Wisc researchers deploy drones for cranberry moth control

By Ann Bailey | August 25, 2015

A Wisconsin research team intends to fly small unmanned aircraft systems (UAS) above cranberry marshes to control moths that damage the crop.

Insect damage is a perennial problem for producers of cranberries. The fruit crop annually pumps an estimated $300 million into the economy of Wisconsin, the United States’ No. 1 producer, the Wisconsin Department of Agriculture said.

Test drone flights that drop SPLAT, a pheromone-infused wax, on cranberry beds will get under way late this fall, said Shawn Steffan, University of Wisconsin-Madison professor of entomology and a U.S. Agriculture Department entomologist. The SPLAT leaves the drone the consistency of yogurt, and, eventually, hardens into a soft wax with the consistency of a children’s modeling compound, Steffan said.

Steffan and his research team, together with Brian Luck, a University of Wisconsin College of Agriculture and Life Sciences extension biological engineering professor, are working to build a drone that can drop the SPLAT.

“We have a blueprint and materials,” Steffan said. In about two months he and Luck should have a prototype drone they can take to the field and test, he estimated. The testing, which will get under way after the cranberry harvest, will explore details such as how the SPLAT can be released from the drone and the height at which the drone needs to fly for optimum  coverage of the pheromone-infused wax. During the upcoming winter and spring, the SPLAT application will be refined.

Steffan’s plan is for drones to drop pheromone-infused product, which he refers to as SPLAT wax soup, onto the cranberry beds in dollops the size of Hershey’s Kisses. The dollops slowly release sex pheromones that smell like a female and because the male moths cannot differentiate between the SPLAT and female moths, many of them will die before they find a partner in their continual search for a real female moth.

“You literally pre-empt the population” from reproducing, Steffan said. “Mating destruction is ideal as a way to keep males and females from finding each other. They need the pheromones to find one another, so if you can delay long enough, they eventually will die, without mating.”

Using SPLAT to control moths instead of spraying insecticides on the cranberries has the potential to impact the bottom line of farmers because they will save money on applications. Typically, farmers spray insecticides two to five times during the growing season, Steffan said. Meanwhile, using the SPLAT method of control may make it easier for cranberries to enter European and Asian markets which have stricter pesticide residue levels, he said.

Using SPLAT to control moths in cranberries also has environmental benefits including saving pollinators such as honey bees, from being victims of insecticides. A typical time to spray for cranberry fruit worm is when the adult moths are flying and that is the same time as cranberry bloom when the honey bees are out, Steffan noted.