Spatial drivers of providing and receiving nature's contributions to people
Spatial drivers of providing and receiving nature's contributions to people
A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at University of Canterbury
Spatial drivers of providing and receiving nature's contributions to people
(2024) O’Brien, Sophie Adelaide
Embargoed until March 2027
Land application of winery wastewater : implications for plant growth and soil quality
Land application of winery wastewater : implications for plant growth and soil quality
A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at University of Canterbury
Land application of winery wastewater : implications for plant growth and soil quality
(2024) Nightingale-McMahon, Max
Winery wastewater (WW) is a high-volume biowaste that requires effective disposal systems that minimise environmental impacts and potentially capture value. In New Zealand, approximately 380,000 m3 of WW is generated annually, with the Marlborough region accounting for around 280,000 m3 yr-1. There is growing recognition of the need to improve current WW disposal practices. Land application of WW is a low-cost disposal method that could significantly reduce the environmental risks associated with direct discharge into surface and groundwater bodies. This thesis aimed to determine the likely short and long-term effects of irrigating WW to land at rates where the water and nutrients may be beneficial to soil and plants, with a focus on carbon (C) retention. The specific objectives were to: 1) Quantify how manipulation of WW and receiving soils may improve soil quality and C retention, 2) Determine if organic C (OC) in WW can increase soil C via direct sorption and under what conditions, 3) Quantify the fate of OC in terms of soil organic matter changes and losses via mineralization and leaching, and 4) Elucidate the C sequestration potential via vegetation growth in WW irrigation plots.
A field survey was conducted at three Marlborough vineyards to quantify loading rates and accumulation of WW nutrients in soil. The WW irrigation added ca. 1.8 t ha−1 yr−1 of Na and 4 t ha−1 yr−1 of total OC. WW application increased soil pH, phosphorus, and Na across sites compared to controls. However, soil C decreased under WW irrigation (mean 1.7%) relative to controls (2.3%), equivalent to a loss of ~100 t C ha−1 over 600 mm depth, despite WW adding 4 t C ha−1 yr−1. Findings recommend using K-based over Na-based cleaning chemicals to reduce sodicity. Focusing on C retention and sustainable vegetation growth could increase soil C stocks to offset emissions.
Equilibrium batch experiments aimed to quantify the adsorption capacity of an Anthrosol, representative of common soil types in New Zealand's wine regions, for OC in WW. The soil sorbed up to 1729-4165 mg C kg soil-1 from WW. Increasing WW pH from 5 to 7 led to increased organic C sorption. The use of Na-based cleaners and pH adjustment may increase OC sorption compared to K-based products, but the harmful effects of exchangeable Na on soil structure and plant health may negate potential benefits.
A glasshouse mesocosm experiment investigated changes in ecosystem C balance when WW was applied to Lolium perenne (perennial ryegrass). Irrigating WW resulted in the mesocosms being a net C sink, retaining approximately 327 g C m-2 compared to 84 g C m-2 for controls over 118 days. However, gains were mostly due to high C input from WW, with small leaching losses. Signs of necrosis were observed in WW-treated Lolium perenne, corroborated by decreased above-ground biomass production. Soil respiration could mineralise up to 40% of added C from WW during peak biomass production.
The impact of WW irrigation on nutrient dynamics and biomass production in four New Zealand native plant species (Phormium tenax, Coprosma robusta, Cordyline australis, Kunzea robusta) and Lolium perenne was investigated in a glasshouse pot trial. WW irrigation significantly increased soil pH, electrical conductivity, Na, and ammonium, and decreased nitrate. No significant differences in above-ground biomass were found for native species, but Kunzea robusta exhibited necrosis. Lolium perenne biomass significantly decreased under WW treatment. There were significant increases in Na in native plant foliage, with Kunzea robusta having the highest concentration. WW application resulted in increased leachate total C, Na, Mg, Ca, and electrical conductivity.
This thesis demonstrates that land application of WW can lead to accumulation of nutrients, particularly Na, in soil and plants. While OC in WW represents a potential resource for improving soil quality and C sequestration, the fate of this C requires further investigation as significant losses were identified in long-term WW application sites. The adsorption capacity of the studied soil for WW-derived organic C indicates loading limits to prevent leaching and infiltration issues. WW application to Lolium perenne resulted in a net C sink, but with reduced plant growth, indicating the need for appropriate application strategies. Native plant species exhibited differential responses to WW irrigation, with some showing potential for phytoremediation and C sequestration.
Future research should focus on developing regional WW application guidelines based on soil properties, assessing the long-term stability of adsorbed OC, investigating Na toxicity thresholds and phytoremediation potential of native species, and optimising C retention and biomass production in WW irrigation systems. Improving WW disposal practices through effective nutrient assimilation and promoting sustainable vegetation growth could contribute to the environmental and economic sustainability of New Zealand's expanding wine industry.
The impact of long-term culture on primary bovine myoblasts : implications for cultivated meat production and allergenicity
A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at University of Canterbury
(2025) Trlin, Hamish John Francis
With global demand for meat products growing and traditional methods of production nearing their limits, alternative methods of meat production are required. While cultivated meat is a promising alternative to traditional meat, information about the impact of long-term culture on cultivated cells is lacking. Here, I compare the use of high impact methods of stem cell isolation and enrichment in cultivated meat research and product development to alternative low impact methods, define the impacts of isolation and long-term cell culture on the allergenicity of cultivated cells, and determine the broader impact of long-term cell culture on protein abundance and modification in cultivated cells.
Chapter 2 demonstrates that enzymatic digestion and fluorescence-activated cell sorting remain the preferred methods for myoblast isolation and enrichment. While whole tissue explant isolations and collagen pre-plating enrichment have theoretical benefits as low impact alternatives, these methods were unable to produce sufficiently pure populations of myoblasts for use in long-term cell culture. Chapter 3 then reveals differences in the relative abundance or detection of allergens in native and cultured cells, demonstrating why allergenic equivalence should not be assumed. Significant reductions in the abundance of major protein allergens Bos d 6 and Bos d 13 suggest the allergenic potential of cultivated beef meat may be reduced compared to traditional beef meat. However, an increased detection α-Gal in cultured cells, alongside an increased abundance of currently insignificant protein allergens ENO1, ATP5PO, and COL1A2, suggests that allergenicity may be increased. Finally, Chapter 4 identifies significant, ongoing differences in the proteomes of primary bovine myoblast proteomes throughout the duration of long-term culture. More than 70% of proteins are shown to be significantly differently abundant following short or long-term culture, accompanied by changes in the general patterns of glycan modification. These results clearly demonstrate that culture duration has a significant effect on primary stem cell populations.
This thesis provides evidence that allergens are differently abundant in native and cultivated cells, calling to question the present assumption of allergenic equivalence between traditional and cultivated meats. While the clinical significance of these results have yet to be determined, they highlight a need for the optimisation of myoblast isolation and culture to reduce differences between native and cultured cells. Minimising these differences is likely to improve the characteristics of primary cultivated cells, thus cultivated meat, while reducing allergenic potential.
Uniformity is a myth : insights from Aotearoa New Zealand Pleurotus on intraspecific variation in fungal genotypes and phenotypes
A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at University of Canterbury
(2024) Hera, David
The aim of my thesis is to contribute to our understanding of intraspecific variation in fungi through the study of five Pleurotus species in Aotearoa New Zealand, exploring phenotypic and genotypic variation by applying methodology spanning systematics, ecology, biology, genomics, conservation, and food science. Intraspecific variation drives evolution, breeding, and food production practices, with implications for conservation, pathogenicity, biotechnology, and agriculture. Although well-studied in animals and plants, few mycological studies have focused directly on intraspecific variation, despite its growing recognition in the field. Edible oyster mushrooms (Pleurotus) are ideal model organisms because they experience natural selection in the wild and artificial selection in cultivation.
As a foundation to assess phenotypic and genotypic variation in Pleurotus species of Aotearoa, I first conducted a phylogenetic study to clarify the species boundaries within the genus (Chapter 2). I constructed a multi-gene phylogeny using ITS, LSU, RPB1, RPB2 and Tef markers. I discovered a cryptic indigenous subspecies within P. pulmonarius and resolved taxonomic ambiguities around P. djamor in Aotearoa. Confusion over species boundaries has previously led to the importation of this species, which has a potential for invasion and hybridisation with indigenous species. These refined species boundaries have significant implications for conservation and biosecurity.
Building on the refined species boundaries, I assessed how vegetative and reproductive growth traits vary between and within species. This study included three clonal replicates of 104 strains of five Pleurotus species grown in controlled conditions (Chapter 3). I discovered that intraspecific trait variation matched or exceeded interspecific variation, and found remarkably high levels of variation between clonal replicates of strains. Cultivated strains displayed less intraspecific variation than wild strains, suggesting the impact of cultivation history on phenotypic variation. My findings stress the necessity of true biological replication in mycology and challenge conventional definitions of individuality.
To understand genotypic variation within a wild-collected fungus, I conducted population genomic analyses and the first Pleurotus pangenome analysis using 29 P. purpureo-olivaceus strains from across the South Island (Chapter 4). I found a highly conserved core genome and overall genetic homogeneity, which was contrasted by diverse mating type loci and a large accessory genome. Instead of multiple populations isolated by distance or topographical barriers, my findings support a single panmictic South Island P. purpureo-olivaceus population with unrestricted gene flow.
Variation in fungi occurs at many levels and affects conservation, biodiversity, food production, and biotechnology. Both fundamental research and practical applications of fungi can benefit from considering the range of phenotypes and genotypes rather than species means and reference strains. My work contributes to a holistic understanding of fungal species and individuality, advancing fungal biology and informing cultivation practices and strategies for biodiversity conservation in the face of global environmental change. The diversity of Pleurotus phenotypes supports the identification of productive strains for indigenous oyster mushroom cultivation to enhance agricultural resilience, although further research and collaboration with indigenous communities – iwi Māori – are essential to ensure appropriate benefit sharing.
Development of functional food with pea cooking water and the effect on human postprandial glycaemic response
A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University
(Lincoln University, 2024) Zhang, Yanyu
High GI carbohydrates are associated with several diseases, including diabetes, obesity, and cardiovascular disease (CVD). The rate of starch digestion and absorption significantly impacts metabolic responses. Slowly digestible carbohydrates are advantageous for managing metabolic disorders such as diabetes and hyperlipidaemia and are found in legumes, pasta, and whole-grain cereals. Peas, a high-quality protein source, are typically consumed after soaking and cooking. Pea cooking water is the by-product of split yellow peas, often regarded as an ideal egg white substitute in bakery products due to its emulsifying properties. Pea cooking water (PCW) was recently reported to be rich in proteins, fibres and micronutrients. However, current research has not specifically investigated the nutritional aspects of pea cooking water, although significant nutrient loss is known to occur during cooking.
This study investigated the potential of pea cooking water to manage glycaemic responses in carbohydrate-rich foods by examining its effects on human glycaemic levels as well as the structural and textural properties of these foods. This study examines the structural and nutritional modifications that occour to pasta when PCW or pea flour (PF) are incorporated into the formulation. The inclusion of freeze-dried PCW (PCWFD) in pasta significantly (P<0.05) reduced the optimal cooking time (OCT) and altered water absorption capacity due to its unique structural attributes. Compared to traditional wheat pasta, PCWP exhibited a lower OCT (P<0.05), reduced swelling index (P<0.05), and higher cooking loss when substituting 20% of semolina with PCWFD (P<0.05). Additionally, pasta substituted semlina with 10% and 20% PCWFD showed increased tensile strength and decreased cutting force (P<0.05), maintaining an intact microstructure and consistent particle size distribution.
The incorporation of PCWFD modified protein-starch network of the pasta. The modified protein-starch networks in PCWP and PFP resulted in slower glucose release and a lower glycaemic response (P<0.05). The study explored the impact of varying cooking times and PCWFD levels, finding that longer cooking times and higher PCWFD concentrations affect cooking loss and water absorption, influencing glycaemic response. PCWP performs comparably or better than traditional pea flour pasta in in vitro glucose digestion tests. The food matrix does not disrupt the effect of PCW in reducing and slowing glucose release, as demonstrated by comparisons with rice boiled in PCW versus normal water.
PCW incorporation significantly reduced postprandial glycaemic responses in human subjects (P<0.05), attributed to the high protein content and fibre effects on gastric emptying. The lower glycaemic index (GI) effect is also due to the higher protein content, lower starch content, and protein-starch interactions. Despite a fully gelatinized structure, PCWP maintain a reduced glycaemic response. These findings highlight the potential of PCW as a functional ingredient to enhance the nutritional profile of pasta, reduce glycaemic responses, and promote sustainable food processing practices. The present work addressed the potential health benefits of PCW to develop of functional food by investigating the effect on human postprandial glycaemic response. It represented a functional and innovative approach to food development while promoting environmentally sustainable practices.
Spatial agroecology: modelling multiple ecosystem services in periurban landscapes
Spatial agroecology: modelling multiple ecosystem services in periurban landscapes
A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University
(Lincoln University, 2024) Morris, Richard Minton
Urban growth and agricultural intensification share a common trait of reducing landscapes' capacity of producing the critical ecosystem services (ES) on which they depend. The objective of the work described in this thesis was to develop a spatially explicit ES-based design method for the configuration of landscapes to generate regulating ES. Literature review, which is described in Chapter 2, identified a nexus of four research fields - Ecological Urbanism, Landscape Ecology, ES science and agroecology - as an unexplored framework for this ES-based design approach. The method used in this work is described in Chapter 3, where a key flaw in current ES modelling tools forms the basis for a Geographic Information Systems (GIS)-based conceptual model, ESMAX. Present models are characterised by 'the biophysical gap', an oversight of spatial interactions between ES-supplying landscape components. This inhibits their application to spatial design i.e., the configuration of those components to enhance ES performance. ESMAX is structured around the fundamental natural phenomena of distance-decay as exhibited by all regulating ES, enabling an original method of quantifying and visualising regulating ES produced by different configurations of landscape components. The results of Chapter 3 conceptually validated the model and provided the data for Chapter 4, which proposed a model for assessing landscape multifunctionality (or simultaneous supply of multiple ES) from different landscape configurations. Importantly, the results for different configuration options generate a solution space with which to negotiate specific ES demands and specific contextual spatial constraints. Chapter 5 applied ESMAX and the solution space in an agricultural context. This spatial agroecological approach determined that different configurations of the same total area of trees in a 1 ha paddock produce markedly different levels of ES performance, and that this approach may be useful in supporting an adaptive transition from conventional agriculture to agroecologically based farming systems. Chapter 6 applied spatial agroecology to a 190 ha periurban development site, demonstrating how the same apportioned area of agroecological systems, when subdivided and distributed differently across the site, has a significant bearing on multiple ES production. This suggests that urgent consideration should be given not only to placing trees on farm, but how trees should be placed on farm. Similarly, it supports not only the integration of agriculture with urban systems, but the specific spatial design of agroecological systems to address the regulating ES demands of the urban system. The spatial agricultural approach outlined in this thesis highlights the potential for agroecology in the Anthropocene as a spatially effective source of multiple regulating ES to surrounding communities at various scales.
Using portfolio analysis to assess diverse agricultural landscapes under climate change: A case study in the Marlborough wine region
A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University
(Lincoln University, 2024) Barry, Michelle
Farmers and growers are increasingly aware of climate change related risks for their operations as they observe a greater frequency in extreme weather events and changes in crop growth cycles. While reactive adaptation by farmers to climatic variability has always occurred, this may not be sufficient in the long term when anticipatory and planned adaptation is required, e.g., changes in cultivar or the development of new markets. Geographical and biological diversification of agricultural production systems has been proposed as a potential climate change adaptation strategy. Understanding how alternative crops, land-uses and management practices will perform under future climates and deliver to stakeholder goals is critical before extensive land-use and practice change occurs. Developing this understanding is difficult due to the high degree of uncertainty of future climatic conditions and the ability of commonly applied economic analysis tools to account for this deep uncertainty. To address these challenges, this PhD developed a stakeholder centred climate change adaptation process that utilises Portfolio Analysis to identify diversified vineyard portfolios and characterised their riskiness across a range of climate change scenarios. In developing this process, the study applied a mixed methods framework, integrating qualitative and quantitative approaches. These included a literature review, stakeholder mapping, focus groups, biophysical assessment and economic modelling, integrated in a case study on Marlborough Sauvignon Blanc.The research found that Portfolio Analysis can be effectively integrated with social and biophysical science to develop diversified vineyard portfolios that are more robust against a range of possible climate futures, helping to inform decision making in the context of deep uncertainty. To accelerate adoption, adaptation needs to be integrated into wider wine business and industry decision making and strategy development. Recognising that adaptation sits alongside existing ambitions and priorities, particularly around environmental sustainability, is also critical.
Three essays on advancing modelling of sustainable rural land use change decision making in Aotearoa New Zealand
A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University
(Lincoln University, 2025) Wang, Le
Understanding the processes driving the development of niche industries is crucial for achieving sustainable agricultural transitions. In Aotearoa New Zealand (NZ), niche agricultural products, primarily from horticultural industries, have long existed but have struggled to evolve into mainstream agricultural systems. The total land area dedicated to these alternative systems remains small compared to pastoral farming, such as dairy and sheep/beef farming. Since the 1980s, the expansion of dairy farming and a large reduction in sheep number have dominated agricultural land use change in Aotearoa NZ. However, the last decade has witnessed a shift in some of the most intensively farmed dairy regions, such as Canterbury, Marlborough, and Southland, where dairy farming has declined in total area while horticultural land use has grown. These divergent trends provide an opportunity to investigate the dynamics of rural land use change and the potential for transitioning toward more sustainable agricultural systems. This thesis explores the drivers, dynamics, and patterns of rural land use change in Aotearoa NZ through three interconnected essays, each addressing critical aspects of the transition process. Essay One employs machine learning methods, particularly artificial neural networks (ANNs), to identify and evaluate the key drivers of sustainable land use transitions. Using data from the 2021 Rural Decision Makers Survey, this essay highlights the importance of farmer and farm characteristics, values, and demographics in influencing land use decisions. Essay Two develops an opinion dynamics model to examine how farmers’ attitudes towards land use change evolve within agricultural communities. The model captures the role of social networks and peer influence in shaping decision-making processes, offering insights into mechanisms of consensus or polarization among farmers. Essay Three integrates the methodologies and findings from the first two essays into an agent-based modelling (ABM) framework. This essay simulates rural land use transitions in Canterbury over a 25-year period, considering farm-level heterogeneity, social interactions, and real-world geographical characteristics. The results reveal key patterns of land use change, including a gradual shift from sheep and beef farming to horticulture, while dairy farming shows limited transition.
Collectively, the three essays provide a comprehensive framework for understanding and modelling sustainable land use change from the perspective of decision-makers. This research contributes to the literature on agricultural land use by combining machine learning, social network analysis, and agent-based modelling to offer robust evidence and actionable insights. The findings highlight opportunities for fostering sustainable land use transitions and inform policies and interventions to support alternative land use systems in Aotearoa NZ.
A transdisciplinary approach to understanding the connections between soil and people, through food production
A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University
(Lincoln University, 2024) Gillespie, Julie
There is a disconnect between soil, food, and people, that is being exacerbated as our populations become increasingly urban-based. This presents a ‘wicked’ challenge for soil and food security that soil science alone is unable to address. Resolving this issue requires understanding the extent and nature of the current (dis)connections, providing an opportunity to extend beyond the disciplinary boundaries of soil science. This research aims to develop an understanding of the (dis)connections between soil and people through the conduit of food in a place-based context by operating at the interface of mātauraka Māori (Māori knowledge) and soil science. This thesis provides two soil-centred examples of TDR in an Aotearoa New Zealand context, applying the He Awa Whiria (braided rivers) epistemological framework to guide the weaving of knowledges.
To develop insight into how soil science and mātauraka Māori can be woven together and gain an understanding of historical connections between soil, food, and people, a case study guided by the questions of Mana Whenua regarding their past horticultural land use at Pōhatu (Flea Bay), Te Pātaka o Rākaihautū (Banks Peninsula), is undertaken. In this study, mātauraka Māori identified likely māra (garden) sites in the bay with oral histories identifying features such as gravel additions to the soil to improve drainage and retain warmth. Analysis of soil horizons modified with rounded beach gravels identified phytoliths with a morphotype consistent with kūmara leaves. Undertaking this study has demonstrated the importance of relationships when weaving knowledges, and the benefits of recognising equal value of the knowledges involved.
Building on the results and learnings from the Pōhatu case study, a TDR methodology is applied to develop the place-based Food-Landscape Networks (FLN) framework, placing soil at its centre. The FLN framework applies a holistic approach to understanding the reciprocal connections between soil, food, and people in contemporary local food production systems. To assess the suitability of the FLN framework for understanding connections between soil, food, and people, it has been applied to three food-landscapes in Waitaha (Canterbury). Applying the framework makes visible the (dis)connections between soil, food, and people in three food-landscapes with the primary disconnection being people and soil across all three food-landscapes, as well as identifying where interdisciplinary collaboration is needed.
This thesis enhances understanding and demonstrates the importance of engaging with mātauraka Māori as a knowledge of equal value to soil science for addressing complex, soil-centred environmental challenges facing Aotearoa New Zealand. The application of the transdisciplinary FLN framework illustrates the complexity of understanding the reciprocal connections between soil and people, highlighting the limitations of soil science in understanding and addressing this disconnect alone. This signals the need for interdisciplinary approaches, nested within TDR, for consumer disconnects to be addressed. The co-production of knowledge by weaving knowledges together to assess and understand these connections provides an opportunity to connect, and reconnect, people with where food comes from to work towards soil and food security.
Understanding the bioaccessibility of grape phenolics in association with milk proteins
Understanding the bioaccessibility of grape phenolics in association with milk proteins
A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University
Understanding the bioaccessibility of grape phenolics in association with milk proteins : A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University
(Lincoln University, 2025) Matiwalage, Iresha Nirmalie Wickramanayake
Embargoed until March 2027
Edible insects, mātauranga, diet, and lifestage to explore the potential of Aotearoa New Zealand insects as food
A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University
(Lincoln University, 2025) O'Connor, Chrystal Te Ohorere
With growing global concerns about food security and environmental sustainability, insects as food could provide a promising alternative protein source. However, research on entomophagy (eating insects) has predominantly focused on Western perspectives, who perceive edible insects as a novel concept, and there is limited exploration of Indigenous knowledge systems. This thesis investigates the potential of native Aotearoa New Zealand insects as sustainable and nutritious food sources, integrating mātauranga Māori (indigenous Māori knowledge) with Western scientific approaches.
A survey of Māori participants (n=172) revealed that insects are culturally significant, with 47% of participants having consumed insects or knowing whānau (family) who had. Larvae of the huhu beetle (Prionoplus reticularis White, 1843) was identified as the most consumed insect, with 89% of participants naming it as a traditional food source. The survey also indicated that participants were significantly more likely to consume insects that were native to Aotearoa New Zealand, fed rākau rongoā (medicinal plants), or historically eaten by Māori (P<0.05). Most participants indicated they would eat insects either processed or whole (49%, N=78), with a total of 87% of participants indicating they would be willing to eat insects in some form (processed 37%, N=59, whole 4%, N=7). Through integration of mātauranga Māori, ecological factors, and nutritional considerations, three Lepidoptera species were selected and studied as whole insects; kawakawa looper (Cleora scriptaria (Walker, 1860)), brindled bell moth (Epalxiphora axenana Meyrick, 1881), and brown headed leafroller (Ctenopseustis obliquana (Walker, 1863)), and two culturally significant plant diets; kawakawa (Macropiper excelsum (G.Forst.) Miq.), and mānuka (Leptospermum scoparium Forst.). The selection process considered factors such as sustainability of rearing processes, life cycle length, plant associations, and cultural significance.
Amino acid (AA) and mineral analysis, using high-performance liquid chromatography (HPLC) and inductively coupled plasma mass spectrometry (ICP-MS) respectively, showed that all three species met FAO/WHO requirements for essential AAs of 40%, with the essential AA to non-EAA ratios ranging from 41.1% to 44.5%. The brindled bell moth showed significantly higher levels of several minerals, including sodium, magnesium, potassium, and calcium, with iron content (21.4 mg/100g dry weight (DW)) (P<0.05) that exceeded New Zealand recommended daily intake. Diet studies with the brown headed leafroller showed that larvae and pupae reared on either mānuka or kawakawa had significantly higher levels of macrominerals, particularly sodium, magnesium, potassium, and phosphorus, compared to those on laboratory diets. Larvae reared on mānuka demonstrated higher concentrations of several essential AAs, including histidine, isoleucine, threonine, and valine, with total essential AA content (223.2 mg/g DW) significantly higher than those on laboratory diet (166.6 mg/g DW) (P<0.05). The dietary influence was more significant than life stage in determining amino acid composition.
Mātauranga Māori recognises that kawakawa leaves eaten by the kawakawa looper have enhanced medicinal properties. Supporting this knowledge, metabolomic analysis using rapid evaporative ionisation MS (REIMS) revealed distinct chemical changes in leaves eaten by the kawakawa looper (444 features, 16.08% differing from non-eaten leaves). These changes were unique and specific to insect herbivory, as artificially damaged leaves showed no significant differences from control leaves. The metabolomic response also varied between species, with the kawakawa looper and brindled bell moth showing the most distinct profiles (20.79% features differing), suggesting species-specific interactions between insects and kawakawa.
This research provides the first comprehensive analysis of native Aotearoa New Zealand insects as a sustainable food source, integrating mātauranga Māori and Western scientific approaches. The findings establish a foundation for developing nutritious insect-based foods that align with cultural values and environmental sustainability, demonstrating the potential of native insects in addressing food security challenges in Aotearoa New Zealand and globally.
Grubs up? How insects become food in Aotearoa, New Zealand
Grubs up? How insects become food in Aotearoa, New Zealand
A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University
(Lincoln University, 2025) Hyde, Caitlin
The consumption of alternative proteins is often proposed as a means to alleviate global problems such as environmental degradation and food insecurity. However, achieving such changes remains challenging. To explore this issue, this thesis presents an in-depth case study of the edible insect sector in Aotearoa, New Zealand, a small novel food sector that emerged in the mid-2010s before rapidly declining. This thesis explores the sector’s decline by examining what leads to a thing becoming food. Through this process, the conceptual category of food is also interrogated.
This thesis mobilises a sub-field of geography, sometimes referred to as the ‘becoming food’ literature, a relational approach to food which attends to the embodied practices that lead to a thing being eaten. To better understand the differences between practices and their implications, this literature was brought into conversation with the concept of multiplicity from material semiotics. While both approaches are relational and attend to practices, material semiotic approaches conceptualise relationality differently, not drawing a boundary around where relations end. Their integration enables analysis to extend beyond the relations of eater-eaten to explore broader aspects of production and consumption while maintaining a focus on embodied practice.
To attend to differences, this study incorporated various 'site types' including edible insect research projects, restaurants, farms, food events, and retail outlets. Following the emphasis on practices common to becoming food studies and material semiotics, the methods of participant observation and autoethnography were employed, alongside semi-structured interviews and document analysis.
This thesis examines how insects become food by articulating several enactments of edible insects that have emerged in the Aotearoa sector. Insects were variously enacted as 'good food' (positioned as solutions to various problems), as novelty items (contradicting industry efforts to normalise them), and as pests (in tension with their status as food). The tensions between these enactments and the ambiguity in the status of insects as food led to their decline in the Aotearoa market. Unless edible insects performed a distinctive function, they were replaced with less difficult alternatives that could fill the same role.
While edible insects did become food in many situations, the edible insect sector was largely unsuccessful. Becoming food and market success has typically been equated in the becoming food literature. However, by drawing on multiplicity, this thesis demonstrates the need to treat these as distinct phenomena, contributing to a more nuanced understanding of the becoming food process and providing insight into food transitions and novel food acceptance. Although edible insects have not yet fulfilled their initial promise of reducing hunger and environmental pressures, their potential to transform our food system may lie not in mass consumption but in their power to challenge our assumptions about what food is.