Phillip Kaufman, PhD (left), Zachary Kaplan, MS (center) and Caitlin Taylor, BS (right)
Program Project 3: Ecological and insecticide-resistance models of tick vectors in Florida Specific
Aim 3: Characterize occurrence and possible mechanisms of acaricidal resistance in Amblyomma americanum.
Dr. Phil Kaufman became a professor at University of Florida(UF) in 2005 as a veterinary entomologist. He received his BS in Animal Science at University of Illinois and his MS in Entomology at Wisconsin Madison where he studied vegetable entomology. Through his masters projects he gained interest in entomology and learned about veterinary entomology which tied his interest in bugs and furry animals together. He completed his PhD at the University of Wyoming working on the horn fly and after worked as a research Associate at Cornell developing integrated pest management systems for dairy and poultry farms. In 2017, he was one of the initial investigators on the Southeast Center of Excellence of Vector Borne Diseases with his research focusing on studying insecticide resistance in ticks. The initial five year timeline of the center allowed Dr. Kaufman to study resistance proactively. Typically ticks are studied by collecting ticks where they occur and bringing them into the lab to answer specific questions. This grant provided the necessary support Dr. Kaufman and his lab to study resistance in ticks in a lab and field setting.
Zachary (Zach) Kaplan completed his MS at UF working on this project with Dr. Kaufman and his committee chair Dr. Emma Weeks titled “A Survey of Pesticide Resistance and Potential Resistance Mechanisms in Amblyomma americanum”. Zach received his BS at UF in Entomology while working as an undergraduate in Dr. Kaufman’s lab where he reared stable flies and mosquito colonies and assisted with research projects, which sparked his interest in the Masters program. Zach’s masters research focused on resistance of permethrin in lone star ticks (Amblyomma americanum). To study this Zach worked with captive deer farms that used permethrin sprays on the deer to control biting-midges that are known to transmit epizootic hemorrhagic and bluetongue viruses. Lone star ticks are known to commonly feed on deer, and would be exposed to the permethrin sprays as well. So Zach’s hypothesis was there would be a selection pressure on the lone star ticks that were feeding on the captive deer, compared to lone star ticks collected at wildlife management areas. Zach used a value called a resistance ratio to compare the resistance levels of several wild and captive farm tick populations. The resistance ratio can be calculated by dividing the concentration of permethrin required to kill 50% (LC50) of a suspected resistant tick strain by the LC50 of the susceptible strain. Zach’s research found that there was a slight elevation of resistance in both wild and farmed ticks, suggesting that the levels of permethrin used on the captive deer farms was not selecting for resistant lone star ticks. This has implications for the general public in that permethrin can be used by hikers and others on their clothing to repel ticks. If the lone star ticks were developing resistance, then the repellent effect may also be lost.. Last November, Zach presented this work at the Entomological Society of America, and was awarded second place in the student competition. His masters work also included studying other chemicals such as fipronil efficacy in the lone star tick, which he recently published:click here to read more.
(left to right) Zach Kaplan, Yuexun Tian, Caitlin Taylor and Dr. Weeks
Photo of 2,000 engorged larvae on the left and Zach performing a larval packet test (LPT) on the right
Caitlin Taylor has been working on gathering more data to understand permethrin resistance in lone star ticks following Zach’s graduation Caitlin received her BS in Animal Science at UF with a minor in entomology. After her undergraduate degree she worked at the USDA, with a colleague of Dr. Kaufman, rearing house flies and parasitoids, and it was through this experience that she became interested in and applied for the lab manager position with Dr. Kaufman. Caitlin’s job is to rear and select lone star ticks to create a colony that is completely resistant to permethrin so we can better understand their genetics and detect resistance in the field before it occurs. To force permethrin resistance Caitlin uses a method called the larval packet test, where thousands of tick larvae are exposed to a dose of permethrin that allows only 20% to survive. With treatment at every generation, the ticks with the genetics present that allow survival in the presence of ever-increasing permethrin exposures bring the colony closer to being fully resistant. One generation of ticks takes 6-8 months for Caitlin to raise before starting the process all over again. While raising ticks, Caitlin is also working with Dr. Kaufman to develop a novel test to detect resistance in the DNA of the ticks. We look forward to hearing more about their research as it progresses.
Through this research project several undergraduates have had the ability to gain experience in research working in the Kaufman lab, some have even gone on to masters programs. Zach’s masters work provided him with opportunities to network, which led to his current position as a Regular Fellow with the Center for Global Health at the CDC in Atlanta’s Division of Parasitic Diseases and Malaria. The molecular and insect-rearing experience he gained as a graduate student with Dr. Kaufman and his mentor, Dr. Emma Weeks, a former PI of this project, gave him invaluable experience to succeed in his internship.
Studying resistance in ticks is important as little work has been done in the United States especially on the Amblyomma genus of ticks. Please check back in June when we interview another researcher studying a tick that can reproduce inside your home, Yuexun Tian, a PhD student at UF advised by Dr. Kaufman and Dr. Cynthia Lord.
Here are some videos of engorged lone star ticks from Caitlin!