VOA慢速英语--佛罗里达州使用转基因蚊子对抗疾病（在线收听）

Officials in the Florida Keys plan to release genetically modified mosquitoes next year in an effort to fight insect-borne diseases.

Genetically modified means an organism's genetic structure has been changed through genetic engineering.

The test project in the Keys, a group of islands off Florida's southern coast, will involve the Aedes aegypti mosquito. The mosquito is not native to Florida. But it does transmit several diseases to humans, including dengue fever and the Zika virus.

In the Keys, nearly 50 cases of dengue have been reported so far this year.

The project is led by biotechnology company Oxitec. It is an American-owned company based in Britain. The plan calls for the release of millions of male, genetically modified mosquitoes to mate with females that bite humans.

The company says its male mosquitoes, which do not bite, are genetically engineered with a protein that makes any female offspring unable to survive. The process aims to lower the overall population of the insects to reduce the transmission of disease.

Kevin Gorman is an Oxitec scientist. He told The Associated Press the company completed similar projects in the Cayman Islands and Brazil that went "extremely well."

"We have released over a billion of our mosquitoes over the years," Gorman said. "There is no potential for risk to the environment or humans."

In a press release, Oxitec noted numerous studies by government agencies supporting the safety of the project. The Environmental Protection Agency and the U.S. Centers for Disease Control and Prevention approved the experimental project. Several government agencies in Florida approved it as well.

Some groups, however, worry that the use of genetically modified organisms could change the planet's natural balance. At a recent meeting of the Florida Keys mosquito control board, several people questioned the effects of the project.

"You have no idea what that will do," Barry Wray told the board. He is the director of the Florida Keys Environmental Coalition.

Some experts have also questioned whether or not the modified mosquitoes can effectively crash the mosquito population in Florida as planned.

"The mosquitoes created in a lab have not gone through a natural selection process, in which only the fittest survive and mate," said Max Moreno, an expert in mosquito-borne diseases at Indiana University. He is not involved with the company or the test project.

Moreno asked, "Once they are released in the natural environment, will they be as fit as the naturally occurring males and able to outcompete them for mates?"

Another question is whether the mosquitoes could have unplanned effects on the environment. For example, if a spider, frog or bird eats the mosquito, will the modified protein have any effect on the predator?

Moreno said an ecosystem is so complex and involves so many species that it would be nearly impossible to test all of them beforehand in a laboratory.

Still, Keys mosquito board members voted 4-1 in favor of the project. One of the supporters was Jill Cranny-Gage. She told the meeting that insecticides and other chemical methods have become less effective against the Aedes aegypti mosquito.

"The science is there," Cranny-Gage said. "We're trying everything in our power, and we're running out of options."

I'm Bryan Lynn.

Words in This Story

transmit – v. to cause a virus of disease to be given to others

offspring – n. the child of a person or animal

potential – n. qualities or abilities that may develop and permit someone or something to succeed

predator – n. animal that hunts and kills other animals for food

ecosystem – n. a biological community of interacting organisms and their physical environment

species – n. a group of animals or plants that are similar and can produce young animals or plants

beforehand – adv. before a particular time or event

option – n. a choice