Male Diamondback moths have been released in New York state genetically modified and designed to wipe out crop pests. Field evidence shows that these moths, whose female offspring die, could help control this important crop pest.
Oxitec, the British biotechnology company behind the trial, has already conducted field trials of this method to control mosquitoes that spread diseases like Dengue. The experimentation on the GMO moth is the first against a crop pest, the company says.
Relentless parasite
The larvae of the Diamondback moth (plutella xylostella) eat the leaves of brassica plants such as cabbage, broccoli and canola. Moths are major pests worldwide, causing damage estimated at $5 billion per year.
How the kamikaze moth was born
To create its GMO moth, Oxitec added two genes to the moths still sensitive to pesticides. A gene simply codes for a red fluorescent protein, so that insects can be easily identified in the wild.
The other gene kills larvae soon after hatching, but is activated only in females.
So when male moths mate with wild females, all females die at birth. Males survive and pass on the lethal gene to their offspring.
Since half of the offspring of genetically modified males die every generation, the lethal gene should disappear after a few generations.
To suppress wild populations, more GMO moth males would need to be continuously released.
In the field tests conducted for the first time two years ago at the Cornell University Agricultural Experiment Station in New York, between 1000 and 2500 male specimens were released on several occasions.
As expected, the GMO variety did not persist in nature after the test period. “We haven't detected any of them around,” says Neil Morrison by Oxitec.
The company hopes to get approval to start selling its GMO Diamondback moth to farmers in the United States. It would be a “natural” substitute for pesticides (more so, given that moths quickly develop resistance to these substances). With the same technology, other types of parasites could also be addressed.
But the GM moth will have to be used with other methods as part of an integrated approach, he says Michael Bonsal from the University of Oxford.“It's not an ultimate weapon. It's just another tool."
Not just GMO moth
Oxitec also conducted tests with GMO mosquitoes in the Cayman Islands, Brazil, Panama and Malaysia. A second test is now underway in Brazil and Oxitec hopes to get the green light for a test in the United States as well.
References: Frontiers in Bioengineering and Biotechnology, DOI: 10.3389/fbioe.2019.00482
