Scientists at Kansas State University (K-State) have discovered that the salivary glands of a tiny insect may hold a key to developing pest resistance in plants.

A team of K-State researchers found that by using technology to silence a gene in the salivary glands of pea aphids, the insect’s lifespan was cut by more than 50%.

"What we found is that when we silenced the most abundant transcript (gene), the aphids died in a few days," says K-State Professor of Entomology John Reese.

The findings could lead to new ways to control insects in plants, including such important crops as wheat, alfalfa, soybeans, corn and sorghum, Reese says.

Finding ways to develop insect-resistant crops also brings scientists closer to finding ways to reduce agricultural producers’ dependence on pesticides. That helps the environment and lowers growers’ input costs.

"If we can figure out how to get a plant to prevent the functioning of an insect pest’s gene, we can turn that plant into a non-host for that pest," Reese says.

Reese was part of a research team that included Assistant Professor of Entomology Yoonseong Park and former graduate student Navdeep Mutti, as well as molecular geneticists.

In the study, which was published in the Journal of Insect Science, the researchers injected siRNA into the salivary glands of adult pea aphids, a pest that can be particularly damaging to alfalfa yields. Aphids treated in this way could not survive more than a few days on plants.

Saliva is important in the interaction between aphids and host plants, Reese says. Proteins, including enzymes of aphid saliva, are thought to play several roles – some of which may overcome a plant’s defenses and possibly stimulate plant defenses in non-host plants.

At stake are billions of dollars worth of crops grown every year in the U.S. and around the world. For example, a study first published by Iowa State University in 2005 found that soybean aphids alone had the potential to cause approximately 3 million acres to be sprayed – an economic toll on its own – and to cause yield losses of more than 55 million bushels, meaning an economic impact of more than $250 million in an outbreak year.

Information on the Iowa State study can be found at http://www.ipm.iastate.edu/ipm/icm/node/53.

The K-State research was supported by a USDA grant and by the Kansas Agricultural Experiment Station.