Dissertations / Theses on the topic 'Arthropoda (Australia)'

This study was carried out in a woodland on the campus of University of Western Sydney at Richmond, Australia to investigate seasonal effects and recovery speed of arboreal arthropods after disturbance. Twenty one pairs of Melaleuca linariifolia Sm. trees were sampled using insecticide spraying in a log2 nine period sequence (1-32) of weeks supplemented by additional samples to incorporate seasonal (weeks 24 and 48) and annual (week 52) samples. Using species accumulation curves, it was found that four collectors provided a reasonable representation of a tree's fauna and that a single tree does not provide a representative sample of the arthropod fauna found on trees of this species in the study area. The application of richness and evenness indices in different seasons showed significant changes in diversity. It was clear from the findings of the study that careful attention needs to be paid to experimental design. Under replication is the normal situation in previous studies and the effects of location, season and disturbance are all critical factors affecting the estimation of diversity.
Doctor of Philosophy (PhD)

This study was carried out in a woodland on the campus of University of Western Sydney at Richmond, Australia to investigate seasonal effects and recovery speed of arboreal arthropods after disturbance. Twenty one pairs of Melaleuca linariifolia Sm. trees were sampled using insecticide spraying in a log2 nine period sequence (1-32) of weeks supplemented by additional samples to incorporate seasonal (weeks 24 and 48) and annual (week 52) samples. Using species accumulation curves, it was found that four collectors provided a reasonable representation of a tree's fauna and that a single tree does not provide a representative sample of the arthropod fauna found on trees of this species in the study area. The application of richness and evenness indices in different seasons showed significant changes in diversity. It was clear from the findings of the study that careful attention needs to be paid to experimental design. Under replication is the normal situation in previous studies and the effects of location, season and disturbance are all critical factors affecting the estimation of diversity.

The results of the 3-year project successfully indicated that petroleum-derived spray oils can be used for effective control of a range of citrus pests including citrus leafminer, Asiatic citrus psyllid, chaff scale, red scale, citrus red mite. The results suggested that it should be possible, through use of horticultural and agricultural mineral oils and enhanced natural enemy activity, to reduce the number of pesticide sprays applied annually in China from 14-16 sprays to significantly fewer sprays in most regions. The results are also valuable as references for the implementation of citrus integrated pest management programs in Australia and other citrus-growing countries. However, despite extensive use of PDSOs in citrus and other crops since the late 1800s, few studies have been undertaken to determine their disruptive effects on orchard ecosystems or to compare their effects with those of synthetic pesticides, and these studies are limited in their sc

Broadscale forest clearance is a major human-induced disturbance with devastating consequences for biodiversity. With a rise in public awareness of biodiversity, the last few decades have seen an increasing number of reforestation activities aimed at recreating natural habitat. To date, research on the outcomes of reforestation for biodiversity have mostly focused upon the recovery of vegetation structure and composition, with relatively little attention being paid to the recovery of fauna, especially invertebrates. Arthropods inhabiting soil and leaf litter constitute a considerable proportion of the biomass and diversity of a given faunal community, and exhibit strong associations with ecological functioning (i.e. soil formation, decomposition). The recovery of soil and litter arthropods in restored landscapes is therefore important, not only for the recovery of biodiversity but also for the re-development of a functioning ecosystem, a goal of most types of reforestation programs. However, we know little about the patterns of development of arthropod assemblages in reforested landscapes or the mechanisms underpinning any such patterns. The broad objective of this study was to investigate the effects of selected factors on the colonisation patterns of restored rainforest patches by soil and leaf litter arthropods. Criteria for selecting factors for study included their potential influence on the development of arthropod assemblages and their potential for manipulation by restoration practitioners. The study was conducted on the Blackall Range near Maleny, a mid-elevation (250-530 m a.s.l.) basaltic plateau in subtropical eastern Australia (26°S, 152°E). The plateau supported subtropical rainforest until European settlement in the 19th century, when most of the rainforest was cleared for pasture. The factors selected for study, in relation to the colonisation of restored habitat patches by soil and litter arthropods, were as follows: 1. the isolation of restored habitat patches from remnant forest; 2. the efficacy of inoculation (re-introduction of rainforest soil and litter arthropods) to restored habitat patches; 3. the quality and quantity of substrate (i.e. mulch) used during the initial stages of rainforest restoration; 4. the degree of shading and depth of substrate, and their interaction; and, 5. the short- and longer-term impacts of glyphosate herbicide on arthropod assemblages. To test explicitly the effects of these factors on arthropod colonisation of restored habitat patches, an experimental approach was adopted in this study. The first four factors were addressed by means of a manipulative field experiment. Small-scale habitat patches were created by adding sterilised mulch to an area previously treated with glyphosate herbicide, and covered with shadecloth, to simulate various conditions of forest restoration which may be experienced by colonising arthropods. In order to test for the impacts of a glyphosate herbicide on rainforest arthropods, I carried out a separate field experiment in which experimental patches were established within remnant rainforests. The experimental approach adopted in this study allowed for the construction of replicated units, while controlling for extraneous factors (e.g. heterogeneity of litter composition, habitat area, age of restoration), to enable robust examination of the effects of selected factors. To monitor assemblage composition, arthropods were collected using two methods: pitfall traps and extraction from litter. Responses of arthropods were analysed at two main levels of taxonomic resolution: ‘coarse’ arthropods (all arthropods sorted to Order/Class) and ants, identified to species. Before the field experiments, a survey was carried out to collect reference information on the distribution of soil and litter arthropods in remnant rainforests (undisturbed reference sites) and cleared pasture (disturbed reference sites) in the study region. Regardless of the sampling method (pitfall or litter extraction) or taxonomic resolution employed (coarse arthropods or ant species), the composition of arthropod assemblages clearly differed between rainforest and pasture. The information obtained from this survey generated potential bio-indicators of forested and cleared habitats, assisting interpretation of the data obtained from the field experiments. The effects of habitat isolation and inoculation were tested using ‘restored’ habitat patches which were established within cleared pasture at increasing distances (0, 15, 100 and ca. 400 m) from the edges of rainforest remnants. After nine months, rainforest-dependent taxa were found to have only colonised the habitat patches closely adjacent to rainforest remnants. Attempts to increase the extent of arthropod establishment by inoculation were unsuccessful: the majority of rainforest arthropods from the raw inoculum failed to persist within the isolated plots. The results indicated that many forest-dependent soil and litter arthropods may have a limited capacity to colonise isolated restoration sites, and/ or small experimental plots in the short term. Inference from the experiment was potentially limited by the relatively small temporal and spatial scales of restoration treatments. Avoiding these limitations in future research may require controlled and replicated efforts in experimental restoration over larger areas, based on collaborations between researchers and practitioners. To test the effects of quality and quantity of substrate on arthropod colonisation, habitat patches were established by adding either sterilised hay (a conventionally used mulching material in restoration projects) or woodchip mulch (a structurally more complex alternative), each at two depths (3-5 cm, 10-15 cm). Habitat patches were positioned within pasture adjacent to the edges of rainforest remnants to minimise the effect of isolation, and were all unshaded to create conditions similar to those during the initial stages of rainforest restoration. Despite its simple composition, hay performed better than woodchips in facilitating colonisation by arthropods characteristic of rainforest. However, neither hay nor woodchip mulch inhibited arthropods invading from the surrounding pasture. Shallow hay was favoured by ants characteristic of rainforest, but other groups of arthropods (e.g. Coleoptera, Isopoda) were associated with deep hay (10-15 cm). The optimum amount of hay may therefore vary among different groups of arthropods. The effects of shading and mulch depth, and potential interactions between them, were tested using habitat patches created with varying degrees of shading (none, 50% or 90% shading) and two depths of woodchip mulch (3-5 cm or 10-15 cm deep). The presence of shading, at both 50% and 90%, encouraged colonisation of habitat patches by arthropods characteristic of rainforest. However, only the more complete shading treatment (90%) inhibited re-invasion of restored patches by arthropods from the surrounding pasture habitat. Effects of mulch depth were significant only for rainforest-associated ant species which responded positively to shallow mulch within shaded plots. These results suggest that moderate levels of canopy closure, as produced by tree spacings typical of timber plantations, may be sufficient to facilitate colonisation of reforested land by rainforest arthropods. However, greater canopy shading (90%) is likely to be needed to inhibit re-invasion of arthropods from surrounding pasture habitat. Using deeper woodchip mulch does not necessarily create more suitable conditions for rainforest arthropods or offset the deleterious effects of the lower levels of shading. Paired herbicide-treated and control plots were created within rainforest remnants to test the short- (approximately three days) and long-term (approximately three months) impacts of herbicide application on soil and litter arthropod assemblages on the floor of the remnant rainforests. The results found no deleterious effects of glyphosate herbicide formulated as Roundup® Biactive™ on rainforest soil and litter arthropods; hence, this herbicide appears suitable for the control of unwanted plants in rainforest restoration projects, from the perspective of arthropod biodiversity. The outcomes of this study also have a number of important implications for the monitoring of the development of soil and litter arthropod assemblages in restored rainforests. First, pitfall traps (a commonly used sampling technique) can provide sufficient information on the state of arthropod assemblages in the context of subtropical rainforest restoration projects, although samples collected by this method alone do not necessarily represent the whole suite of soil and litter arthropods (e.g. cryptic arthropods that live in soil and litter). Second, a combination of higher-taxon sorting of all arthropods, together with species-level sorting of a significant major taxon (ants), provides a feasible compromise between comprehensiveness and detail in monitoring responses of arthropods. Third, ‘composite habitat indices’, such as those developed in this study to quantify the extent to which a site resembles rainforest or pasture in terms of its arthropod assemblage, can help alleviate problems associated with the patchy distribution of arthropod taxa in monitoring samples. The experimental approach adopted in this study provided information that would otherwise have been limited by post-hoc empirical studies alone. This study’s results demonstrated that the selected aspects of different restoration techniques and management affect the colonisation of soil and litter arthropod assemblages in rainforest restoration of old fields.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Faculty of Science, Environment, Engineering and Technology
Full Text

Since European settlement, around 93% of the Western Australian wheatbelt has been cleared for agriculture, leading to a range of environmental problems, including erosion, salinity, and loss of biodiversity. Recently, oil mallees have been developed for use in the reduction and prevention of salinity, and in the production of oil, activated carbon, and electricity. While some work has been done on aspects of mallee ecology in order to maximize productivity, little is known about their usefulness as a source of biodiversity in natural and agricultural systems.This study concentrates on the canopy arthropod fauna of the mallees. While canopy research involving arthropods is common in tropical systems, there is limited information on temperate systems and still less relating to agro-forestry or conservation plantings in agricultural areas.Sampling was conducted in alleys of oil mallee vegetation and in remnant vegetation in the wheatbelt of Western Australia. Three mallee species: Eucalyptus polybractea, E. kochii subsp. borealis, and E. loxophleba subsp. lissophloia, and two native remnant species: Eucalyptus wandoo subsp. wandoo and E. astringens were used in the study. Trees were sampled for arthropods by canopy knockdown spraying in October 2005 and May 2006. Samples were sorted to the ordinal level in the laboratory. Coleoptera (beetle) specimens were identified to the species level. Leaf and soil samples were taken at each site and from each tree species in order to determine the levels of nutrition available to herbivorous arthropods. Leaves were also collected for terpenoid (essential oil) extraction and formylated phloroglucinol (sideroxylonal) analysis to determine the influence of leaf chemistry. Data were tested for homogeneity of variance and transformations were done where necessary. A range of statistical analyses including, analyses of variance, LSDs, coefficients of correlation, MDS ordinations, ANOSIM analysis, and the BEST procedure, were conducted on the data collected.It was determined that, for this study, chemical knockdown would be an ideal method for sampling such arthropods. A preliminary study examined the effect of repeated sampling of the same tree on canopy arthropod assemblages and found there was no effect of re-sampling on the ordinal level richness or total abundance of arthropods collected at the second sampling, six months later. As a consequence, we can be reasonably confident that the results in other sections of the thesis have not been confounded by the need to re-sample the same trees.The effect of oil mallee host species on canopy arthropod assemblages was examined. It was found that while there were minor differences in the presence or absence of some of the leaf blemishes recorded between species, with leaf folding being more prevalent on E. kochii and psyllids more common on E. loxophleba, there was no significant difference between the species in terms of ordinal richness or total abundance of arthropods. As there were very few differences observed between the three mallee species, it made it relatively simple to compare mallees generally with remnant vegetation. This was important, as mallees were treated as a single entity being compared to the two remnant species in other parts of the thesis.The ordinal richness and total abundance of canopy arthropods in two types of eucalypt vegetation, woodland eucalypts in remnant vegetation and mallee eucalypts in farm alley plantings was compared. Intuitively, we would expect native remnant vegetation to support a greater diversity of arthropods than any planted vegetation, simply by virtue of the native vegetation being in place for a longer period of time. The results of this study however, did not support this view. Arthropod richness and abundance were not significantly different between the tree species. Leaf blemishes and their associated sedentary arthropods also showed no significant differences between the species and overall very few differences between the mallee and remnant vegetation types were evident.The influence of major soil and leaf nutrients on arthropod assemblages, both in natural and planted eucalypt stands, were explored. It appears that arthropod abundance, in particular, is related to soil and leaf nutrient levels. There was, however, only limited evidence of increased arthropod ordinal richness in response to greater nutrient levels. Generally, high nutrient levels tended, instead, to reduce arthropod ordinal richness. Of the soil nutrients, phosphorus was the most influential, with high levels of phosphorus tending to relate to higher arthropod abundances. For leaf nutrients, phosphorus and nitrogen were important, with high levels of phosphorus being associated with lower ordinal richness, while high levels of leaf nitrogen were related to higher arthropod abundances. As high soil phosphorus and high leaf nitrogen tended to occur together, it is difficult to say whether one or the other is responsible for increases in arthropod abundance, though intuitively one would suggest that good soil nutrition led to enhanced plant quality, which in turn increased arthropod abundance.The role of leaf essential oils and other secondary plant compounds in determining arthropod abundance and ordinal richness was also examined. A number of secondary plant compounds were present in the host tree species tested, and there were wide variations in the levels of these compounds between the species tested. A range of relationships, including deterrent and attractant effects, were observed between arthropod assemblages and the various secondary plant compounds. Generally speaking, mallee species had high cineole and low pinene levels and remnant species had the opposite. Sideroxylonals showed no such pattern with vegetation type, being high in E. loxophleba and absent in the other mallee species. In terms of their influence on arthropods, the compounds varied in their effects. Pinene had a generally negative effect, while cineole had a generally positive one. Sideroxylonal, however, was more complicated in its effects as it had a negative effect on ordinal richness, but was positively correlated with Hemiptera numbers. This suggests that it is highly unlikely that any one of these compounds can explain the pattern of arthropod assemblages observed in isolation. It seems more probable that complex interactions between these chemicals cause changes in nutritional quality and palatability of foliage, influencing the feeding behaviour, development, distribution and abundance of herbivores, in turn affecting predator densities and feeding behaviour.The ways in which arthropod biodiversity may be influenced by the factors of host tree species, soil and plant nutrition and leaf chemistry were examined in more detail using the order Coleoptera as an example. Season of sampling was found to have an influence, with both beetle richness and abundance being higher at the first than the second sampling. Site, on the other hand, had very little influence. Of all the tree species, E. polybractea had both the highest beetle species richness, and high levels of beetle abundance. Strong similarities were apparent between beetle assemblages resident on the same tree species. No influence of soil or leaf nutrients on either beetle richness or abundance was observed. However, beetle abundance was found to have a negative relationship with leaf pinene. Cineole levels were lower in the remnant species (which tended to have similar assemblages), while pinene was high in E. loxophleba subsp. lissophloia and the remnant species. The other major leaf chemical examined, sideroxylonal had no significant impact on beetle richness or abundance. Statistical analysis selected cineole as the single factor best explaining the pattern of beetle assemblages observed, though this result should be treated with caution due to possible confounding of the results as a consequence of interaction between the factors.The broad aim of this research was to determine whether oil mallee plantings enhance arthropod biodiversity in agricultural landscapes. The results of this thesis show that oil mallees do support high levels of arthropod biodiversity. Overall, the mallees had a level of diversity, not dissimilar to that of high quality remnant vegetation. When planted in alleys across agricultural fields, they represent a significant change in the vegetative and architectural diversity of the landscape, and can have a positive influence on the environment by supporting beneficial arthropods and other native animals, reducing dryland salinity, and improving the aesthetics of the wheatbelt.Aside from their environmental credentials, oil mallees also provide the potential for farmers to make an income from something designed to benefit the environment. If oil mallee farming can be developed appropriately, it has the potential to benefit not only farmers and the environment, but the community of Western Australia as a whole.

Includes copies of author's previously published works
Guano deposits in caves form a rich food resource supporting diverse arthropod communities. Guano piles consist of distinct micro - habitats, fresh, moist, highly basic guano and older, dry, slightly acidic guano. Micro - habitat variation is strongly controlled by seasonal guano deposition that, in turn, effects the structure of arthropod communities. The maternity chamber of Bat Cave, Naracoorte, South Australia, contains extensive guano deposits supporting 38 species from three classes and 12 orders. This community was studied to determine spatial and temporal variation of arthropod communities, and biogeographic relationships between different regions in Australia. Species richness forms a positive linear relationship with pH, in situ moisture content and guano deposition. Many species show strong associations with fresh guano and hence are strongly seasonal, although some species are present throughout the year. Arthropod community structure in winter was found to be more closely related to prior summer arthropod structure than to subsequent seasons. Starlight Cave near Warrnambool, western Victoria, the only other maternity site for Miniopterus schreibersii bassanii, contained 43 species from 39 families and 14 orders. Seven species are common to both caves. The community structure of Starlight Cave was found to be more homogeneous than Bat Cave with samples clustering by season rather than sample year as was the case at Bat Cave. Different cave morphology was found to significantly alter the micro - habitat conditions and, hence, community structure in Starlight Cave compared with Bat Cave. Migration of guano associated arthropods at local, regional and continental scales was assessed using mtDNA and allozyme electrophoresis the pseudoscorpion genus Protochelifer as a model organism. Phylogenetic tree reconstruction revealed a wide geographic distribution of cavernicolous species across southern Australia. Cave colonisation is believed to have occurred only once, followed by dispersal to the Nullarbor Plain and other caves in south - eastern Australia. Dispersal was possibly phoretic on cave bats or occurred prior to aridification of surface environments that currently restricts migration. The distribution of guano - associated arthropods from arid, semi - arid and monsoonal karst areas in Australia are compared with temperate south - eastern Australia. Different climatic areas show large biogeographical differences in community structure, although similar families ( Urodinychidae, Reduviidae, Anobiidae, Carabidae and Tineidae ) are present in many Australian guano communities. Several potential mechanisms of dispersal are discussed including phoresy, colonisation from soil, terrestrial migration and interstitial cavities. Endemism to specific caves cannot be definitely assigned to any species, although 13 species show restricted distribution.
Thesis (Ph.D.)--School of Earth and Environmental Sciences, 2006.

Includes copies of author's previously published works
Guano deposits in caves form a rich food resource supporting diverse arthropod communities. Guano piles consist of distinct micro - habitats, fresh, moist, highly basic guano and older, dry, slightly acidic guano. Micro - habitat variation is strongly controlled by seasonal guano deposition that, in turn, effects the structure of arthropod communities. The maternity chamber of Bat Cave, Naracoorte, South Australia, contains extensive guano deposits supporting 38 species from three classes and 12 orders. This community was studied to determine spatial and temporal variation of arthropod communities, and biogeographic relationships between different regions in Australia. Species richness forms a positive linear relationship with pH, in situ moisture content and guano deposition. Many species show strong associations with fresh guano and hence are strongly seasonal, although some species are present throughout the year. Arthropod community structure in winter was found to be more closely related to prior summer arthropod structure than to subsequent seasons. Starlight Cave near Warrnambool, western Victoria, the only other maternity site for Miniopterus schreibersii bassanii, contained 43 species from 39 families and 14 orders. Seven species are common to both caves. The community structure of Starlight Cave was found to be more homogeneous than Bat Cave with samples clustering by season rather than sample year as was the case at Bat Cave. Different cave morphology was found to significantly alter the micro - habitat conditions and, hence, community structure in Starlight Cave compared with Bat Cave. Migration of guano associated arthropods at local, regional and continental scales was assessed using mtDNA and allozyme electrophoresis the pseudoscorpion genus Protochelifer as a model organism. Phylogenetic tree reconstruction revealed a wide geographic distribution of cavernicolous species across southern Australia. Cave colonisation is believed to have occurred only once, followed by dispersal to the Nullarbor Plain and other caves in south - eastern Australia. Dispersal was possibly phoretic on cave bats or occurred prior to aridification of surface environments that currently restricts migration. The distribution of guano - associated arthropods from arid, semi - arid and monsoonal karst areas in Australia are compared with temperate south - eastern Australia. Different climatic areas show large biogeographical differences in community structure, although similar families ( Urodinychidae, Reduviidae, Anobiidae, Carabidae and Tineidae ) are present in many Australian guano communities. Several potential mechanisms of dispersal are discussed including phoresy, colonisation from soil, terrestrial migration and interstitial cavities. Endemism to specific caves cannot be definitely assigned to any species, although 13 species show restricted distribution.
Thesis (Ph.D.)--University of Adelaide, School of Earth and Environmental Sciences, 2006.

Pycnogonida is a subphylum of marine arthropods showing unique characteristics. Their position within the Arthropoda is not yet clear, but strong evidence has, suggested they may be the extant sister taxon to all other arthropods. The phylogenetic affinities among the extant families of pycnogonids: Ammotheidae, Colossendeidae, Callipallenidae, Nymphonidae, Phoxichilidiidae, Pycnogonidae, Austrodecidae, Rhynchothoracidae, and the position of problematic genera such as Endeis, Pallenopsis and Tanystylum, are uncertain. Traditionally, it has been assumed that an evolutionary trend of gradual reduction of numbers of segments of the appendages, mainly involving chelifores, palps and ovigers (head appendages) has taken place within the group. Modern cladistic techniques have not been applied to resolve phylogenetic conflicts of the sea spiders. I approached the problem of the uncertain higher-level phylogenetic affinities of pycnogonids to propose hypotheses of relationships based on cladistic analysis of morphological characters, thereby testing the hypothesis of a reduction trend. Additionally, I used a preliminary molecular approach to confront the morphological results. This is one of the first attempts to use molecular data in the study of systematics of pycnogonids. Phylogenetic relationships among the main lineages of extant sea spiders were studied using cladistic analysis of 36 morphological characters and 38 species from all the recognized families. A preliminary exemplar method was employed, and different assumptions of multistate character transformations were used to trace the evolution of the head appendages. Fragments of nuclear ribosomal DNA (18S and 28S) were sequenced to reconstruct the phylogenetic relationships among six higher taxa of sea spiders. Hypotheses of relationships were obtained from separate and combined analyses of these data sets under both maximum parsimony and maximum likelihood criteria. Trees derived from the molecular data set were compared with those from the set of 36 morphological characters previously analysed. Estimates of phylogeny were found to be significantly different between the molecular and the morphological data set and possible causes for incongruence, such as the coding of inapplicable characters in morphology and a very reduced set of taxa in the molecular analysis, are discussed. The position of Colossendeidae was a major cause of conflict, being supported as a relative of Ammotheidae by morphological characters but appearing closely related to Callipallenidae and Nymphonidae with DNA data. With the molecular characters, Austrodecus is identified as a basal taxon for the rest of the pycnogonids included, differing from its close relationship to ammotheids shown by morphology. Using morphological data, the family Ammotheidae appeared as paraphyletic as did Callipallenidae. Pallenopsis was related to Anoplodactylus according to DNA but not morphology. Although no clear pattern of overall relationships among sea spiders is yet defined, several patterns useful for future systematic work have been noted. New sets of characters and compilation of data from all available sources will probably provide a better picture. Ontogenetic transformation could give some insights into character evolution, and knowledge of ecological traits is needed to complement morphological observations. A collection of fresh material of numerous species of sea spiders from the Great Barrier Reef and other localities of Queensland was useful for the phylogenetic analyses and also contributed to the knowledge of the marine fauna of Australia. Thirty-three species of tropical shallow-water sea spiders collected from the Queensland coast, the Great Barrier Reef and the Coral Sea are reported here. Among these were six undescribed species in the genera Austrodecus, Anoplodactylus and Pycnogonum, and other nine species, mostly of Indo-West pacific distribution not previously recorded for Australia.

There is currently little knowledge about the dynamics of invertebrates in Australian viticultural ecosystems. This study was conducted in Coonawarra vineyards over three seasons (years) and has focused on identifying natural enemies, their seasonal phenology, multiple species interactions, and potential for the suppression of the pest lepidopteran Epiphyas postvittana (Tortricidae). The work presented in this thesis shows that endemic natural enemies have far greater potential to control E. postvittana than has been realised. An initial survey identified a diverse and abundant range of potential natural enemies. Of these, the species most likely to attack E. postvittana include a predatory mite Anystis baccarum and a number of hymenopteran parasitoids. The most abundant parasitoid in the vineyards was a braconid, Dolichogenidea tasmanica. Understanding the characteristic behaviour of parasitoids in response to host density can help to gauge their potential for pest suppression. The results of large-scale field experiments showed that the response of D. tasmanica to the density of E. postvittana was inversely density-dependent, and that parasitism was consistently higher in Cabernet Sauvignon compared with Chardonnay varieties. Despite the fact that interactions among multiple species of natural enemies can increase or decrease pest suppression, particularly when they share a common prey/host, few multispecies interactions have been investigated. Laboratory studies identified a novel interaction between the predatory mite A. baccarum an abundant predator in the vine canopy, the parasitoid D. tasmanica and host E. postvittana larvae. Although A. baccarum readily ate E. postvittana eggs and free roaming larvae, they could not access larva in their silk leaf rolls. However, the addition of D. tasmanica significantly increased predation of E. postvittana larvae, by altering the behaviour of host larvae and increasing their vulnerability to the mite. Experiments conducted at a landscape level in the Coonawarra showed that D. tasmanica was also present in habitat other than vineyards including native vegetation. However, it was not present in highly disturbed habitats. Although the exact mechanism for this remains unknown, results indicate that viticultural practices and resources in the surrounding landscape can influence the presence of parasitoids. Together, the findings presented in this thesis make a significant contribution towards developing sustainable pest management in Australian viticulture.
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Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2008

There is currently little knowledge about the dynamics of invertebrates in Australian viticultural ecosystems. This study was conducted in Coonawarra vineyards over three seasons (years) and has focused on identifying natural enemies, their seasonal phenology, multiple species interactions, and potential for the suppression of the pest lepidopteran Epiphyas postvittana (Tortricidae). The work presented in this thesis shows that endemic natural enemies have far greater potential to control E. postvittana than has been realised. An initial survey identified a diverse and abundant range of potential natural enemies. Of these, the species most likely to attack E. postvittana include a predatory mite Anystis baccarum and a number of hymenopteran parasitoids. The most abundant parasitoid in the vineyards was a braconid, Dolichogenidea tasmanica. Understanding the characteristic behaviour of parasitoids in response to host density can help to gauge their potential for pest suppression. The results of large-scale field experiments showed that the response of D. tasmanica to the density of E. postvittana was inversely density-dependent, and that parasitism was consistently higher in Cabernet Sauvignon compared with Chardonnay varieties. Despite the fact that interactions among multiple species of natural enemies can increase or decrease pest suppression, particularly when they share a common prey/host, few multispecies interactions have been investigated. Laboratory studies identified a novel interaction between the predatory mite A. baccarum an abundant predator in the vine canopy, the parasitoid D. tasmanica and host E. postvittana larvae. Although A. baccarum readily ate E. postvittana eggs and free roaming larvae, they could not access larva in their silk leaf rolls. However, the addition of D. tasmanica significantly increased predation of E. postvittana larvae, by altering the behaviour of host larvae and increasing their vulnerability to the mite. Experiments conducted at a landscape level in the Coonawarra showed that D. tasmanica was also present in habitat other than vineyards including native vegetation. However, it was not present in highly disturbed habitats. Although the exact mechanism for this remains unknown, results indicate that viticultural practices and resources in the surrounding landscape can influence the presence of parasitoids. Together, the findings presented in this thesis make a significant contribution towards developing sustainable pest management in Australian viticulture.
Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2008

This study investigated the role that native insectary plants can play in promoting predatory arthropods, and thereby to enhance biological control of vineyard pests in Australia. I also set out to clarify if light brown apple moth (LBAM), Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae) is the main lepidopteran pest of grapevines in vineyards. Economic damage is caused to grapevines each season by pest species and E. postvittana is considered the dominant insect pest in Australian vineyards. However, recent observations suggested that species of tortricids other than E. postvittana may also act as pests. I investigated which tortricids are present in local vineyards, and whether the diversity of tortricids varied significantly among vineyards. I used molecular methods to determine the species of tortricids present in the canopies of grapevines over two growing seasons. This study confirms that E. postvittana is the most common tortricid pest in South Australian vineyards. Acropolitis rudisana (Walker) (Lepidoptera: Tortricidae), lucerne leafroller, Merophyas divulsana (Walker) (Lepidoptera: Tortricidae), and cotton tipworm, Crocidosema plebejana (Zeller) (Lepidoptera: Tortricidae) are also present in grapevine canopies but have not been reported previously. I also sought to determine if three native candidate native insectary plants, Christmas bush, Bursaria spinosa (Cav.) (Apiales: Pittosporaceae), prickly tea-tree, Leptospermum continentale (Forst. and G.Forst) (Myrtales: Myrtaceae), and wallaby grasses, Rytidosperma ssp. (DC) (Poales: Poaceae) have the capacity to support populations of predatory arthropods throughout the year, and if they may also provide habitat for economically damaging vineyards pests. Surveys were conducted in Adelaide Hills, Barossa Valley and Eden Valley vineyards over a 12-month period. The data were analysed to answer the following questions. What is the biological and functional diversity associated with each plant species? What are the features of an effective, functional native insectary plant assemblage for use in and around vineyards? What is the level of similarity and dissimilarity between the arthropod faunas of each plant species? Each plant species was found to support diverse predator species, which should attack a range of other arthropod pests across their life stages. It may also be possible to increase the functional diversity of predatory arthropods by more than three times when B. spinosa or L. continentale is incorporated into a landscape containing vineyards. Rytidosperma ssp. provides valuable complementary habitat for predatory species other than those commonly found in association with the woody perennials. When Rytidosperma ssp. are included in a viii plant assemblage with each woody plant species, this could result in an average net increase in predator morphospecies richness of at least 27%. Species distribution modelling was used to examine the potential range of each plant species under different climatic conditions. The insectary plants are naturally adapted to all of the major wine growing regions within Australia. Vineyard managers are encouraged to explore the use of B. spinosa, L. continentale and Rytidosperma ssp. as insectary plants in their vineyards. This information could help wine grape growers to manage pests like LBAM, save time and money by producing grapes with lower pest incidence, while enhancing the biodiversity of their vineyards.
Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food & Wine, 2019

Insecticides of botanical origin have played an important role in human attempts to manage arthropod pests. In addition, they have provided templates for synthesis of novel compounds, associated with their modes or action and/or biochemical target(s). Numerous investigations have been conducted, including many recently, on the arthropod activity of plant extracts and essential oil in many regions of the world, including the Americas, Europe and Asia. However, similar work has not been conducted in Australia. It was hypothesised there was a high likelihood that novel secondary compounds with significant insecticidal activity occurred in Australian plant species, in particular within essential oils of the family Myrtaceae. The key objectives of this work were to: (1) identify essential oils with high bioactivity, in particular those exhibiting insecticidal/acaricidal activity; (2) to elucidate the chemistry and identify the active component(s) of highly active oils; (3) to determine activity and host range of selected, highly active oil(s)/components; and (4) to conduct studies to determine mode(s) of action and possible use(s) of the selected oil(s)/components.

Environmental stress resulting from factors such as over grazing can have far-reaching effects on an ecosystem. This thesis aimed to increase the understanding of the wider biodiversity impact of stress and disturbance in semi-arid systems. The response of the arthropod community, and in particular the ant community, to changes in vegetation associated with over grazing, including the loss of perennial shrubs, was examined in the Flinders Ranges region of South Australia.
Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2006

Climate change researchers are predicting more variable rainfall in the coming decades. This is important for grasslands because they are highly responsive to inter- and intrannual rainfall patterns. At the same time, root damage from soil-dwelling arthropods has the potential to exacerbate, or in some cases reverse, the effects of rainfall variability in grassland. Plant community changes are likely to affect aboveground arthropod communities as a result. Recent literature on the effects of rainfall on grassland ecosystems and soil-dwelling invertebrates are synthesized in chapters one and two, respectively. While reduced rainfall amounts are expected to result in lower soil water content, the effects of variable rainfall are unclear and depend highly on grassland type. Plant functional types within grassland communities are likely to play a role in determining these responses and will interact with above- and belowground arthropod communities. Soil-dwelling insects are known in Australia for their high densities during pest outbreaks, especially scarab larva. While these organisms are affected by soil water content, they are predicted to be less vulnerable than organisms aboveground due to physiological and behavioural adaptations. Therefore, they are likely to damage plant roots in grassland ecosystems, even under fluctuating soil moisture. In this thesis I aimed to better understand the responses of grassland organisms that were subjected to rainfall regimes predicted under climate change for SE Australia. I also sought to determine if root damage by local scarab beetles could change the productivity and diversity of the aforementioned grassland in response to rainfall alterations. As such, I attempted to answer the following questions: 1) how will varying water regimes and root damage impact the performance of grasslands at the individual species level; 2) how will changing the amount and frequency of rainfall affect soil water content and how soil water content changes impact grassland plant and invertebrate communities when coupled with increased root herbivore densities and; how are above- and belowground plant community traits relevant to arthropod herbivore performance affected by both extreme rainfall and increased root herbivore density . I hypothesized that rainfall alterations would lead to shifts in grassland productivity and composition, on both the individual and community level. Additionally, root damage would exacerbate the effects of water stress on grassland communities. Finally, grassland community plant traits (e.g. nutrient density, diversity, apparency, etc.) were hypothesized to shift in response to the most extreme forms of water limitation, affecting aboveground herbivore performance. In Chapter three, I examined plant growth, phenology, productivity and physiology to evaluate the effects of rainfall regime and root damage on plant performance. I found that simulated rainfall reduction had a much larger impact on plant productivity than root damage. However, the magnitude of reduction in biomass due to water stress was highly dependent on grass species. Water stress and larval activity interacted leading to increased biomass root:shoot ratios for two grass species. Plant growth and flowering time was affected by water treatments, but not larval activity. I did find, however, strong trends in the concentration of silicon in plant tissue in response to water stress. In Chapter four I measured the responses of grassland plots under altered rainfall and increased root herbivore densities. I found rainfall had a much stronger influence on grassland productivity and plant community composition than increased root herbivore densities. Where the plant community was affected by rainfall, there was evidence of plant-mediated effects on aboveground invertebrate community structure. In Chapter 5 I use the same experimental plots as above but with a focus on plant trait changes in response to extreme rainfall, as well as the other rainfall scenarios. I found that extreme drought can have severe and immediate effects on plant communities in terms of apparency and plant traits that are potentially important for aboveground herbivore performance. Interactions with root herbivory treatments are mixed; in some cases it had a stimulatory effect on plant traits and in others a depressive effect. Plant traits also shift with rainfall regime and, overall, summer drought and reduced frequency rainfall elicited plant trait responses counter to arthropod herbivore performance. Increased rainfall did not have as much of an effect as expected, possibly because of the high sand content and, thus, porosity of the soil at the site. The effects of watering regimes in this thesis were expected to be measurable and to interact with damage caused by root feeders. However, for the most part reduced amount and frequency watering regimes resulted in very similar response levels and root damage effects tended to be negligible. At the community level, responses of root damage and altered water regimes were even less pronounced and almost exclusively interacted in ambient (control) water treatments. It can therefore be assumed that plants use a stress hierarchy when responding to both stressors; here, available soil water seems to be at the top and moderate root damage a lesser concern. This work brings the field one step closer to understanding the complex relationships above- and belowground that are expected to shift in grasslands under climate change. Researchers should strive to understand ecological interactions, no matter how difficult they are to elucidate.