Hungry beetles snub crops implanted with the insects’ genetic material, scientists report in the February issue of Science. When the pests munch the engineered plants, beetle RNA in the leaves switches off key genes and they don’t feed.
The Colorado potato beetle is a dangerous pest that has become resistant to many chemical pesticides. In order to protect potato plants from the beetle, researchers transplanted fragments of beetle’s genes into the crops. The team chose machinery in plant cells called plastids to house the insect genes. Chloroplasts, which perform photosynthesis, are the most common type of plastids. They are found in the very part of the plant that potato beetles dine on.
When laced with the insect gene fragments, the potato plants produce genetic material called double-stranded RNA that disables key genes in the beetles. Double-stranded RNA turns those genes off by stopping their instructions from being converted into proteins.
“It was not long before the insects’ guts started to break down,” says Jiang Zhang, a coauthor of the new study and geneticist at the Max Planck Institute of Molecular Plant Physiology in Potsdam, Germany. “Within three days, the adults had stopped feeding and left the potato plants alone. After four days, all the larvae that feasted on potato plants were dead.”
The Colorado potato beetle is notorious because it quickly develops resistance to insecticides that are used to control it. This has become a serious issue on the east coast and is becoming a problem in Kentucky. With a limited number of insecticides available, some homeowners have exhausted their control options.
The common black and yellow-striped “potato bug”, is the most serious insect ravager of potato crops. Both the striped beetle and the black-spotted, red larva feed on potato leaves. Their damage reduces yield and kills plants. In addition to potatoes, Colorado potato beetles can be a serious threat to tomato, eggplant, and pepper crops.