WASHINGTON TOWNSHIP - Researchers at the Philip E. Marucci Center for Blueberry and Cranberry Research had helped reduce pesticide use in blueberry fields by about 60 percent in recent years, when they suffered a setback.

"We got this new invasive species," said Dean Polk, the statewide Fruit Integrated Pest Management agent, of the tiny but destructive Spotted Wing Drosophila, an Asian fruit fly that first appeared in South Jersey in 2011.

It lays its eggs on blueberry fruit, and its larvae develop inside the fruit. It has caused millions of dollars in losses to farmers in the past two seasons, and it has knocked progress in integrated pest management backward, Polk said.

IPM is a way of controlling pests through cultural methods that minimize chemical use.

"When you don't know something about a pest, the first thing you do to reduce risk is to spray," Polk said, adding he knows of no growers that like to use pesticides.

"It's expensive, and it's dirty," he said.

Customers demand that blueberries look perfect, and there can't be larvae in a single berry, Polk said. So now center researchers are testing different insecticides to see what is the "softest"- or least toxic to beneficial insects, humans, mammals and fish - that can be used against the new fruit fly, which has no natural predators locally.

The center's scientists have been helping growers deal with a variety of pests for years.

They have developed traps to entice pests such as the Oriental beetle using pheromones. The Oriental Beetle Mating Disruption Pheromone was developed locally, and it recently became registered for sale. It releases the female beetle sex pheromone so males hang out where it is applied instead of finding real females to mate with, said Cesar Rodriguez-Saona, an associate professor who worked on its development.

To help farmers deal with another big pest, the blueberry maggot, the researchers worked with growers to improve field sanitation and to spray only when the adult fly is caught in nearby traps, Rodriguez-Saona said.

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