The pink bollworm is a major pest of cotton worldwide
By BBC News Online’s Helen Briggs
The first release of a genetically modified insect is expected to take place in the United States this summer.
A moth has been engineered to contain a gene from a jellyfish in the first stage of a genetic experiment designed to eradicate the cotton-destroying pest from the wild.
A total of 3,600 of the moths will be set free under a cage within a one-hectare (three-acre) cotton field in Arizona.
The experiment is likely to raise concern among environmental groups.
But the researchers behind it say there is “minimal” risk of the genetically modified insects escaping. As an added precaution, the insects have been sterilized.
Thomas Miller of the Department of Entomology, University of California, told BBC News Online: “It is very important for us that the public understands what we’re doing and why. We are not trying to create something that causes more trouble than we already have.
“We have plenty of trouble with pink bollworm. It’s an absolute nightmare and it’s caused a lot of people to go bankrupt.
“There’s two things about this release. Number one, we’re only going to use sterilised insects in the first go around. Even if they get out, there’s no chance of them breeding.
“Second of all, they are going to be in field cages. The people who are going to do this work have years of experience working with these field cages.
“They know what is involved in maintaining them and the only way an enclosed population is going to get loose is if a hurricane comes through and rips the field cages to shreds. There hasn’t been a hurricane in Arizona in these areas in living memory.
“One thing we do know: the native population is a champion at survival. It has so far resisted any attempts to eradicate it except in central California.
“Our ultimate plans are to insert conditional lethal genes that will fight against this enormously successful tendency to survive and infest cotton.”
US regulators have yet to give the greenlight to the release but Professor Miller says he is optimistic the field trials, planned for the summer, will be given the go-ahead in the next few weeks.
The pink bollworm, a major pest of commercial cotton in the southwest, is not native to the US but hitched a ride there in the 1920s, probably in cotton shipments from India.
The larvae are tiny white caterpillars with dark brown heads that burrow into cotton bolls causing devastation to the crop. They grow into greyish-brown moths.
The engineered moths contain a genetic marker, a green fluorescent protein (GFP) derived from the jellyfish, which makes caterpillars inheriting the gene glow green under fluorescent light.
In the first stage of the experiment, the scientists plan to release the moths under aseven-metre (24-foot) long cage
in a small test site remote from commercial cotton fields.
Although the laboratory insects are confined to a cage, they will be able to mate with native insects already present on the cotton at the time of the release, allowing the scientists to track the spread of the gene through the population.
The field trials could pave the way for the first attempt to eradicate insects from the wild by releasing genetically modified laboratory strains. By inserting an inherited lethal trait into the moth the scientists believe they might be able to “get rid of the pink bollworm” from the US altogether.
Similar research is focusing on the disease-carrying mosquito. Researchers from the US and Taiwan have modified the yellow fever mosquito to make it produce a powerful antibacterial protein, limiting its ability to transmit disease.
If such insects were ever released in the wild, they might supplant infected natural populations, helping in the fight against human disease.
Besides insects, a number of other transgenic animals are on the way. The US Food and Drug Administration (FDA) is currently deciding whether to allow a fast-growing genetically modified salmon on to American dinner plates. Scientists believe genetically modified carp may already be in commercial use in China while genetically modified
tilapia may be in use in Cuba.
Other examples of aquatic GMOs include transgenic channel catfish, modified Pacific oysters and hybrid striped bass.