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Taking on a Pest with Deadly Sex

Scientists are turning to sex and genetics to combat an especially troublesome pest estimated to cost farmers $5 billion worldwide annually, The New York Times reports.

At the Cornell University Agricultural Experiment Station in upstate New York, researchers are testing whether genetically modified diamondback moths can be used as a safe alternative to pesticides to control the bugs, which continues to evolve to resist new kinds of pesticides and even radiation. Working with British biotech Oxitec, Anthony Shelton, an entomologist at Cornell, is "hoping to substitute sex for sprays" as a strategy to kill the critters, the paper says.  

Oxitec has developed a gene comprising DNA from a virus and a bacterium that is deadly to female insects. Female larva with the gene must be regularly fed tetracycline in order to survive, and in the wild the larva dies before they reach adulthood. 

The company reported in a study that male diamondback moths with the gene wiped out communities of normal moths living in small cages. While female moths mating with the transgenic male moths had as many offspring as those that mated with normal males, the female offspring of the genetically modified male moths died before they could reproduce. 

Now, Cornell researchers plan to explore whether the genetically altered male moths can survive in larger areas. Next summer the moths will be released into the field, a plan that has drawn criticism from some who fear unseen consequences, such as harm to wildlife that feed on the moths. 

Even if the transgenic moths prove safe and effective, however, some think that the approach may not succeed commercially. "What almost always happens is the pesticides take precedent," University of Queensland entomologist Michael Furlong told NYT. "The growers can't resist spraying, as it's the easiest thing to do."