Mating disruption (MD): pheromone-based tool where dispensers of artificial sex pheromones from (usually) females are placed in orchard and reduces the probability of males finding females (Fig. 1). In turn, mating reduced and egglaying reduced below economic threshold.

Several mechanisms by which MD may happen

• Competition occurs when males are not able to locate females because MD dispensers compete with females, and thus waste time and energy orienting to MD point sources.
• Sensory Impairment is at play when males exposed to MD dispensers display a decrease or total loss in responsiveness attributed to adaptation of sensory receptors and/or habituation.
• Camouflage occurs when the background provided by MD dispensers make the pheromone plume from a female imperceptible by males.

Pros of MD:

• can be part of an Integrated Pest Management (IPM) program
• can reduce need for targeted insecticides
• approved for use on both conventional and organic farms
• often provides season-long pest suppression with a single application
• does not wash off in the rain
• does not contribute to pesticide residues at harvest
• has no negative impact on natural enemies, pollinators or other beneficial arthropods.
• low to no impact on the environment and workers

Cons of MD:

• limits in our knowledge of the pests (e.g., behavior, life history traits, neurobiology)
• socio-economics factors (e.g., costs of MD technology manufacturing; costs of MD implementation; fit with other IPM tools)
• environmental and landscape factors (e.g., microclimate, crop architecture and scale)

Some considerations:           

–    Size and location of orchard: orchards less than five acres or near a source of the pest may not obtain optimal results

• Border sprays may be needed if source of pest nearby
• Pest level: high populations (above 1% crop damage the previous season) will need to be controlled with insecticide first year of MD
• Other non-target pests that were controlled by insecticide for target pest may see resurgence
• Distribution of dispensers: Grid pattern primarily along edges

MD pheromone systems in apple are available for codling moth, Oriental fruit moth, dogwood borer, peachtree borer and lesser peachtree borer as well as for some leafroller species (OBLR, Pandemis, omnivorous leafroller, light brown apple moth) and more recently San Jose Scale.

Overall, developed for over 20 insect species and used on more than 2.3M acres of specialty crops in the U.S.

Checking efficacy: monitoring traps are needed to track pest activity and density to assess efficacy of MD. Target not killed so need to make sure adequate control achieved by reducing trap catches (as an indicator that males are not finding females). What is action threshold for monitoring traps in MD orchards? Should it be 1 moth per trap per week? No clear answer.

SCRI Planning grant objectives:

1. Establish the first national research and extension community of practice on MD;
2. Engage stakeholders in a survey to identify MD research priorities; and
3. Develop a transdisciplinary, multi-state, multi-commodity SCRI CAP research and extension grant proposal.
4. The CAP proposal will aim to increase adoption and develop improved MD technologies within a socio-economic framework that integrates research and extension activities centered around stakeholder needs.

For my objectives: Need data on MD trap catches and fruit damage on spatial scale of orchard.

San Jose Scale (SJS) mating disruption

Damage: San José scale sucks sap from branches, leaves and fruit causing overall decline in plant vigor, growth, and yield. If left uncontrolled, San José scale can ultimately kill plants. On fruits, San José scale feeding causes slight depressions with red to purple haloes. If San José scale populations are low, fruit damage is usually concentrated on the bottom of the fruit. When infestations occur early in the season, fruit may become small, deformed, and poorly colored.

Monitor: During dormancy, watch for trees that retained leaves during winter and check both branches and trunks for the insect. Mark infested areas on trees to identify where sprays should be applied the following growing season. At pink stage, place commercially-available pheromone traps to detect the presence of males on the northern or eastern side of trees at a height of six to seven feet. Check traps at least weekly. Traps are effective for four to six weeks. Monitor for crawlers by wrapping two-sided sticky electrical tape (coated with a thin layer of petroleum jelly) around infested tree limbs at both ends of the infested area. Start checking tape for crawlers approximately four to six weeks after bloom.

Management:

• Prune out infested branches.
• Use of 2% horticultural oil with or without an insecticide just before or right after bud break, before flowers open.
• Insecticides containing insect growth regulators (e.g., pyriproxyfen or buprofezin), neonicotinoids, organophosphates, or spirotetramat can be effective. Note that late-fall and postharvest applications are NOT effective for SJS control.
• Mating disruption: Research on MD for SJS was conducted at MSU in sweet cherry and apple. In sweet cherry, ~200 dispensers per acre set up late May compared to grower standard. ½ to 1 acre plots with 4 monitoring pheromone traps. Results show that MD reduce numbers of SJS in traps and also suggest that using MD in alternate years could be an effective strategy for reducing SJS populations and worked better at reducing populations than grower standard. Research in apple orchards suggests that MD for SJS works with 100 dispensers per acre. Pacific Biocontrol, Trece, and ShinEtsu each have an experimental product for SJS mating disruption that could be commercialized in the near future.

Average number of SJS in monitoring traps per treatment per week. From Pochubay et al. 2020.

For more information about San Jose Scale, you can visit this bulletin.

SCRI Planning grant objectives for MD:

1. Establish the first national research and extension community of practice on MD;
2. Engage stakeholders in a survey to identify MD research priorities; and
3. Develop a transdisciplinary, multi-state, multi-commodity SCRI CAP research and extension grant proposal.
4. The CAP proposal will aim to increase adoption and develop improved MD technologies within a socio-economic framework that integrates research and extension activities centered around stakeholder needs.

A survey on use patterns and barriers to implementation of MD will come out this summer, please fill it out!

Happy growing season!

Reference

Pochubay et al. 2020. Further investigation of hand-applied mating disruption for San Jose scale in sweet cherries. https://www.canr.msu.edu/nwmihort/uploads/files/SJS%20mating%20disruption_2020.pdf

This article was posted in Insects and tagged Apples, Christelle Guédot, insects, Mating Disruption.