Evaluation of Slug Refuge Traps in a Soybean Reduced-Tillage Cover Crop System.

Amy L Raudenbush,Van R Haden,Adrian J Pekarcik,Kelley J Tilmon

doi:10.3390/insects12010062

Abstract

Simple SummarySlugs have become more frequent pests of field crops, including soybean. Monitoring slugs during the day is difficult because slugs are nocturnal, so trapping is often used to monitor populations. A variety of traps have been developed, though there are few direct comparisons of the different trap types. The objective of this study was to compare trapping efficiency of two types of slug refuge traps in soybeans. We tested a traditional shingle trap and a modified shingle trap with a water-filled pitfall trap beneath it. The modified shingle traps captured significantly more slugs than the traditional shingle trap, mainly due to the pitfall component (which was significantly cooler than the shingle component). As slug density decreased, this trend was most pronounced, suggesting that the modified shingle trap is a more sensitive sampling tool which may be useful in agronomic slug research.As more farmers adopt no- or reduced-tillage and/or cover crop land management practices, slugs have become more frequent pests of field crops, including soybean. Monitoring slugs visually is difficult because they are nocturnal, so several trapping methods have been developed, though comparisons of trap types are rare. The objective of this study was to compare trapping efficiency of two types of slug refuge traps in reduced-tillage soybeans following cover crop termination. We tested a traditional shingle trap and a modified shingle trap with a water-filled pitfall trap beneath it. Traps were deployed in 24 pairs in 2018 and 2019 in experimental soybean plots. We counted slug captures weekly over a 5-week time period each year. In 2018, we counted the total number of slugs under each trap type. In 2019, counts were categorized into specific trap components (shingle vs. in/on/under the pitfall). Temperature was also recorded in 2019. The modified shingle traps captured significantly more slugs than the traditional shingle traps, mainly due to the pitfall component. This trend was most pronounced as slug density decreased, suggesting that the modified shingle trap is a more sensitive sampling tool which may be particularly valuable when used for research purposes.

Highlights

The importance of terrestrial mollusks, primarily slugs, as non-insect pests of agronomic crops, including corn (Zea mays L.) and soybean (Glycine max L.), has been well documented [1,2,3,4,5,6,7,8]
There are four main slug species that have been reported in field crops in the northeastern U.S, including the gray field slug, Deroceras reticulatum (Müller), marsh slug, D. laeve (Müller), dusky slug, Arion subfuscus (Draparnaud), and banded slug, Arion fasciatus (Nilsson) [6,7]
This study compares a traditional shingle trap with a modified trap featuring a shingle placed over a water-filled pitfall trap

Summary

Introduction

The importance of terrestrial mollusks, primarily slugs, as non-insect pests of agronomic crops, including corn (Zea mays L.) and soybean (Glycine max L.), has been well documented [1,2,3,4,5,6,7,8]. Spring planting coincides with the cooler temperature and higher humidity favored by slugs, putting seeds, cotyledons, and new foliage at risk. This can cause decreased emergence, plant stand losses, and/or reduced yields [7,9,11]. Slug damage is a particular problem in systems with reduced tillage intensity (e.g., no-till or conservation tillage) or following cover crops where crop residues and microenvironmental conditions are favorable for slugs [1,2,3,4,5,7,12,13,14]. Musick found that slugs cause up to 60% plant stand loss in no-till field corn, but only 5% loss in conventional tillage systems [1]

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