title: Seasonal Comparison of Lipid Composition and Metabolism in Parasitised and Non-Parasitised Clover Root Weevil (Sitona lepidus)

authors: Brown, Jolene Mary

subjects: Clover root weevil

abstract: Since its arrival in New Zealand the clover root weevil (Sitona lepidus (syn. flavescens) (Coleoptera: Curculionidae) (CRW) has caused serious damage to New Zealand’s agricultural sector. The introduction of the biocontrol agent, Microctonus aethiopoides has caused a significant reduction in the population of CRWs. 

During their research on the CRW, AgResearch scientists discovered that the abdominal fat body and lipids present in the haemolymph in adult CRW varied with season, sex, insect age and parasitism. Parasitism has been reported to change the lipid composition of other species of insects. The purpose of the present study was to compare the chemical composition of the lipids present in parasitised and non-parasitised CRW adults, and determine how these lipids change with physiological state and parasitoid development. The investigation into how M. aethiopoides initiates these changes was extended to examine the roles of juvenile hormones and teratocytes in lipid regulation.

A one-step method of extraction and derivatisation was created to determine the fatty acid profile of CRWs. This method gave higher recovery percentages and higher reproducibility than the traditional two-step methods that were trialled, and enabled individual CRWs to be analysed. The fatty acid profile of the CRW was similar to that of other insects reported containing mainly the 16 carbon saturated and monounsaturated fatty acids and the 18 carbon saturated, monounsaturated and polyunsaturated fatty acids.

The one-step method was also used to track differences in the fatty acid profiles of individual CRWs with differing sex, age, parasitism and physiological state. The fatty acid profiles of male and female CRWs were similar, with only significant differences between the concentrations of the 16:1 and 18:0 fatty acids. Due to variation between individual samples in the entire sample set, no obvious correlations were found between physiological state and fatty acid composition, or distinctions between state of parasitism and fatty acid profile. Basic statistical methods were utilised initially, however, the complexity of the data set required multivariate analysis. PCA, LDA and QDA were utilised but again no correlations or distinctions were found when the whole sample set was analysed. Results from the Gisborne subset, collected from the same location and at the same time, had reduced variation between individuals, and this allowed some distinctions to be made between parasitised and non-parasitised samples.

Teratocytes are cells that have dissociated from the serosal membrane that occur in the haemolymph of CRWs that have been parasitised by M. aethiopoides. The fatty acid composition of these cells was investigated using the one-step method and a MALDI-TOF spectrometry method, which detects triacylcglycerols. The fatty acid profile of teratocytes was not significantly different to that of the CRW. 

Juvenile hormones (JHs) control postembryonic development and adult reproduction. They are present in all insects and JH III is the most common of the six possible JHs. The LC-MS method of Miyazaki et al was modified and this allowed for the determination of JH III within samples of 50 CRW adults. The comparison between parasitised and non-parasitised samples found that parasitised samples had significantly higher levels of JH III than did their non-parasitised counterparts.

text: Seasonal Comparison of Lipid Composition and Metabolism in Parasitised and Non-Parasitised Clover Root Weevil (Sitona lepidus) Since its arrival in New Zealand the clover root weevil (Sitona lepidus (syn. flavescens) (Coleoptera: Curculionidae) (CRW) has caused serious damage to New Zealand’s agricultural sector. The introduction of the biocontrol agent, Microctonus aethiopoides has caused a significant reduction in the population of CRWs. 

During their research on the CRW, AgResearch scientists discovered that the abdominal fat body and lipids present in the haemolymph in adult CRW varied with season, sex, insect age and parasitism. Parasitism has been reported to change the lipid composition of other species of insects. The purpose of the present study was to compare the chemical composition of the lipids present in parasitised and non-parasitised CRW adults, and determine how these lipids change with physiological state and parasitoid development. The investigation into how M. aethiopoides initiates these changes was extended to examine the roles of juvenile hormones and teratocytes in lipid regulation.

A one-step method of extraction and derivatisation was created to determine the fatty acid profile of CRWs. This method gave higher recovery percentages and higher reproducibility than the traditional two-step methods that were trialled, and enabled individual CRWs to be analysed. The fatty acid profile of the CRW was similar to that of other insects reported containing mainly the 16 carbon saturated and monounsaturated fatty acids and the 18 carbon saturated, monounsaturated and polyunsaturated fatty acids.

The one-step method was also used to track differences in the fatty acid profiles of individual CRWs with differing sex, age, parasitism and physiological state. The fatty acid profiles of male and female CRWs were similar, with only significant differences between the concentrations of the 16:1 and 18:0 fatty acids. Due to variation between individual samples in the entire sample set, no obvious correlations were found between physiological state and fatty acid composition, or distinctions between state of parasitism and fatty acid profile. Basic statistical methods were utilised initially, however, the complexity of the data set required multivariate analysis. PCA, LDA and QDA were utilised but again no correlations or distinctions were found when the whole sample set was analysed. Results from the Gisborne subset, collected from the same location and at the same time, had reduced variation between individuals, and this allowed some distinctions to be made between parasitised and non-parasitised samples.

Teratocytes are cells that have dissociated from the serosal membrane that occur in the haemolymph of CRWs that have been parasitised by M. aethiopoides. The fatty acid composition of these cells was investigated using the one-step method and a MALDI-TOF spectrometry method, which detects triacylcglycerols. The fatty acid profile of teratocytes was not significantly different to that of the CRW. 

Juvenile hormones (JHs) control postembryonic development and adult reproduction. They are present in all insects and JH III is the most common of the six possible JHs. The LC-MS method of Miyazaki et al was modified and this allowed for the determination of JH III within samples of 50 CRW adults. The comparison between parasitised and non-parasitised samples found that parasitised samples had significantly higher levels of JH III than did their non-parasitised counterparts.

year: 2014

title: Maximum margin principal components

authors: Luo, Xianghui

subjects: Machine learning

abstract: Principal Component Analysis (PCA) is a very successful dimensionality reduction technique, widely used in predictive modeling. A key factor in its widespread use in this domain is the fact that the projection of a dataset onto its first $K$ principal components minimizes the sum of squared errors between the original data and the projected data over all possible rank $K$ projections. Thus, PCA provides optimal low-rank representations of data for least-squares linear regression under standard modeling assumptions. On the other hand, when the loss function for a prediction problem is not the least-squares error, PCA is typically a heuristic choice of dimensionality reduction -- in particular for classification problems under the zero-one loss. In this paper we target classification problems by proposing a straightforward alternative to PCA that aims to minimize the difference in margin distribution between the original and the projected data. Extensive experiments show that our simple approach typically outperforms PCA on any particular dataset, in terms of classification error, though this difference is not always statistically significant, and despite being a filter method is frequently competitive with Partial Least Squares (PLS) and Lasso on a wide range of datasets.

text: Maximum margin principal components Principal Component Analysis (PCA) is a very successful dimensionality reduction technique, widely used in predictive modeling. A key factor in its widespread use in this domain is the fact that the projection of a dataset onto its first $K$ principal components minimizes the sum of squared errors between the original data and the projected data over all possible rank $K$ projections. Thus, PCA provides optimal low-rank representations of data for least-squares linear regression under standard modeling assumptions. On the other hand, when the loss function for a prediction problem is not the least-squares error, PCA is typically a heuristic choice of dimensionality reduction -- in particular for classification problems under the zero-one loss. In this paper we target classification problems by proposing a straightforward alternative to PCA that aims to minimize the difference in margin distribution between the original and the projected data. Extensive experiments show that our simple approach typically outperforms PCA on any particular dataset, in terms of classification error, though this difference is not always statistically significant, and despite being a filter method is frequently competitive with Partial Least Squares (PLS) and Lasso on a wide range of datasets.

year: 2017

title: An integral rite of passage: embedding the aesthetic in adventure education in the pursuit of wellbeing

authors: Wagstaff, Ruth

subjects: wellbeing

abstract: The context for this study was the implementation of an arts integrated unit examined through the lenses of wellbeing, adventure education, children’s spirituality and aesthetic experience. The author’s personal experiences as a holistic educator, connecting theory and practice in educational settings, informed the devising of the learning experiences incorporated into this contemporary ‘Rites of Passage’, arts integrated unit. They also informed the qualitative methods selected for this research. Students reported on their own and others’ perceived state of “wholeness” and completeness of experience and the New Zealand Maori concepts of “hauora” – mental and emotional, physical, social and spiritual wellbeing were examined. Qualitative analysis of the data revealed that a holistic, integrative approach to learning was valued by the students and contributed significantly to their experience of wellbeing and wholeness. The coded data was considered in terms of a heuristic clustering of responses around the relational categories of Self, Others and the Environment. Connection, Relationship and Belonging emerged as the most important themes and, unexpectedly, Inclusion emerged as an important consideration to the participants in this study. Creative and resilience-building learning activities, as within this ‘Rites of Passage” unit and the integral “Wilderness Camp”, are supportive of the health and wellbeing of young learners. Such learning opportunities provide for intra-personal and inter-personal development, and contribute to their sense of self, place, meaning and purpose.

text: An integral rite of passage: embedding the aesthetic in adventure education in the pursuit of wellbeing The context for this study was the implementation of an arts integrated unit examined through the lenses of wellbeing, adventure education, children’s spirituality and aesthetic experience. The author’s personal experiences as a holistic educator, connecting theory and practice in educational settings, informed the devising of the learning experiences incorporated into this contemporary ‘Rites of Passage’, arts integrated unit. They also informed the qualitative methods selected for this research. Students reported on their own and others’ perceived state of “wholeness” and completeness of experience and the New Zealand Maori concepts of “hauora” – mental and emotional, physical, social and spiritual wellbeing were examined. Qualitative analysis of the data revealed that a holistic, integrative approach to learning was valued by the students and contributed significantly to their experience of wellbeing and wholeness. The coded data was considered in terms of a heuristic clustering of responses around the relational categories of Self, Others and the Environment. Connection, Relationship and Belonging emerged as the most important themes and, unexpectedly, Inclusion emerged as an important consideration to the participants in this study. Creative and resilience-building learning activities, as within this ‘Rites of Passage” unit and the integral “Wilderness Camp”, are supportive of the health and wellbeing of young learners. Such learning opportunities provide for intra-personal and inter-personal development, and contribute to their sense of self, place, meaning and purpose.

year: 2011