Building attract-and-kill systems for management of the brown marmorated stink bug in apple orchards

Building attract-and-kill systems for management of the brown marmorated stink bug in apple orchards

Summary

The project aims to develop an attract-and-kill program against brown marmorated stink bug (BMSB) for adoption by commercial apple growers in the mid-Atlantic region.

Before the field season, we administered a mid-project survey to tree fruit growers in the mid-Atlantic, and received updated data on adoption of pheromone-based tools from almost 140 respondents located in West Virginia, Virginia, Maryland, and Pennsylvania. We collaborated with 10 growers from five mid-Atlantic states to compare management of BMSB using attract-and-kill technology and standard management practices in commercial orchards and to utilize pheromone-baited traps to guide specific management decisions.

We maintained a project blog (http://williammorrison.wix.com/sare-blog) (20+ total posts), created a video about attract-and-kill principles on YouTube (526 views), and the research group has had 3 teleconferences, and two in-person meetings to discuss coordination of outreach and research efforts for the project. We held a very successful field day in July 2016 with over 150 stakeholders in attendance. Finally, the results generated by this project have been presented at 10+ international, national, and regional academic conferences and seminar series, as well as 5 Extension conferences and meetings.

Objectives/Performance Targets

Performance target: Fifty apple growers in the mid-Atlantic will adopt pheromone-based tools for managing BMSB on 650 acres. Their adoption will reduce total full-block insecticide applications by 40%, decreasing costs from $154 to $92 per acre for season-long BMSB management, with additional savings in fuel and labor.

Accomplishments/Milestones

1. Ten growers will complete customized recording templates and evaluate the benefits and constraints of these practices with the project team in-person, by phone, or email. Milestone partially met/in progress. The team has developed a customized reporting template containing 10 in-depth questions about pheromone-based monitoring tools and attract-and-kill strategies for distribution to each of our collaborating growers. These will be delivered in-person, and team personnel will discuss with growers about their experiences and take notes in January 2017. Informal discussions have already occurred, with our collaborating growers enthusiastic about the use of pheromone-based monitoring as a decision-making tool for BMSB, but concerned about the time required for frequent (weekly) sprays at attract-and-kill sites. However, we will capture more specific and quantifiable feedback when we distribute our template in early 2017.

2. After Year 1 results are disseminated, 100 growers will complete a mid-term questionnaire administered through grower meetings and the project team will evaluate progress, develop necessary modifications for Year 2, and implement them. Milestone met March 2016. We had ~140 apple growers in Virginia, Maryland, Pennsylvania, and West Virginia respond to the survey at Winter Fruit School Meetings.

3. In Year 2, ten growers will re-establish plots with attract-and-kill systems in combination with traps in apple, and each grower will receive support from project team members during the growing season for management issues. Milestone fully met and completed in September 2016. We had 10 collaborating growers work with us for a second year on evaluating attract-and-kill for control of BMSB in apple orchards. We regularly updated growers on pest management issues, including problems with secondary pests and moth pests in orchards. The team advised growers on the need for subsequent intervention when they hit a prescribed threshold for pheromone-based monitoring traps, which happened more frequently in 2016 than 2015, as 2016 had much higher populations (2.5x more adults detected). Across all orchards, lower fruit injury was present in attract-and-kill blocks compared with grower standard blocks, though not statistically significant.

4. At the end of the project, 100 growers will complete an overall project performance evaluation questionnaire, and the project team will analyze and deliver project outcomes including benefits and challenges of attract-and-kill systems via workshops, grower meetings, and online networks. Milestone partially met/in progress. An end-of-project questionnaire has been developed and will be distributed at winter grower meetings and fruit schools during Jan-April 2017.

Impacts and Contributions/Outcomes

In the winter and early spring of 2016, we were able to gather mid-project survey data about the efficacy that our efforts are having from almost 140 growers in the mid-Atlantic. This survey was distributed to growers at 10+ regional and state Extension meetings, and reached an estimated audience of 400+ growers.Using this survey, we were able to assess the nature of the problem with BMSB and adoption of tools to mitigate its effects during the middle of the project.

The number of growers reporting experiencing BMSB damage on their farms was slightly down to 71% (decrease of 15% from the previous year), which conforms with other data indicating that 2015 was a very low population year. Importantly, in 2016 there was a 10% increase in interest for adoption of pheromone-based monitoring tools for BMSB, with planned adoption in the following year or current use on 2,250 additional acres of apple over 2015, a number well above our performance target. In total, 56% of growers reported being interested in attract-and-kill, and 67% of growers reported being convinced that attract-and-kill could adequately manage BMSB.

In the spring of 2016, the research team continued collaboration with 10 growers to implement side-by-side comparisons of attract-and-kill technology with standard management practices for BMSB in apple orchards. Pheromone-baited traps were again deployed in both types of blocks to guide BMSB management decisions if BMSB populations began to overwhelm the system. These trials ran concurrently in five states from approximately June to October.

Generally, we sampled fruit at three points in the season: early, mid, and at harvest. However, early flowering of apple followed by heavy frost damage limited the number of harvests we could make in a subset of the blocks. Nonetheless, most of the blocks in the study were spared the worst damage. For those blocks that were affected, only a harvest sample of fruit was collected.

In 2016, we had 2.5 times greater populations of adults, and >27 times greater nymphal BMSB populations, providing a good comparison to the very low population prior year. At harvest, there was statistically equivalent frequency of damage on perimeter trees between the attract-and-kill block (32%) and the grower standard (38%). In the interior trees, there was about half the amount of damage in the attract-and-block (15%) compared with the grower standard (27%). There was about half the severity of damage in perimeter and interior attract-and-kill trees compared with fruit in the grower standard block.

The use of attract-and-kill appears highly efficacious in managing the threat posed by BMSB. At the same time, use of attract-and-kill reduced the number of trees treated in the orchard by 97% and the amount of insecticide active ingredient used by 80% compared to typical full block or alternate row middle treatments for BMSB. This reduces the cost of insecticides from ~$30-100 per acre in the grower standard to ~$6-20 per acre in the attract-and-kill treatment.

While pheromone-based tools for monitoring BMSB appear ready for widespread adoption, one significant hurdle remains for the adoption of attract-and-kill, and that is the price of pheromone. The cost of pheromone per acre for attract-and-kill at the rate used in our study has been estimated at between $900-1500 per acre for a season. However, the amount of pheromone being deployed, the way in which it is deployed, and the number of attract-and-kill sites needed in a block, and the frequency of sprays for attract-and-kill sites still need to be optimized to improve the cost-benefit ratio. In choosing each of these factors in the current study, we remained conservative in order to protect the grower. However, we have now demonstrated that this technique is effective at controlling BMSB, and so now it is a matter of altering other considerations to make it also economical for widespread adoption. Moreover, as commercial companies improve their pheromone production procedures, we anticipate costs will go down.

In July 2016, the research team organized a field day in Maryland specifically to highlight the work being performed with pheromone-based tools for the monitoring and management of BMSB on collaborating grower orchards. We had attendance of over 150 growers from around the region participate, and we showcased attract-and-kill technology, demonstrated the use of threshold-based monitoring, and discussed the behavioral basis for why pheromone-based technology works so well. We also highlighted some of the challenges of the project, and future directions. In addition, another field day on the West Virginia University Organic Farm was organized by WVU, with attendance of 40 growers and members of the public. Pheromone-based monitoring and management tools were also discussed there. We have been able to demonstrate the utility of pheromone-based monitoring and management tools to apple growers in the mid-Atlantic who are poised to adopt pheromone-based decision support tools for BMSB management.

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