http://hdl.handle.net/1893/28 This community contains the ePrints and eTheses produced by Biological and Environmental Sciences staff and students. 2026-10-24T16:52:25Z http://hdl.handle.net/1893/38403 Title: The genetic and transcriptional basis of variation in fungal entomopathogen susceptibility Author(s): McKeon, Chintamani Rose Abstract: Herbivorous insects pose a major threat to global crop production, and there is growing need for biological alternatives to chemical control. Entomopathogenic fungi are a possible candidate, yet how susceptibility varies, what drives it, and whether it is consistent across environments remain poorly understood — questions crucial to their long-term viability as biocontrol agents. This thesis investigates variation in susceptibility to entomopathogenic fungi in Helicoverpa armigera, a globally significant crop pest with a history of resistance evolution. We asked whether heritable variation in susceptibility existed across outbred families; whether resistance or tolerance better explained survival differences; whether transcriptional differences were constitutive or induced; and whether susceptibility loci were consistent across pathogen species and host-plant diets. Survival varied substantially across larval families challenged with Beauveria bassiana, consistent with a genetic basis to susceptibility differences. Results were most consistent with resistance as the dominant mechanism — pathogen load declined between days two and six post-exposure, and family mortality correlated positively with fungal burden, with limited evidence for tolerance. Larval weight was the strongest predictor of pathogen load, with the lightest larvae carrying 12–20-fold more fungal DNA than the heaviest. Transcriptomic analysis identified 145 differentially expressed genes between susceptibility extremes, of which 85% reflected constitutive differences; induced immune responses were detectable only in the most susceptible families. Susceptible families constitutively expressed higher levels of a predicted immune down-regulator (PGRP-LB) and trypsin-like serine proteases. A genome-wide association study revealed susceptibility to B. bassiana and Metarhizium anisopliae was highly polygenic, with 5–107 QTLs across four pathogen–diet combinations and minimal overlap between treatments. Together, these findings reveal that resistance to entomopathogenic fungi in H. armigera is polygenic, context-dependent, and architecturally complex. This underscores the importance of understanding the genetic and environmental context of host-pathogen interactions when evaluating the long-term prospects of fungal biopesticides as biocontrol agents. 2026-05-01T00:00:00Z http://hdl.handle.net/1893/38398 Title: Associations between mycorrhizal dominance and woody species diversity shift with stand development and climate across subtropical and tropical forests in Taiwan Author(s): Vilà‐Cabrera, Albert; Astigarraga, Julen; O'Sullivan, Kirsten S W; Clemmensen, Karina E; Tyyskä, Henna; Greenwood, Sarah; Cubino, Josep Padullés; Chen, Jan‐Chang; Jump, Alistair S. Abstract: Mycorrhizal symbioses influence woody species diversity, but whether this association shifts with forest stand development remains underexplored. Using forest inventory data across subtropical and tropical forests in Taiwan, we found that woody species diversity was lower in ectomycorrhizal (EM)-dominated than in arbuscular mycorrhizal (AM)-dominated forests, while forests with mixed mycorrhizal strategies supported the highest woody species diversity. However, these associations were strongest in early development stands and tended to converge towards high diversity in late development stands despite differences in mycorrhizal dominance. These results are consistent with stronger conspecific negative density dependence in AM-dominated forests and niche partitioning among mycorrhizal strategies at early developmental stages, while alternative recruitment dynamics associated with AM- and EM-dominated canopies may promote high woody species diversity at late developmental stages. Climate modulated these patterns, with the negative association between EM dominance and woody species diversity strongest in cold regions, while the diversity peak in mixed AM–EM forests was most pronounced in median climates and diminished towards warm and cold climates. In addition, woody species evenness was more consistently highest in forests with mixed mycorrhizal strategies across stand development stages compared to woody species richness, suggesting that mycorrhizal coexistence promotes more equal species abundances. These findings highlight that associations between mycorrhizal strategies and woody species diversity depend on forest developmental stage, underpinning new understanding of subtropical and tropical forest recovery under global change. 2026-09-28T00:00:00Z http://hdl.handle.net/1893/38381 Title: Legacy impacts of the pandemic on the recruitment of new participants at parkrun in Scotland Author(s): Gilburn, Andre S Abstract: The COVID-19 pandemic reduced physical activity during lockdown and had legacy impacts differentially affecting specific demographics. Key knowledge gaps remain in relation to the legacy impacts on rural communities which can require specific health intervention plans. Active leisure events like parkrun promote community exercise. Participation at parkrun was lower when events resumed after lockdown with disproportionate losses of females and those in deprived areas. It is unclear how the pandemic impacted recruitment at parkrun. This study compared the demographics of new participants at parkrun events in Scotland in the years before and after the pandemic. The study found a significant reduction in new participants, with more populated areas more resilient to losses, suggesting rural communities are engaging in more crowd avoidance post- pandemic. The age of new participants declined post- pandemic and the gender ratio shifted towards males. Prior to the pandemic the finishing time of new participants had been slowing, as parkrun became more inclusive, but the pandemic reversed this trend resulting in disproportionate losses of the least fit. The study also suggests the pandemic could have introduced a new barrier to engaging in physical activity, fear of catching COVID, which disproportionately affected women in rural communities. 2026-09-05T00:00:00Z http://hdl.handle.net/1893/38380 Title: Management of invasive alien plants in forests: A global perspective Author(s): Keen, Lizzie; Hardwick, James; Novoa, Ana; Gómez, Rocío; Willby, Nigel J; Mill, Aileen C; Pattison, Zarah Abstract: 1. Forests are critical to the provision of goods and services. They experience many threats including the presence of invasive alien plants (IAPs) which can impact native biodiversity and ecosystem functioning. However, there is a lack of synthesis around outcomes and costs of managing IAPs in forests. 2. We conducted a systematic review to identify (i) where IAP management is reported globally, (ii) which IAP species are being managed, (iii) which methods are being used and (iv) which are the most effective, relative to a control or baseline condition, at managing IAPs in forests. 3. Studies assessing outcomes of IAP management in forests were conducted in 26 countries. The United States dominated the evidence base, accounting for 61% of included studies, covering the widest range of IAP species. This likely reflects a combination of extensive forest cover, high IAP prevalence, and research infrastructure and investment. 4. Across 192 studies, 623 combinations of species and management treatments were studied. Chemical application was most popular (41% of methods) and generally had a high success rate. Most methods had mixed outcomes, with the use of animals for grazing being the most varied. Low replication across treatments made it difficult to draw firm conclusions about management effectiveness. 5. Only 15% of included studies evaluated the effect of seasonal timing on management outcomes, despite evidence from these studies that seasonality can influence success. Furthermore, only 6% of studies reported management costs, and reporting was inconsistent among those that did. 6. Synthesis and applications. This review exposes urgent and critical knowledge gaps in forest IAP management, which need addressing to meet global targets for biodiversity and forest health. These gaps include highly uneven global research effort, narrow species focus, limited method replication, overlooked seasonal effects, and inconsistent cost reporting. A strong legacy of using chemical methods may also be deterring efforts to develop non-chemical approaches. Immediate action is needed to develop standardised methodologies and reporting channels to close these gaps and thus aid informed choice of management options by practitioners. 2026-07-01T00:00:00Z