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Start date: 2020Subject: search.filters.subject.410603 Soil biology

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    Diversity of entomopathogenic fungi (EPF) in soil across adjacent forest and pasture habitats and their interactions with arthropod hosts : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Ecology at Massey University, Manawatu, New Zealand
    (Massey University, 2025-10-29) Guerrero, Michelle
    Entomopathogenic fungi (EPF) are natural pathogens of insects that play a critical role in regulating arthropod populations and maintaining ecological balance. These fungi are commonly found in the soil, where they interact with invertebrates and with other microorganisms, making soil an essential reservoir for collecting EPF isolates. Understanding the distribution and prevalence of EPF across different habitats is crucial for their effective utilization in the biological control of agricultural pests. In this thesis, the diversity of entomopathogenic fungi (EPF) in adjacent forest and pasture habitats of the North Island, New Zealand, was comprehensively investigated. This study utilized an integrative approach, combining traditional techniques such as insect baiting and semi-selective plating with advanced molecular methods, including metagenomics and metabarcoding, to explore EPF communities across these contrasting habitats. In Chapter 1, I introduced the current understanding of EPF and identified key research gaps, setting the foundation for the study. Chapter 2 focused on the incidence of EPF across forest, forest-pasture boundary, and pasture habitats and the association with soil invertebrates. The results showed the highest EPF prevalence in forest soils, followed by boundary zones and finally pastures, demonstrating the influence of habitat conditions on EPF diversity. In Chapter 3, I characterized EPF isolates, primarily Beauveria spp. and Metarhizium spp., and found that forest and boundary soils caused up to 80% mortality in Tenebrio molitor larvae within seven days, indicating their insecticidal potential. Chapter 4 expanded the analysis by applying metagenomic and metabarcoding approaches, revealing additional fungal taxa, such as Cordyceps, Lecanicillium and Ophiocordyceps, which traditional methods could not detect. Chapter 5 assessed the efficacy of EPF isolates against agricultural pests, with pasture-derived isolates achieving higher pathogenicity and potential as cost-effective biocontrol agents. Finally, in Chapter 6, I synthesized these findings, emphasizing the ecological importance of soil habitats as reservoirs for EPF diversity and the adaptability of local isolates to specific environments. I recommended future research to expand studies into transitional zones, conduct field trials, and investigate the evolutionary mechanisms underpinning EPF adaptation and pathogenicity.
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    Sound of the underground : revealing the unheard and unseen world of soil beings through sonic and generative design : a thesis presented in partial fulfilment of the requirements for the degree of Master of Design at Massey University, Wellington, New Zealand
    (Massey University, 2024) Bell, Zoe
    Sound of the Underground is an immersive installation revealing the unheard and unseen world of soil life. One teaspoon of soil contains more microorganisms than humans on earth (Sprunger 2), a vulnerability that is exacerbated by their inaudibility and invisibility to human life. Their lives elude our sensory capacity within the modern world, and therefore our current processes and relationships with soil are to treat it like ‘dirt’: a dead, dark and quiet place in which capitalist exploitation and extraction damage topsoil health. The result of this impacts the health of the planet and its human and non human inhabitants. Investigating the role of sound in the human experience and as vibrational communications belowground, the research reveals how two worlds are becoming closer. As anthropogenic (human) noise traverses the biophillic sound of soil webs, these worlds are more reliant on each other than we may believe. As a project emerging from Aotearoa New Zealand, a Te Ao Māori worldview acknowledges the sensitivities and complexities of our soils, as well as the indivisible link between oneone ora and tāngata ora. The research is guided by the He Awa Whiria or Braided River framework. This mixed-method approach allows the research to move between a Māori worldview of our relationships with soil and western-centric ecoacoustic research. Methods of acoustic investigation are employed to reveal the unheard. Ecoacoustics record the sound of soil organisms and pick up frequencies beyond the human hearing range. These recently developed research methods are unearthing the need to understand how we can better care for enhanced soil futures. The unseen is explored by participating in wairākau or composting, then examining samples under the microscope. I harness generative design methods to create audio-reactive evolving systems that draw from ideas of mauri and the nature of soil life. Sound of the Underground was supported by Wellington-based artist and filmmaker, Mumu Moore, who incorporates sounds of Taonga Pūoro (traditional Māori instruments). The installation explores the conversations expanding both the human and soil realms, immersing you in ancient vibrations that will lead you deeper into relationship with our soils.