Author ORCID Identifier

http://orcid.org/0000-0002-3692-5991

Year of Publication

2016

Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation

College

Agriculture, Food and Environment

Department

Entomology

First Advisor

Dr. John J. Obrycki

Abstract

Demand for food, fuel, and fiber has been increasing, escalating the intensification of agriculture during the past fifty years. A more comprehensive understanding of the impact of landscapes on sustainable agriculture production is required to meet the continual increase in human demand. This not only includes how chemical inputs are used but also how cultivated and surrounding landscapes are managed for ecosystem services. This research explains how land cover on landscape and farm scales impact ant and spider-mediated pest suppression. I successfully developed and optimized molecular methods to test ant gut contents from both laboratory and field-caught specimens. A multi-year field study indicated that spatial scale played a significant role in both ant and pest abundance and diversity when land cover at the landscape scale was analyzed, where an increase in scale generally correlated with an increase in the intensity of the relationship between landscape fragmentation and community response. I found that ant and pest populations can potentially be managed at the landscape scale via specific cover types and habitat fragmentation. Farm scale field margin composition significantly influenced spider and pest within field abundances and spatial associations, particularly early in the season. In a field cage study, ants were found to interfere with reductions in pest-induced leaf damage caused by spiders within the soybean system despite the fact that the pest was non-honeydew producing. Finally, I found that chemical disturbance via imidacloprid and fungicide seed treatments did not impact pest populations or ant predation rates but did significantly increase ant diversity by decreasing the abundance of a dominant ant species. However, there were impacts found on ant individuals within a lab mesocosm where imidacloprid induced sub-lethal intoxication but fungicides were lethal to Tetramorium caespitum.

Digital Object Identifier (DOI)

https://doi.org/10.13023/ETD.2016.441

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