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Canola, also known as rapeseed (Brassica napus L.), is an oilseed that produces a healthy food-grade oil, canola meal by-product, and biofuel. It is the fourth most grown grain in Australia. Genetically modified (GM) canola currently represents approximately twenty percent of national canola production; hence, with clashing public and industry perceptions of genetically modified organisms (GMOs), transparency and traceability must be enabled throughout the supply chain to protect markets and relationships with consumers. GM canola must not cross-contaminate non-GM canola as our largest export market, Europe, has extremely strict protocols on GMOs. GM and non-GM canola cannot be differentiated by the human eye, with polymerase chain reaction (PCR) methods currently the main alternative, which is expensive and time-consuming. This thesis evaluates the potential to differentiate GM from non-GM canola using the novel, rapid, and non-destructive technique of hyperspectral imaging combined with machine learning. Hyperspectral imagery captures and processes wavelengths beyond simply red, green, and blue. It has a pre-existing multitude of uses including the characterisation and variety identification of other grains. In this study 500 images each of non-GM and GM canola seeds were captured. Seeds were placed on a black background with two lights sources. Images were captured from the 400nm to 1000nm wavelengths, a total of 80 bands, at a 25-millisecond exposure time. These images were run through a convolutional neural network in Keras for analysis. The high dynamic range and raw files were combined into a NumPy file for the hyperspectral image generator. Contrary to expectations, however, the models using the bitmap image files performed similarly to the models receiving the hyperspectral images. Regardless, both produced high validation accuracies around 90%, indicating a detectable phenotypical difference between the two, and further studies could lead to the developmen

Tea flavor comprises two groups of chemical compounds that contribute to taste (non-volatile compounds in water) and aroma (volatile organic compounds, VOCs). Aromatic substances are the most crucial components of tea quality and stimulating the consumers’ sense of smell. My PhD research focused on understanding the factors which can impact or improve aromatic substances in tea leaves from the pre-harvest application of organic manure to post-harvest treatments. This study explored the interaction between the tea plant–microbiome and the mechanism of how the application of organic fertilizer change the metabolites of the tea plant, particularly VOCs changes, and furthermore, to provide a theoretical reference for the control of green tea aromatic quality through analysis of real-time aromatic characteristics during tea brewing. The results showed that the application of organic manure in tea plantations can trigger significant changes in the metabolic pathways of amino acids, sugars and fatty acids in tea leaves related to aroma. The application of organic manure in tea plantations can significantly change the composition and abundance of rhizosphere-associated bacterial communities. Organic acids and fatty acids affected by the application of organic manure were potential regulators mediating the plant-bacteria interaction in the rhizosphere soil. Proteiniphilum, Fermentimonas, Pseudomonas, Saccharimonadales, Gaiellales, Acidobacteriales and Gaiellales were the potential genera that can regulate relative contents of organic and fatty acids. Esters, aldehydes, alcohols, fatty acids and alkaloids were the predominant volatile groups in tea infusions. The variation of the same volatiles between the tea infusion and the corresponding headspace tended to balance during the tea brewing process. Two to three minutes was identified as the best duration for the tea brewing that maximized the abundance of aromatic chemicals in the headspace released from the tea infusions. T

Ozone (O3) has distinct advantages over other stored grain pest treatments, such a toxicity to a broad range of organisms and rapid auto-decomposition to oxygen without leaving residues, making it a promising fumigant to protect stored grains. This research project focused on understanding how stored grain insects and barley respond to ozone. Several studies have assessed the efficacy of O3 against pests in stored maize and wheat grain, but little is known about the toxicity of O3 on stored grain pests in barley and its effects on barley quality and germination. My results indicated that more than 2 days of ozone treatment should be considered as the endpoint to evaluate insect mortality rate due to delayed toxicity of O3. C×t product 36 mg h/L (700ppm × 24 h) offered complete mortality for all stages of the two species tested insects R. dominica and T. castaneum, without affecting barley commercial quality. As barley is to be used for malting purposes, it is important to understand that effect of ozone on barley germination, whether positive or negative. Relevant short period treatment (20 min) with ozone at 700ppm can facilitate barley germination, but it was adversely impacted for longer O3 exposure times, such as 24 h. Ozone treated barley seed released a greater number and quantity of volatile organic compounds (VOCs). However, alcohols and hydrocarbons gradually decreased, whereas aldehydes and organic acids markedly increased with increasing time of ozone treatment. Acetic acid was identified as a potential ozone stress-specific marker. Furthermore, the dosage-dependent function of acetic acid on barley germination was verified and results indicated that low dosage (0.05 - 0.5 mg/g of barley) of acetic acid could lead to increasing germination rate. Potential chemical biomarkers from barley seeds during germination were identified using gas chromatography mass spectrometry (GC/MS). Statistical assessment of the data via principal component analysis demonstrat

Blueberries (Vaccinium corymbosum L.) are cultivated worldwide due to their important commercial value and the health benefits of the fruit. Botrytis cinerea is a highly destructive horticulture pathogen with a host range of 1400 plant species, including blueberry. Worldwide its management costs billions of dollars annually. Biosecurity controls require that international shipments of products be pest-free, which is increasingly difficult due to the ban of key pesticides. Instead, biological control strategies can be used to manage postharvest fruit pathogens. Surveys on postharvest blueberry in Western Australia were conducted to assess the fungal species associated with fruit decay and their pathogenicity. The fungi isolated were Botrytis cinerea, Alternaria alternata, Cladosporium cladosporioides, Penicillium brevicompactum, Epicoccum nigrum, Aureobasidium pullulans, Diaporthe australafricana, a Verticillium sp., and a Ceriporia sp. Botrytis cinerea, A. alternata, C. cladosporioides A. pullulans, and D. australafricana were pathogens. The other four were not. Two methods were used to evaluate the eight fungi as putative antagonists against B. cinerea. Firstly, each antagonist was screened for direct antagonism against B. cinerea on half-strength potato dextrose agar (PDA). Secondly, the involvement of secondary metabolites was evaluated by growing each antagonist on a dialysis membrane placed on the surface of half PDA for four days before removing the membrane and placing B. cinerea in the centre of the PDA plates and monitoring its growth. E. nigrum was found to be the most effective antagonist, followed by Verticillium sp., the Ceriporia sp. and A. pullulans using both methods. The eight putative antagonists were then screened for their ability to produce non-volatile organic compounds (NVOCs) in the presence and absence of B. cinerea using direct immersion solid-phase microextraction (DI-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). The met

The prospects of lupin grain as an animal alternative and functional food have increased over recent decades due to its high protein content and low level of anti-nutritional fractions that can help to improve the nutritional value and human health benefits. Australian Sweet Lupins are used in making foods such as tempe, miso and traditional soy sauces. Soybeans are used in food products such as meals, drinks, and sports beverages. They aretherefore, very beneficial to demonstrate the possibility of lupin milk and soybean proteins to produce cheese without the saturated fat found in dairy milk. This thesis focuses on proteomic analysis of soybean and lupin seed milk in cheese products made with different coagulation methods, using a range of proteome technologies including isoelectric focusing (IEF), two-dimensional gel electrophoresis (2D-PAGE) and liquid chromatograph mass spectrometry (LC-MS). Two narrow-leaf lupin cultivars PBA Jurien and Mandelup cultivar and one cultivar (Bunya) of soybean (Glycine max) were studied for proteomic analysis to identify their diverse proteins. Whole and split-seed milk from soybean were extracted via two filtration methods, cheesecloth and centrifugation. A total of 97 protein spots were identified, 49 of which displayed different abundances. Of the two separation techniques, centrifuge separation gave higher protein and more intense protein spots than cheesecloth separation. In addition, split-seed soybean milk contained fewer allergenic proteins, then did whole-seed milk. Also, the results indicate that cheese can be obtained from soybean milk filtered by either cheesecloth or centrifugation. This thesis also investigates the influence of filtration techniques on lupin seed milk. A total of 230 proteins were identified, of which 60 protein spots showed differential abundance, different proteins either present or absent, or differential protein quantity between the samples of lupin milk. For both cultivars, cheesecloth separatio

Australian agricultural are facing growing challenge to biosecurity threats. Insect pests are a major issue negatively effecting both the quality of stored grain and consumer health. Fumigation is a widely used method for control of a variety of insect pests due to its high degree of efficacy and cost effectiveness. Phosphine is the main fumigant deployed for the control of stored grain insect pests. However, researcher has shown that most of the stored grain insect pests have developed resistance to phosphine, which has been leading to ineffective control of many important stored grain insect species like C. pusillus and C. ferrugineus. As a result, there is an urgent need to identify and evaluate an alternative fumigant. Ethyl formate is proposed as a viable alternative to phosphine due to its status as a registered food additive, favourable environmental properties and low toxicity to humans. In comparison with all previous studies, fumigation experiments were conducted using a continuous flow-through laboratory process to maintain constant concentrations of ethyl formate and low levels of respiratory CO2 (<0.08%). The procedure minimised the effects of sorption by exposing test insects without media and minimised the effect of CO2 by use of continuous flow. The toxicity data of ethyl formate obtained from this experiment are more robust as the continuous flow-through system operated under a constant concentration of ethyl formate at a constant 25° C and 62.5% r.h. and low CO2 concentrations during the 6 h exposure period. Ethyl formate as fumigant offers quick and higher efficient to kill both susceptible and resistant strains of C. pusillus and C. ferrugineus at lower dosage level. There was no significant different mortality between susceptible and resistant strains of C. pusillus e g., the observed Ct product at LD50=13.09 and 12.75 mg h/L and LD99.5=28.17 and 29.55 mg h/L, and for C. ferrugineus at LD50=13.11 and 13.26 mg h/L and LD99.5=29.28 and 28.22 mg h

Stored grains are paramount commodities to be preserved and stocked for future supply to the market according to the requirement. However, one of the major problems during storage is insect pests, of which insects from Trogoderma sp. especially khapra beetle (Trogoderma granarium) is considered the world most dangerous stored grain insect pests. Therefore, it has been listed as quarantine insect pests in many counties. For timely management of quarantine pest, effective and rapid diagnostic methods are required. Until now, diagnostic technology is mainly based on morphology of insects which require trained taxonomists. Recently, diagnostics based on metabolites and hyperspectral imaging coupled with machine learning is gaining importance. However, very little is known about the metabolites in Trogoderma sp. and how the host grain, gender, and geographical distribution affect the metabolomic profiling in these species is still unknown. In this thesis, volatile organic compounds (VOCs) emitted by Trogoderma variabile at different life stages were analysed as biomarkers which can help us to understand the biochemistry and metabolomic. Some compounds were identified from T. variabile different stages, which could be used as diagnostic tool for this insect. Gas chromatography coupled to mass spectrometry (GC–MS) was used as a technique to study the metabolite profile of T. variabile in different host grains. However, there are several factors that affect the volatile organic compounds including extraction time and number of insects. The results indicated that the optimal number of insects required for volatile organic compounds (VOC) extraction at each life stage was 25 and 20 for larvae and adults respectively. Sixteen hours were selected as the optimal extraction time for larvae and adults. Some of the VOCs compounds identified from this insect can be used as biomarkers such as pentanoic acid; diethoxymethyl acetate; 1-decyne; naphthalene, 2-methyl-; n-decanoic acid; d

The Mediterranean fruit fly Ceratitis capitata (Medfly), is a highly polyphagous insect species with a host range of over 400 plant species. It is one of the most destructive horticultural insect pests which has resulted in huge pre and postharvest losses, costing billions of dollars every year for pest management. Quarantine and phytosanitary treatments are essential to ensure no live Medfly in imported and exported fruit, vegetable and hay. However, it is increasingly difficult to be clarified due to the ban of key pesticides, methyl bromide, an ozone-depleting substance, and chemical residues related food and consumer safety issues. Therefore, the non-chemical strategies, including the controlled atmosphere (CA), heat and low temperature and irradiation treatments have been applied for eradication of fruit flies in postharvest fruits. However, the response of Medfly to low-temperature and low-oxygen has not been extensively studied in the lab diet and blueberries. My Ph.D. research has systematically evaluated low-temperature and low-oxygen treatments of Medfly on a lab diet and two blueberry cultivars. The results demonstrated that in the lab diet, both the 1st and 3rd larval instars were the most cold-tolerant stages. In blueberries, the 3rd larval instar was the most cold-tolerant stage. In the low-oxygen/high-nitrogen treatment, the 3rd larval instar was the most tolerant stage at 25°C. No significant differences in sex ratios of survived Medfly were observed between treated and non-treated Medfly populations after both low-temperature and low-oxygen treatments. This study improved our understanding of Medfly responses to low-temperature and low-oxygen treatments. The results and knowledge will help refine current fruit fly postharvest management and develop more efficient and environmentally friendly control approaches, which will contribute to the integrated postharvest pest management strategies for Medfly.

In many citrus areas around the world and within citrus-producing regions of Australia, the California red scale (CRS), Aonidiella aurantii (Maskell) (Hemiptera: Diaspididae), is considered the most important pests of citrus. The main biological control agents of Ao. aurantii in this zone are the parasitoid Aphytis melinus DeBach (Hymenoptera: Aphelinidae). In order to improve the biological control of Ao. aurantii several biotic and abiotic factors were studied, that may affect the efficiency of A. melinus in the laboratory and the field. More concretely, reproductive potential and age-specific fecundity schedules of Ao. aurantii were studied in the laboratory at constant temperatures (20, 23 and 27°C), while the biological parameters of its parasitoid A. melinus were conducted at 27°C. Results revealed that the net reproduction rate (Ro) was considerably higher for Ao. aurantii than A. melinus, which reached 28.14 at 27°C, indicating its high reproductive capacity. Moreover, the net reproduction rate obtained for A. melinus indicates a low substitution potential for each female having Ao. aurantii as a host under laboratory conditions. The intrinsic rate of increase (rm) of A. melinus (0.188 ♀/♀/day) was significantly greater than that of Ao. aurantii (0.080) at 27°C. Plants produce volatile organic compounds (VOCs) in response to herbivore attack, and these VOCs can be exploited by parasitoids of the herbivore as host location cues. The VOCs from non-infested and Ao. aurantii-infested citrus fruit were investigated using headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). The data showed that more than 52 different compounds were identified, and different emissions associated attributed to herbivore activity were found for all fruit species (lemon, orange, mandarin and Tahitian lime). However, a single compound was exclusively produced by infested lemon fruit, while two compounds were significantly increased

The lesser grain borer, Rhyzopertha dominica (Fabricius) and the red flour beetle, Tribolium castaneum (Herbst) are serious insect pests of stored grain and a broad range of other stored products. Phosphine is widely used as a fumigant to protect the stored commodity from insect damage. However, phosphine resistance by stored grain insects has been occurred worldwide. The mechanism of phosphine resistance reported that it might include changes in respiratory and metabolic function. Lower respiration of the resistant insects may reduce the rate of phosphine entering insect bodies. Changes in the metabolism of resistant strain insects may prevent metabolic crises or supplies more energy. In this thesis, the respiration rate, the emission of VOCs and lipid content of phosphine susceptible and resistant strains of R. dominica and T. castaneum were investigated. Two novel methods have been explored and validated, including the headspace solid phase microextraction (HS-SPME) and direct immersion solid phase microextraction (DI-SPME) technologies. The optimal conditions for both methods were investigated, and the optimized conditions were used for our study to determine the volatile organic compounds (VOCs) from insects and the insect cuticular hydrocarbons. This thesis has confirmed that the respiration rate of the susceptible strain insects was significantly higher than the resistant strains. Phosphine can reduce the respiration rate of both susceptible and resistant strains when treated with average concentrations ranged from 2 to 20 ppm. However, the rate of respiration of the resistant strains was unexpectedly increased under a high level of phosphine (320 ppm) which indicated that resistant strain insect metabolism was elevated. Moreover, two characteristics were used as indicators to determine the metabolic differences between phosphine susceptible and resistant strains of R. dominica and T. castaneum including VOCs and lipid contents. The GC-MS response of most of

The diamondback moth (DBM), Plutella xylostella (L.) (Lepidoptera: Plutellidae), is one of the most destructive insect pests of brassicaceous crops, which has shown problematic resistance to almost every common insecticide. In certain parts of the world, the economic production of crucifers has become nearly impossible due to the failure in controlling DBM. Consequently, increased efforts worldwide have been undertaken to implement biological control programs that are principally employing its natural enemies such as Diadegma semiclausum and Trichogramma pretiosum. D. semiclausum is a specialist DBM larvae parasitoid and one of the most common parasitoids in Australia. T. pretiosum is a generalist egg parasitoid, and it inserts its eggs into the host eggs, including DBM. However, limited studies have been conducted on these two parasitoid wasps regarding how they detect DBM, how their olfactory systems guide them to localize the DBM and what olfactory genes are involved in these DBM-seeking and oviposition behaviours. Without this knowledge, it is difficult to utilize them at maximum efficiency and effectiveness in DBM management programs. In this study, analytical chemistry, electrophysiology, scanning electron microscopy, genomics, transcriptomics, bioinformatics and molecular biology approaches were applied to investigate the olfactory systems of D. semiclausum and T. pretiosum. Eight candidate attractants were identified from DBM-infested canola Brassica napus, while some of them were found to be able to initiate significant antennal responses from the parasitoid wasp D. semiclausum. Male and female D. semiclausum exhibited different antennal responses to various tested volatile compounds. Candidate olfactory genes, including 17 odorant-binding proteins (OBPs) and 67 odorant receptors (ORs), were identified and characterized from D. semiclausum. Similarly, a total of 22 OBPs and 121 ORs were identified and characterized from T. pretiosum. These genes may play pi