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Testing Spillover of Nocturnal Predators in Agroecosystems: The Influence of Ditch Type and Prey Availability

Woloschuk, John Robert
http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1573840600112587

Abstract Details

2019, Master of Science (MS), Bowling Green State University, Biological Sciences.
Predators of crop insects are influenced by a number of variables which affect their foraging in agroecosystems. Though many of these predators, and their movement between crop and non-crop habitats, has been documented, the impact of variation in non-crop habitats is less understood. Here, we sought to understand how ditch geomorphology and prey availability at ditches and cornfields influences the potential spillover of web spiders, ground spiders, and bats. We examined 10 farms across Northwest Ohio, each possessing either a narrow conventional ditch, wider two-stage ditch, or very wide self-forming stream ditch. At each site, we surveyed and collected prey and predators along a transect extending from the ditch up to 200m into the adjacent cornfield, and conducted stable isotope analysis on samples. Stable isotope analysis (δ13C & δ15N) revealed that both web and ground spiders along ditches consume more prey that ate C3 vegetation (e.g. possibly emergent insects or ditch herbivores), while spiders in the fields consume mostly prey that ate C4 vegetation (possibly pests of corn). Guano isotopes indicate bats have highly variable prey consumption (median value around 38.3% of diet made up of C4,with large credible intervals). Web spiders were more abundant along ditches but increased in fields over the course of the season (p=0.001). Bat activity was higher at ditches than in adjacent cornfields in July-August, with both high and low aquatic insect emergence. However, August-September bats showed higher activity deep within the fields during periods of high aquatic prey availability at ditches (p=0.032). Isotopes suggest that spiders do not spillover between ditches and fields, but they were abundant in fields and ate prey with a C4 (corn-based) diet. Recording data and isotopes together suggest bats do consume prey from both ditches and cornfields. Ditch geomorphology was not found to have an effect on the response of abundance or activity of predators and prey alike. Further investigation of ditch geomorphology influence on predator foraging and potential spillover is needed, with more sites and throughout the crop season.
Kevin McCluney, PhD (Advisor)
Jessica D'Ambrosio, PhD (Committee Member)
Karen Root, PhD (Committee Member)
77 p.
Agriculture; Biology; Ecology
Spillover Predation; Agroecosystems; Agricultural Ditches; Bats; Spiders; Stable Isotopes; Crop Pests; Emergent Insects

Recommended Citations

Citations

  • Woloschuk, J. R. (2019). Testing Spillover of Nocturnal Predators in Agroecosystems: The Influence of Ditch Type and Prey Availability [Master's thesis, Bowling Green State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1573840600112587

    APA Style (7th edition)

  • Woloschuk, John. Testing Spillover of Nocturnal Predators in Agroecosystems: The Influence of Ditch Type and Prey Availability. 2019. Bowling Green State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1573840600112587.

    MLA Style (8th edition)

  • Woloschuk, John. "Testing Spillover of Nocturnal Predators in Agroecosystems: The Influence of Ditch Type and Prey Availability." Master's thesis, Bowling Green State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1573840600112587

    Chicago Manual of Style (17th edition)

bgsu1573840600112587
162
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This open access ETD is published by Bowling Green State University and OhioLINK.