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Science & Technology

The (Losing) Battle Against Mosquitoes In Texas

Sep 5, 2019; Providence, Rhode Island, USA; Mosquitoes that carry the EEE virus are benefiting from more plentiful rainfall and
File Photo/USA TODAY NETWORK via Reuters Co
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Sep 5, 2019; Providence, Rhode Island, USA; Mosquitoes that carry the EEE virus are benefiting from more plentiful rainfall and warmer winters. Credit: File Photo/Providence Journal-USA TODAY NETWORK

TPR's Jerry Clayton spoke with an entomologist who specializes in mosquitoes about current and future efforts to control them.

Jerry Clayton: Mosquitoes are a fact of life in Texas, and the battle against the pesky biting insects is never ending. But there are some new weapons on the horizon. Zach Adleman is an associate professor of entomology at Texas A&M University. He joins us today. Thanks for being here, Zach.

Zach Adelman: Oh, you're very welcome. Great to be here.

Clayton: First of all, how big of a problem are mosquitoes in Texas?

Adelman: Well, you can ask a lot of folks, I don't think you're going to find a lot of friends for mosquitoes. So in addition to nuisance biting, you know, they're capable of transmitting a number of viruses to people. I'm sure everybody remembers Zika virus and all the trouble that caused here in Texas. And if you go back a few years, we have West Nile virus and that can cause many, many thousands of deaths as well. And so those viruses are still here and they can they can come back again.

Clayton: What is our best current method of controlling mosquitoes?

Adelman: Just figuring out where they breed and stopping standing water from from piling up. And you can do that. Look around your house, birdbath, buckets, anything that can catch water and get rid of them. But other than that, going around and spraying chemical pesticides and hope you get them all, which you never do.

Clayton: And are these chemicals, are they sprayed from aircraft as well?

Adelman: That is certainly done, especially if it's right after a hurricane or a major storm where they anticipate a lot of flood water based mosquitoes. There can be extraordinarily dangerous to large herds of cattle because they can actually exsanguinate cows if they come out in the tens of thousands after a major storm.

Clayton: You're going to need to explain that word to me

Adelman: Exsanguinate means to suck all of the blood out of

Clayton: A mosquito can do that?

Adelman: Not one, but swarms of tens of thousands or hundreds of thousands of them.

Clayton: I've heard the terms sterile mosquito, genetically modified mosquito, even the trademark "Friendly Mosquito." Are they all the same?

Adelman: They're not all the same...There are a couple of different sterile mosquito approaches that have been tried in the United States. Only one of them is genetically modified in terms of the actual nuclear genome. Others carry a symbiotic bacteria called Wolbachia and others can just be...I don't think we've done radiation and do sterilization in this country yet, but it's been done in other parts of the world.

Clayton: And how effective do these kind of treatments seem to be?

Adelman: They seem to be very effective. The numbers that I've seen of, you know, more than 90 percent reduction in the number of fighting females over the course of the summer.

Clayton: So how do they apply these mosquitoes?

Adelman: So initially I think they were releasing adult males to go out and seek females. But I think some strategies… just put egg papers on...if you dip a little bit piece of paper in the water and the water will kind of wick up the paper and make it wet, they lay their eggs on those wet surfaces. You can take that paper out of the water and dry it. Those eggs will stay viable for many months. And so then you can just take that paper again and put it in water and those eggs will hatch. And I think some of these newer approaches, if it's done using these, just putting these egg papers and water out in the in the world where mosquitoes breed and then letting them come out naturally with that.

Clayton: Have there been any kind of pilot projects that you're aware of in Texas using sterile mosquitoes?

Adelman: Yeah, I think they've already done some Wolbachia based releases and I think they're gearing up to do the Oxitec mosquitoes as well.

Clayton: Oxitec, those are the trademarked friendly mosquitoes.

Adelman: Yes.

Clayton: Are we winning the battle against mosquitoes in Texas?

Adelman: No, we're not winning anybody battles. It's a yearly struggle. So mosquito populations will always kind of dip over the winter and then they start rising gradually over the summer. And by the time you get the fall, they're going to be in full swing. And then that cycle repeats again. And we do our best to keep those numbers as low as we can, but it doesn't ever go away. And there's no there's no winning the battle at this point.

Clayton: Is there anything good about mosquitoes?

Adelman: Well, you got to remember that there are more than three thousand species of mosquitoes. And so some don't bother humans at all and don't bother the animals that we care about at all. But the ones that that I'm interested in targeting are a few species that that cause the most nuisance and also the ones that transmit disease. And and we can't find any redeeming qualities for those just yet.

Clayton: Zack Adelman, thank you for being here today. We appreciate it.

Adelman: You are very welcome.

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