Browsing by Author "Flaherty, Leah"
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ItemThe effect of garlic mustard (Alliaria petiolata, Brassicaceae) on the diversity and composition of oribatid mite communities(2017) Kuczmarski, Paige; Flaherty, LeahGarlic mustard (Alliaria petiolata, Brassicaceae) is a non-native plant that rapidly invades North American forest understories. While garlic mustard has been shown to impact native vegetation, the effect on belowground communities, which are essential in controlling nutrient availability and decomposition, is unclear. My objectives were to investigate the impact of garlic mustard invasion on the community composition and species richness of oribatid mites (Acari: Oribatidae), which are bioindicators of soil health in forest ecosystems. Soil samples were obtained in June 2016 from two sites: Mill Creek Ravine, Edmonton AB and Broadmoor Public Golf Course, Sherwood Park AB. A paired sampling strategy was used to compare areas colonized with garlic mustard to those with native vegetation. Soil samples were collected from six pairs of plots, equalling 12 samples at each of the two sites, for a total of 24 samples. Following Berlese funnel extraction, oribatid mites ≥300 µm were identified. The effect of site and garlic mustard invasion on oribatid species richness, will be evaluated using mixed-model ANOVA and individual-based rarefaction. Oribatid community composition will be assessed with non-metric multidimensional scaling. This project will improve understanding of the impact of invasive species, particularly garlic mustard, on belowground communities. ItemEffects of larval host and natural microsporidian infection on adult life history traits of the forest tent caterpillar (Lepidoptera: Lasiocampidae)(2023) Preti, Flavio; Flaherty, Leah; Evenden, Maya L.Host affiliation and entomopathogenic infections play a major role in shaping population dynamics of the forest tent caterpillar (FTC), Malacosoma disstria Hübner (Lepidoptera: Lasiocampidae). The effect of these individual factors has been studied, but it is unknown whether interactions between these factors significantly impact FTC life history traits. In the laboratory, we investigated a tritrophic interaction among larval diet, larval microsporidian infection, and FTC life history traits. Larvae were reared on foliage of trembling aspen, Populus tremuloides Michx (Malpighiales: Salicaceae) or sugar maple, Acer saccharum Marshall (Sapindales: Sapindaceae), or an artificial diet. Natural levels of microsporidian infection were assessed through microscopy and categorized as none (0 spores), low (1–100 spores), or high (>100 spores). Microsporidian infection and larval diet individually, but not interactively, impacted FTC life history traits. Moths with high infection had smaller wings, but infection did not increase the probability of wing malformations. Wings of FTC reared on fresh maple foliage were significantly smaller, had a higher probability of wing malformation, and a lower likelihood of cocoon production than FTC reared on other diets, but displayed higher overall survival. While microsporidian infection did not influence FTC-diet interactions, we provide further evidence on how these main effects may individually contribute to shaping FTC adult life history traits, and, ultimately, cyclical population dynamics. Future research should consider how larval mortality, distinct infection levels, and geographical source of FTC populations affect this tritrophic interaction. ItemAn endophytic fungus interacts with crown level and larval density to reduce the survival of eastern spruce budworm, Choristoneura fumiferana (Lepidoptera: Tortricidae), on white spruce (Picea glauca)(2019) Quiring, Dan; Flaherty, Leah; Adams, Greg; McCartney, Andrew; Miller, J. David; Edwards, SaraA two-year field study was carried out to determine whether inoculating white spruce, Picea glauca (Moench) Voss, with a native endophytic fungus, Phialocephala scopiformis DAOM 229536 Kowalski & Kehr (Helotiales, Ascomycota), decreased the performance of eastern spruce budworm, Choristoneura fumiferana Clemens, developing on these trees. Second instars were reared at three densities in the mid crown and at one density in the lower, mid, and upper crown. Larval survival (i.e., survival of larvae to pupation) was lower on endophyte-inoculated trees than on control trees in the mid crown and especially the upper crown but was similar in the lower crown, resulting in a significant interaction between endophyte and crown level. A similar but marginally insignificant interaction was observed for overall survival up to adult emergence (i.e., total survival). Larval survival and total survival were approximately 22% and 19% lower, respectively, when developing in the upper crown of endophyte-inoculated trees than in control trees. Larval survival remained relatively constant, with increased density on control trees but decreased with density on endophyte-inoculated trees, resulting in a significant interaction between endophyte and larval density. Sex ratios of emerged adults and wing lengths of emerged females were not influenced by the endophyte. Our results suggest that endophytic fungi could be useful additions to integrated pest management programs. ItemGlobal urban environmental change drives adaptation in white clover(2022) Santangelo, James S.; Ness, Rob W.; Cohan, Beata; Flaherty, LeahUrbanization transforms environments in ways that alter biological evolution. We examined whether urban environmental change drives parallel evolution by sampling 110,019 white clover plants from 6169 populations in 160 cities globally. Plants were assayed for a Mendelian antiherbivore defense that also affects tolerance to abiotic stressors. Urban-rural gradients were associated with the evolution of clines in defense in 47% of cities throughout the world. Variation in the strength of clines was explained by environmental changes in drought stress and vegetation cover that varied among cities. Sequencing 2074 genomes from 26 cities revealed that the evolution of urban-rural clines was best explained by adaptive evolution, but the degree of parallel adaptation varied among cities. Our results demonstrate that urbanization leads to adaptation at a global scale. ItemIndependent and interactive effects of diet and entomopathogenic microsporidia on an outbreaking forest insect defoliator(2024) Flaherty, Leah; Preti, lavio; Ishangulyyeva, Guncha; Erbilgin, Nadir; Whidden, Taylar; Evenden, Maya1. Insect herbivore diet mediates interactions with entomopathogens, yet this is relatively unexplored for microsporidia. Here, we examine a diet-mediated tri-trophic interaction between an outbreaking forest defoliator, forest tent caterpillar (FTC) Malacosoma disstria Hübner and Nosema sp. microsporidia. 2. We conducted two experiments where diet quality was manipulated by incorporating lyophilized aspen (Populus tremuloides Michaux) foliage into an artificial diet, which was compared to a standard artificial diet. Diet quantity varied between fully fed and partially starved conditions, simulating an outbreak scenario. Microsporidia infection occurred naturally or was induced via experimental inoculation. We assessed FTC survival, microsporidia infection and load, and sublethal effects of treatments on FTC traits. 3. Plant secondary metabolite concentrations in aspen-augmented diets varied between experiments. In Experiment 1, the aspen-augmented diet contained lyophilized aspen foliage with low concentrations of secondary metabolites, which increased FTC survival and reduced microsporidia infection. Diet quality and infection load also interactively influenced adult wing traits in Experiment 1. In Experiment 2, the aspen-augmented diet contained lyophilized aspen foliage with higher concentrations of secondary metabolites, which negatively affected FTC. No diet mediated interactions with microsporidia were observed in Experiment 2. 4. Diet quality (Experiments 1 and 2), diet quantity (Experiment 2) and microsporidia infection (Experiments 1 and 2) directly influenced FTC survival and/or had sublethal effects on FTC that may have cascading effects on population dynamics and dispersal. 5. We demonstrated that diet quality can mediate interactions between FTC and microsporidia, but these interactions depend on the defensive chemistry of the FTC diet. To our knowledge, this is the first study to report diet-mediated interactions between an outbreaking forest pest and microsporidia and one of only a few studies to examine this tri-trophic interaction among Lepidoptera. ItemInfluence of a foliar endophyte and budburst phenology on survival of wild and laboratory-reared eastern spruce budworm, Choristoneura fumiferana on white spruce (Picea glauca)(2019) Quiring, Dan; Adams, Greg; Flaherty, Leah; McCartney, Andrew; Miller, J. David; Edwards, SaraA manipulative field study was carried out to determine whether the foliar endophyte fungus, Phialocephala scopiformis DAOM 229536, decreased the performance of eastern spruce budworm, Choristoneura fumiferana larvae developing on white spruce trees. Overwintered second-instar budworm larvae from a laboratory colony or from a wild population were placed on endophyte positive or negative trees one or two weeks before budburst. The presence of the endophyte in the needles reduced the survival of C. fumiferana from both a wild population and a laboratory colony. Survival for budworm juveniles up to pupation and to adult emergence was 13% and 17% lower, respectively, on endophyte positive trees. The endophyte did not influence the size or sex of survivors and budworm survival was not influenced by any two- or three-way interactions. Budworm survival was higher for wild than for laboratory-reared budworm and for budworm placed on trees a week before budburst. This may be the first field study to demonstrate the efficacy of an endophytic fungus against wild individuals of a major forest insect pest. The efficacy of the endophyte at low larval densities suggests that it could be a useful tactic to limit spruce budworm population growth in the context of an early intervention strategy. ItemResponse of native and exotic longhorn beetles to common pheromone components provides partial support for the pheromone-free space hypothesis(2020) Rassati, Davide; Marchioro, Matteo; Flaherty, Leah; Poloni, Riccardo; Edwards, Sara; Faccoli, Massimo; Sweeney, JonLonghorn beetles are among the most important groups of invasive forest insects worldwide. In parallel, they represent one of the most well-studied insect groups in terms of chemical ecology. Longhorn beetle aggregation-sex pheromones are commonly used as trap lures for specific and generic surveillance programs at points of entry and may play a key role in determining the success or failure of exotic species establishment. An exotic species might be more likely to establish in a novel habitat if it relies on a pheromone channel that is different to that of native species active at the same time of year and day, allowing for unhindered mate location (i.e., pheromone-free space hypothesis). In this study, we first tested the attractiveness of single pheromone components (i.e., racemic 3-hydroxyhexan-2-one, racemic 3-hydroxyoctan-2-one, and syn-2,3-hexanediol), and their binary and tertiary combinations, to native and exotic longhorn beetle species in Canada and Italy. Second, we exploited trap catches to determine their seasonal flight activity. Third, we used pheromone-baited “timer traps” to determine longhorn beetle daily flight activity. The response to single pheromones and their combinations was mostly species specific but the combination of more than one pheromone component allowed catch of multiple species simultaneously in Italy. The response of the exotic species to pheromone components, coupled with results on seasonal and daily flight activity, provided partial support for the pheromone-free space hypothesis. This study aids in the understanding of longhorn beetle chemical ecology and confirms that pheromones can play a key role in longhorn beetle invasions.