Behind the Scenes: Time To Make The Ticks
Written by Dr. Lexi White and Dr. Tom Mather, Center for Vector-Borne Disease at the University of Rhode Island
At University of Rhode Island’s Center for Vector-Borne Disease, senior research associate Dr. Lexi White and director Dr. Tom Mather are gearing up this month to “make” the ticks for NEWVEC researchers. This core NEWVEC activity (called Tick Core) starts fresh every October when the adult stage of these ticks begin their life cycle.
The work begins with collecting hundreds of unfed adult blacklegged ticks (Ixodes scapularis) in local hotspots then using lab animals as the source of blood to produce engorged female ticks. Once the blood-fed females are collected, they are stored individually in precise humidity, temperature, and daylight cycles to mimic some of what is happening to wild ticks. It turns out, raising ticks takes a lot of patience, as each step in the process takes about a month. Eventually, each female lays a single egg mass, typically containing 1,500–2,000 eggs. Then it’s time to wait for the larvae to hatch from the eggs.
Once the larvae are questing and clustered at the top of a vial, we know they’re ready to eat. At this point, all larvae are free of germs. Our next step is to produce blood-fed larvae that will become either germ-free or germ-infected nymphs (depending on the experimental need). At the Tick Core, we maintain two different colonies, one with no germs and another with ticks infected with Borrelia burgdorferi, the bacteria that causes Lyme disease. In nature, blacklegged ticks often acquire this germ when taking a bloodmeal from a white-footed mouse. Here at URI, we also have a lab colony of white-footed mice that help us maintain a more natural B. burgdorferi infected tick colony. This lets us create ticks for researchers that are as similar as possible to wild ticks.
Once larval ticks are fed on rodent hosts in the lab, they go back in the incubator for another month to molt into nymphs, and then another month or two to get hungry and exhibit host-seeking behavior. At the end of this process, we typically end up with 15–20 thousand new ticks ready to go to NEWVEC collaborators around New England in the spring and early summer for various research studies, which recently have included questing tick behavior studies (Dr. Neeta Connally and team at Western Connecticut State University), minimal risk natural product tick control testing (Dr. Mather and team at the University of Rhode Island), and natural product tick repellent testing (also URI). We’ve even grown our own lone star ticks (Amblyomma americanum) for tick control product testing.
While most people might question why we need to grow more ticks, maintaining a tick colony gives NEWVEC scientists the ability to design experiments with more statistical power and control, while asking research questions using ticks just one generation away from the wild. Having a tick colony is a behind-the-scenes step that makes NEWVEC science stronger and brings us closer to solutions for tick management.
