Date of Award

Summer 8-19-2022

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Entomology

Advisor

Allison Gardner

Second Committee Member

Jessica Leahy

Third Committee Member

Philip Fanning

Abstract

Increased temperature variances are being recorded in Maine due to climate change, contributing to increased densities of blacklegged ticks (Ixodes scapularis) and concomitant increase in reported cases of tickborne diseases across the state. Understanding the interactions between mean temperature and temperature variance in relation to overwinter tick survival is crucial in understanding the tick’s geographical expansion limits to create better prediction models for their expansion. The goals of this study were to determine the interacting microclimate effects of winter temperature variance and mean temperatures on tick mortality, which month nymphal blacklegged ticks experience highest mortality, and assess the connection between blacklegged tick nymphal lipid content and overwinter survival. Furthermore, I assessed the knowledge and attitudes of Maine landowners regarding using land-based management practices that reduce tick populations to address this gap of knowledge in research. I monitored an outdoor tick overwintering enclosure in Orono and Presque Isle, ME, for six months over two winter seasons (November – May) to assess monthly nymphal mortality and hourly temperatures and used laboratory temperature-controlled experiments to explore the effects of temperature variance and mean on tick mortality. In the outdoor enclosure, tick mortality declined over time with December often having the highest overwinter survival. Months with the coldest temperatures and highest temperature variance often had high lipid usage. In the laboratory experiment, ticks exposed to low temperature, high temperature variance died at the fastest rates compared to warmer temperatures and lower frequency temperature variance. In this study, we propose a mechanism to explain how mortality may be driven by repeated thawing, causing ticks to expend more energy than what is compatible with overwinter success. Through focus groups with Maine landowners, we determined lack of knowledge and low self-efficacy in landowners may play a large role in preventing landowners from implementing landscape-based management practices that reduce tick habitat. Specifically, we documented lack of knowledge in both landscape-based management practices and their efficacy, and where landowners can find land management recommendations. We propose that public outreach educators should try to improve landowner knowledge and self-efficacy about landscape-based management practices, efficacy, and guidance across all socioeconomic gradients to reduce tick exposure risk. Collectively, these biophysical findings provide insight for more accurate tick expansion prediction models and the social perceptions identified educational knowledge gaps to be improved to reduce tick exposure risk overall

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