This thesis reports laboratory and field investigations on the aspects of biology of the Stethorus vagans, an Australian ladybird that feeds on all stages of two-spotted mite, Tetranychus urticae. Aspects of the biology of S. vagans were studied in the laboratory at constant and fluctuating temperatures. They regularly fed on all stages of T. urticae and there was no significant difference in male and female longevity at different temperatures. For field studies potted French bean plants infested with T. urticae were exposed in the field. Adult S. vagans was found to consume a range of alternative prey if the primary host was not available, but only one of the alternative hosts had the potential to support reproduction. Time partitioning behaviour and prey consumption rates were assessed, and how S. vagans located their prey was investigated. S. vagans exhibited many of the attributes of an effective biological control agent such as high reproductive level, location of prey at low levels, reproduction at low densities, and ability to feed on alternative hosts. It is concluded that S. vagans has a number of characteristics likely make them useful as a natural enemy of T. urticae / Doctor of Philosophy (PhD)

Around two hundred years ago Goethe made the statement: ‘Let us not seek for something behind the phenomena – they themselves are the theory’. This would appear to be the antithesis of the claim of certain contemporary schools of epistemological thought, that a ‘theory’ is a construction of the human mind. Yet Goethe’s scientific aims are resonant with a present day ecological need: to find a form of ‘nature study’ which springs from a desire to care for things rather than merely to explain them, which can help to create a harmony between human and non-human nature. Goethe’s approach is phenomenological in that it seeks to uncover things ‘on their own terms’; it is integral in that it embraces both art and science. A Goethean methodology is used to study four Australian native plants: Grevillea buxifolia, Scaevola remosissima, Banksia integrifolia and Kunzea ambigua. It is suggested that Goethe’s way of ‘nature study’ fulfils the contemporary need for a participatory knowing which is responsible for the thing being researched, and various possibilities are indicated for further research and application – in the biological sciences and in disciplines such as architecture, landscape design and environmental education. / Master of Science (Hons)

Specialist and generalist phytoseiid mites are widely used for biological control of spider mites. Understanding dispersal attributes of these mites is important to implementing more stable, cost-efficient integrated pest management. In this regard, we studied dispersal of phytoseiid mites from a local ambulatory phase of movement within a prey patch to a longer-range phase that includes emigration (aerial take-off and dispersal distance) and immigration to a new plant. Specialist phytoseiids showed higher ambulatory and aerial dispersal than generalist species. Somewhat different dispersal strategies were seen between Neoseiulus fallacis (more specialized predator) and N. calfornicus (more generalized predator): The most important difference was earlier and continuous dispersal of N. californicus from a prey patch. Cues from spider mite infestation suppressed the dispersal rates for specialists, but either increased or did not change the dispersal rates for generalist phytoseiids. Aerodynamic calculations support the hypothesis that Phytoseiulus persimilis may not require a standing take-off behavior to become airborne. However, with less vertical profile, a mite may become airborne more by standing erect (N. fallacis), than a species that does not show standing take-off (N. calfornicus). Jumping behavior by P. persimilis was observed for the first time among Phytoseiidae. Falling speed ranged from 0.4 to 0.73 m/s for 13 phytoseiid species and 0.79 to 0.81 for two-spotted spider mite. These values were quite similar to theoretical estimates for specialist phytoseiids, but less for generalists. From falling speed estimates and other morphological data, it was possible to predict aerial dispersal distance of phytoseiids using analytical models. After landing on bare soil following aerial dispersal, high mortality of N. fallacis was observed in the field during summer. Distance from the landing point to target plants showed negative log linear relationships. Soil surfaces and management actions influenced survival and recovery. Environmental conditions greatly affected survival of the predator. We speculated that phytoseiids that fell on ground were moving to the target plants via both ambulatory and aerial means. / Graduation date: 2001

Animals living in groups are frequently exposed to conflicts of interest which can escalate into aggression. Aggressive interactions may be a means to resolve incompatibility among objectives. Nevertheless, aggression may undermine the benefits of group living by disrupting the relationships between opponents. Thus, conflict management mechanisms have evolved to cope with the potential damage brought about by aggressive interactions. The aim of my thesis was to investigate the mechanisms to prevent aggressive escalation and to mitigate its negative consequences in 2 communities of wild spider monkeys (Ateles geoffroyi yucanensis). I also examined the factors, such as relationship characteristics, affecting the occurrence of these mechanisms. Spider monkeys live in communities with a high degree of fission fusion dynamics in which individuals frequently split and merge into subgroups of variable composition. The implications of this social system for conflict management were also explored. To characterise spider monkeys’ social relationships, two components were identified and labelled compatibility and risk. These components were further related to relationship characteristics, such as kinship, sex combinations, and tenure in the community. Kin had more compatible relationships than non kin, but there was no difference for risk. Male-male dyads were characterised as being significantly more compatible and riskier than either female-female dyads or male-female dyads. Furthermore, individuals with longer tenure had riskier relationships than individuals with shorter tenure. Among the post-conflict management mechanisms spider monkeys did not engage in reconciliation, redirected aggression, or bystander affiliation. However, an option afforded by their high degree of fission fusion dynamics was used in the aftermath of aggression. Fission from former aggressors was more likely to occur within one hour of the aggressive conflicts than in control periods. Furthermore, individuals sharing riskier and less compatible relationships had significantly shorter latencies to fission compared to those with less risky and more compatible relationships. These patterns suggest that fission may function to reduce the possibility of renewed aggression and cope with increased post-conflict anxiety. Indeed, anxiety levels were higher in the recipients of aggression during the first 5 post-conflict minutes compared to baseline levels. Whereas fission may be a mechanism to cope with the negative consequences of aggressive escalation, fusion of subgroups could lead to uncertainty and hostility. Indeed, aggression increased in the first five post-fusion minutes compared to baseline levels. There was also an increase in post-fusion friendly behaviours, which may function as signals of good intentions. This view was confirmed as post-fusion aggression was reduced when friendly behaviours took place. In addition, shorter latencies of post-fusion aggression and friendly behaviours were found between individuals with riskier relationships compared to those with less risky relationships. Prevention of aggressive conflicts may also be achieved by adjusting subgroup size to the availability of feeding resources thereby reducing competition. The effectiveness of this flexible adjustment was demonstrated during a period of drastic reduction in food sources caused by two consecutive hurricanes at the field site. Mean subgroup size and fusion rates were significantly reduced in the post-hurricane compared to pre-hurricane periods. Hence, my thesis adds to the study of social relationships and conflict management in non-human animals by making several contributions. I provided the first evidence of relationship components in new world monkeys. I then examined the potential of fission-fusion dynamics as a means to manage conflicts among community members. I was the first demonstrating that fission is a post-conflict mechanism. Fission from the former aggressor was especially used by individuals with riskier and less compatible relationships. Subgroup fusion increased aggressive conflicts, especially between individuals with riskier relationships, but post-fusion friendly behaviours reduced them. The effectiveness of fission-fusion dynamics in conflict management was further demonstrated by how the spider monkeys coped with the potential increase in conflict among community members due to a dramatic reduction in food supplies due to two hurricanes. Overall, spider monkeys appear to deal with conflicts using the full range of the flexible social options afforded by their social system.

Gorse, Ulex europaeus, is a serious weed of agriculture and forestry in New Zealand. The mite Tetranychus lintearius feeds on gorse in Europe and was released in New Zealand during autumn 1989 as a potential biological control agent. The aim of my laboratory study was to increase available knowledge on its development and aggregation. As the quality of gorse declined as a food resource (as indicated by chlorophyll content) a significant decline in egg production, and an increase in development time of mites was found. Mean egg production at 15℃ ranged from 37.8 to 45.2 eggs/female over 10 days in the experimental treatments and development time from 39.2 to 43.3 days. Density of adult female mites (1, 2, 5, 10, 15, 20/spine) also had a significant effect on the number of eggs produced/female over ten days (mean daily egg production/female, 0.78-0.88). Mean development time from egg to adult decreased from 40.6 to 39 days as density increased from 1 to 50 mites/spine. The resident New Zealand strain of T lintearius, imported originally from Cornwall, is now widely established but has not established successfully on the west coast of the South Island or in the north of the North Island. Four new strains recently introduced from coastal Portugal and Spain, areas climatically similar to these New Zealand regions, may be more successful. Thus, although egg production and survival of all strains were significantly reduced when subjected to daily periods of simulated rainfall in laboratory experiments, those of the newly introduced strains were least affected. Laboratory experiments with the resident New Zealand and Cambados strains also showed that individuals aggregated actively at 10-20℃, but the latter aggregated more strongly at these temperatures. This strong aggregation behaviour may increase survival in warm, wet climates and suggests that Cambados strain mites could become established and so increase gorse control in Westland and Northland.

Thesis (M. Ag. Sc.)--University of Adelaide, Dept. of Entomology, 1985. / Mounted illus. Includes bibliographical references (leaves 141-153).

Thesis (Ph. D.)--University of Canterbury, 2007. / Typescript (photocopy). Includes bibliographical references (leaves 115-120). Also available via the World Wide Web.

Thesis (B.Sc.(Hons.)) -- University of Adelaide, Dept. of Entomology, 1972.

Silk is a natural protein produced by members of the class Arachnida (over 30,000 species of spiders) and by several worms. Silk-based materials have been investigated for medical and biotechnological applications for many years. Although silkworm silk has been studied extensively because of ready availability of the protein, lately the advancements in recombinant technology has made production of spider silk proteins increasingly available. Due to the characteristics like biocompatibility, biodegradability and mechanical strength, silk is highly desirable as a biomaterial for medical purpose. Along with this, techniques for functionalization, has further aided in the development of silk into highly sophisticated material for advanced applications. The main objective of this thesis has been to investigate novel strategies for functionalization of the recombinant spider silk protein Masp2. Two distinct approaches were used, chemical modification and genetic fusion. In the first modification, we created an infection responsive silk nanospheres by chemically grafting a thrombin sensitive peptide to the silk protein encapsulating antibiotic. These particles were then evaluated for in vitro infection responsive drug release and antimicrobial activity. From these assessments, we found that these particles can release the drug effectively in the presence of infection providing the evidence that these particles are enzyme responsive and can be used to formulate targeted drug release. In the second modification, spider silk was genetically modified with a heparin binding peptide to create a fusion protein which can prevent both thrombosis and infection simultaneously. This fusion protein was evaluated for its heparin binding ability and anticoagulant properties in its solution form. Furthermore, due to the similarity in structure of HBP with antimicrobial peptides, it is predicted that the fusion protein will also show antimicrobial property. After establishing these properties, next this fusion protein was utilized as a coating for hemodialysis catheter. Deposition of coating was evaluated after which anticoagulant and anti-infective properties of the protein as a coating material was investigated. This thesis provides evidence of successful production of a recombinant silk-based biopolymer that can be chemically and genetically embedded with a various functional motif to create a hybrid product for different applications.

Outbreaks of spider mites (Acari: Tetranychidae) in vineyards have been increasing with the expansion of the industry in Virginia. Only three effective acaricides are registered on grapes and as resistance begins to occur, control options are limited. Biological control of spider mites by inoculative or inundative releases of predatory mites has been tried on a wide range of crops including grapes. This project examined the feasibility of using <i>Neoseiulus fallacis</i> (Acari: Phytoseiidae) as a potential large-scale biological control agent in vineyards. Slide dip bioassays were conducted on <i>N. fallacis</i> to determine the toxicity of insecticides, fungicides and herbicides commonly used on grapes in Virginia. In addition to laboratory experiments, commercially obtained <i>N. fallacis</i> were released in vineyards with spider mite infestations. The populations of both mites were then monitored on a regular basis to determine dispersal and distribution patterns. Among the insecticides tested in the laboratory bioassays, carbaryl, azinphos-methyl, phosmet, cyhexatin, and pyridaben all caused significantly higher mortality than the control treatment. Fungicides tested were not toxic to the predator, but three herbicides caused high mortality. Glufosinate caused 100% mortality after 24 hours and both oxyfluorfen and paraquat had adverse effects on <i>N. fallacis</i>. The use of materials that were found to be toxic to the predator would not be compatible with inoculative releases of <i>N. fallacis</i>. Field release results were variable. Three releases were made in 1999 and 2000., Recovery of the predator was low following the releases at two of the sites, probably due to lack of prey. At the third site enough predators were recovered to analyze the spatial distribution of the predator and prey populations. It appears that there is no similar aggregation pattern between the predator and prey at the same point in time although there is an indication of the predator spreading is response to the prey distribution. A more complete season of sampling would give more conclusive evidence of this trend. Although the distribution of the two populations were dissimilar, the predator was present throughout the season and did spread through the entire plot indicating that the predator may be able to colonize the vineyard if it successfully overwinters. / Master of Science