By Richard Levine
In May 2016, the U.S. Centers for Disease Control and Prevention, the Entomological Society of America (ESA), the IPM Institute of North America, and the North Central IPM Center held a meeting called the “Integrated Tick Management Symposium: Solving America’s Tick-Borne Disease Problem.” Entomologists and public-health officials from the USDA, DOD, USGS, several universities, and other institutions, gave presentations and held roundtable discussions.
While the full extent of the topics discussed is too large to be covered here, some interesting and important points include:
1. Deer are an important factor.
Higher deer numbers mean higher tick numbers.
“Deer reduction is the only way we have to restore the risk landscape to what it was before the 1980s when we really started having problems,” said Sam Telford, a professor at Tufts University.
Later I asked him how many deer should ideally be found per square mile in order to reduce tick populations. His answer was about 6-10. That’s a problem because in some areas the number is typically about 60-70 deer per square mile, and in some places the number can be as high as 200.
Areas that are open to hunting have fewer deer, but Dr. Telford and others have found that hunters are not bringing the numbers down sufficiently. Citing a previous study, Dr. Kirby Stafford from the Connecticut Agricultural Experiment Station, said that hunters “could not or would not reduce the number of deer below 30-40 deer per square mile.”
Dr. Telford proposed an idea that could encourage hunters to bring the numbers down even lower by giving them an economic incentive to do so. In the U.S., it is illegal for a hunter to sell venison and other game meat because it has not been inspected by the Department of Agriculture, which is required by the 1906 Federal Meat Inspection Act.
“I’m actually looking for a congressman or senator who will insert a sentence in the Farm Bill which will exempt deer from the Meat Inspection Act,” he said. “If you commercialize the deer, you can imagine how quickly you’re gonna have help on top of the regular hunting season.”
In other words, deer numbers will be reduced if “people are allowed to make a buck out of a buck.”
2. There are many tools in the IPM toolbox.
Besides reducing the number of deer, there are many other things we can do to prevent tick-borne diseases. Among them, according to Dr. Stafford, are personal protection measures like the use of repellents, habitat management that removes vegetation and other things that support tick populations, chemical controls such as insecticides and some botanical compounds, biopesticides, anti-tick vaccines, and the application of pesticides to animals that ticks feed on, such as deer and rodents.
One tool known as the 4-Poster Deer Treatment System attracts deer to a bin filled with corn. As the deer lower their heads to eat the corn, they come into contact with foam posts that have been treated with acaracides (pesticides that kill ticks and mites), and the acaracides are then applied to the deer as their heads and necks rub against the posts. The chemical that is used, permethrin, is safe for humans — in fact, it is the active ingredient in shampoos that are prescribed for head lice.
Other strategies focus on rodents, such as white-footed mice and chipmunks. One method involves providing fibers that contain an acaricide. The rodents gather the fibers and incorporate them into their nests, which exposes them to the acaracides and kills the ticks that feed on them. Another device is similar to the 4-Poster Deer Treatment System in that it uses food to lure rodents into a box, where acaracides are applied to them as they travel towards the food.
3. At one point, participants were asked to break into groups and discuss topics such as tick surveillance programs, new integrated tick management technologies, and funding. Some of their conclusions were:
– There is no silver bullet, but deer reduction, improvements in suburban planning, and educating the public will certainly help. Dr. Tom Mather, from the University of Rhode Island, noted that most people who participated in a citizen science program were unable to identify ticks. In fact, five percent of them reported bed bugs as ticks, which is part of what he calls Tick Literacy Deficit.
– Investment is needed not only for ticks that feed on humans, but for those that feed on livestock and domestic animals as well. Funding to support the TickSpotters program on a national level would be money well spent.
– Tick surveillance should be standardized, and data from states and counties should be shared and used to coordinate actions at the federal level.
– State and county governments are not replacing open positions for people who work on ticks, and more people are needed. When a tick expert retires from a good surveillance program, there is often a lapse and a gap.
– Tick control commissions should be established, just as there are mosquito control districts in many states. Another possibility is to expand the role of existing mosquito control districts into VECTOR control districts, which would include ticks and other arthropods that transmit diseases.
In the closing remarks, ESA President May Berenbaum summarized integrative tick management in two words: “It’s complicated.”
There is no one-size-fits all tool, and no single individual has the expertise to meet all of these challenges, so it is absolutely essential for people to collaborate and cooperate.
“Because it’s complicated, it’s a very hard story to tell,” she said, as she encouraged participants to “please help make policymakers and other audiences aware of the magnitude of the problem and the magnitude of the challenges this presents, and to raise awareness to the point that integrated tick management becomes a national priority.”
Richard Levine is Communications Program Manager at the Entomological Society of America and editor of the Entomology Today Blog.