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Gene-disabling pesticides raise fears of unintended effects

NEW YORK – Scientists and biotechnology companies are developing what could become the next powerful weapon in the war on pests – one that harnesses a Nobel Prize-winning discovery to kill insects and pathogens by disabling their genes.

By zeroing in on a genetic sequence unique to one species, the technique has the potential to kill a pest without harming beneficial insects. That would be a big advance over chemical pesticides.

“If you use a neuro-poison, it kills everything,” said Subba Reddy Palli, an entomologist at the University of Kentucky who is researching the technology, which is called RNA interference. “But this one is very target-specific.”

But some specialists fear that releasing gene-silencing agents into fields could have unintended effects on wildlife and even human health. The Environmental Protection Agency, which regulates pesticides, will hold a meeting of scientific advisers today to discuss the potential risks.

“To attempt to use this technology at this current stage of understanding would be more naïve than our use of DDT in the 1950s,” the National Honey Bee Advisory Board said in comments submitted to the EPA before today’s meeting.

RNA interference is of interest to beekeepers because one possible use, under development by Montsanto, is to kill a mite that is believed to be at least partly responsible for the mass die-offs of honeybees in recent years.

Monsanto has applied for regulatory approval of corn that is genetically engineered to use RNAi, as the approach is called for short, to kill the western corn rootworm. And it is trying to develop a spray that would restore the ability of its Roundup herbicide to kill weeds that have grown impervious to it.

Some bee specialists submitted comments saying they would welcome attempts to use RNAi to save honeybees. Groups representing corn, soybean and cotton farmers also support the technology.

“Commercial RNAi technology brings U.S. agriculture into an entirely new generation of tools holding great promise,” the National Corn Growers Association said.

Some scientists are calling for caution, however. One laboratory study by scientists at the University of Kentucky and the University of Nebraska, for instance, found that a double-stranded RNA intended to silence a rootworm gene also affected a similar gene in the ladybug, killing that beneficial insect.

Concerns about possible human health effects were ignited by a 2011 paper by researchers at Nanjing University in China. They reported that snippets of RNA produced naturally by rice could be detected in the blood of people and mice who consumed the rice and could even affect a gene that regulates cholesterol. Such a “cross kingdom” effect would be extraordinary and was met with skepticism. At least three studies subsequently challenged the findings.