure, the deer were anesthetized, blood was drawn, and deer were manually infested with 20 I. scapularis mating pairs in feeding capsules. Tick mortality was monitored up to nine days post-attachment. Results of formulation screening indicated that loose/granular formulations were substantially more palatable to deer, relative to block formulations, and would be more effective under field conditions. Dose range-finding concluded fipronil feeds with doses of 25 ppm and higher would eliminate 100% of I. scapularis parasitizing deer. Additionally, 10 ppm fipronil feed controlled a considerable proportion of ticks, and results suggested 100% ticks could be eliminated if fipronil sulfone was present in plasma at ≥25.1 ppb. These results were paramount in developing a low dose fipronil deer feed for tick control and should provide valuable insights prior to execution of future field trials.

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“…was reported in the United States in populations of ticks from dogs with a history to exposure to spot-on formulations of this acaricide [ 5 ]. Nevertheless, later studies did not detect fipronil resistance in Florida and California, suggesting this acaricide provides suitable tick management [ 18 ]. In Brazil, resistance to fipronil in R. sanguineus s.l.…”

Section: Discussionmentioning

confidence: 99%

Detection of ivermectin and fipronil resistance in Rhipicephalus sanguineus sensu lato in Maha Sarakham, Thailand

Siriporn,

Juasook,

Neelapaijit

et al. 2023

Vet World

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Background and Aim: Administration is the main strategy for controlling ectoparasites in dogs. Ivermectin and fipronil are most extensively used to prevent and treat Rhipicephalus sanguineus sensu lato infestation in dogs in Thailand. Several researchers have reported resistance to acaricides in R. sanguineus s.l. globally, but documentation of acaricide resistance in the tick population in Thailand is lacking. In this study, we investigated the status of resistance to commonly used acaricides in Thailand in R. sanguineus s.l. Materials and Methods: Engorged brown dog tick females (10 tick populations) were field-collected directly from parasitized dogs in Maha Sarakham, Thailand, for toxicological bioassays with ivermectin and fipronil. Bioassays were performed in three replicates at 25°C-27°C and 80%-85% relative humidity under a 12-h/12-h photoperiod. The 50% of lethal concentration and its confidence intervals and the slope were estimated for each tick population using probit analysis. Resistance ratios (RRs) of field ticks were characterized based on the relative susceptible population of each acaricide. Results: Six tick populations (P1-6) were tested for resistance to ivermectin, three of which (P2-4) exhibited low-level resistance to ivermectin (RR = 2.115-2.176). Of four tick populations (P7-10) treated with fipronil, two exhibited moderate-to-severe resistance (P7 and P9, RR = 21.684 and 4.387, respectively). All tick populations deemed resistant to acaricides had a history of exposure. Conclusion: Based on RR values, four R. sanguineus s.l. tick populations from Maha Sarakham province were resistant to ivermectin and fipronil. To the best of our knowledge, this represents the first documentation of acaricide-resistant populations of R. sanguineus s.l. in Thailand, and recommendations on tick control programs must be formulated with veterinarians and pet owners to prevent the development of further resistance. Keywords: bioassay, dog, fipronil, ivermectin, resistance, Rhipicephalus sanguineus sensu lato, Thailand.

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Evidence of Permethrin Resistance and Fipronil Tolerance inRhipicephalus sanguineuss.l. (Acari: Ixodidae) Populations From Florida and California

Cited by 9 publications

References 23 publications

Repellent activity of essential oils to the Lone Star tick, Amblyomma americanum

Repellent activity of essential oils to the Lone Star tick, Amblyomma americanum

Development of a low-dose fipronil deer feed: Bait-screening and range-finding to determine the optimal formulation to control blacklegged ticks (Ixodes scapularis) feeding on white-tailed deer (Odocoileus virginianus)

Detection of ivermectin and fipronil resistance in Rhipicephalus sanguineus sensu lato in Maha Sarakham, Thailand

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