2018
Control of Slugs in a Multi-Trophic Context: Using Friends to Manage Foes
Contributor/Checkoff:
Category:
Sustainable Production
Keywords:
Biotic stressCrop protectionField management Pest
Parent Project:
This is the first year of this project.
Lead Principal Investigator:
Ivan Hiltpold, University of Delaware
Co-Principal Investigators:
Project Code:
Contributing Organization (Checkoff):
Institution Funded:
Brief Project Summary:

Slugs feed on soybeans as they emerge. However, natural predators of slugs could play a critical role in managing this pest. Despite their great potential in complementing slug control, very little is known about the preying behavior of ground beetles on slugs in soybeans. This research assessed the response of these beneficial insects to various environmental cues. To do this, trials assessed the response of ground beetles to different soybean cultivars suffering or not from slug damage, characterize the volatile blends ground beetles are responding to and assessed ground beetle preferences for slugs with different vigor status.

Key Benefactors:
farmers, agronomists, Extension agents

Information And Results
Project Deliverables

1) One YouTube Video at https://www.youtube.com/watch?v=fSMX74XhSbI
2) Two poster presentations: Ecological Society of America, Eastern Branch annual meeting and Univ. of Delaware Graduate Research Meeting
3) Five oral presentations: Entomological Society of America, Eastern Branch annual meeting; keynote address at COST FA 1405 meeting, Thessaloniki, Greece; Departmental seminars, The Ohio State University and University of Maryland; Delaware AgWeek 2019

Final Project Results

Updated November 5, 2019:
In a series of olfactometer experiments, we have demonstrated that ground beetles are indeed responding to plant volatiles emitted by soybean fed on by slugs. We have tested three cultivars together in on olfactometer setting, and the beetles appeared to preferentially choose Cultivar 1 over Cultivar 2 and 3. These two last cultivars didn’t attract the ground beetle significantly more than the empty control arms.

In a second set of experiments, we have tested the beetle response to either a soybean plant damaged by a slug, a healthy soybean plant, a slug only, and soil only. Again, differences were observed between cultivars. The beetles were spending significantly more time in the arm with the damaged Cultivar 1 than in any other arm. Slugs only were more appealing to the predatory insects than the plant alone or bare soil, and no distinction could be made between healthy plants and bare soil. Similar behavior was recorded with Cultivar 2, however, when exposed to Cultivar 3, the predatory beetles didn’t express any preference of the proposed treatments, even for the slugs alone. The volatiles emitted from the damaged plants, the healthy plants and the slugs only are currently collected and analyzed. We are currently designing experiments to better understand the mechanistic of the defense induction by slugs in soybean (along with the volatile collection and analyzes).

Based on the data collected, it seems very clear that predatory ground beetles do respond to soybean cues emitted after slug damage. However not all cultivars are equally defended against slug herbivory as some were not recruiting the natural enemies of the mollusk herbivores. This has never been demonstrated with slugs before and will therefore be a
nice addition to the current body of literature. In addition, this information can be useful to breeders and growers willing to use ecosystem services to manage slugs in soybean. More has to be done to really understand these interactions but this first step is very promising and opens a lot of new avenues both in research and applications. One avenue could be to
use cover crops to conserve ground beetle populations over winter.

View uploaded report PDF file

The project "Control of Slugs in a Multi-Trophic Context: Using Friends to Manage Foes" found that ground beetles are respond to plant chemcials emitted by soybeans fed on by slugs. Based on the data collected, it seems very clear that predatory ground beetles do respond to soybean cues emitted after slug damage. However not all cultivars are equally defended against slug herbivory as some were not recruiting the natural enemies of the mollusk herbivores. This has never been demonstrated with slugs before and will therefore be a nice addition to the current body of literature. In addition, this information can be useful to breeders and growers willing to use ecosystem services to manage slugs in soybean. More has to be done to really understand these interactions but this first step is very promising and opens a lot of new avenues both in research and applications. One avenue could be to use cover crops to conserve ground beetle populations over winter.

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.