University of Florida scientists find brown dog ticks resistant to major pest control treatment

For several years the brown dog tick has been eluding homeowners and pest control professionals after treatment, leading many homeowners to drastic measures to get rid of the pests. After years of studying the brown dog tick (Rhipicephalus sanguineus), University of Florida entomologists are learning why some chemicals are no longer effective against the pest, and which ones still work.

In 2009, University of Florida entomologist Phil Kaufman received a USDA Southern Regional IPM grant to study whether the brown dog tick was developing resistance to permethrin and fipronil, the two major active ingredients in spot treatments for pets. Kaufman said that he would get calls from people whose houses were overrun with ticks after they tried unsuccessfully to get rid of them.

Many homeowners took drastic measures, including getting rid of their pets or furniture, throwing out possessions, and even moving, according to a UF/IFAS press release.

Life stages of the brown dog tick, Rhipicephalus sanguineus Latreille. Clockwise from top right: larva, male, female, nymph. Photograph by James Newman, University of Florida.

Life stages of the brown dog tick, Rhipicephalus sanguineus Latreille. Clockwise from top right: larva, male, female, nymph. Photograph by James Newman, University of Florida.

Kaufman and his colleagues analyzed ticks collected by pest management professionals from 29 residences and 2 dog kennels. Many of these submissions were provided in suitable numbers to allow testing. In their tests, the larvae that were produced from blood-fed adults were tested by exposing the immature ticks to specific concentrations of either permethrin or fipronil.

Although some of the findings were not optimistic for continued use of pyrethroid-based products, they were informative. All of the populations exhibited resistance to permethrin, while some populations were tolerant to fipronil. In fact, some of the resistant rates were so high that they could not be calculated precisely.

Tests showed tick tolerance, rather than resistance, to fipronil. Unfortunately, with the high rate of resistance to permethrin, and the recent generic formulations of fipronil becoming available at reduced costs, experts worry that the added pressure on the chemical may result in fipronil-resistant tick populations in the future. However, new products may help delay this possibility.

Results from the study were published in the March and May 2015 issues of the Journal of Medical Entomology.

What is a pet owner to do? Prevention and monitoring for ticks are the best ways to keep tick populations from becoming unwieldy. Vacuuming the carpet and feeling for ticks on the pet are the best ways to detect ticks before they multiply into an infestation. Brown dog ticks can complete their life cycle inside people’s homes and can lay 5,000 or more eggs a year. They prefer warm humid climates, and although they will feed on humans, they prefer feeding on dogs.

Kaufman strongly recommends keeping the dog if a tick infestation begins, as brown dog ticks will feed on humans without the presence of a dog. Additional tips include:

  • Check pets regularly for ticks, and if ticks are found, remove them promptly. The pet treatments alone may not provide adequate results.
  • Work with your veterinarian on suitable acaricides, as several options have emerged in the past year.
  • If an infestation is found, work with a pest control company to alleviate the problem.
  • Kennel dogs at night if your home is infested. Place double-sided tape (or folded over tape) around the kennel to intercept ticks crawling toward or away from the dog.

The brown dog tick does not transmit Lyme disease but does transmit two diseases of dogs: canine eherlichiosis and canine babesiosis. Symptoms of canine ehrlichiosis include lameness and fever; those for babesiosis include fever, anorexia and anemia. These diseases are rarely found in humans.

More information on the brown dog tick can be found at .

Source: Eiden, A.L., Kaufman, P.E., Oi, F.M., Allan, S.A., Miller, R.J. (2015). Detection of permethrin resistance and fipronil tolerance in Rhipicephalus sanguineus (Acari: Ixodidae) in the United States. J. Med. Entomology 52(3): 429-436: DOI: 10.1093/jme/tjv005

One Response

  1. Interesting findings. As we learn more about the long term effects of pest control methods, hopefully it will allow us to figure out better ways of controlling pests. Thanks for sharing this!

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