The common eastern bumblebee queens (Bombus impatiens) endure cold winter months by entering a diapausal state post-fertilization. During this overwintering period, these animals use stored energy reserves while maintaining a low metabolic rate. Bumblebees are thought to use primarily lipids to fuel this critical overwintering period, despite the fact that bee mitochondria do not appear equipped to break down this metabolic fuel. For some insects, lipids stored in the fat body can be converted to the amino acid proline, and this metabolic fuel has recently been discovered to be readily oxidized by bumblebee workers. My research, therefore, investigates the role of proline during overwintering in bumblebee queens. Using cellular respirometry, I determined the metabolic capacity of the muscle cells of queens to use various fuels, and if this capacity changes throughout overwintering. Surprisingly, the tested queens showed a much lower potential to oxidize proline than workers, and their capacity did not change during a four-month overwintering period. The metabolic properties of muscle tissue were further characterized using metabolic enzymes activity profile. These results further demonstrate the low potential for proline metabolism and the limitations of bumblebee queens’ capacity to oxidize lipids. Body composition was measured to determine how the various energy stores (lipid, glycogen, protein) change during overwintering; however, no decrease in concentration was observed. Overall, this work clarifies the constraints of B. impatiens metabolism during overwintering.

Peatland ecosystems in the eastern Georgian Bay, Ontario, region often provide overwintering habitat for the eastern massasauga rattlesnake (Sistrurus c. catenatus), a species considered at-risk across its range. Suitable overwintering habitat requires a resilience zone with peat temperatures above 0°C and a water table position sufficient to provide moisture without risk of flooding and these ecohydrological conditions commonly occur in raised peatland microforms (hummocks). Due to a changing climate, these peatlands are at risk of increased wildfire frequency and burn severity which may threaten overwintering habitat availability and suitability. In 2018, a wildfire burned over 11,000 ha of the eastern Georgian Bay landscape which serves as critical habitat for the massasauga. We monitored water table position, snow depth, rainfall, and peat thermal dynamics in hummocks in three burned and three unburned peatlands to assess the potential impacts of wildfire on massasauga overwintering habitat. We found that hummocks were able to provide unfrozen and unflooded habitat regardless of peat burn severity and that surface complexity and peatland-scale characteristics provided the greatest control on microhabitat suitability. This research highlights the importance of conserving peatland ecosystems that provide resilient species at risk habitat. / Thesis / Master of Science (MSc) / The eastern massasauga rattlesnake is a species at risk native to Ontario and parts of the USA. In the eastern Georgian Bay region, massasaugas overwinter in wetlands for up to half the year. This is a sensitive period because flooding or freezing within the hibernacula can be fatal. Due in part to climate change, wetlands in this region are at increased wildfire risk which may threaten the quality of massasauga overwintering habitat. In 2018, a wildfire burned over 11,000 ha of land along eastern Georgian Bay, some of which was massasauga habitat. We monitored the water table position and soil temperature in potential massasauga overwintering habitat to assess its quality after wildfire. We found that wetlands provide unflooded and unfrozen habitat even when burned, and that wetland surface complexity is likely an important regulator of overwintering habitat quality. This research highlights the importance of identifying and protecting wetland ecosystems that provide resilient habitat in the face of a disturbance.

Many hardy annual flowers will live through the winter if there is sufficient snow protection. Since snow cover is not consistent from year to year it has been suggested that hardy annuals planted in late summer and provided with some kind of protection before severe freezing begins will live through the winter successfully. Not only would this enable plants to bloom four to six weeks earlier, but would also enable gardeners to utilize flowers not commonly grown in northern Utah.

This thesis investigated the relationships between the feeding behaviour and use of stored fat in overwintering Atlantic salmon parr remaining destined to remain resident in freshwater the following year. Experiments investigated the responses to periods of food shortage at different times of the year to assess the influence of season. Investigations were carried out to examine how feeding motivation and fat storage were influenced by changes in those environmental cues that indicate the change of season. The effect of the normal winter behavioural pattern upon feeding and fat was also investigated.

In this thesis I present complex experimental data on the physiological and molecular adaptations during diapause development and overwintering in a linden bug, Pyrrhocoris apterus (Heteroptera, Pyrrhocoridae). I focus on adjustments of the enzymatic complement, which is involved in the biosynthesis of cryoprotectants, and heat shock proteins, which are expressed in response to temperature stress.

Container grown perennials are a popular product offered by nurseries and greenhouses and included in their production but little research has been reported on proper overwintering techniques for herbaceous perennials and ornamental grasses. In the first experiment rooted liners of Pennisetum alopecuroides, Pennisetum "Hameln" and Pennisetum "Little Bunny," were potted. Treatments included, utilizing two overwintering covers, two fertilizer rates (low or high) and two substrate moisture contents (wet or dry). Covering with either a double layer of Dewitt N-Sulate™ insulation fabric or a double layer of Dewitt N-Sulate™ insulation fabric and a single sheet of 4 mil white polyethylene plastic on top of the insulation fabric, wet substrate treatments, low fertility rates and combinations of both, improved survival and vigor for all three tested Pennisetum species and cultivars. In the second experiment, rooted liners of P. alopecuroides, P. "Hameln" and P. "Little Bunny," were potted. Treatments included, two transplanting times (young or old), two fertilizer rates (low or high) and two substrate moisture contents (wet or dry) at the UHC and Poplar Ridge Nursery (Montross, VA) (PR). Vigor was improved for P. alopecuroides (at PR) and P. "Little Bunny" (at both locations) with the young transplanting time. In the third experiment, older plant material of P. alopecuroides, P. "Hameln" and P. "Little Bunny," were subjected to fertility treatments of no additional fertilizer or top-dressed at a low, medium or high rate . A high fertility rate reduced survival and vigor for P. "Little Bunny." In the fourth experiment rooted liners of Echinacea purpurea "Hot Papaya," Echinacea purpurea "Milkshake," Gaillardia x grandiflora "Gallo Peach," Heuchera x villosa "Pistache," Heuchera x villosa "Brownies," P. alopecuroides, P. "Cassian," P. "Hameln" and P. "Little Bunny," were potted and overwintered at the UHC or Poplar Ridge Nursery (Montross, VA) (PR) or Riverbend Nursery, Inc. (Riner, VA) (RB). Treatments included, utilizing two overwintering covers, two fertilizer rates (low or high) and two substrate moisture contents (wet or dry). Vigor at the UHC, was reduced with the high fertility rate for E. "Hot Papaya" and H. "Brownies." A double layer of Dewitt N-Sulate™ insulation fabric and white polyethylene plastic on top of the cover, in combination with the wet substrate moisture treatment improved vigor of E. "Hot Papaya."A double layer of Dewitt N-Sulate™ insulation fabric in combination with the wet substrate moisture content and the high fertility rate reduced P. "Cassian" vigor. No overwintering cover reduced P. "Hameln" vigor. No overwintering cover and the high fertility rate reduced P. "Little Bunny" vigor. Vigor at PR was improved with the high fertility rate for E. "Milkshake," G. "Gallo Peach" and H. "Brownies." At RB, a double layer of Dewitt N-Sulate™ insulation fabric in combination with the low fertility treatment and no cover in combination with the high fertility treatment reduced vigor for E. "Milkshake" and P. "Little Bunny," respectively. No cover in combination with the wet substrate moisture treatment reduced vigor for G."Gallo Peach." / Master of Science

Migratory species are expected to demonstrate habitat selection that occurs at multiple spatial and temporal scales. Western monarch butterflies migrate seasonally to overwinter in groves at geographically predictable locations along the California coast. To date, overwintering habitat selection by western monarch butterflies has been studied assuming that habitat selection occurs where overwintering aggregations form, meaning at the spatial scale where monarchs form dense overwintering aggregations within overwintering groves. We argue that since western monarch butterflies are migratory, studies of habitat selection could have commingled selection at different scales into a single spatial scale. This likely leads to ignoring some levels of habitat selection, confounding the scale of habitat selection itself, and potentially misidentifying the habitat attributes under selection. Therefore, we explore monarch overwintering habitat selection to determine whether an explicit spatial framework is necessary.We studied nine groves on the coast of California and at each grove we collected temperature, humidity, and light data from grove edges, grove interiors, and aggregation locations over several weeks of the overwintering season. We tested the hypothesis that monarchs aggregate in locations within groves that have consistent attributes across groves. We find that locations on the outer edges of groves differed significantly in particular attributes of daily temperature and light from the interior of groves. Yet we find neither evidence supporting the hypothesis that the aggregation locations have a unique microclimate that differs significantly from other locations inside the grove nor that aggregation locations are uniform in their microclimatic attributes across overwintering groves. Rather, we find that the microclimatic attributes at the aggregation locations vary spatially with latitude. Thus, the overwintering climatic attributes that appear to be under selection varied spatially based on locations within groves and based on latitude of each particular grove. We conclude it will be necessary to consider spatial effects when studying western monarch butterfly overwintering habitat selection and that interpretations of habitat selection to date have commingled habitat selection at multiple spatial scales.

The American dog tick, Dermacentor variabilis, is an obligate blood feeding ectoparasite. This tick is a known vector of pathogens that affect the health of wildlife, humans, and livestock and is abundant in Manitoba. The etiological agent of bovine anaplasmosis, Anaplasma marginale, along with members of the spotted fever group rickettsiae are bacteria that are transmitted by this tick. I examined the distribution of these bacteria in Manitoba’s tick population using molecular techniques. During the eradication of an outbreak of bovine anaplasmosis in Manitoba, there was no evidence the bacterium had spilled over into the tick population. Rickettsia montanensis was detected with a mean prevalence of infection of 9.8% (range, 0.00 - 21.74% among localities) in 8 of 10 localities within the province. It was also determined that 19.9% (SE ±1.14) of adult questing ticks collected in one vector season overwintered through to the next spring.

A growing world population drives an ever-increasing need for food and energy. These challenges, along with depletion of water and fossil fuel resources, call for improvements in crop production systems and the cultivars used within them. Perennial cropping systems present an attractive solution to many of these problems. A greater understanding of the genetic control of over-wintering ability within crop species is one way to begin the process of making perennial cropping systems a possibility. In this study an F3:F4 family derived from a cross between Sorghum bicolor (L.) Moench and S. propinquum (Kunth) Hitchc. segregating for rhizome production was phenotyped in both field and greenhouse environments for traits relating to rhizomatousness and over-wintering. Several statistical models were created to correlate rhizome growth and over-wintering. A known rhizome quantitative trait locus (QTL) region was saturated with SSR markers and the QTL interval was reduced from previous estimates of about 16 Mb or 7 cM to 12 Mb or 2 cM, a 25% or 71% reduction in physical or linkage distance respectively. Two previously unidentified QTL regions associated with over-wintering were also identified. Our results also support the hypothesis that rhizome growth is important and possibly necessary for over-wintering in Sorghum.

Ecology of Veliidae and Mesoveliidae (Hemiptera: Heteroptera: Gerromorpha) was studied in selected European species. The research of these non-gerrid semiaquatic bugs was especially focused on voltinism, overwintering with physiological consequences and wing polymorphism with dispersal pattern. Hypotheses based on data from field surveys were tested by laboratory, mesocosm and field experiments. New data on life history traits and their ecophysiological consequences are discussed in seven original research papers (four published journal papers, two submitted papers and one communication in conference proceedings), creating core of this thesis.