2019
Causes and developing solutions on outbreaks of slugs in Soybeans Year 1
Contributor/Checkoff:
Category:
Sustainable Production
Keywords:
Biotic stressCrop protectionField management Pest
Parent Project:
This is the first year of this project.
Lead Principal Investigator:
Raul Villanueva, University of Kentucky
Co-Principal Investigators:
Project Code:
Contributing Organization (Checkoff):
Institution Funded:
Brief Project Summary:

The presence of slug damages in soybean fields has been more noticeable during the past 20 years. Slug outbreaks were observed in Henderson Co., Kentucky in corn in 2016, and in 2017 approximately 150,000 acres of soybeans were replanted due to slug damage; this represent approximately 10% of the total acreage in KY and between 4.2 to 4.6 million dollars on seed expenditures for replanting. In this project we included a double crop system (wheat and soybeans) as we hypothesize that insecticide treatments of wheat seeds can have an impact on the abundance of slugs and reduction of ground beetles (natural enemies of slugs).

Unique Keywords:
#insects and pests
Information And Results
Project Deliverables

Final Project Results

Updated November 8, 2022:
I. State of the Project Objective(s):
1. Evaluate abundance of mollusks and ground beetles in fields using neonicotinoid treated and untreated wheat seeds
This objective was completed in wheat with funds from this project (1 year grant). There were not major differences on the populations of slugs, carabids or spiders in fields using neonicotinoid treated or untreated wheat seeds.

2. Quantify abundance of mollusks and ground beetles in fields where neonicotinoid treated and untreated soybeans seeds were planted as a double crop following Objective 1, as well as to compare with long season soybean fields in commercial and experimental fields.
This objective was completed in soybeans with funds from this project (1 year grant).
There were not major differences on the populations of slugs, carabids or spiders in fields using neonicotinoid treated or untreated soybean seeds.
3. Conduct neonicotinoid residue analysis on slugs and ground beetles, from the different treatments utilized on Objectives 1 and 2.
Both slugs were captured in low numbers, neoticoid analysis were not completed

4. Validate field study results with laboratory bioassays for wheat and soybeans.
Laboratory studies with adult and immature slugs were conducted in wheat and soybeans however, results were not adequate.

5. Transfer all information generated in this study to end users through the use of digital, printed and extension conferences.
Partially completed

II. Statement of quantifiable progress toward project objective(s) achieved during this reporting period.
1. Evaluate abundance of mollusks and ground beetles in fields using neonicotinoid treated and untreated wheat seeds (Note: these plots were planted on October 31, 2017, as this is a project in a double crop system, see layout on Procedures section),
2. Quantify abundance of mollusks and ground beetles in fields where neonicotinoid treated and untreated soybeans seeds were planted as a double crop following Objective 1, as well as to compare with long season soybean fields in commercial and experimental fields
Objectives 1 and 2 are presented together as they were completed in a double crop system where wheat was planted in November 2017 and soybeans on June 2018.
Population densities of slugs, carabids and spider in wheat and soybeans in a double crop system field
Wheat with and without Cruiser® seed treatment were planted on Nov-2017. Soybean with and without Poncho® seed treatment were planted on July 2018. Slug, carabid, and spider data (Fig. 1) were collected using pit fall traps.
Significance differences (p>0.05) were not found on the numbers of slugs, carabids, or spiders found in plants grown from untreated (Fig. 1a) vs. insecticide treated seeds (Fig. 1b) collected in pit fall traps. By mid-May carabids reached the highest numbers in wheat while slugs decreased, and did not increase populations in soybeans in 2018 (Fig. 1c).
Composition of carabid tribes in wheat and soybeans in a double crop system field
Carabids and spiders collected from pitfall traps were sorted, and identifications are being conducted. In this report only carabid findings are presented.
WHEAT: Four carabid tribes were found in wheat from April to June (see Fig. 2 and 3a). Chlaenini was the most abundant with 51% of all carabid specimens found.
SOYBEANS: in addition to the four carabid tribes found in wheat, two additional tribes were found in soybeans, Megacephalini, and Scaritini (Fig. 2 and 3b). Harpalini was the most abundant, 72% of specimens from all tribes.
3. Conduct neonicotinoid residue analysis on wheat, soybeans, slugs and ground beetles, from the different treatments utilized on Objectives 1 and 2,
These objective was not conducted as slugs and ground beetles were not present in great numbers. We tested molluscicides but the slugs were absent after the first application of the products Deadline™ (metaldehyde) and Sluggo™ (ironphosphate)

4. Validate field study results with laboratory bioassays for wheat and soybeans, and
Slugs were captured in wheat and soybean fields. They were reared in plastic boxes with air flow that contained a 5-cm layer of moist potting soil mix. Parafilm M® was used to keep the lid in place and constant relative humidity. Slugs were fed with fresh lettuce and soybean seedlings twice a week (Fig. 4a). Egg hatching (Fig. 4b), feeding behavior and immature development were recorded (Fig. 4c).
5. Transfer all information generated in this study to end users through the use of digital, printed and extension conferences.
Several presentations were conducted in Kentucky, Illinois, to different growers and commodity meetings, and in the Annual Meeting of the Entomological society of America (see poster attached), where information was delivered to growers, consultants, researchers and students. In addition, articles were written in the Kentucky pest news blog and the Ag Families magazine (see attachment at end of report)

III. Activities planned between now and the next reporting period.
This was the final report. However, a fact sheet will come from this publication as well as an peer reviewed article.

IV. iProblems and/or obstacles that may impact the completion date, cost or scope of the project.
Funds of the project were used to pay for a well-qualified personnel that had experience working with insects in agriculture at North Carolina State University. This person left the position in the REC-UK and was recruited for NCSU. The identification of the insects will be completed during 2019 by a Carabid specialist that works in Pennsylvania.

List any obstacles, new developments or market/industry/research changes that impacted or may impact the completion date, cost or scope of the project.
Environmental conditions in 2018, might have reduced the populations of slugs that impacted the results of this study.

The United Soybean Research Retention policy will display final reports with the project once completed but working files will be purged after three years. And financial information after seven years. All pertinent information is in the final report or if you want more information, please contact the project lead at your state soybean organization or principal investigator listed on the project.