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: Natural Amenities and Age Related Population Change in New Zealand.

authors: Simone, Francisca Rosa

abstract: Modern day migration literature suggests that natural amenities play a significant role in attracting migrants and thereby influencing population change. Empirical studies however, often find natural amenities of little significance. It can be argued that these conflicting findings are a result of the empirical complexity of representing amenities as well as the way in which causal relationships have been identified. 

The effects of population change are not evenly distributed across New Zealand, with growth typically being focused on the main metropolitan areas, while other areas are experiencing population stagnation or decline. Queenstown is experiencing rapid population growth in all ages (with the exception of 20-29). This uncharacteristic migration is argued to partially be due to the regions high level of natural amenity. 

This study uses three separate natural amenity indices as well as proxies for the main migration related drivers of population change in order to answer our central question; Are natural amenities a significant factor in determining age related population change in New Zealand? Global and exploratory local models have been run for six age groups each representing a demographic group in New Zealand. While there is much room to improve these models in the future the local models have identified several significant areas in New Zealand where there is predominately a positive relationship between natural amenities and population change.

text: Natural Amenities and Age Related Population Change in New Zealand. Modern day migration literature suggests that natural amenities play a significant role in attracting migrants and thereby influencing population change. Empirical studies however, often find natural amenities of little significance. It can be argued that these conflicting findings are a result of the empirical complexity of representing amenities as well as the way in which causal relationships have been identified. 

The effects of population change are not evenly distributed across New Zealand, with growth typically being focused on the main metropolitan areas, while other areas are experiencing population stagnation or decline. Queenstown is experiencing rapid population growth in all ages (with the exception of 20-29). This uncharacteristic migration is argued to partially be due to the regions high level of natural amenity. 

This study uses three separate natural amenity indices as well as proxies for the main migration related drivers of population change in order to answer our central question; Are natural amenities a significant factor in determining age related population change in New Zealand? Global and exploratory local models have been run for six age groups each representing a demographic group in New Zealand. While there is much room to improve these models in the future the local models have identified several significant areas in New Zealand where there is predominately a positive relationship between natural amenities and population change.

year: 2016

title: Māori leaders wellbeing: A self-determination perspective

authors: Roche, Maree A.

subjects: Positive psychology

abstract: This research draws on interviews with 18 Māori leaders from various leadership positions within business, community, political and marae organisations, to garner an understanding of how their leadership roles interact with their own well-being. Analysis of interviews revealed that crosscultural developments in self-determination theory could be gained by incorporating Māori tikanga and values into a model of well-being for Māori leaders. Largely, the principles of tino rangatiratanga (autonomy and self-determination), mana (respect and influence), whānau (extended family), whakapapa (shared history) and whanaungatanga (kin relations, consultation and engagement), were united into a model of leader well-being. This ensured that mātauranga Māori (Māori knowledge) informed our model of Māori leader well-being, while also drawing on the burgeoning Western research in the area of well-being, specifically self-determination theory. Overall, we find that similarities exist with self-determination theory and Māori tikanga and values. However, in contrast to self-determination theory, autonomy and competence are developed within relationships, which means that ‘others’ underpin Māori leaders’ well-being. From this perspective, we present a view of the psychological and well-being resources that Māori leaders draw on to guide them through complex times.

text: Māori leaders wellbeing: A self-determination perspective This research draws on interviews with 18 Māori leaders from various leadership positions within business, community, political and marae organisations, to garner an understanding of how their leadership roles interact with their own well-being. Analysis of interviews revealed that crosscultural developments in self-determination theory could be gained by incorporating Māori tikanga and values into a model of well-being for Māori leaders. Largely, the principles of tino rangatiratanga (autonomy and self-determination), mana (respect and influence), whānau (extended family), whakapapa (shared history) and whanaungatanga (kin relations, consultation and engagement), were united into a model of leader well-being. This ensured that mātauranga Māori (Māori knowledge) informed our model of Māori leader well-being, while also drawing on the burgeoning Western research in the area of well-being, specifically self-determination theory. Overall, we find that similarities exist with self-determination theory and Māori tikanga and values. However, in contrast to self-determination theory, autonomy and competence are developed within relationships, which means that ‘others’ underpin Māori leaders’ well-being. From this perspective, we present a view of the psychological and well-being resources that Māori leaders draw on to guide them through complex times.

year: 2015