With one full season’s experience under their belt, western state entomologists and Extension specialists have refined trapping and treatment recommendations for the invasive spotted wing drosophila for the upcoming cherry season.
But they’re quick to admit there’s still a lot about this newcomer that they just don’t know, such as treatment thresholds, population dynamics and alternate hosts.
To help answer some of those questions, the U.S. Department of Agriculture earlier this year awarded a $5.8 million, 4½-year multistate grant to fund development of an integrated pest management program for the pest. Oregon State University is the lead institution. Also participating are the University of California, Washington State University and the Agricultural Research Service.
Much of the early research into SWD was funded by commodity groups, such as the California Cherry Advisory Board and the Washington Tree Fruit Research Commission.
Different trap and bait preferences
One of the questions researchers say they hope to answer in the near-term is the best trap design and bait. Most traps consist of a container filled with a liquid bait attractant and with openings to allow the fly access to the bait.
“There are clearly as many different designs of traps as people looking at this in the research community,” says Rufus Isaacs, an entomology professor and Extension specialist at Michigan State University in East Lansing. He is heading up the state’s SWD response team funded by a Michigan Specialty Crop Block Grant and the university’s Project GREEEN.
Traps picked up SWD for the first time in Michigan last season after most of fruit had already been harvested.
This season, Isaacs says he will be joining a West Coast group comparing five or six different trap designs and baits.
“So I think by the end of this summer we will have a much better idea which is the best trap for specific regions of the country,” he says.
California researchers, for example, favor a 1-quart white yogurt container because of its sturdiness, inexpensive cost and availability, says Bob Van Steenwyk, a University of California Cooperative Extension pest management specialist in Berkeley. The white background color also makes it easier to see if you’ve caught flies.
Last year, UC recommended drilling 15 to 20 3/16-inch holes around the sides to provide fly access to the bait.
This year, Van Steenwyk says they’re recommending covering the top with 1/8-inch hardware cloth or screening instead of drilling the holes. It appears the open-top design catches more flies, he says.