Department of Pathobiology, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA
In 1997 the exotic African tortoise tick, Amblyomma marmoreum, was identified in Florida outside importation facilities on a reptile-breeding premises where it had become established.1 Subsequent investigations found that at least 11 exotic tick species had been imported into Florida on reptiles, with at least seven species disseminated beyond importation facilities.4,10 These findings suggested that there was an unregulated flow of exotic ticks into the United States. This was a cause for concern given that the international trade in live reptiles is increasing and that some of the imported ticks are associated with diseases of veterinary or public health significance.3 This concern was heightened when A. marmoreum was confirmed as a capable vector of heartwater,8 a fatal disease of domestic and wild ruminants, and when exotic large reptile ticks (Amblyomma sparsum) infesting a shipment of leopard tortoises (Geochelone pardalis) imported into Florida from Africa were found to be infected with Cowdria ruminantium,5 the causative agent of heartwater.
These findings prompted immediate studies to identify an acaricide that would kill tick infestations on reptiles in a safe and efficacious manner and to develop methods for eradication of tick infestations from premises housing reptiles. The results of these studies are summarized in this abstract.
Identification of Acaricide to Control Exotic Tick Infestations
Since no acaricide was registered in the United States for use on reptiles at the onset of this study, those acaricides registered for use on other domestic animals were chosen for investigation. They were amitraz, carbaryl, chlorpyrifos, cyfluthrin, fipronil, lindane, permethrin and pyrethrins. All acaricides were tested for activity against A. marmoreum ticks, and five (amitraz, carbaryl, chlorpyrifos, cyfluthrin and permethrin) were tested for toxicity on leopard tortoises. Only cyfluthrin and permethrin produced 100% tick mortality at a dilution of 1% in acetone, with both producing high mortality (>85%) when used in dilutions up to 0.01%. The only side effect of any duration was eye irritation which was seen only with carbaryl and chlorpyrifos.
This study demonstrated that cyfluthrin and permethrin were acaricides effective in killing A. marmoreum ticks and both were safe when used on leopard tortoises. However, cyfluthrin, unlike permethrin, has been found to be toxic for snakes and lizards even at very low doses.6 Consequently, permethrin was the acaricide chosen for further safety testing, and Provent-a-Mite™ (Pro Products, Mahopac, NY), a formulation of permethrin specifically manufactured for use on reptiles,9 was the product selected. Provent-a-Mite™ was tested for use on African spurred tortoises (Geochelone sulcata), rosy boas (Lichanura trivirgata) and green iguanas (Iguana iguana), using 10 times the recommended dosage every fifth day for a total of six applications. For each treatment, Provent-a-Mite™ was sprayed directly on the animal (for tortoises) or directly on the substrate (for snakes and lizards). No signs of ill health were detected in any of the tortoises, snakes or lizards exposed repeatedly to excessive amounts of Provent-a-Mite™.
Development of Methods for Eradication of Exotic Tick Infestations
During our investigations of exotic tick infestations in Florida,3 it became evident that numerous shipments of infested reptiles had been imported and that at least two exotic tick species, A. marmoreum and A. sparsum, had already become established as breeding populations. Consequently, there was an urgent need to develop methods to eradicate these tick infestations in order to minimize the risk that such exotic vectors of heartwater would spread to native fauna and thus become established as indigenous tick species, as has happened in past years in Florida with the iguana tick Amblyomma dissimile2 and the rotund toad tick Amblyomma rotundatum7.
We developed a protocol whereby all reptiles on the infested premises were treated with permethrin (Provent-a-Mite™) and removed to a tick-free area. Then the premises were sprayed by a licensed pest control company with a cyfluthrin product specifically formulated for premises treatment (Tempo®, Bayer Corporation, Kansas City, MO) on two occasions 2 wk apart, ensuring that all surface areas including housing and burrows were treated. Finally, 1 wk after the second premises treatment, sentinel tortoises, such as Hermann’s tortoises (Testudo hermanni), which roam freely and whose skin area is easy to inspect, were placed on the treated premises for 10 days. If the sentinel tortoises remained free of ticks, the infestation was considered to have been eradicated from the premises. Using this protocol, we have successfully eradicated both A. marmoreum and A. sparsum infestations from reptile premises in Florida.
A permethrin product specifically manufactured for use on reptiles (Provent-a-Mite™) has been found to provide excellent control of exotic ticks on tortoises, snakes and lizards. Use of this permethrin product on reptiles, together with spraying of the environment with a cyfluthrin product specifically formulated for premises treatment (Tempo®), have been shown to be effective in the eradication of exotic ticks from infested reptile premises. The recommended method of administration of Provent-a-Mite™ differs by reptilian species. For tortoises, the product is sprayed directly onto the animal from a distance of a few inches (10 cm), using one 1-sec burst of spray into each leg opening for small tortoises and two 1-sec bursts for large tortoises. For snakes and lizards, the animals are removed from their containers and the product is sprayed from a distance of about 12–15 in (30–40 cm) directly onto the substrate at the rate of one 1-sec burst per 1 ft2 (30 cm2), with the snakes and lizards returned to the treated container only after the spray has completely dried and all vapors have dissipated.
1. Allan, S.A., L.A. Simmons, and M.J. Burridge. 1998. Establishment of the African tortoise tick Amblyomma marmoreum (Acari: Ixodidae) on a reptile-breeding facility in Florida. J. Med. Entomol. 35:621–624.
2. Bequaert, J. 1932. Amblyomma dissimile Koch, a tick indigenous to the United States (Acarina: Ixodidae). Psyche. 32:45–47.
3. Burridge, M.J. 2001. Ticks (Acari: Ixodidae) spread by the international trade in reptiles and their potential roles in dissemination of diseases. Bull. Entomol. Res. 91:3–23.
4. Burridge, M.J., L.A. Simmons, and S.A. Allan. 2000. Introduction of potential heartwater vectors and other exotic ticks into Florida on imported reptiles. J. Parasitol. 86:700–704.
5. Burridge, M.J., L.A. Simmons, B.H. Simbi, T.F. Peter, and S.M. Mahan. 2000. Evidence of Cowdria ruminantium infection (heartwater) in Amblyomma sparsum ticks found on tortoises imported into Florida. J. Parasitol. 86:1135–1136.
6. Mutschmann, F. 1991. Ektoparasitenbekämpfung bei Reptilien mit synthetischen Pyrethroiden? In: Internationales Colloquium fur Pathologie und Therapie der Reptilien und Amphibien. Deutsche Veterinarmedizinische Gesellschaft, Giessen/Lahn, Germany, Pp. 95–106.
7. Oliver, J.H., M.P. Hayes, J.E. Keirans and D.R. Lavender. 1993. Establishment of the foreign parthenogenetic tick Amblyomma rotundatum (Acari: Ixodidae) in Florida. J. Parasitol. 79:786–790.
8. Peter, T.F., M.J. Burridge, and S.M. Mahan. 2000. Competence of the African tortoise tick, Amblyomma marmoreum (Acari: Ixodidae), as a vector of the agent of heartwater (Cowdria ruminantium). J. Parasitol. 86:438–441.
9. Pound R. 2000. Mite and tick control for reptiles. United States patent no. 6,121,318.
10. Simmons, L.A., and M.J. Burridge. 2000. Introduction of the exotic ticks Amblyomma humerale Koch and Amblyomma geoemydae (Cantor) (Acari: Ixodidae) into the United States on imported reptiles. Int. J. Acarol. 26:239–242.