Insect Mating Disruption Strategies on the Grow in Fruit and Nut Orchards
April 14, 2020 
USDA-ARS Research Entomologist Dr. Charles Burks says pheromone mating disruption for pests has seen exponential growth, with 400,000 to 500,000 acres of tree nuts using the technique in the West. That’s about one-third of the acreage.
Photo by Paul Skowronski
Fruit production in the West poses unique pest challenges, and biological tools are increasingly part of the solution.
Attendees at the Biocontrols USA 2020 Conference & Expo held in Portland, OR, during early March, learned about biocontrol topics such as mating disruption strategies through the use of pheromones as well as sterile insect releases.
Mating Disruption for NOW
Dr. Charles Burks, Research Entomologist with USDA-ARS discussed research on the use of pheromone products for mating disruption on key pests of almonds, walnuts, and pome fruit.
Navel Orangeworm (NOW), in particular, is a significant issue in tree nut crops. Throughout the early 2000s, the pest management strategy for NOW in almonds was a combination of sanitation, monitoring and well-timed sprays, and timely harvest. Pheromone traps were used to time sprays but amounts and products were based on previous year’s damage.
Since 2008, mating disruption using aerosol products with timers has been added to the mix and has shown positive results. More recently a hand-applied pheromone device has become available as well. It requires more labor and doesn’t disperse as well but is mechanically simpler and offers cost tradeoffs, Burks said. Over the last decade there has been exponential growth in the use of these tools, with 400,000 to 500,000 acres of tree nuts now under mating disruption in the region — about one-third of the acreage.
Mating disruption is a preventative technique. There is a greater benefit when used over the long term — year after year — and a wider area, Burks said.
The species specificity aspect of pheromone tools is both its greatest strength and also a weakness. Mating disruption does not have non-target effects, but you are left with other pests to deal with. That said, this selectivity also allows natural enemies to help manage pests. Burks pointed out that NOW parasites Copidisoma plethoricum and Goniozus legneri are more abundant when mating disruption is used instead of insecticides, and that parasites do contribute to commercially useful control.
Sterile Insect Release
Codling moth (CM) is a key apple pest in the region, as well. Traditional control options include insecticides, mating disruption, and virus. However, this pest has developed resistance to conventional pesticides and the efficacy of these tactics as stand-alone controls has diminished, according to Chris Adams, Oregon State University Assistant Professor of Tree Fruit Entomology.
Adams discussed Sterile Insect Release (SIR) as a tactic that has been successfully used to control CM in British Columbia, and how research has looked at ways to optimize this tool by investigating release patterns, the ratio of sterile to wild CM needed, and innovative release mechanisms such as drones.
Area-wide eradication models have been explored in Canada, with some level of success, but require high levels of investment and infrastructure. Adams discussed another model, farm-level management, which also shows promise. Growers manage the decisions on releases in this model, so costs are more market driven. The focus is to make SIR more IPM tool than eradication program.
Adams said in release experiments to determine the optimum ratio of sterile to wild CM, a 40:1 ratio delivered 90% suppression. However, a 20:1 ratio showed 75% suppression, which is still very good. If you can get populations down that low, other techniques can do the rest.
“This could be the most cost effective,” he said.
To see the rest of the 2020 Biocontrols USA Conference Program and get updates on upcoming events, visit BiocontrolsUSA.com/inquire.
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