Graduation Term

2016

Degree Name

Master of Science (MS)

Department

School of Biological Sciences

Committee Chair

Joseph M. Casto

Abstract

Certain developmental stressors can lead to developmental trade-offs in young organisms. Hematophagous ectoparasites are a common stressor experienced by European starlings, and we wished to explore what aspects of an ectoparasite infestation drove trade-offs. The first part of this study was to test the hypothesis that blood loss was the sole mediator of trade-offs due to hematophagous ectoparasite infestation. We used nestlings that were exposed to mites in the nests, nestlings in mite-reduced nests experiencing supplementary blood loss, and nestlings in mite reduced nests with no supplementary blood loss. We also used a new heat treatment to reduce mites in the nest while reducing any side effects on the nestlings. We found that nestlings in mite-enhanced nests did display decreased growth and blood parameters, but nestlings undergoing supplementary blood loss displayed no developmental deficiencies. Nest treatments also did not have a significant effect on nestling immune function. Finally, we found that the heat treatment did reduce mites in the nest prior to hatching, but this effective was lost by the times the nestlings fledged.

Our previous study gave us some insight into the effects of mites on nestling development. However, since the differences in mite abundance were not significant later on in nestling development, some of the results were harder to interpret. In order to properly determine the factors driving trade-offs in the presence of a mite infestation, we had to reassess the different ways we could reduce mite abundance in starling nests. We used this second study to analyze different mite control methods on their efficacy and their effects on nestling development. We examined the effects of treating the nests with pesticides, milfoil and heat. We found that while the pesticide treatment was the only one to yield less mites than mite enhanced nests, their nestlings’ development in growth, physiological traits and immune function were rarely different than nestlings in mite enhanced nests. Heat treated nests also showed some developmental deficiencies, while not reducing mite abundance.

It appears that blood loss alone does not account for developmental deficiencies associated with mite infestation, but in order to fully understand the effects of these ectoparasites on nestling development, acaricidal treatments with little impact on nestling development must be found and implemented.

Access Type

Thesis-Open Access

DOI

http://doi.org/10.30707/ETD2016.Odetunde.A

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