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Rachel Morreale is building a better mosquito. 

Better from a human perspective at least, because the insects she grows in a Lee County Mosquito Control District lab in Buckingham are being used against the bug itself. 

The idea is to release hundreds of thousands of sterilized male Aedes aegypti on Captiva in hopes that they impregnate females with nonviable offspring. 

"I think they’re the most wily mosquito ever and they can breed in something as small as a bottle cap," Morreale said of this problematic species. "It’s mind-blowing when you think about potential habitat. They’re everywhere." 

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Aedes aegypti carry diseases like Zika and Dengue fever and are actually native to Africa. 

They were brought to this continent hundreds of years ago during the slave trade. 

This aggressive species has adapted to human conditions over thousands of years and breeds in things like discarded tires, native plants, bird baths and even trash. 

"It’s a lot of the junk that we leave around, flower pots and containers," said mosquito district spokesman Eric Jackson. "That’s really what they go to, and they’ll get inside your house. You may have water that you’re not paying attention to and they’ll get in there." 

The mosquitoes being grown in the Buckingham lab were captured from Captiva so that the district's brood will be as similar to the local population as possible. 

Larvae are fed sugar, and females, once hatched are fed a pork blood to provide the protein necessary to create the eggs. 

Then that generation of males then goes through the X-ray machine and is tested for fertility. 

And although the mosquito control district is going to be releasing thousands of mosquitoes on Captiva in April, the males don't bite. 

"You will notice them but it’s not like we’re increasing the biting pressure," Jackson said. "It’s not like you’re going to get bitten by one of the mosquitoes we release." 

More: Collier Mosquito Control District adds $3.4M helicopter to its fleetA test group of mosquitoes was released on the island earlier this year. 

No chemicals, bacterial agents or radiation is used to alter the insects, he explained. 

With this species, males live for about a week, with females living a month or even six weeks. 

At least one of the males flew the length of several football fields, showing that the lab-reared mosquitoes are more than capable of tracking down females. 

"The 400 meters is a big deal because they're notorious for staying where they are," Morreale said. "They just don’t tend to move that much, so having that dispersal of 400 meters shows we are making a quality mosquito." 

Jonathan Day is an entomologist professor and researcher at the University of Florida and said these sterilization techniques work with many types of insects. 

"The reason that sterile male techniques work at all with insects is that most female insects only mate once," Day said. "(Females) have a storage vessel in the abdomen that store sperm from a single mating and she will fertilize each egg individually, and every egg that she lays after will not be fertilized." 

Mosquitoes thrive in the region's extensive networks of beaches, bays, salt marshes, rivers, tidal creeks and mangrove forests.

The same ecological conditions that draw tourists and provide great fishing, boating and kayaking also make for ideal mosquito breeding grounds.

This species breeds only in freshwater. While saltwater species are typically stronger fliers and are more aggressive, freshwater species are usually the disease carrying variety. 

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Freshwater mosquitoes are the ones health officials typically fear most, as these species are capable of transmitting malaria, dengue fever, St. Louis encephalitis, West Nile virus and chikungunya fever, which can cause fever and severe joint pain.

Aedes aegyptia have adapted to some chemical treatments, so switching to a sterilization gives researchers the confidence that these methods will continue to work in the future. 

"The female will have no way of knowing if the sperm from a mating encounter is viable or not and she will then go on over the course of her life, and she may end up laying three, four or five batches of eggs — 150 to 200 eggs (total)," Day said. 

With the males, too much exposure to X-rays can cause more physical damage. 

Researchers want to treat the males just enough to ensure they're sterile. Any more exposure than that could backfire and render the males incapable of even finding females.  

"The downside of using X-rays is that you have to be really careful with the dosage," Day said. "If the male mosquitoes get too much they may be less competitive when it comes to mating. It’s a pretty fine balance to make sure that male mosquito is treated to the point where it’s sperm is infertile but not the point where that male is not competitive, or possibly even dies soon after being released." 

Connect with this reporter: @ChadGillisNP on Twitter. 

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