Investigating the mechanism of a non-consumptive effect of a predator on the disease dynamics of its prey

Hearon, Luke

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https://hdl.handle.net/2142/120147 Copy

Description

Title

Investigating the mechanism of a non-consumptive effect of a predator on the disease dynamics of its prey

Author(s)

Hearon, Luke

Issue Date

2023-05-01

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

Cáceres, Carla

Committee Member(s)

• Allan, Brian
• Dolezal, Adam

Department of Study

Entomology

Discipline

Entomology

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• predator-prey
• entomology
• kairomone
• infochemical
• disease ecology
• trade-off

Abstract

Predators frequently affect their prey through non-consumptive pathways. These non-consumptive effects can cause shifts in behavior and physiology that alter the disease dynamics in the prey population. In the Chaoborus–Daphnia–Metschnikowia predator–prey-host–pathogen system, the presence of Chaoborus cues increases the susceptibility of Daphnia to infection by Metschnikowia, but the mechanism of this effect is yet unknown. This study investigated two potential mechanisms. Firstly, authors previously observing the non-consumptive effect on infection have hypothesized, but not directly tested, that it is the result of increased feeding rate, either due to increased foraging behavior or due to increased body size in the presence of the cue. Secondly, I hypothesize that the morphological defenses reported to be produced in the presence of Chaoborus kairomone cause a resource allocation trade-off between defense production and immune function. I tested these hypotheses by rearing Daphnia in a factorial design in the presence/absence of Chaoborus kairomone and the presence/absence of Metschnikowia spores, measuring life history traits, morphology, and feeding rate. My results did not support either hypothesis. While kairomone increased infection rate, feeding behavior did not increase, nor did body size. Morphological defenses were not produced in response to the kairomone, yet infection still increased. While the mechanism of the Chaoborus kairomone on Daphnia infection remains unknown, I have tested and rejected two likely hypotheses as to its functioning.

Graduation Semester

2023-05

Type of Resource

Thesis

Copyright and License Information

Copyright 2023 Luke Hearon

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