Scientists Discover Genetic Mechanisms that Allow Insect Adaptation to New Host Plant

Rothamsted Research scientists, in collaboration with researchers from the Liverpool School of Tropical Medicine and Bayer CropScience AG in Germany, have identified novel genetic changes that underlie an insect host shift and the emergence of a new subspecies of crop pest with natural resistance to pesticides.

A subspecies of peach potato aphid (Myzus percicae nicotianae) has evolved to feed and survive on tobacco plants. This subspecies has reduced sensitivity to the secondary metabolite nicotine (tobacco plants produce this as a potent natural insecticide) and neonicotinoids, a class of synthetic insecticides. Study leader Dr. Chris Bass and his team identified genetic mutations involved in the initial steps of the host shift of peach potato aphid to tobacco. They found that a detoxification enzyme CYP6CY3, naturally present in all aphids, is responsible for the metabolism of nicotine to less toxic compounds. However, for this process to occur at significant levels that allow survival of aphids feeding on tobacco plants, the gene producing this enzyme needs to be present in many more copies than the normal two copies, up to 100 copies in the most resistant aphids. Professor Lin Field of Rothamsted Research said "We now have further understanding of the molecular mechanisms that can drive insecticide resistance and this can be utilized when developing pest management strategies."

The study is published in the journal Proceedings of the National Academy of Sciences (PNAS) available at: 10.1073/pnas.1314122110. The news release can be read at http://www.rothamsted.ac.uk/news/emergence-new-crop-pests-genetics-action.