Date of Award
Summer 8-23-2025
Document Type
Masters Thesis
Degree Name
M.S. in Biological Sciences
Organizational Unit
College of Natural Science and Mathematics, Biological Sciences
First Advisor
Anna A. Sher
Second Advisor
Shannon M. Murphy
Third Advisor
Patrick Martin
Copyright Statement / License for Reuse
All Rights Reserved.
Keywords
Coleoptera, Diorhabda, Predation, Tamarisk beetle, Tamarix, Trophic cascade
Abstract
Top-down trophic interactions can regulate herbivorous insect population growth. When the herbivore of interest is a biocontrol of an invasive plant, predation can be counterproductive to conservation goals. We compared the top-down impacts of different predator guilds on larval Diorhabda beetles, a biocontrol herbivore released in the Upper Colorado River Basin to manage invasive trees in the genus Tamarix. To test the strength of predation on larval Diorhabda by different predator guilds, we compared the rates of change of larvae among four different predator exclusion treatments. To test the strength of predation by birds specifically, we compared predation among sites on plasticine models of Diorhabda larvae and against other potential explanatory environmental variables. We found that predation is occurring on larval Diorhabda by birds and invertebrates and that birds exerted a stronger predation pressure on larval Diorhabda than invertebrate predators.
Copyright Date
8-2025
Publication Statement
Copyright is held by the author. User is responsible for all copyright compliance.
Rights Holder
Kelly A. Tobin
Provenance
Received from ProQuest
File Format
application/pdf
Language
English (eng)
Extent
80 pgs
File Size
1.6 MB
Recommended Citation
Tobin, Kelly A., "Top-Down Effects on a Biocontrol Beetle in the Upper Colorado River Basin" (2025). Electronic Theses and Dissertations. 2651.
https://digitalcommons.du.edu/etd/2651