Refining an attracticidal sphere management system for spotted-wing drosophila in small fruit production

Final report for LNE16-350

Project Type: Research and Education
Funds awarded in 2016: $198,902.00
Projected End Date: 10/31/2019
Grant Recipient: USDA-ARS
Region: Northeast
State: West Virginia
Project Leader:
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Project Information

Summary:

Spotted wing drosophila (SWD) represents a serious threat to the livelihood of small fruit growers in the USA. This invasive pest is now in all Northeastern states, and decimated small fruit crop yield and quality after arrival. Losses are estimated to potentially reach $718 million annually in the USA. SWD attacks healthy, intact blueberries, caneberries, strawberries, and cherries by laying eggs in ripening fruit before harvest. Emerging maggots feed in the fruit causing rapid quality decline and consumer rejection. Threatened small fruit production in the Northeast alone includes 70,000 acres. Low thresholds for damage and infestation in fresh markets and zero tolerance for infested fruit for exportation have led some growers to either cease production or begin applying weekly or semi-weekly preventative insecticide applications in the absence of sensitive monitoring tools. This approach is not ecologically or economically sustainable. Alternative strategies for managing SWD in commercial small fruit operations that reduce the need for frequent insecticide applications, prevent outbreaks of secondary pests, and improve ecosystem services provided by beneficial arthropods are critically needed. Over the course of this project, we educated growers across the Northeast and Midwest about the threat posed by SWD to small fruit, SWD biology, ecology and behavior; management tactics and the benefits of IPM practices. We saw a marked increase in growers interested in using IPM tactics, from 50% to 87%. Growers using monitoring traps or fruit infestation samples to determine if protective insecticide applications also rose from 42% and 48% for traps and fruit infestation to 66% and 60%, respectively. And while grower spray applications remained on average at ~5 sprays per farm, these sprays were much more targeted and only applied after flies were being detected. Growers also expressed strong interest in other IPM tactics including attract and kill. And while attracticidal spheres, a visually attractive attract and kill system for SWD, reduced infestations in raspberry and blueberry on some farms, this was not always the case. Moreover, this system did not work in blackberry. It appears that this system works better at lower densities (<16 flies per plant), but becomes overwhelmed when fly densities become higher (64 flies per plant).  However, even at high densities, damage was reduced by 50% when an attracticidal sphere was present. Thus, this attract and kill tool may be a good means to reduce early-season populations, but as populations grower in the later season, other tools such as insecticides will likely be necessary. Refining monitoring traps to determine when these populations are rapidly increasing and developing a particular threshold for treatment will be critical to integrating these various pest management tactics. Moreover, other potential tactics that growers are interested in including , border sprays, degree day models and improved sanitation practices are areas of research worth pursuing and validating as they could also help reduce insecticide inputs against this invasive pest.  

 

Performance Target:

 Fifty farmers in the Northeast will adopt  IPM-based strategies, such as attracticidal spheres, to aid SWD management on an average of 1 acre per farm. Adoption will result in up to 4 fewer insecticide applications per season for a savings of $91/acre in small fruit plantings

 

Introduction:

Spotted wing drosophila (SWD) represents a serious threat to the livelihood of small fruit growers in the USA. This invasive pest is now in all Northeastern states, and decimated small fruit crop yield and quality after arrival. Losses are estimated to potentially reach $718 million annually in the USA. SWD attacks healthy, intact blueberries, caneberries, strawberries, and cherries by laying eggs in ripening fruit before harvest. Emerging maggots feed in the fruit causing rapid quality decline and consumer rejection. Threatened small fruit production in the Northeast alone includes 70,000 acres. Low thresholds for damage and infestation in fresh markets and zero tolerance for infested fruit for exportation have led some growers to either cease production or begin applying weekly or semi-weekly preventative insecticide applications in the absence of sensitive monitoring tools. This approach is not ecologically or economically sustainable. Alternative strategies for managing SWD in commercial small fruit operations that reduce the need for frequent insecticide applications, prevent outbreaks of secondary pests, and improve ecosystem services provided by beneficial arthropods are critically needed.

Ripening small fruit experience intensifying pressure from SWD, and in response, growers’ pest management practices have changed substantially; severely disrupting IPM programs or in some cases, halting small fruit production altogether. Growers who are continuing to produce small fruit, protect them with frequent insecticide applications, and endure increased production costs. Additionally, because bramble crops can have both ripening fruit and blossoms on the same plant simultaneously, increased threats to native and managed pollinators remain an issue.

Recruited Northeastern growers incorporated SWD monitoring traps and/or fruit injury assessments as monitoring tools for SWD presence/absence on their farms, more frequent harvest intervals and attracticidal spheres as part of their SWD management programs in small fruit to demonstrate the benefits of incorporating IPM tactics. While refinement of monitoring traps continues, there still is not a standard protocol and no established thresholds for treatment.  However, growers do use both of these tactics quite frequently (over 66% use traps, and 60% use fruit infestation samples) to determine if SWD are present on their farms and if they need to begin to use protective insecticide applications.

Additionally, attracticidal spheres were also integrated into grower farms. Flies attracted to spheres fed and were removed from the foraging population due to the toxicant-laced sucrose feeding stimulant integrated into the sphere system. Spheres were deployed at a rate of 1 per every 3 meters in 1 acre plots at either high (upper third of canopy) or low (lower portion of the canopy) deployment locations on the plant canopy and compared with a grower standard management program. In Year 1, significant reductions in infestation in raspberries were recorded when spheres were present compared with the grower standard, but no differences were recorded in Year 2.  In blueberry, significant reductions were recorded in one location in Year 2 only, with no differences among treatments recorded in Year 1 and all other farms in Year 2.  Infestation in blackberries was never reduced by presence of attracticidal spheres. To understand why these differences among crops and years occurred, we conducted further studies to determine at what fly density/plant does detectable infestation occur (at 0, 4, 16 or 64 flies per plant).  We found that at 64 flies/plant, injury is incurred for both blueberries and blackberries (>10-fold greater injury levels compared with lower fly densities), but if a sphere is present, infestation is reduced by ~50%. But, this level of injury is too high for growers to tolerate indicating that spheres are more effective at lower infestations as a stand-alone tool,. At higher densities, attracticidal spheres likely can assist in reducing fly infestations and fruit injury, but would need to be used in combination with conventional insecticide sprays.  In this case, having a monitoring trap and associated threshold that could indicate when fly density becomes too great and insecticide applications are also needed would allow these two management tools to work together effectively.  Until this occurs, however, growers will need to make decisions based on fly presence or absence in terms of the need for insecticide applications.

Moreover, because spheres use conventional insecticides themselves as toxicants for the system, they still are not commercially available due to regulatory issues.  Despite these hurdles, our educational program seemed effective as we saw a marked increase in growers interested in using IPM practices (87% by the end of the project).  We know that growers are very interested in adopting tactics as they become available.  In particular, trap-based treatment thresholds for monitoring traps, border sprays, attract and kill and degree day models are all of high interest to growers with both smaller and larger farms.  Thus, as new tactics are available, it seems likely that many growers will be willing to adopt them.

Cooperators

Click linked name(s) to expand
  • Dr. Cesar Rodriguez-Saona (Educator and Researcher)
  • Dr. Anne Nielsen (Educator and Researcher)
  • Dr. Kevin Rice (Researcher)
  • Brent Short (Researcher)
  • Dr. Jaime Pinero (Educator and Researcher)
  • Tracy Leskey (Researcher)

Research

Hypothesis:

Implementing an attracticidal sphere system in small fruit production will reduce SWD damage, delay the onset of insecticide use and prolong the interval between sprays, while increasing beneficial arthropod abundance compared with standard management practices.

 

Materials and methods:

Attracticidal sphere deployed in blueberry.
Blueberry damage samples.
Attracticidal spheres deployed in raspberry.

 

Originally developed to manage apple maggot fly in apple orchards, attracticidal spheres are also attractive and lethal to SWD. We collaborated with growers to evaluate efficacy of attracticidal spheres at seven commercial raspberry, blueberry and blackberry plantings on farms located in MD, NJ, and WV. At each farm, we will evaluated two key factors: 1) attracticidal sphere presence, and 2) deployment strategy to balance both performance and cost. The first treatment, the control, consisted of a small fruit plot managed using standard grower practices. Other treatments included small fruit plots protected by attracticidal spheres at a rate of 1 per 3 meters deployed either in the upper or lower third of the canopy of plants.Trials were conducted during two growing seasons.  

Attracticidal spheres consisted of two parts: 1) a red flat-topped plastic base (Great Lakes IPM, Vestaburg, MI) and 2) a semispherical cap formulated with a mixture of sugar, wax, insecticide and red dye. Caps were formulated at a 1% concentration of spinetoram (Delegate) as the active ingredient. Spinetoram is an effective insecticide against SWD, and also labeled in small fruit. Environmental moisture, such as morning dew or rainfall, activated the release of the sugar and insecticide from the cap, coating the sphere base. Flies were visually attracted to spheres, alighting upon the surface and  triggered to feed by the presence of sugar, thereby also ingesting a lethal dose of toxicant.

As described above, SWD were managed in the control plot by grower standard management practices. In treatment plots, attracticidal spheres were suspended from individual plants/bushes or trellis wire at predetermined densities and heights. Spheres were deployed at earliest fruit set in both blueberry and raspberry plantings prior to SWD infestation. During deployment, spheres were hand-misted to induce initial release of sugar and insecticide. Spheres were monitored and replaced, as needed, until harvest. All ripe fruit were harvested routinely (at least once a week) to maximize visual apparency of and minimize competition with attracticidal spheres. Treatment and control plots were managed for other pests and diseases based on current management recommendations. SWD populations and infestations were monitored closely by collaborating growers and project team members throughout the trial. Growers applied SWD-targeted insecticides to treatment plots if populations and infestation of fruit from SWD rise above manageable levels.

Fruit infestation data were collected to serve two key purposes: 1) provide real-time monitoring/scouting information to the collaborating growers and 2) optimize and evaluate efficacy of the attracticidal sphere system. Monitoring traps baited with SWD lures and filled with a recommended drowning solution were deployed at first bloom in treatment and control plots and checked weekly or twice weekly to record SWD population dynamics until completion of harvest. Throughout the harvest period, 10 ripe fruit from 10 plants/bushes were sampled weekly from all plots and assessed for SWD infestation. Although a trap-based threshold does not exist for SWD, monitoring traps  detect weekly increases or decreases in SWD populations; data were shared rapidly with collaborating growers to permit application of any necessary insecticides. Insecticide program records and yield data were used to calculate the economic costs and benefits of the attracticidal sphere system. Furthermore, attracticidal sphere attractiveness to pollinators were assessed during bloom by recording visitations via a series of 5 min. direct observation bouts. Beneficial insect and secondary pest abundance were sampled using standard techniques (pitfall and sticky traps, and mite brushing). ANOVA were used to compare SWD abundance in collected fruit and lure traps, visitation of pollinators to spheres, abundance of beneficial insects and secondary pests, and differences in marketable yield between treatments.

 

 

 

 

Research results and discussion:

Year 1. Attracticidal spheres were deployed in the upper and lower third of raspberry, blueberry or blackberry plantings of at least one acre at a rate of 1 per every 3 meters on 7 commercial farms in WV, MD and NJ.  SWD fruit infestations rates were compared among treatments. For blueberries, SWD populations were quite low at the time of ripening (0.10-0.30 SWD per sample), and no significant differences were observed among treatments. In raspberry plots, attracticidal spheres significantly reduced SWD in raspberry fruit by 40% compared with control plants (F = 6.8, P < 0.0001), though there was no difference if spheres deployed at the top or bottom of the plants. Attracticidal spheres did not reduce SWD infestation rates in blackberry compared with the grower standard with all samples yielding at least 4 SWD/sample.

Year 2. Attracticidal spheres were deployed identically in Year 2. Again, as in Year 1, attracticidal spheres did not reduce infestations in blackberry plots compared with the grower standard.  In raspberry, there also was no significant difference among treatments in WV and NJ indicating that spheres were reducing populations as well as grower standard.  For blueberries, infestations were reduced significantly in plots in WV using attracticidal spheres (either deployed low or high in the canopy) compared with the grower standard, but no difference was detected in NJ plots. However, because of the variation in results among crops and years, we investigated at what density of SWD do we see an effect from attracticidal spheres in terms of protecting fruit, and when does the densities of flies overwhelm the system.  In this case, raspberry or blueberry plants with known numbers of fruit were placed in field cages.  Flies were released at densities of 0, 4, 16 or 64 flies per cage.  Raspberry and blueberry plants were protected by a sphere either deployed high or low in the canopy, and compared with an unprotected control. Results revealed that 0, 4, and 16 flies per plant, we observed little injury to fruit, but at 64 flies per cage, injury increased by >10-fold.  Interestingly, those plants protected by spheres at high densities had fruit injury that was ~50% less than controls indicating that spheres were reducing fly density, and subsequently fruit injury.

Impact on Pollinators and Beneficial Insects. Spheres were observed for 30 minute increments during the morning and afternoon in flowering raspberry and blackberry plantings. A total of 18h of observation was conducted. During that time, over 1,500 beneficial insects visited plants with or without spheres present, but only 2 syrphid flies and no bees landed on spheres indicated the risk to non-target organisms is low.  Secondly, we looked at potential non-targets that may encounter attracticidal spheres by coating red spheres with Tangletrap and deploying them in raspberry and blackberry plantings. Nontarget captures were generally low across all farms, with Geocoris and parasitoids captured most commonly. 

Research conclusions:

Attracticidal spheres can reduce fly densities and fruit infestation in raspberry and blueberry, but less so for blackberry.  However, this IPM tactics is likely not a stand-alone treatment.  At higher fly densities, protective capacity of spheres is lost and likely will require additional intervention with insecticide applications.  Thus, having a monitoring trap that provides a threshold for growers indicating that insecticide applications will be necessary for this behavioral control tactic, i.e., attract and kill, to be implemented.  Based on high grower interest in adopting IPM tactics, it is likely that if attracticidal spheres could be commercialized, growers would use them on their farms.

Participation Summary
7 Farmers participating in research

Education

Educational approach:

During winter grower meetings in 2017, 2018 and 2019, researchers presented information on: 1)  biology, ecology and behavior of SWD with implications for pest management; 2) limitations  of current management tactics for SWD in small fruit plantings; 3) changes in insecticide use patterns in small fruit plantings due to SWD invasions and the consequences of insecticide inputs into small fruit agroecosystems; 4) basic concept and utility of the attracticidal sphere systems and optimized deployment of attracticidal spheres based on available data; 5)benefits (no impact on pollinators and reduced infestation of SWD) and challenges (not commercially available) of using attracticidal spheres in small fruit crops; and 6) use of monitoring traps and fruit infestation as triggers for insecticide applications to further protect fruit.

In 2017 and 2018, ~400 growers attended winter meetings in which this educational curriculum in MD, WV, NJ, PA and MI was presented.  In 2019, ~120 growers attended a field day held at the Appalachian Fruit Research Station highlighting the findings of the entire project as well as the curriculum above.

 

 

 

Milestones

Milestone #1 (click to expand/collapse)
What beneficiaries do and learn:

One hundred Northeastern growers will receive a survey to establish baseline information regarding current SWD management, secondary pests, pollinators, and willingness to adopt alternative strategies, including attracticidal spheres.

Proposed number of farmer beneficiaries who will participate:
100
Actual number of farmer beneficiaries who participated:
150
Proposed Completion Date:
May 31, 2017
Status:
Completed
Date Completed:
May 31, 2017
Accomplishments:

Over 150 growers were participated in educational sessions aimed at providing current information regarding SWD management, secondary pests, pollinators, and willingness to adopt alternative strategies, including attracticidal spheres.  Growers were reached at regional meetings in MD, WV, NJ and MI.  We included MI as seasonal weather patterns and SWD problems being experienced are very similar to the northeast. 

 

Milestone #2 (click to expand/collapse)
What beneficiaries do and learn:

Fifty growers will return surveys and participate in educational programs.

Proposed number of farmer beneficiaries who will participate:
50
Actual number of farmer beneficiaries who participated:
74
Proposed Completion Date:
May 31, 2017
Status:
Completed
Date Completed:
May 31, 2017
Accomplishments:

Surveys were completed by 74 growers from MD, WV, NJ and MI, all states with growers heavily affected by SWD in small fruit.  Results of the surveys indicated that 68% of grower had SWD present on their farms with 66% reporting injury on 499 acres or 12.8 acres per grower.  Over 77% used conventional insecticides, while only 42% use a monitoring trap, while 48% monitor for fruit damage.  Over half of the respondents indicated that they were interested in using IPM-based management strategies for SWD.

Milestone #3 (click to expand/collapse)
What beneficiaries do and learn:

Survey results will be disseminated to commercial companies such as Trece and AgBio/ChemTica to generate interest in attracticidal sphere production and commercialization.

Proposed number of agriculture service provider beneficiaries who will participate:
2
Actual number of agriculture service provider beneficiaries who participated:
2
Proposed Completion Date:
May 31, 2017
Status:
Completed
Date Completed:
May 31, 2017
Accomplishments:

While we did not distribute surveys, we instead initiated and held conference calls with two commercial companies.  Both have visited our facility and viewed attracticidal sphere production procedure.  While interested in spheres, they also expressed some reservations over the registration process for insecticide use as this would be likely considered a new use.  Additionally, they both expressed interest in lure and traps to improve monitoring procedures. 

Milestone #4 (click to expand/collapse)
What beneficiaries do and learn:

Growers will learn about attracticidal spheres for SWD management through grower meetings, Extension presentations and online resources.

Proposed number of farmer beneficiaries who will participate:
200
Actual number of farmer beneficiaries who participated:
250
Proposed Completion Date:
March 31, 2018
Status:
Completed
Date Completed:
June 30, 2018
Accomplishments:

Leskey New England Fruit and Veg Conference Spotted Wing

At regional Extension meetings in winter 2017- spring 2018, our team discussed the use of attracticidal spheres for SWD as well as its origins for apple maggot management.  Meetings were held in NJ, PA, MD, WV and MI. 

Milestone #5 (click to expand/collapse)
What beneficiaries do and learn:

Seven growers in MD, NJ, and WV will agree to collaborate in on-farm research trials to document the utility of attracticidal spheres for management of SWD. Each grower will receive twice-weekly team support for season-long management of SWD and other pests.

Proposed number of farmer beneficiaries who will participate:
7
Actual number of farmer beneficiaries who participated:
7
Proposed Completion Date:
September 30, 2017
Status:
Completed
Date Completed:
September 30, 2017
Accomplishments:

Attracticidal spheres were deployed at the top or bottom of small fruit plants on 7 commercial farms in WV, MD and NJ in blueberries, raspberries and blackberries. Spheres were deployed at a rate of 1 sphere every three meters in the upper third of the canopy, 1 sphere every three meters in the lower portion of the canopy, and no spheres as a control. Each plot was at least 1 acre in size. SWD fruit infestations rates were compared among treatments. For blueberries, SWD populations were quite low at the time of ripening, and no significant differences were observed. In raspberry plots, attracticidal spheres significantly reduced SWD in raspberry fruit compared with control plants (F = 6.8, P < 0.0001),though there was no difference if spheres deployed at the top or bottom of the plants. Attracticidal spheres did not reduce SWD infestation rates in blackberry and will investigate why this is the case in future studies in 2018.

Finally, the team investigated if non-target pollinators and beneficial insects visited attracticidal spheres. Spheres were observed during the morning and afternoon in flowering raspberry and blackberry plantings. A total of 18h of observation was conducted. During that time, over 1,500 beneficial insects visited plants with or without spheres, but only 2 syrphid flies and no bees landed on spheres indicated the risk to non-target organisms is low.

Milestone #6 (click to expand/collapse)
What beneficiaries do and learn:

One hundred growers will attend field days at research and commercial farms in both years to learn about attracticidal sphere system deployment, benefits, and considerations.

Proposed number of farmer beneficiaries who will participate:
100
Actual number of farmer beneficiaries who participated:
120
Actual number of agriculture service provider beneficiaries who participated:
5
Proposed Completion Date:
July 16, 2019
Status:
Completed
Date Completed:
July 16, 2019
Accomplishments:

A large field day was held at the Appalachian Fruit Research Station on July 16, 2019 that highlighted research conducted as part of this project.  Researchers from USDA-ARS and Rutgers  discussed the benefits and challenges of attracticidal spheres.  The benefits, based on data collected to date, indicate that at low to moderate populations, SWD populations and infestation can be reduced, but as populations increase, they cannot serve as a stand-alone tactic.  Additionally, we discussed the most up-to-date monitoring and management tactics available for SWD including using of so-called ‘dry traps’ (red sticky cards) as well as liquid-based traps in combination with kairomone lures.  Approximately, 125 people attended the event. 

Milestone #7 (click to expand/collapse)
What beneficiaries do and learn:

First year results will be shared with commercial companies to maintain engagement in potential production of attracticidal spheres.

Proposed number of farmer beneficiaries who will participate:
2
Proposed number of agriculture service provider beneficiaries who will participate:
2
Actual number of farmer beneficiaries who participated:
7
Proposed Completion Date:
December 31, 2017
Status:
Completed
Date Completed:
December 31, 2017
Accomplishments:

We provided summaries to commercial companies who have been interested in this project.  While both are still pursuing lure/trap development, both also continue to be concerned about use of conventional insecticides as toxicants in attracticidal spheres.  Toward that end, with recent work demonstrating that non-nutritive sugars such as Sweet-n-Low may be toxic to some insects including SWD, we began pursing identification of and rates necessary for non-nutritive sugars to be used as a killing agent/toxicant for SWD. 

Milestone #8 (click to expand/collapse)
What beneficiaries do and learn:

In Year 2, seven growers will again establish plots with attracticidal spheres for SWD
management and each grower will receive twice-weekly team support.

Proposed number of farmer beneficiaries who will participate:
7
Proposed Completion Date:
September 30, 2018
Status:
Completed
Date Completed:
September 30, 2018
Accomplishments:

 

Attracticidal spheres were deployed at the top or bottom of small fruit plants on 7 commercial farms in WV, MD, MA and NJ in blueberries, raspberries and blackberries. Spheres were deployed at a rate of 1 sphere every three meters in the upper third of the canopy, 1 sphere every three meters in the lower portion of the canopy, and no spheres as a control. Each plot was at least 1 acre in size. SWD fruit infestations rates were compared among treatments. Again, as in 2017, attracticidal spheres did not reduce infestations in blackberry plots.  In raspberry, there also was no significant difference among treatments in WV and NJ indicating that spheres were reducing populations as well as grower standard.  For blueberries, infestations were reduced significantly in plots in WV using attracticidal spheres (either deployed low or high) compared with the grower standard, but no difference was detected in NJ plots.

Because of the variation in results among crops and years, our team investigated at what density of SWD do we see an effect from attracticidal spheres in terms of protecting fruit, and when does the densities of flies overwhelm the system.  In tis case, raspberry or blueberry plants with known numbers of fruit were placed in field cages.  Flies were released at densities of 0, 4, 16 or 64 flies per cage.  Raspberry and blueberry plants were protected by a sphere either deployed high or low and compared with an unprotected control. Results revealed that 0, 4, and 16 flies per plant, we did not observe much injury to fruit, but at 64 flies per cage, injury increased by ~10- and 20- fold in raspberries and blueberries, respectively, for controls.  Interestingly, those plants protected by spheres at those densities had fruit injury that was ~50% less indicating that spheres were having an impact on fly densities and subsequent fruit infestation.

Finally, we looked at potential non-targets that may encounter attracticidal spheres by coating red spheres with Tangletrap deployed in raspberry and blackberry plantings. Fortunately, nontarget captures were low across farms, with Geocoris and parasitoids captured most commonly. 

 

 

Milestone #9 (click to expand/collapse)
What beneficiaries do and learn:

Results from the project will be shared with commercial companies to facilitate the commercialization process and ensure that growers can adopt this tactic.

Proposed number of agriculture service provider beneficiaries who will participate:
2
Actual number of agriculture service provider beneficiaries who participated:
2
Proposed Completion Date:
December 31, 2018
Status:
Completed
Date Completed:
December 31, 2018
Accomplishments:

While both companies continue to express interest in the project, they have found that the use of conventional insecticides is a stumbling block for manufacturing/labelling.  To try and mitigate this issue, we have evaluated non-nutritive sugars such as Sweet-n-Low as a toxicant for SWD in attracticidal spheres.  Unfortunately, this approach was not successful as the sugars, while reducing mortality slightly, were not lethal enough to serve as a replacement for toxicants.  However, we have received a grant to continue to work on this system with apple maggot fly as a target pest.  Our goal is to work with IR-4 to try and develop a minor use exemption for a conventional insecticide material.  With this in hand, commercialization will become more likely. 

Milestone #10 (click to expand/collapse)
What beneficiaries do and learn:

In Year 3, at least fifty growers will complete a project performance evaluation questionnaire and the project team will analyze and deliver project outcomes including benefits and challenges of attracticidal spheres via workshops, grower meetings, and online networks.

Proposed number of farmer beneficiaries who will participate:
50
Actual number of farmer beneficiaries who participated:
40
Proposed Completion Date:
August 31, 2019
Status:
Completed
Date Completed:
August 31, 2019
Accomplishments:

Berry growers in the mid-Atlantic (primarily NJ, MD and WV) were surveyed at winter fruit schools and other Extension meetings in the winter and spring of 2019; 40 surveys were returned.  Nearly two-thirds reported having SWD on their farms and 50% reported damage.  Most (76%) applied insecticides with 79% applying at least 3 applications and 52% at least applications against this pest. Pyrethroids and carbamates were used most frequently followed by spinosyns and neonicotinoids.  Fortunately, less than 10% reported secondary pest outbreaks with those who did reporting mites.

Growers did report practicing IPM tactics with over two-thirds monitoring with traps and/or looking directly for fruit damage. Of these growers, 87% were interested in using IPM against SWD and 21% indicated they already were.  Greatest level of interest were for trap-based thresholds followed by border sprays and attract and kill.  Degree-day models, sanitation and protective netting were seen as less attractive options.  

Overall, based on results from our survey taken at the start of this project, the percentage of growers reporting injury from this pest and the use of conventional insecticides hadn’t changed. However, the percentage of growers using a monitoring trap increased from 42% to 66%.  Moreover, those using fruit injury as a monitoring tool also increased from 48% to 60%.  And the interest in using IPM tactics increased from just over 50% to 87%. 

SWD&BMSB_IPMSchool2019

Milestone Activities and Participation Summary

56 Consultations
1 Journal articles
1 On-farm demonstrations
2 Published press articles, newsletters
12 Webinars / talks / presentations
1 Workshop field days

Participation Summary

520 Farmers
2 Number of agricultural educator or service providers reached through education and outreach activities

Learning Outcomes

40 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation
2 Service providers reported changes in knowledge, attitudes, skills and/or awareness as a result of project outreach
2 Agricultural service providers reported changes in knowledge, skills, and/or attitudes as a result of their participation
Key areas in which farmers reported changes in knowledge, attitude, skills and/or awareness:

Based on surveys taken at the start and conclusion of this project, we know that while growers continue to battle SWD with insecticide applications, there was an increase in those interested in IPM tactics from 50% to 87%.  The percentage of growers using a monitoring trap on their farm to indicate SWD presence increased from 42% to 66%.  This is remarkable considering that there is no trap-based threshold for this pest. However, presence or absence of SWD in a trap is a trigger for treatments to be used against this insect. Moreover, those using fruit injury as a monitoring tool also increased from 48% to 60%.  Thus, it appears that while IPM tactics for this pest are limited, there is a strong interest in using what is available. These results make sense considering most growers (52% surveyed here) are spraying 5+ times per season. For smaller growers (averaging 10.6 acres per farm) and larger growers (averaging 675 acres per farm), an average of 4.8 insecticide applications were made against this pest, likely reducing the number of sprays from 8+ recorded in earlier years.  Smaller growers averaged 23.6% injury, while larger growers averaged less than 4%. 

Among IPM tactics looked on favorably by small growers, trap-based treatment thresholds and attract and kill were considered most desirable, with high interest reported for degree day models and border spray practices. For larger growers, trap-based treatment threshold and border sprays generated the most interest, while degree day models, improved sanitation practices, and attract and kill were also ranked highly. Regardless of farm size, little interest for exclusion netting was reported.

Performance Target Outcomes

Target #1

Target: number of farmers:
50
Target: change/adoption:

Fifty small fruit farmers in the Northeast will integrate attracticidal spheres to aid in management of SWD on an average of 2 acres per farm

Target: amount of production affected:

100 acreas

Target: quantified benefit(s):

Reduction in insecticides by up to 4 applications per year.

Actual: number of farmers:
25
Actual: change/adoption:

25 growers indicated they were using vinegar based traps and/or fruit injury to monitor for SWD presence and damage.

Actual: amount of production affected:

For those with smaller farms, an average of 10.6 acres was monitored with vinegar-based traps and/or fruit damage assessments. These same tactics were used on large farms averaging 675 acres per farm. Total acreage verified was 2756 acres.

Actual: quantified benefit(s):

While these tools did provide growers with information on presence of SWD, the average number of sprays applied on smaller and larger farms was ~4.8 applications per season against this insect in blueberries and brambles which is down from 8+ applications per season.

Performance Target Outcome Narrative:

Our performance target indicated that “Fifty farmers in the Northeast will adopt IPM-based strategies, such as attracticidal spheres, to aid SWD management on an average of 1 acre per farm. Adoption will result in up to 4 fewer insecticide applications per season for a savings of $91/acre in small fruit plantings”. 

We have been able to verify that 25 growers have adopted IPM tactics, namely vinegar-based monitoring traps and fruit damage assessments, for monitoring SWD presence on 2756 acres of blueberries and brambles.  Unfortunately, these tactics serves as a presence/absence indicator.  Growers use these tools to determine if they need to start spraying insecticides against SWD (if fruit are ripening and flies are present, growers will begin spraying).  On average, growers made ~4.8 applications against this pest regardless of farm size or crops. Considering application frequency was documented at 8+ sprays by the eFLy project, particularly, for later ripening cultivars, growers are reducing the number of applications against this pest and waiting until flies are detected (presence/absence).  However, until a threshold is developed for traps, it is unlikely that conventional sprays will be reduced further.

Growers are very interested using IPM tactics (an increase from 50% to 87% during the course of this project) with strong interest in trap-based treatment thresholds, border sprays, attract and kill and degree day models in particular.  In all likelihood, if these tactics are developed and/or commercially available in the case of attracticidal spheres, growers would likely use them. In the case of attracticidal spheres, the key stumbling block has been dealing with regulatory labeling issues. 

 

25 Farmers changed or adopted a practice

Additional Project Outcomes

1 Grant applied for that built upon this project
1 Grant received that built upon this project
$324,854.00 Dollar amount of grant received that built upon this project
2 New working collaborations
Additional Outcomes:

Based on the advances made, we applied for a received a USDA-NIFA-CPPM award to continue refine the attracticidal sphere system, but for apple maggot fly.  The project is entitled, “Developing a multi lifestage management strategy for apple maggot, a persistent tree fruit pest in the northeast, through integration of attract-and-kill and biological control” and is being led by Dr. Jaime Pinero at the University of Massachusetts. Our hope was to identify a lethal non-nutritive sugar as a toxicant for apple maggot as well as SWD based on reports in the literature.  Through our work, we have found these materials do not provide the toxicity needed for an attract and kill system. Therefore, we are going to work with IR-4 to use a conventional insecticide such as Delegate and try to obtain a minor use permit.  This regulatory challenge is one the key reasons we haven’t been able to find a commercial partner to manufacture spheres despite high grower interest.

Success stories:

In 2017, our attracticidal sphere system for SWD was highlighted by Entomology Today, the Entomological Society of America Blog, and by Fruit Grower News, extending the outreach of this project in the digital realm. 

Et Tu, Fruite_ Attracticidal Sphere Lures Fruit Flies to Their Demise
https://entomologytoday.org/2017/03/07/et-tu-fruite-attracticidal-sphere-lures-fruit-flies-to-their-demise/

Attracticidal sphere lures spotted wing drosophila to their demise – Fruit Growers News
https://fruitgrowersnews.com/news/attracticidal-sphere-lures-spotted-wing-drosophila-demise/

Annually, we have been contacted by individual growers (3-5/year) on where they could purchase attracticidal spheres, again demonstrating the interest growers have in this IPM technique.  Unfortunately, we still do not have a company manufacturing them.  But our hope is to surmount the regulatory challenges to increase the likelihood of commercialization

Assessment of Project Approach and Areas of Further Study:

Growers are extremely concerned about SWD and the potential for infestation in harvested fruit.  For larger growers, this issue becomes even more profound as larger-scale crops like blueberry can be rejected for processing due to larval presence.  Thus, it becomes critical to: 1) develop tactics that can be adoptable for growers of various scales of acreage; and 2) have experimental acreage of different scales to evaluate new IPM tactics to determine if they will work under various scenarios.

Second, some IPM tactic may require further regulatory approvals, and developing a strategy on how to gain these approvals could ultimately be critical for the project’s long-term success.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.