Project Details:

Title:
Evaluating control methods for a new leaf-mining pest of soybean in Minnesota

Parent Project: This is the first year of this project.
Checkoff Organization:Minnesota Soybean Research and Promotion Council
Categories:Insects and pests
Organization Project Code:10-15-44-23163
Project Year:2024
Lead Principal Investigator:Robert Koch (University of Minnesota)
Co-Principal Investigators:
Keywords:

Contributing Organizations

Funding Institutions

Information and Results

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Project Summary

This project addresses a priority item listed under the category of Soybean Pest Management in the FY2023 request for proposals: ”Soybean farmers need continued research into cultural, chemical and biological control mechanisms for management of soybean insects including, but not limited to, soybean aphid, Japanese beetle and soybean gall midge.”

Macrosaccus morrisella (sometimes called the soybean tentiform leafminer) is a tiny moth native to North America. It was found attacking soybean in the United States for the first time in 2021 (Koch et al. 2021). The immature stage (larva) of this moth lives and feeds inside leaves (Davis and De Prins 2011), leading to loss of functional leaf area (i.e., defoliation). In 2022, M. morrisella was found infesting soybean across a broad area of southern Minnesota and eastern South Dakota, with some infestations causing up to 40% defoliation in parts of fields (Koch, unpublished data). Such levels of defoliation by insect pests can significantly decrease soybean yield (Owen et al. 2013).

The appearance of a leaf-mining insect like M. morrisella in Midwest soybean is a significant concern, especially because other leaf-mining moths are significant pests of soybean in other places, like the leaf-mining moth Aproaerema modicella in Africa, Asia, and Australia (Gaur and Mogalapu 2018, Buthelezi et al. 2021). Furthermore, the leaf-mining moth M. robiniella, a related species of M. morrisella, is a significant pest of ornamental plants in Europe (Davis and De Prins 2011). Thus, research is urgently needed to assess the potential impacts of M. morrisella and how to manage its infestations. Unfortunately, there is only limited knowledge on M. morrisella in the forest systems where it historically occurred in Eastern North America (Davis and De Prins 2011) and even less knowledge about it in soybean (Koch et al. 2021).

Project Objectives

To build the foundation for the development of management programs for M. morrisella, we propose the following goals and objectives:

Goal 1: Assess the effectiveness of insecticides for management of M. morrisella

• Objective 1: Evaluate the toxicity of insecticides against adults of M. morrisella in the laboratory
• Objective 2: Evaluate the efficacy of insecticides against M. morrisella in soybean fields

Goal 2: Assess host preference and varietal resistance of soybean to M. morrisella

• Objective 1: Determine host preference and varietal resistance of two native plants and several soybean varieties for M. morrisella
• Objective 2: Characterize relationship between abundance of M. morrisella in soybean fields and in native plants in wooded areas in close proximity

Project Deliverables

This project will provide several important deliverables that will advance M. morrisella management in Minnesota. This project will produce foundational knowledge on the chemical control, host preference and varietal resistance of soybean against M. morrisella. This knowledge will improve the general understanding of the biology of this pest and establish the foundation for the development of management. This knowledge will be housed on the UMN Extension website and made widely available to farmers and the agricultural community through our extension programming and through the communication channels of Minnesota Soybean. Finally, this project will facilitate the training of an undergraduate student in Entomology, who will gain expertise in pest ecology and integrated pest management.

Progress of Work

Updated September 5, 2023:
Goal 1: Assess the effectiveness of insecticides for management of M. morrisella
• Objective 1: Evaluate the toxicity of insecticides against adults of M. morrisella in the laboratory
Bioassays were completed to evaluate the toxicity of Agri-Mek and Endigo against adults through oral, contact and oral+contact exposure routes. Data from this experiment are currently be summarized and analyzed.
• Objective 2: Evaluate the efficacy of insecticides against M. morrisella in soybean fields
A site to perform this experiment was identified near Henderson, MN. The insecticide application will occur in early to mid August.

Goal 2: Assess host preference and varietal resistance of soybean to M. morrisella
• Objective 1: Determine host preference and varietal resistance of two native plants and several soybean varieties for M. morrisella
Methodology was developed to evaluate the host range of this insect and seed were obtained for the experiment. Initial replications of the laboratory experiment comparing soybean, edamame and several other legumes were initiated in July and further replications will be conducted in August. Similar methods will be used for a comparison among soybean varieties and will be conducted in September and October.
• Objective 2: Characterize relationship between abundance of M. morrisella in soybean fields and in native plants in wooded areas in close proximity
Multiple locations around the state were identified for this sampling. Sampling was initiated during this reporting period and will likely continue into September.

Updated November 8, 2023:

View uploaded report Word file

Final Project Results

Benefit to Soybean Farmers

Macrosaccus morrisella is a new pest that might pose a significant threat to soybean production. Currently, knowledge about this pest in soybean is limited and the potential economic impacts to soybean production is unknown. This limits the ability of farmers to prepare for and respond to the pest. Investment in this project will enable us to provide recommendations to inform farmers about their risk for this pest. More specifically, recommendations for chemical and cultural control (i.e., varietal resistance) will be generated to help the farmers with actionable management tactics to protect their crops.

Indirectly, the proposed work rearing this insect in the laboratory should advance our abilities to maintain year-round colonies of this insect. Having the ability to produce M. morrisella in the laboratory year-round would advance all aspects of M. morrisella research and greatly increase the rate at which management recommendations are being developed to help farmers protect their crop from this pest.

Performance Metrics

This project has a high likelihood for success. The methods we proposed for collecting and rearing M. morrisella have been used successfully during the summer of 2022 during preliminary investigations. The proposed methods have a high likelihood of success because our laboratory has vast experience in establishing and keeping colonies of soybean pests, including tiny insects such as soybean aphid. Furthermore, the proposed methods have been previously used in our laboratory to evaluate the toxicity of insecticides to other small insects.

This project will have several key quantifiable performance metrics directly relevant to the proposed objectives. The first metric is the number of adults of M. morrisella used to establish the toxicity of multiple insecticides against this pest. The second metric is the number of field areas sprayed with insecticides for the assessment of potential control of M. morrisella infestations. The fourth metric is the number of plant species and soybean varieties used to screen for host preference and varietal resistance of soybean against M. morrisella. The fifth metric is the number of fields and wooded areas sampled for M. morrisella throughout the field season. The sixth metric will be the number of direct and indirect contacts made with farmers and the agricultural community through our extension programming.

Project Years