July 26, 2018. Written by Tianna DuPont, WSU Extension.
Imagine biological control released by drones. Betsy Beers, Washington State University and Nathan Moses-Gonzales, M3 Consulting are working to add Sterile Insect Release (SIR) to your toolbox for codling moth management. They demonstrated their new project at a field day hosted by the Okanogan Horticultural Society in Tonasket this month.
Think ‘mobile mating disruption.’ Sterile Insect Release (SIR) has been used for codling moth control in British Columbia since the early 1990s. The idea is that codling moths (male and female) are irradiated so that they are sterile. A large number are released in order to overwhelm the native population so that many wild (fertile) females mate with sterile males. Females that mate with sterile males produce no offspring, reducing the size of the next generation. SIR is used on about 8,200 acres in Canada as part of an area wide program where it serves as their main form of control. With the exception of a few experimental studies, none were used commercially on the US side of the border.
As we all know, “We can use some help with codling moth in high pressure orchards,” said Beers. SIR would be a tool to use in these situations. SIR might be especially helpful as a substitute for Entrust that is harmless to natural enemies in an organic program.
The goal of Beers’ and Gonzales’s project is to “make SIR work in Washington,” explained Beers. To make SIR successful they need to learn what rates are effective, how it can be incorporated in an integrated program with mating disruption and current sprays, and how we can practically release large numbers of sterile moths cost effectively. “We hope to identify any weak points of SIR in our context and fix them,” Beers explained.
One key difference in this initiative is they are incorporating unmanned aircraft (UAS, or drones) to release the insects. Release by drone seems to not only be faster, (if the area was contiguous they could do 600 acres in 2 hours), but it seems to maintain higher quality of moths. For SIR to work the moths “Need to be sterile but sexy,” …. explained Melissa Tesche, General Manager of the OK-SIR program in BC. If the insects are not maintained at the proper cold temperature in storage they start to wake up and beat their wings. They can quickly start to lose scales, becoming tattered and less attractive to the female moths. M3 consulting is working hard to maintain quality by keeping them at cool temperatures until they are released. One key is that they are designing the unmanned aircraft specifically for this task of release around the needs of the insect.
The project, funded by the Washington Tree Fruit Research Commission, is working in twelve orchards in Okanogan County, Washington. A major research question they are working on is – How many moths is enough? Each collaborating orchard group has three eight-acre treatment blocks where one block receives the standard rate of one petri dish (800 moths) per acre, one block receives three times the standard rate and one block is the control receiving only standard organic mating disruption and sprays. All SIR treated
blocks also receive standard mating disruption and organic sprays.
Researchers are hopeful. Damage is low after the first codling moth generation, but the preharvest information will be more telling. One participant in the project said that last year they had to spray virus ten times in addition to mating disruption last year. But this year with the sterile moth release, they have only had to spray twice so far and hope to not have to do more than two more sprays.
Many questions remain. How many acres? How much will it cost? The list goes on. We will have to stay at the edge of our seats until the next update at winter meetings this year to find out the answers.
Department of Entomology
Washington State University
Tree Fruit Research & Extension Center
Wenatchee, WA 98801Phone: 509.663.8181 x234