Integrated Tick Management: New solutions to a growing health concern

Research Assistant Megan Dyer samples nymphal deer ticks in test arenas using a customized press board covered with flannel.

Research Assistant Megan Dyer samples nymphal deer ticks in test arenas using a customized press board covered with flannel.

Getting TickSmart to stay TickSafe has never been easier, thanks to the research and outreach of URI’s TickEncounter Resource Center (TERC) and its TickEncounter website (www.tickencounter.org).

According to Entomology Professor and TERC director Thomas Mather, over the past five  years, TickEncounter has become one of the nation’s leading resources on tick bite protection and tick-borne disease prevention. Its goal is to link tick science with people’s experiences, and increasingly one of those experiences is finding a tiny disease-carrying tick embedded in your skin. That’s a problem! And among the solutions to solving the tick problem is treating your yard with effective tick-killing insecticides, however not everyone is a fan of chemical controls.

There are a number of “natural” products available, (i.e. substances that do not have to carry an EPA pesticide registration number) that claim to provide tick control benefits but up until now very little research has been done to determine just how effective those products are.

Enter Mather and his team or researchers who are conducting trials on a class of products termed “minimal risk natural products,” some of which are already being sold to control ticks in backyards.

The whole project came about after a 2006 Centers for Disease Control-sponsored survey conducted in Connecticut  indicating that people are reluctant to spend more than $100 for tick control in their yards but that they would be more inclined to do tick control if they had access to minimal risk natural products.

But evaluating these products poses challenges. “Studies to test tick control products typically need to involve large plots of land with abundant tick populations to be statistically robust,” Mather explained. “They can be costly to perform and there are other issues related to sorting out the killing effect of the product from other natural tick killing effects, like from low humidity, or just the time in the season.

All treatments were applied to test arenas using recommended concentrations and at high pressure to ensure distribution into the leaf litter. A plastic spray shield prevented any drift away from the arena.

All treatments were applied to test arenas using recommended concentrations and at high pressure to ensure distribution into the leaf litter. A plastic spray shield prevented any drift away from the arena.

“The potential complexities of designing such elaborate field tests is one reason that there have not been a lot of these minimal risk natural products evaluated to date,” he said. So, when an opportunity arose to apply for a CDC-sponsored cooperative agreement to evaluate minimal risk natural products for integrated tick management, Mather and his team proposed a different approach—one using multiple small plots with ticks grown in the laboratory but with the treatments conducted under field conditions. He had done something similar 32 years ago while getting his Masters Degree at the University of Delaware, testing mosquito growth regulating products in three-foot-square sections of salt marsh as his thesis project.

Actually Dr. Steven Alm, a CELS entomologist who spends most of his time at East Farm, already had available small “arenas” –one-foot diameter rings that are six inches high and made of PVC plastic that he uses in his turf insect studies.  For the tick product testing, two wooded sections of East Farm made ideal sites.

In the test sites, the rings are distributed in organized arrays on the forest floor and then deer ticks…lots of deer tick nymphs raised in Mather’s lab are placed inside the rings—60 per ring. Natural leaf litter is the substrate inside each ring, just like in the tick’s preferred habitat around the edges of people’s yards. Then the controls are applied—the positive control is bifenthrin (trade name Talstar) which is an industry standard used by many tick control firms. As a negative control, plain water was sprayed.

Last summer, the team tested three minimal risk natural products–two products from EcoSmart (whose CEO, Steve Bessette, is a URI accounting alum), EcoPCO, and Essentria IC3 were tested along with a fungal product called MET 52EC by spraying the leaf litter in the rings—six replicates for each treatment. A shield was used when spraying to confine the products to just the area in the ring, and netting was used over the rings to prevent any passing animals from contacting the ticks.

The researchers then went back with flannel-covered discs that fit into each ring, pressing them down onto the leaf litter. The live ticks cling to the flannel and are counted. (A common way to get an idea of the tick population in a wooded area is to drag around a flannel “flag”). The researchers are interested in both the initial knockdown rate (measured shortly after the applications) as well as any residual effects of the tick control products.

To test the residual effects of the products, the researchers placed more ticks into already-treated and weathered rings two weeks after the sprays were applied. Talstar, the industry standard, performed well, providing 100% kill even after two weeks; the EcoPCO product performed nearly as well in the initial knockdown trial but not as well in the residual test. The final findings of the tests are still pending more testing and Mather plans on including additional minimal risk natural products this year.

The project is being funded by a nearly $900,000 CDC grant and will continue for three years. In the third year, testing will be expanded into yards of selected local homeowners.

Mather said he and his crew of researchers are pleased with the progress so far. “We completed testing on three products with controls in a fairly robust way and got results in a month and a half of field work, which is pretty good.”

Mather also has made arrangements with two local companies, Ocean State Tick Control and the F.A. Bartlett Tree Experts, both of which use bifenthrin in their tick control applications. This spring, the plan is to recruit homeowners who do not currently use tick control on their properties and compare tick densities in those yards with yards treated by either Bartlett or Ocean State. After a season to collect baseline information, and another year of testing additional minimal risk natural products at the East Farm outdoor testing lab, the most effective minimal risk natural control products will be selected and applied to the previously un-treated yards.

“By the third year we hope to have determined that one or two of the minimal risk products actually work,” said Mather. “Hopefully, the testing we do will provide another option for people to do tick control in their yard,” he added.

Up to now, says Mather, well-timed applications of bifenthrin do work (he has it done in his own yard)—he suggests an initial application just before Memorial Day and another follow up application between June 10-20 to suppress the tiny nymphal stage ticks.

Mather says he feels one reason he and his team landed the grant was partially because of the highly successful outreach efforts they have with the TickEncounter site, which already has been viewed by hundreds of thousands of site visitors. The site offers a large array of information on tick control, preventative measures and even articles on the experiences of tick disease victims.

Assisting Mather on the project are graduate students Megan Dyer, Jason LaPorte, and a new student Lindsay Herlihy, along with former Ph.D student Katie Berger and research and outreach staffers Brian Mullen, Roland Duhaime, Matt Requintina, and Professor Alm.