Genetically engineered moths have been released into the wild to wipe out pests

ETGG49 Cabbage moth or diamondback moth

(CNN)Genetically modified diamondback moths designed to wipe out wild pest populations were released in fields for the first time in New York state.

Diamondback moths are migratory pests found in the Americas, Europe, New Zealand and Southeast Asia, but especially in areas where crops can be grown yearround.
In these parts -- where it's not too hot nor too cold -- are where diamondback moths cause the greatest problems, including billions of dollars in damages to cruciferous crops such as cabbage, broccoli, cauliflower and canola. They're one of the most damaging insects because of their high reproduction rate and resistance to most insecticides.
    To address these problems in a sustainable, environmentally friendly way, researchers have successfully genetically engineered (GE) male diamondback moths to control the pest population of their wild counterparts, according to findings published Wednesday in the journal Frontiers in Bioengineering and Biotechnology.
    "There's a lot of interest in using genetically engineered insects for controlling medically important diseases," said Anthony Shelton, lead author of the study and entomology professor at Cornell University's College of Agriculture and Life Sciences.
    "In agriculture, though, I think we can take the advantage of genetically engineered insects to control a major pest species."

    Engineering a self-limiting strain of moths

    The moths were engineered by Oxitec, a developer of insect biological control systems that is known for its modified mosquito releases to reduce mosquitoes that carry malaria or dengue fever.
    When rearing the moths, developers incorporated what they call a self-limiting gene that makes female offspring die shortly after hatching.
    Typically, tetracycline, an antibiotic used to suppress the gene, is included in the moths' diet so that female moths can be produced as well.
    "However, when you want to release populations of males, you do not include tetracycline," Shelton said. "So all the female larvae that are feeding on the artificial diet will die. And then you'll just have thousands and thousands of males which you can release in the field."
    In cabbage field studies in Geneva, New York (about 260 miles from New York City) the moths were marked with different fluorescent powders, released together, then captured in a trap. The GE moths behaved similarly to their wild counterparts in regard to factors that would determine their potential to suppress pests.
    They traveled the same distance and survived roughly as much as their wild counterparts did, in a ratio of two modified insects to one wild type, which was "remarkable" because in previous programs the ratio was much higher, Shelton said.
    The GE moths also competed equally to the wild moths for female mates. However, wild female moths that mate with GE moths will not produce viable offspring -- the self-limiting gene passed to offspring prevents them from surviving, leading the authors to conclude that with ongoing releases, pests can be suppressed in a targeted, sustainable way without using insecticides.
    The GE moths would eventually have no one to mate with, which means they would decline as well and disappear from the environment within a few generations, the authors said. More releases would be needed to continue to suppress wild populations.

    Positives for crop protection

    With a method that could largely reduce the amount of pests and insecticides needed to eradicate them, the "potential impact for the growers and producers of those crops is huge," said Alton Sparks, an entomology professor in the University of Georgia's College of Agriculture.