Pyrethroid insecticides losing control over Oriental fruit moth | Resistance | Michigan Farm News

Pyrethroid insecticides losing control over Oriental fruit moth

Category: Fruits & Vegetables

by David Jones, and Bill Shane, Michigan State University Extension, and David Mota-Sanchez, MSU Department of Entomology

peach-moth-damage-mfn-2018
Peach shoot damage and fruit ooze from oriental fruit moth damage. Photo by Dave Jones, MSU Extension.

Oriental fruit moth, Grapholita molesta, is a common insect pest in Michigan peach and apple orchards. In peach orchards, this moth causes damage to the shoots in the early season and fruits following shuck split.

Oriental fruit moth has three generations per season, and peach growers must time effective insecticides to target the peak flights of the pest. Historically, the pyrethroid class of insecticides has been a popular choice in Michigan peach orchards because of their high efficacy, broad spectrum of activity and low cost.

However, following heavy damage to Michigan peach orchards during the 2016 growing season in spite of management with these products, many peach growers began to suspect resistance to the pyrethroid class of insecticides could be developing.

In 2017, Michigan State University conducted insecticide bioassays on field-trapped adult oriental fruit moth collected from peach orchards in west central and southwest Michigan. Groups of oriental fruit moth were exposed to three concentrations of esfenvalerate. Esfenvalerate is the active ingredient in the widely used pyrethroid insecticide for oriental fruit moth, Asana, and its generic equivalents.

Unfortunately, 2017 results indicate this material is no longer a good choice for managing oriental fruit moth. Mortality in field-collected males to esfenvalerate was less than 50 percent in all test groups, and fell as low as 13 percent in some treatments. Avoid depending on products with esfenvalerate for managing oriental fruit moth if you are in regions where pyrethroid insecticides have been routinely used on apples and peaches. Data on other pyrethroid insecticides is not yet available.

“This is yet another challenge for our fruit growers,” said Kevin Robson, horticulture specialist with Michigan Farm Bureau. “It’s difficult for them to keep up sometimes, but hopefully new research will find alternatives that are effective, safe and widely available. We suggest that growers make it a habit to consult with MSU on the most recent research, because things can change quickly. It’s always good to be prepared.”

Pyrethroid insecticides have value for managing other insects such as tarnished plant bug, and there is some evidence that resistance of oriental fruit moth to pyrethroids declines when other effective insecticides are included in rotation. MSU will continue studies on oriental fruit moth susceptibility to this product and other pyrethroid materials in 2018.

Summarized below are the non-pyrethroid insecticide options to pick from when considering future management plans for this insect pest.

Non-pyrethroid insecticides registered for managing oriental fruit moth.

Compound trade name

Chemical class

Effectiveness

Residual activity

Imidan

OP

Excellent

14 days

Exirel

Diamide

Excellent

10-14 days

Altacor

Diamide

Excellent

10-14 days

Delegate

Spinosyn

Excellent

7-10 days

Assail

Neonicotinoid

Excellent

10-14 days

Rimon

IGR

Excellent

10-14 days

Voliam Flexi

Premix

Excellent

10-14 days

Intrepid

IGR

Good

10-14 days

Diazinon

OP

Good

10-14 days

Avaunt

Oxadiazine

Fair

7-10 days

Lannate

Carbamate

Fair

7-14 days

Sevin

Carbamate

Fair

7-14 days

Esteem

IGR

Fair

7-10 days


Other insecticides with pyrethroid class active ingredients are also likely at risk at this time. While data on additional products will be coming in 2018, use caution with the products on the table below. Note that the rating label on all these products is “excellent,” but based on recent data there is some doubt on their accuracy.

Pyrethroid-based insecticides registered for managing oriental fruit moth.

Compound trade name

Chemical class

Current labeled effectiveness rating

Residual activity

Danitol

Pyrethroid

Excellent

7-10 days

Lambda-Cy

Pyrethroid

Excellent

7-10 days

Baythroid

Pyrethroid

Excellent

7-10 days

Perm-Up

Pyrethroid

Excellent

7-10 days

Leverage

Premix

Excellent

10-14 days

Endigo

Premix

Excellent

10-14 days

Voliam Xpress

Premix

Excellent

10-14 days

MSU Extension suggests deploying mating disruption for oriental fruit moth in peach orchards to help combat the pest.

Populations of oriental fruit moth in many areas of the state are very high at this time, and deploying this strategy will help curb population growth in orchards. Do not be discouraged if high populations of oriental fruit moth persist for a year or two after you begin using this practice; the oriental fruit moth populations likely took several years to get this high and may take time to go back down again.

Deploying effective insecticides timed with peak flights along mating disruption will help peach growers get back to a reasonable management scenario for this pest.