Efficacy of a low dose fipronil bait against blacklegged tick (Ixodes scapularis) larvae feeding on white-footed mice (Peromyscus leucopus) under laboratory conditions

Abstract

Background: Lyme disease is the most prevalent vector-borne disease in the USA with cases continuing to increase. Current control measures have not been shown to be impactful, and therefore alternatives are needed. Treating pathogen reservoirs with low dose systemic acaricides in endemic areas may provide a useful tool for disrupting the cycle of the vector and pathogen. The purpose of this study was to determine the efficacy of a 0.005% fipronil bait, presented orally to white-footed mice, in controlling blacklegged tick larvae (larvae). Methods: Sixty mice were assigned to 3 treatment groups and three untreated control groups. All individually housed mice in treatment groups were exposed to 0.005% fipronil bait for 48 hours. Larvae were manually applied to mice within feeding capsules at one of three timepoints: Day 1, Day 9 and Day 15 post-exposure. For 4-days posttick attachment, replete larvae were collected from water moats underneath each cage and attached larvae were observed by microscopy. Plasma from 4 treated mice at Day-1, Day 13 and Day 19, and 4 control mice (n = 16) was collected to obtain fipronil plasma concentrations (CP). Results: Fipronil bait did not appear to produce neophobia in mice, as the amount of bait eaten at 24-and 48-hours exposure did not differ significantly. The 48-hour fipronil bait exposure prevented 100% of larvae from feeding to repletion at Day 1, Day 9 and Day 15 post-treatment. Within the treatment groups, all larvae observable within the capsules expired and were prevented from detaching by Day 4. In contrast, within the control groups a total of 502 replete larvae were collected from moats and 348 larvae observable within the capsules successfully detached. CP averaged 948.9, 101.2 and 79.4 ng/ml for mice euthanized at Day 1, Day 9 and Day 15, respectively. No fipronil was detected in control mice. Conclusions: We provide early indication that low dose fipronil bait, orally presented to white-footed mice, can effectively control blacklegged tick larvae. Future research should modify the exposure duration and post-exposure tick attachment timepoints to simulate various field scenarios under which successful efficacy might be obtained. Low dose fipronil bait could provide a cost-effective, practical means of controlling blacklegged ticks and other arthropod vectors.

Evaluating the use of a low dose fipronil bait in reducing black-tailed prairie dog (Cynomys ludovicianus) fleas at reduced application rates

“…Vector control through use of insecticides provides a promising solution for reducing flea abundance. Oral baits formulated with low concentrations of insecticide, can systemically control ectoparasites such as ticks and fleas feeding on rodents ( Borchert et al, 2009 ; Poché et al, 2020 , Poché et al, 2017 ; Pelletier et al, 2020 , Poché et al, 2017 , Poché et al, 2020 ), meaning that the insecticide is absorbed by the ectoparasite during blood feeding. Several insecticidal compounds have demonstrated promise in controlling on-host fleas, systemically, when administered orally to host rodents ( Borchert et al, 2009 ; Davis et al, 1999 ; Slowik et al, 2001 ; Jachowski et al, 2011 ).…”

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)

“…However, under field conditions, the fipronil feed will be presented using a species-specific delivery system and the low fipronil dose (25 ppm) should reduce environmental risk. Fipronil has proven to be efficacious against I. scapularis parasitizing Peromyscus leucopus under laboratory (Poché et al 2020a), simulated field (Poché et al 2021(Poché et al , 2023b, and natural field conditions (Williams et al 2023a), suggesting that feed consumption may reduce tick burdens in non-target Borellia burgdorferi reservoir hosts such as Peromyscus leucopus (Mather et al 1989) chipmunks represent another Borellia burgdorferi reservoir species (McLean et al 1993) that could potentially be targeted with a fipronil feed, and future researchers might consider investigating this potential.…”

“…A fipronil-based bait for oral administration to white-tailed deer could potentially disrupt the I. scapularis life cycle by eliminating blood-feeding adult females and significantly reducing egg laying and subsequent larval hatch the following spring. Previous research indicates fipronil to be an effective oral acaricide against tick larvae feeding on Peromyscus leucopus and Mus musculus mice (Poché et al 2020a(Poché et al , 2021. Fipronil has also proven effective in controlling arthropods infesting other ruminants such as cattle (Bos taurus) (Poché et al 2013(Poché et al , 2015.…”

Tick-borne Diseases, Transmission, Host Immune Responses, Diagnosis and Control

“…Besides this, fipronil baits made by using low dose of acracides and organic attractants can be used to control blacklegged ticks and other arthropod vectors [190] . For Lyme disease abatement besides tick control tick bites must be avoided in high risk areas [191] . However, for minimize tick attack and invasion on livestock and farm yard animals various plant orgin active constituents such as oil combinations, crude extracts, and pure compounds were also used.…”