Browsing by Subject "cold tolerance"
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Item Complete data for Overwinter survival of Corbicula fluminea in a central Minnesota lake(2021-11-01) Weber, Megan M; Cibulka, Daniel; mmweber@umn.edu; Weber, Megan M; Minnesota Aquatic Invasive Species Research CenterCorbicula fluminea is regarded as one of the most pervasive freshwater aquatic invasive species in the world. It has been widely cited to have a lower lethal temperature threshold of 2 degrees Celcius, which suggests the species would be unable to survive in Minnesota outside of areas of thermal refuge from sources such as power plant, water treatment facility, and other raw water user effluent). In August 2020 a volunteer participating in Starry Trek, an aquatic invasive species early detection event, recovered live C. fluminea from an inland Minnesota lake with no known thermal refuge (Briggs Lake, Sherburne County). This data set documents the distribution, overwinter survival, and size class structure of the population in Briggs Lake and observational data at a nearby lake (Big Lake, Sherburne County) where additional clams were discovered by a volunteer towards the end of the Briggs Lake project timeline. The data from this study are available here for public use.Item Data and code for forecasting overwintering mortality of Spathius galinae in North America(2021-04-26) Wittman, Jacob T; Aukema, Brian H; Duan, Jian J; Venette, Robert C; wittm094@@umn.edu; Wittman, Jacob TFrom publication: Evaluating the cold tolerance of biological control agents is often necessary to optimize their release and performance. We used field and laboratory assays to determine the cold hardiness of the parasitoid Spathius galinae Belokobylskij & Strazanac, an approved classical biological control agent of emerald ash borer (Agrilus planipennis Fairmaire) in North America. Supercooling points and lower lethal temperature of mature (cocooned) S. galinae larvae were measured in controlled cooling assays in the laboratory. Most S. galinae larvae died after reaching their supercooling point, which occurred at -25.0°C on average. Several larvae, however, initiated freezing but later eclosed, suggesting S. galinae may be partially freeze tolerant. Supercooling points were not affected by chilling rate. In the winter of 2019 – 2020, we monitored development of mature S. galinae larvae in ash segments above and beneath the snow in three locations in Minnesota, USA. Nearly 100% of S. galinae larvae died after air temperatures reached -29°C in Minnesota. Using models developed from our data, we forecast eclosion rates of S. galinae based on minimum winter temperatures across the range of ash (Fraxinus spp.) in North America. Our results indicate that S. galinae populations may suffer high overwintering mortality in areas where winter temperatures regularly decrease below -28°C, but a small portion of the population may be able to survive lower temperatures.Item The effects of feeding and overwintering conditions on emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) energy reserves and flight performance(2017-07) Tussey, DylanThe emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) is an invasive beetle from Asia that has been confirmed in 30 states as of July 2017. The spread of A. planipennis has been markedly slower in Minnesota than in other states. Cold winter temperatures are thought to be the primary factor for the slower spread. The goals of this study were to determine the role of adult feeding on A. planipennis energy reserves and flight capacity, as well as to elucidate any sub-lethal effects of winter conditions on A. planipennis flight capacity. In 2015 and 2016, adult A. planipennis were reared from infested green ash logs collected in Hennepin and Ramsey Counties, MN. A separate experiment was conducted by collecting infested logs from St Paul, MN and stored in two locations during the winter of 2015-2016. Grand Rapids, MN, and St Paul, MN, to determine how winter conditions affect A. planipennis energy reserves and flight capacity. Adults were individually placed in cages and provided with fresh, lab-grown shamel ash (Fraxinus uhdei Wenzig) leaves on which to feed for 0-20 days before being flash frozen or flown on a custom flight mill for 24 hours under constant light. Beetles were subjected to nutrient analysis using either petroleum ether or colorimetric assays. Feeding treatments were compared for weight and lipid gain, flight velocity and total distance flown.Item Genetic and Horticultural Characterization of Hydrangea quercifolia Bartr. (Oakleaf Hydrangea) Throughout its Natural Range of Occurrence(2020-06) Sherwood, AndrewOakleaf hydrangea (Hydrangea quercifolia Bartr.) is an understory shrub native to the southeastern United States. The species occupies a small native range, and little is known about its genetic diversity, needs for conservation or range of phenotypic variation for horticultural traits. This study had two primary objectives. 1) To characterize the structure of the genetic diversity throughout the species range and begin to understand what factors contribute to this structure. 2) To characterize variation for horticulturally important traits. Samples were collected from 188 plants in 73 locations throughout the species range and were genotyped using genotyping by sequencing. A Structure analysis identified 6 genetic clusters which are geographically structured. Although these clusters are weakly differentiated, each has unique alleles. An environmental association analysis determined that environmental variables explain 11.3% of genetic diversity while population structure explains 13.5%. Further, 231 putative adaptive alleles were identified, the majority of which are correlated with precipitation related variables, indicating that precipitation has an impact on genetic diversity in H. quercifolia. Many historically documented populations were found to be either extirpated or at risk of extirpation. The genetic clusters on the southern extent of the species range are relatively small and contain putative adaptive alleles at relatively high allele frequencies. This highlights the importance of preserving representative germplasm from throughout the species range. Seed was collected from 55 populations throughout the species range for the horticultural characterization. Seed germination percentage was characterized in a greenhouse and growth chamber. Plant architecture was characterized as plant height, number of nodes, internode length, number of branches and plant width. Plant architecture was measured in potted and field grown plants in two locations. Tolerance to leaf spot (Xanthomonas campestris L.) was characterized in wild collected seedlings and cultivars by measuring disease severity under natural exposure to inoculum. Cold hardiness was characterized in two winters with a controlled freezing experiment. The first winter, seedlings were tested in January only and the second winter seedlings and cultivars were tested monthly throughout winter. Significant variation among wild populations and cultivars was found for all traits measured in all environments. Mean population seed germination percent ranged from 11% to 93% (mean=61% in greenhouse, 74% in growth chamber). Plant architecture varied by environment, with plants growing larger in Tennessee than in Minnesota. Plant height was correlated with collection site latitude (r=-0.66) with populations from the northeastern extent of the species range being the most compact and populations from Florida being the largest. Leaf spot severity varied significantly among populations and cultivars and was also correlated with latitude in the wild seedlings (r=0.70). Two populations in Florida were identified as sources of resistance to leaf spot while ‘Flemygea’ and ‘Alice’ were identified as having moderate tolerance to leaf spot. Cold hardiness varied among populations and cultivars and among months of the winter. Overall maximum cold hardiness was observed in February (mean LT50=-33.7°C), and several populations maintained an extreme level of cold hardiness into late winter. Midwinter cold hardiness also varied by latitude (r=-0.65). These results indicate that certain wild oakleaf hydrangea populations will be useful for introgressing novel variation into breeding programs.Item Host influence on the cold hardiness of the emerald ash borer, *Agrilus planipennis* Fairmaire (Coleoptera: Buprestidae)(2014-12) Christianson, LindseyThe emerald ash borer, Agrilus planipennis Fairmaire, is an invasive insect in North America that has caused extensive damage to ash trees throughout its invaded range. The range of Fraxinus spp., specifically black ash (Fraxinus nigra) extends farther north than the known A. planipennis distribution. The ability of an insect to withstand cold, or its cold hardiness, is important in limiting its northern distribution. The cold hardiness of A. planipennis from green ash and black ash was assessed using two laboratory measures, supercooling points and lower lethal temperature, in laboratory- and naturally-infested A. planipennis larvae. Supercooling points of A. planipennis larvae from black and green ash, with medians ranging from 25.5 to 32.6°C and 24.0 to 34.2°C respectively, were not significantly different during the winters of 2012-13 and 2013-14, although the laboratory infested larvae tested in November 2011 had significantly warmer supercooling points. Kaplan-Meier estimates of the likelihood of freezing of larvae from black ash and green ash were not significantly different between tree species or between years. A high proportion of larvae died after being frozen, but freezing did not kill all larvae. Lower lethal temperatures for 50% of the population (LT50) were estimated after accounting for the proportion of larvae that would survive freezing. LT50s of larvae from green ash were 35.2°C (95% CI 35.9°C, 34.7°C) in the winter of 2012-13 and 33.4°C ( 34.1°C, 32.1°C) in the winter of 2013-14. Larvae from black ash had estimated lower lethal temperatures of 33.4°C ( 34.4°C, 32.3°C) in 2012-13 and 33.1°C (≤ 37.5°C, 35.5°C) in 2013-14. Agrilus planipennis larvae overwinter under the bark of ash trees, so larvae may not be experiencing winter air temperatures. To determine temperatures under the bark of ash trees, temperature probes were placed under the bark of both green and black ash at 1.4m high and at the base of the tree on the north and south faces. Weather stations recorded air temperature. Daily minimum temperatures under the bark of green ash ranged from 0.5 to 4.7°C warmer than daily minimum air temperatures, and temperatures were 1.2 to 5 degrees warmer under the bark of black ash. Temperatures at the base of the trees provided the most insulation, possibly due to any snow cover adding to the insulative effect of the bark. During the time in which we took measurements, the air temperature fell below 30°C for an average of 16 hours during the winter of 2012-13. Temperatures under the bark of green ash did not reach -30°C, and temperatures under the bark of black ash fell below -30°C, on average, for 2.6 hours. In 2013-14, air temperature was 30°C or colder for an average of 146.1 hours, 78.1 hours under the bark of green ash, and 118.7 hours under the bark of black ash. Because of the differences in air temperatures and temperatures under the bark of trees, we cannot use air temperature to directly predict A. planipennis mortality. Because under-bark temperatures do not reach the temperature required to kill 50% of the population of A. planipennis every year, further research should consider how the larvae survive sublethal temperatures for longer periods of time.Item Managing Halyomorpha halys: Effects of cold tolerance, insecticides, and linguistic uncertainty(2017-06) Cira, TheresaManaging pests effectively and efficiently requires knowledge about their biology. Likewise, clear communication about scientific research pertaining to management is needed for managers to make well-informed decisions. My research pertains to the biology of the brown marmorated stink bug, Halyomorpha halys and communication between scientists about insecticidal categorization. Halyomorpha halys is an exotic invasive species in North America. Many horticultural and agricultural plants in North America are at risk for economic damage due to the highly polyphagous nature of this species. Additionally, H. halys has become a serious nuisance pest in human-made structures in some areas when, in preparation for winter, they aggregate in sheltered structures. Therefore, factors such as cold and insecticides, which affect H. halys distribution and ability to cause crop injury are of particular interest to develop management plans. I first conducted several studies of cold tolerance on H. halys in North America. I found that H. halys exhibits a chill-intolerant cold tolerance strategy, that season, sex, and acclimation location affect cold tolerance (i.e., supercooling points), and that laboratory assays of lethal temperature were able to accurately forecast winter mortality in the field. Second, I studied H. halys diapause in more depth. I present a protocol for rearing diapausing H. halys in the laboratory that exhibit similar cold tolerance (i.e., supercooling points and lower lethal temperatures) as individuals with field-induced diapause. I found that H. halys diapause confers greater cold tolerance than a non-diapausing state, and appears to be necessary to survive overwintering. Additionally, I showed diapausing H. halys actively feed for at least three weeks post-diapause induction, but feeding is mediated by temperature and adult age. Third, I investigated and critiqued the current paradigm for determining insecticidal efficacy on H. halys. I highlighted important sublethal effects of insecticides on feeding that can significantly reduce crop injury without the necessity of high direct mortality to H. halys. Lastly, using an interdisciplinary lens I examined linguistic uncertainty as it pertains to categories and descriptors of insecticides. I demonstrated the presence and consequences of linguistically uncertain terms associated with insecticides and encouraged entomologists to more adequately acknowledge and address these uncertainties in future research.Item Optimizing Methods for Turfgrass Metabolomics(2023-11) Freund Saxhaug, Katrina; Hegeman, Adrian; Watkins, EricSubtle differences in growing environment, harvesting methods, sample processing, and data analysis can lead to unintended variations in metabolomic data, so careful planning of metabolomic experiments is crucial.Item A Perennial Flax (Linum spp.) Breeding Program Using Ideotype Models to Select for Oilseed, Garden, and Cut Flower Cultivars(2021-03) Tork, DavidWild, perennial flax species (Linum spp.) are being domesticated for high-value agronomic and ornamental uses, with added ecosystem services benefits. Perennial flax ideotypes have recently been defined for oilseed, cut flower, and garden breeding objectives, and are being used to drive selection within the Forever Green perennial flax breeding program. Breeding germplasm was grown alongside wild accessions in a common garden in Minnesota (2018-2019) to quantify the effects of past selection and identify top species candidates for continued domestication efforts (Chapter 2). Vase life studies were also performed to investigate postharvest vase life and cut flower potential of perennial flax (Chapter 3). Finally, controlled freezing studies provide an in-depth characterization of perennial flax freezing tolerance, which is a priority breeding goal for all ideotypes (Chapter 4). These findings will advance the development of perennial flax as a new specialty crop in Minnesota by guiding future breeding and selection decisions.Item Risk of invasion by walnut twig beetle throughout eastern North America(2016-08) Hefty, AndreaThe walnut twig beetle (Pityophthorus juglandis Blackman) is a domestic alien invasive bark beetle in the United States of America (USA) that vectors a phytopathogenic fungus. Together, the beetle and fungus cause thousand cankers disease in species of Juglans and Pterocarya. Geographic range expansion by P. juglandis from its native range in the southwestern USA throughout the western United States and isolated areas of the eastern United States provides evidence for human-mediated movement. The disease is now present in more than 120 counties on naïve native and cultivated hosts in the eastern and western USA and in northern Italy. This research describes the cold mortality and host suitability of P. juglandis. I measured the cold tolerance of P. juglandis adults and larvae from a northern California population monthly from January 2013 to May 2014. I found significant seasonal changes in adult supercooling points in fall, winter, and spring. I observed a shift in cold-tolerance strategy in P. juglandis adults from freeze-intolerance (December 2013 and January 2014) to partial freeze-tolerance (February 2014). Adults appear to be more cold-hardy than larvae. Predicted winter survivorship in the southeastern USA is higher than in the northeastern USA. I conducted field and laboratory trials to determine if reproduction by P. juglandis varies between two black walnut (Juglans nigra L.) parent trees and black walnut and butternut (Juglans cinerea L.). Fewer adult offspring developed in branch sections of the black walnut maternal ‘Sparrow’ parent than the paternal ‘Schessler’ parent over three summer months and one winter month in the lab. In the field, P. juglandis reproduction in black walnut and butternut did not differ. In an expanded laboratory study of host suitability, I screened 11 Juglans spp., one Pterocarya sp., and two Carya spp. over two years. Eleven Juglans and one Pterocarya species supported complete brood development. Julgans nigra, J. californica, and J. hindsii had the greatest levels of reproduction. Less suitable hosts include native southwestern United States hosts (J. major and J. microcarpa), Eurasian species (J. regia), Asian butternuts (J. ailantifolia, J. mandshurica, and J. cathayensis), and native eastern United States butternut (J. cinerea) and Japanese walnut-butternut hybrid (J. ailantifolia × cinerea). The two Carya species were not hosts. Finally, I present a framework that provides strategies for accessing stakeholder knowledge of unspecified pathways that may move forest insect pests. Using social science, stakeholder analysis, and design principles, the framework provides risk managers a tool to consult stakeholders for pathway information. The result is a list of pathways that can be validated independently. My research provides biological information of the potentially limiting factors of the spread and establishment of P. juglandis. Although the impacts of thousand cankers disease appear variable, the probability of exposure of walnut to P. juglandis appears to be limited by cold temperatures and host species. The overall risk of P. juglandis to the eastern United States is not determined by this body of work. The national perception of risk or concern over P. juglandis to walnut has decreased since I began this dissertation. Despite the shift in national perception, however, the completion of this work provides state and federal regulators information for improved decision-making regarding trapping and monitoring, quarantines, and how to research unspecified pathways of movement.