Battling mosquitoes with a sterile insect program
By Sarah Mankowitz
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LEHIGH ACRES, Florida (WBBH) — Lee County Mosquito Control is one of the only places in the world using a sterile insect technique to control mosquitoes.
“We actually mass rear Aedes aegypti in the lab and sterilize them in our X-ray machines and then release sterile males into the field, which go and reproduce with females that are occurring out in the wild. And then that helps lower the population,” said Rachel Morreale, manager of applied science and technology for Lee County Mosquito Control.
Basically, they modify mosquitoes so they can’t reproduce.
“We start with our eggs. So, we have a colony of our own local mosquitoes that we found from our colonies or our mosquitoes collected in the area,” Morreale said.
A total of 10,000 eggs at a time are put into each tray, before they are separated by size.
“We start with that larval rearing. And then once we see pupation happening, we drain our larvae and our pupal mixture,” Morreale said.
The goal is to separate the males from the females
“The females are the ones that bite, males don’t bite. So, we radiate our males, sterilize them and then release them out into the wild,” Morreale said.
Since females are bigger, they get stuck in a machine to separate them from the males.
“Once we have those, we allow our males to emerge. And once we have our beautiful, wonderful adults, we then take them over into the chiller and knock them down. And it’s so cold and they just kind of hibernate,” Morreale said.
Then they’re placed in pill cases, and it’s off to the X-ray machine.
“Radiate them for just a few minutes, and then they’re sterile. We give them sugar and water and then send them off into the field. We mark them with a fluorescent powder so we know that they’re males that we released, versus ones that are actually just out in the wild,” Morreale said.
Once they’re flying free, it’s time to do what they do best.
“They are really good at finding ladies, and they will mate with those wild occurring Aedes aegypti females. Then the eggs that are laid by those females won’t hatch. So, then you don’t have that next generation coming through,” Morreale said.
The numbers prove it works.
“We were able to get really great suppression out of our population on Captiva Island. It was around a 79 percent reduction in the population,” Morreale said.
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