By Shannon Kelleher US regulators are fast-tracking a novel, gene-altering insecticide in an unusual move that would greenlight the product for three years of commercial use before a standard testing period is completed. Calantha, a product of the company GreenLight Biosciences, contains the active ingredient ledprona, which uses a mechanism called RNA interference (RNAi) to kill the Colorado potato beetle, a notorious pest, by turning off genes it needs to survive. Calantha would be the first pesticide spray using RNAi, though the technology has been genetically engineered into some corn plants to protect them from the corn rootworms, and RNAi has a history of use in medical therapeutics and vaccines. The EPA just granted GreenLight Biosciences an Experimental Use Permit (EUP) in May, giving the company two years to gather and assess data from use of the new product in limited test plots. But now the new pesticide could be widely sprayed on potato crops around the country as early