By Michael Marks
Cattle fever ticks once threatened the entire U.S. beef industry. They spread disease that’s often fatal to cows. The ticks are contained in South Texas through quarantine and observation. But scientists are moving toward developing another tool to combat the ticks.
Jason Tidwell, a microbiologist in Edinburg who studies cattle fever ticks at the USDA Agricultural Research Service, identified the ticks’ sex chromosome. He spoke to the Texas Standard about how that will help control their population.
This transcript has been edited lightly for clarity:
Texas Standard: Can you explain in simple terms what exactly you recently discovered about the cattle fever tick?
Jason Tidwell: The recent advances in technology for genetics have allowed us the opportunity to sequence the genome of these little bloodsuckers.
And so what I was able to do is identify which one of those chromosomes was actually the sex chromosome. And that gave us the foundational research to jump towards looking at novel methods for tick control.
Now that we have this information – now that we’ve mapped where the sex chromosome is – how can that be potentially applied as a tick control?
Well, that’s a great question, and that was one of the reasons why I was so interested in identifying the sex chromosome is because in other pests, such as mosquitoes that have been utilizing sterilization of the insects to control that population.
One of the more successful programs that we’ve had is the screw worm program. That utilizes a sterile insect technique where they would irradiate lab-reared screw worms, and that would sterilize the males. And they would release the males and they would mate with the females, and the females would not lay any eggs because the males were all sterile.
And the wonderful biology of the screw worm was the females would only mate once. So once they mated with the sterile male, you could control the population. We were able to push that population down to Panama.
And so here, since we’ve identified the sex chromosome, we can start looking at individual genes that are needed for reproduction, and we could possibly come up with genetic controls for cattle fever ticks.
This seems like an ingenious approach, to be able to find the sex chromosome and use that, leverage that, to control the population. But I’m sitting here wondering, why can’t we just use a pesticide?
Well, that’s also a really good question, because that’s what we do now. And one of my favorite movies is “Jurassic Park.” And I remember one of the actors saying, like, “life finds a way.” They adapt.
And that’s exactly what the cattle fever ticks have been doing with being exposed and treated for all the chemicals that we’ve been using for our cattle. They’ve been adapting, and they’ve been coming up with resistance to these chemicals that we have available.
And in different parts of the Western Hemisphere – Brazil and Mexico, for example – they use multiple classes of pesticides to control these cattle ticks on their cattle. And in those areas, they have come up with populations of cattle ticks that are resistant to almost every class of chemical that’s available on the market.
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