title: Aspects of the ecology of black beetle (Heteronychus arator (F.), Coleoptera: Dynastinae)

authors: King, Peter Douglas

abstract: The study included laboratory and field studies of the ecology of the black beetle (Heteronychus arator F.) pre-adult and adult stages and field studies of population dynamics. The objectives were to understand population change and regulation, particularly in relation to host plant species and explore the possibilities of the prediction of outbreaks in order to rationalise the use of control strategies.
Whereas eggs were relatively tolerant to a range of soil moisture conditions, first instar larvae were very susceptible to extremes in soil moisture. In comparison to temperate scarabs, relatively high temperatures were necessary for optimum egg viability, larval feeding, utilisation, growth and survival. Adult oviposition preference, fecundity and survival, and larval food consumption, growth and survival were all influenced by the pasture plant species eaten. All grass species tested with the exception of phalaris were favourable for population growth while phalaris and the legumes tested were unfavourable.
The dynamic nature of the life cycle, the relatively low population densities and dispersal of adults made estimation of populations with reasonable levels of precision difficult. Life tables were constructed which quantified individual and generation mortalities, and identified the key factors causing population change. These were variation in natality, summer mortality and/or winter.- spring disappearance. Significant relationships were found between key mortalities and the level of population development which in turn was related to spring and summer temperatures.
Two very different types of population dynamics were evident. Populations in paspalum pastures which are tolerant to feeding damage were relatively stable. These pastures act as refuge areas during adverse climatic conditions. In contrast, population development was more rapid and large population decreases occurred between autumn and spring in ryegrass based pastures which were less tolerant of damage. Ryegrass based pastures appear to be favourable habitats during spring and summer only, and adult immigration in the spring is necessary for populations to reach high levels. Since spring migration only occurs in warm years, outbreaks in ryegrass based pasture are sporadic.
A population model was constructed which used mean daily air temperatures in September, October and November to simulate population densities over a 23 year period from temperature records. The prediction of high population numbers showed good correlation with years of previous outbreaks. Some density dependence was found to be necessary in the model for paspalum pasture indicating the occurrence of population regulation. It was concluded that except in years of high population numbers, population regulation does not occur in ryegrass based pastures.
Rationalisation of control strategies was discussed in the light of the differences in the two types of population dynamics and the prediction of outbreaks.
This research has revealed the necessity for a well designed population study in order to understand the manner in which mortalities operate and the way they affect numbers. As the first attempt at a quantitative ecological study of black beetle, the results have provided some understanding of black beetle ecology and suggested further areas for investigation.

text: Aspects of the ecology of black beetle (Heteronychus arator (F.), Coleoptera: Dynastinae) The study included laboratory and field studies of the ecology of the black beetle (Heteronychus arator F.) pre-adult and adult stages and field studies of population dynamics. The objectives were to understand population change and regulation, particularly in relation to host plant species and explore the possibilities of the prediction of outbreaks in order to rationalise the use of control strategies.
Whereas eggs were relatively tolerant to a range of soil moisture conditions, first instar larvae were very susceptible to extremes in soil moisture. In comparison to temperate scarabs, relatively high temperatures were necessary for optimum egg viability, larval feeding, utilisation, growth and survival. Adult oviposition preference, fecundity and survival, and larval food consumption, growth and survival were all influenced by the pasture plant species eaten. All grass species tested with the exception of phalaris were favourable for population growth while phalaris and the legumes tested were unfavourable.
The dynamic nature of the life cycle, the relatively low population densities and dispersal of adults made estimation of populations with reasonable levels of precision difficult. Life tables were constructed which quantified individual and generation mortalities, and identified the key factors causing population change. These were variation in natality, summer mortality and/or winter.- spring disappearance. Significant relationships were found between key mortalities and the level of population development which in turn was related to spring and summer temperatures.
Two very different types of population dynamics were evident. Populations in paspalum pastures which are tolerant to feeding damage were relatively stable. These pastures act as refuge areas during adverse climatic conditions. In contrast, population development was more rapid and large population decreases occurred between autumn and spring in ryegrass based pastures which were less tolerant of damage. Ryegrass based pastures appear to be favourable habitats during spring and summer only, and adult immigration in the spring is necessary for populations to reach high levels. Since spring migration only occurs in warm years, outbreaks in ryegrass based pasture are sporadic.
A population model was constructed which used mean daily air temperatures in September, October and November to simulate population densities over a 23 year period from temperature records. The prediction of high population numbers showed good correlation with years of previous outbreaks. Some density dependence was found to be necessary in the model for paspalum pasture indicating the occurrence of population regulation. It was concluded that except in years of high population numbers, population regulation does not occur in ryegrass based pastures.
Rationalisation of control strategies was discussed in the light of the differences in the two types of population dynamics and the prediction of outbreaks.
This research has revealed the necessity for a well designed population study in order to understand the manner in which mortalities operate and the way they affect numbers. As the first attempt at a quantitative ecological study of black beetle, the results have provided some understanding of black beetle ecology and suggested further areas for investigation.

year: 1979

title: Effect of fibre treatments on interfacial shear strength of hemp fibre reinforced polylactide and unsaturated polyester composites

authors: Sawpan, Moyeenuddin Ahmad

subjects: fibres

abstract: Surface treatment of hemp fibres was investigated as a means of improving interfacial shear strength (IFSS) of hemp fibre reinforced polylactide (PLA) and unsaturated polyester (UPE) composites. Fibres were treated with sodium hydroxide, acetic anhydride, maleic anhydride and silane. A combined treatment using sodium hydroxide and silane was also carried out. IFSS of PLA/hemp fibre samples increased after treatment, except in the case of maleic anhydride treatment. Increased IFSS could be explained by better bonding of PLA with treated fibres and increased PLA transcrystallinity. The highest IFSS was 11.4 MPa which was obtained for the PLA/alkali treated fibre samples. IFSS of UPE/hemp fibre samples increased for all treated fibres. This is believed to be due to the improvement of chemical bonding between the treated fibres and the UPE as supported by FT-IR results. The highest IFSS (20.3 MPa) was found for the combined sodium hydroxide and silane treatment fibre/UPE samples.

text: Effect of fibre treatments on interfacial shear strength of hemp fibre reinforced polylactide and unsaturated polyester composites Surface treatment of hemp fibres was investigated as a means of improving interfacial shear strength (IFSS) of hemp fibre reinforced polylactide (PLA) and unsaturated polyester (UPE) composites. Fibres were treated with sodium hydroxide, acetic anhydride, maleic anhydride and silane. A combined treatment using sodium hydroxide and silane was also carried out. IFSS of PLA/hemp fibre samples increased after treatment, except in the case of maleic anhydride treatment. Increased IFSS could be explained by better bonding of PLA with treated fibres and increased PLA transcrystallinity. The highest IFSS was 11.4 MPa which was obtained for the PLA/alkali treated fibre samples. IFSS of UPE/hemp fibre samples increased for all treated fibres. This is believed to be due to the improvement of chemical bonding between the treated fibres and the UPE as supported by FT-IR results. The highest IFSS (20.3 MPa) was found for the combined sodium hydroxide and silane treatment fibre/UPE samples.

year: 2011

title: My responsibility in the face of mass extinction

authors: Gray-Sharp, Katarina

subjects: autoethnography

abstract: Extinction is the “irreversible condition of a species or other group of organisms having no living representatives in the wild, which follows the death of the last surviving individual of that species or group” (Hine and Martin 2015g, para. 1). Mass extinctions are extinctions of the greatest magnitude, occurring “when many diverse groups of organisms become extinct over short periods of time” (Condie 2011, 250). These “are not step-events but rather a step into a prolonged alternative global ecosystem state” (Hull 2015, R941). Five mass extinctions have previously been recorded. A sixth has begun. Humans are the cause of the latest episode.

This thesis develops an Indigenous, non-agential conception of responsibility for considering an ethical problem of wide consequence. Founded in mātauranga Māori and recalling the work of Emmanuel Levinas, it applies Kaupapa Māori autoethnography, narrative, and conceptual analyses alongside exegeses and a replication study. Investigations of responsibility across various positions are encountered: those found in place and polity, those made as visitor and the commanded, those gifted as inherited erudition and in the suffering-with. Now facing the last structural violence, what is my responsibility?

text: My responsibility in the face of mass extinction Extinction is the “irreversible condition of a species or other group of organisms having no living representatives in the wild, which follows the death of the last surviving individual of that species or group” (Hine and Martin 2015g, para. 1). Mass extinctions are extinctions of the greatest magnitude, occurring “when many diverse groups of organisms become extinct over short periods of time” (Condie 2011, 250). These “are not step-events but rather a step into a prolonged alternative global ecosystem state” (Hull 2015, R941). Five mass extinctions have previously been recorded. A sixth has begun. Humans are the cause of the latest episode.

This thesis develops an Indigenous, non-agential conception of responsibility for considering an ethical problem of wide consequence. Founded in mātauranga Māori and recalling the work of Emmanuel Levinas, it applies Kaupapa Māori autoethnography, narrative, and conceptual analyses alongside exegeses and a replication study. Investigations of responsibility across various positions are encountered: those found in place and polity, those made as visitor and the commanded, those gifted as inherited erudition and in the suffering-with. Now facing the last structural violence, what is my responsibility?

year: 2021