Trap or trove: understanding the community-level impacts of agricultural practices and land-use change on prairie restoration ecosystems

Tetlie, Jonathan R.

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https://hdl.handle.net/2142/129819 Copy

Description

Title

Trap or trove: understanding the community-level impacts of agricultural practices and land-use change on prairie restoration ecosystems

Author(s)

Tetlie, Jonathan R.

Issue Date

2025-06-10

Director of Research (if dissertation) or Advisor (if thesis)

Harmon-Threatt, Alexandra

Doctoral Committee Chair(s)

Harmon-Threatt, Alexandra

Committee Member(s)

• Berenbaum, May
• Dolezal, Adam
• Yannarell, Anthony

Department of Study

Entomology

Discipline

Entomology

Degree Granting Institution

University of Illinois Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Community ecology
• neonicotinoids
• land-use
• restoration ecosystems
• plant-pollinator

Abstract

Anthropogenic land-use change and degradation are significant drivers of biodiversity loss. In the Midwestern United states, land-use change and degradation are driven primarily by agricultural intensification, which can eliminate or fragment natural habitats and generate spillover contamination of agricultural chemicals such as neonicotinoids, which have been associated with biodiversity loss. The research reported in this dissertation was aimed at characterizing impacts of conventional agricultural practices, such as pervasive habitat replacement and neonicotinoid contamination, on beneficial organisms and habitat restorations designed to protect and foster biodiversity. Bumble bees comprise a charismatic and ecologically significant group of native pollinators that provide critical ecosystem services, such as pollination, to a wide variety of flowering plants, including native species and agricultural crops. Over the past few decades, marked declines in bumble bee populations have occurred globally. However, these declines are not uniform, as the distribution and abundance of some species have dropped precipitously while others have remained stable or increased their range. In Chapter 1, I present an assessment of local and landscape-level factors that could be driving bumble bee population trends, with a specific focus on common and at-risk species. Over this three-year study, I found that local habitat quality, as measured with the Floristic Quality Index (FQI), had significant positive effects on broad bumble bee metrics such as abundance and richness and the abundance of common and at-risk species. On a landscape scale, land use surrounding my sample sites had a far less uniform effect on bumble bee metrics. Common bumble bee species showed a strong positive association with varying degrees of human development, while the abundance of at-risk species was strongly associated with natural areas. These findings indicate that not all bumble bee species respond to land-use composition and that restoration efforts for species of greatest concern should not follow broad population trends such as overall bumble bee abundance, which can be skewed by common species that are not declining. Despite this disparity, abundance of common and at-risk species was negatively correlated with row crop agriculture, particularly corn and soybean acreage, which reduce the amount of potential natural habitat and introduce contaminants, such as neonicotinoid insecticides, to surrounding natural areas. Neonicotinoid insecticides are the most widely used class of insecticides globally and can linger in the environment long after their initial application. Their use has been identified as a prominent driver of insect declines. In Chapter 2, I investigate the multitrophic effects of the neonicotinoid clothianidin on arthropod community structure and plant fitness in a common garden experiment designed to mirror an early prairie restoration. Using structural equation modeling, I assessed how clothianidin exposure influences arthropod abundances across different feeding guilds, alters interspecific interactions, and affects plant fitness metrics, including aboveground biomass and seed set. I found that clothianidin contamination positively affected pollinator visitation and negatively affected omnivore abundance. However, it did not induce any interspecific interactions in terms of abundance. Instead, plant species and inflorescence abundance had significantly greater effects on arthropod feeding guilds and community structure. This research highlights the importance of plant community composition in prairie restoration ecosystems and suggests that the benefits of increasing restored habitats outweigh the potential risks of increased neonicotinoid exposure to non-target organisms. Most neonicotinoid research centers around aboveground non-target arthropods such as pollinators. Much less emphasis is placed on belowground organisms, such as soil microbes, which are often more exposed to neonicotinoid contamination. In Chapter 3, I present my findings on the impact of clothianidin on soil microbial community structure and potential multitrophic effects on plant phenotypes and pollinator visitation based on the same experimental design described in Chapter 2. Analysis of microbial community structure revealed that plant species was the most significant driver of microbial community structure. Furthermore, clothianidin directly and indirectly altered the diversity of certain microbial functional groups on a plant-specific basis. In some cases, these functional group alterations led to multitrophic consequences on plant phenotypes and pollinators. Findings from this chapter highlight the importance of considering microbial interactions in restoration efforts, as neonicotinoid contamination can potentially disrupt multitrophic interactions and could alter microbial conditions to favor certain plants and, therefore, influence habitat establishment and biodiversity.

Graduation Semester

2025-08

Type of Resource

Thesis

Handle URL

https://hdl.handle.net/2142/129819

Copyright and License Information

Copyright 2025 Jonathan Tetlie

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