Project Details:

Title:
Evaluating soybean aphid management with an expanded toolbox

Parent Project: This is the first year of this project.
Checkoff Organization:Iowa Soybean Association
Categories:Insects and pests, Education, Sustainability
Organization Project Code:450-30-49
Project Year:2016
Lead Principal Investigator:Erin Hodgson (Iowa State University)
Co-Principal Investigators:
Keywords:

Contributing Organizations

Funding Institutions

Information and Results

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Project Summary

Brief review: Soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is an introduced insect from Asia first confirmed on soybean, Glycine max L., in the United States in 2000 (Ragsdale et al. 2011). Widespread soybean aphid outbreaks with populations exceeding 1,000 per plant were observed in the north central region during 2001-2003. At this level, 40% yield loss was documented and soybean aphid significantly reduced seed size, seed coat quality, pod number, and plant height (Ragsdale et al. 2007). Foliar insecticides have been the primary soybean aphid management tool to protect yield since 2000, and now many products are commercially available in Iowa.

Sole reliance on chemical control will not be cost effective or biologically sustainable for soybean aphid. Therefore, soybean breeders screened germplasm for soybean aphid host plant resistance shortly after 2001. Aphid-resistant varieties with a single gene (Rag1) became commercially available in 2010, and offered moderate yield protection. Since then, additional genes and two-gene pyramids (Rag1+2) have been developed and dramatically suppress soybean aphid populations. The pyramided varieties have the same yield as an aphid-free susceptible variety and eliminate the need for foliar insecticides.

Results of ISA-funded research revealed that soybean cyst nematode reproduction increased by 500% when soybeans were infected with aphids (McCarville et al. 2012). This positive interaction was observed on nematode-resistant varieties (PI 88788 source), suggesting that farmers may lose the yield protection conferred by nematode resistance when aphids are present. Managing aphids, even below the economic injury level, may contribute to suppressing soybean cyst nematode and synergistic yield loss. It is unclear the roles aphid resistant-varieties and insecticides play for optimizing soybean yield.

Rationale: In 2014, I organized a farmer focus group in the north central region to better understand soybean pest management issues. Soybean aphid was overwhelmingly perceived as the most important insect pest within the group (Eells 2014); however, emerging pests, like Japanese beetle and stink bugs, were also discussed. Soybean pest management, specifically for soybean aphid, falls in the Iowa Soybean Association’s key categories for research. This proposal will contribute to a better understanding of pest biology, management and yield protection, and will directly apply to farmers.

Project Objectives

Objective 1. During 2016-2018, experimental plots will be used to evaluate insect management tactics, like seed treatments, foliar insecticides, and host plant resistance. These tactics will be evaluated alone and in combination to determine optimum yield protection.

Objective 2. Throughout the project, I will actively participate in extension programs that summarize efficacy data and promote sustainable soybean pest management.

Project Deliverables

Timeline: Each year, the cycle of research and extension activities will be the same:
• Winter: plan list of treatments and protocols; request seed, land, equipment, and vehicles; and present lectures at winter meetings.
• Spring: hire undergraduate student; treat seeds; purchase field and spray equipment; establish plots; plant seed; and present at summer meetings.
• Summer: collect agronomic and pest-related data; and apply foliar treatments.
• Fall: harvest plots; and write summary reports (e.g., Yellow Book, AMT).

Expected Outputs: Data collected every summer will become publically available each year with the following publications:
• Yellow Book for Soybean Insects is free and available electronically at my lab website
(www.ent.iastate.edu/soybeanresearch/content/extension) and at the ISA Publications website (www.iasoybeans.com/programs/production-research/publications).
• Arthropod Management Tests publication will be generated each winter. These publications are nationally recognized for insecticide efficacy evaluations and available to Entomological Society of America members (www.entsoc.org/Pubs/Periodicals/AMT).
• Regular updates during the growing season for soybean aphid and other pests through ICM News, podcasts (www.ent.iastate.edu/soybeanaphid/resources) and ISU Crops blog (http://crops.extension.iastate.edu/cropnews).

As an example of my extension activity related to soybean pest management from 2013-2014, I created the following products and activities:
• 2 refereed journal articles in Arthropod Management Tests [ESA publication] (Hodgson and VanNostrand 2014, 2015)
• 1 CABI article for soybean aphid
• 5 oral presentations and 5 posters at ESA [professional scientific meeting]
• 3 proceeding articles for non-scientific audience
• 25 presentations [2,024 people] and 14 field days [655 people]
• 2 Yellow Books for soybean aphid efficacy evaluations (Hodgson and VanNostrand 2013, 2014)
• 16 articles in ICM News [5,500 subscribers]
• 1 CCA Module, 2 videos for Private Applicator Training, 1 webcast for Plant Management Network, and 3 short YouTube videos

Expected Stakeholder Outcomes:
• recognize soybean aphid and other soybean pests [short term skill];
• improve general pest management approaches, including the effect of multiple pests and the potential for cumulative injury [short term skill];
• implement scouting and adopt economic thresholds for soybean pests [short term knowledge];
• become aware and understand the benefits of host plant resistance for soybean aphid [short term knowledge];
• reduce insecticide use, including seed and foliar treatments [long term skill];
• increase adoption of host plant resistance on commercial farms [long term skill];
• understand the implications for soybean aphid genetic resistance to insecticides [long term knowledge]; and
• improve profit margins by reducing input costs [long term knowledge].

Progress of Work

Update:
Objective 1. Land for small plot evaluation is confirmed at the Northwest Research Farm with the help of Joshua Sievers (Farm Superintendent) and at the Northeast Research Farm with the help of Ken Pecinovsky (Farm Superintendent). Treatment lists have been generated (25 at NW Farm and 30 at NE Farm), including seed- and foliar-applied insecticides, host plant resistance to soybean aphid, and fungicides. We are collaborating with five industry companies in 2015. Seed and seed treatments have been ordered and delivered. Planting will start late April, based on appropriate planting conditions. Five undergraduate students haven been hired and will have staggered start times in May and June.

Objective 2. 2015 Yellow Book for Soybean Aphid was published in December 2015 (http://store.extension.iastate.edu/Product/Yellow-book-for-soybean-aphid). A second publication is in press for Arthropod Management Tests (ESA) in April 2016. A multi-state publication on neonicotinoid seed treatments in soybean was published in January 2016 (https://www.ent.iastate.edu/soybeanresearch/files/page/files/E-268%20The%20Effectiveness%20of%20Neonicotinoid%20Seed%20Treatments%20in%20Soybean%20PRINT%2015.pdf). I co-authored the most popular ICM News article in February summarizing my previous ISA project using seed treatments in soybean (http://crops.extension.iastate.edu/cropnews/2016/02/managing-two-soybean-pests-optimize-yield).

Update:
Objective 1. Efficacy evaluations for soybean aphid were completed at two locations in 2016 (ISU Northwest Research Farm and ISUNortheast Research Farm). We partnered with five industry companies to evaluate foliar and seed-applied insecticides. To help us establish plots and collect pest data, we hired four undergraduate students. Soybean aphid populations were higher than normal this year and exceeded the economic threshold in August at the Northwest Research Farm. Harvest has not been completed for either location yet but is expected within 14 days.

Objective 2. During the summer, I had many extension events and demonstrations on soybean pest management. I also completed several ICM News and ICM Blog articles to promote scouting and treatment thresholds to protect yield. My annual Yellow Book publication that summarizes efficacy evaluation data will be published by the end of the year.

Final Project Results

Updated February 23, 2017:
See report above under October 3, 2016

Benefit to Soybean Farmers

Performance Metrics

Project Years