| Title: | Development of a low-dose fipronil deer feed: evaluation of efficacy against two medically important tick species parasitizing white-tailed deer (Odocoileus virginianus) under pen conditions |
| Author(s): | Poche DM; Wagner D; Green K; Smith Z; Hawthorne N; Tseveenjav B; Poche RM; |
| Address: | "Genesis Laboratories, Inc., Wellington, CO, USA. davidp@genesislabs.com. Pennsylvania State University, University Park, PA, USA. Genesis Laboratories, Inc., Wellington, CO, USA" |
| DOI: | 10.1186/s13071-023-05689-1 |
| ISSN/ISBN: | 1756-3305 (Electronic) 1756-3305 (Linking) |
| Abstract: | "BACKGROUND: Odocoileus virginianus (the white-tailed deer) is a key reproductive host for medically important tick species, including Ixodes scapularis and Amblyomma americanum. Orally administering a systemic acaricide to white-tailed deer has the potential to reduce tick reproduction, abundance and pathogen-infected tick bites. Prior studies have demonstrated considerable efficacy of a low-dose fipronil mouse bait in controlling larval I. scapularis parasitizing the pathogen reservoir, Peromyscus leucopus. No prior studies have evaluated the efficacy of a fipronil product in controlling ticks parasitizing white-tailed deer. METHODS: A pen study was conducted to evaluate the efficacy of a fipronil deer feed in controlling I. scapularis and A. americanum adult ticks. Individually housed deer (n = 24) were exposed to deer feed containing 0.0025% fipronil (fipronil deer feed) for 48 h and 120 h, and a control group of deer were exposed to an untreated placebo. On post-exposure day 7 and day 21, all deer were parasitized with 20 mating pairs of feeding capsule-enclosed I. scapularis and A. americanum. Post-attachment, engorgement and mortality of ticks were recorded. The concentrations of fipronil in plasma, feces and tissues from euthanized deer were estimated using liquid chromatography-mass spectrometry. RESULTS: The fipronil deer feed efficaciously controlled ticks parasitizing pen-reared white-tailed deer. Efficacy in reducing survivorship of blood-feeding female I. scapularis exceeded 90% in all instances except for when ticks parasitized 48-h treated deer at day 21 post-exposure (47.2%). Efficacy in reducing survivorship of A. americanum females exceeded 80% in all instances. In the 120-h exposure group there was 100% tick mortality at day 7 post-exposure for both tick species. A significant correlation was observed between reductions in tick survivorship and concentrations of fipronil sulfone in plasma. The results of tissue analysis suggest that a withdrawal period may be needed to allow for fipronil degradation prior to hunting season. CONCLUSIONS: The results provide proof-of-concept for the use of a fipronil-based oral acaricide in controlling two medically important tick species infesting a key reproductive host. A field trial is necessary to confirm the efficacy and toxicology of the product in wild deer populations. Fipronil deer feed may provide a means of controlling multiple tick species parasitizing wild ruminants to be integrated into tick management programs" |
| Keywords: | Animals Female *Acaricides *Deer *Ixodes Peromyscus *Tick Infestations/drug therapy/prevention & control/veterinary Acaricides Amblyomma americanum Blacklegged ticks Fipronil deer feed Ixodes scapularis Lone star ticks Odocoileus virginianus Systemic inse; |
| Notes: | "MedlinePoche, David M Wagner, Donald Green, Kylie Smith, Zachary Hawthorne, Noah Tseveenjav, Batchimeg Poche, Richard M eng 75D30120C09834/CC/CDC HHS/ Clinical Trial, Veterinary England 2023/03/10 Parasit Vectors. 2023 Mar 9; 16(1):94. doi: 10.1186/s13071-023-05689-1" |
