Publication Date


Document Type


First Advisor

Koop, Jennifer A.

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Biological Sciences


Invasive species are considered a leading threat to global biodiversity. There are three major steps in a successful invasion: 1. A species arrives to a non-native location 2. It establishes a breeding population 3. It spreads beyond the location of arrival. The need to understand what variables facilitate a successful invasion across these steps is pressing, especially when considering systems that are vulnerable to biodiversity loss such as islands. The first chapter of this thesis focuses on the arrival step of an invasion. I present research on insects found on a tourist boat traveling between islands in the Galapagos archipelago. The Galapagos Islands are a World Heritage Site and are of top conservation concern due to their high concentration of unique biodiversity. The island system is shown to be highly susceptible to invasive species. The objective of the study is to identify the diversity of insects present on a tourist boat that frequently moves between islands. In 2019, a total of seven orders and 25 families housing 32 species were found onboard over a 6-day period. Eighteen species were invasive to the Galapagos, four of which were classified as highly invasive based on a classification system developed specifically for the Galapagos. A secondary goal of the project was to determine if the Avian vampire fly (Philornis downsi) potentially uses tourist boats to move between islands, increasing its ability to establish new populations. In 2022, an Avian vampire fly was found on a tourist boat moving between islands supporting the current hypothesis that the invasive fly can use human transport to potentially arrive to other islands. Several insect prevention protocols are proposed to further reduce the number of insects being moved by tourist boats. If it is eventually found these proposed prevention methods are effective in reducing the number of insects using the exterior of boats to move between islands, these methods can be applied to other island systems at risk for losing biodiversity due to invasive species. The most successful invasive species often possess traits that help facilitate completion of each step of invasion. These traits include the ability to reproduce quickly, occupy a variety of niches, capitalize on a broad set of resources, and once the established population is breeding the offspring can disperse quickly. Often these traits are not realized for their invasive potential in a species until they have successfully invaded a system. The second chapter of this thesis investigates whether the Avian vampire fly, invasive to the Galapagos and native to South America, displays traits that would have increased its potential to successfully invade the islands. The prevalence and infection intensity of the Avian vampire fly in a region of its native range of Ecuador were examined. The prevalence and infection intensity were lower in the native range than what has been observed in the Galapagos. In addition, evidence suggests that this parasite has no preference for nest material type or nest size when depositing eggs but does tend to lay eggs in nest that are located near other nests. These results support the idea that the Avian vampire fly is a generalist, a trait that is common among successful invasive species. Altogether, both chapters showcase the need for more research on how to successfully reduce human assisted movement of invasive insects and highlight the need to study native populations of invasive species to develop targeted management plans for their non-native range.


50 pages




Northern Illinois University

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