Thesis (Ph. D.)--University of Canterbury, 2006. / Typescript (photocopy). Includes bibliographical references (leaves 99-118). Also available via the World Wide Web.

Thesis (Ph. D.) -- Lincoln University, 2010. / Also available via the World Wide Web.

Ineffective biological control of the Eucalyptus pest Paropsis charybdis Stål (Coleoptera: Chrysomelidae: Paropsini) in cold areas of New Zealand was believed to be caused a climatic mismatch of the egg parasitoid Enoggera nassaui Girault (Hymenoptera: Pteromalidae). Two Tasmanian strains of the parasitoid were introduced to test climate-matching theory in 2000, with approximately 7000 wasps released. Establishment of the Florentine Valley strain was detected in 2002 using the Mitochondrial (mtDNA) gene Cytochrome Oxidase I (COI) as a strain specific marker. The hyperparasitoid Baeoanusia albifunicle Girault (Hymenoptera: Encyrtidae) and primary parasitoid Neopolycystus insectifurax Girault (Hymenoptera: Pteromalidae) were detected for the first time in New Zealand.
As paropsines have proven highly invasive internationally, a risk assessment of the paropsine threat to New Zealand was undertaken by evaluating the host range of E. nassaui and a reproductive assessment of 23 paropsine species in the genera Dicranosterna Motschulsky, Chrysophtharta Weise, Paropsis Olivier, Paropsisterna Motschulsky and Trachymela Weise. Enoggera nassaui proved polyphagous, but bioassay results proved that Paropsis species were significantly more susceptible to the egg parasitoid than Chrysophtharta species. Resistance within Chrysophtharta was attributed to spine-like chorion modifications. A COI derived Chrysophtharta phylogeny divided the genus into two distinct groupings, which was supported by chorion morphology.
Paropsine reproductive output was tested for key parameters indicating pest potential. Pest species displayed fecundity exceeding 600 eggs at an oviposition rate above 10 eggs per day⁻¹. Several non-pest species were identified as potential pests based on these parameters. The Chrysophtharta phylogeny suggested a moderate relationship between genetic relatedness and reproductive output. The Acacia defoliating paropsine Dicranosterna semipunctata (Chapuis) was evaluated for its susceptibility to E. nassaui and reproductive output. Egg parasitism occurring in bioassay did not translate into biological suppression following a specifically targeted release of E. nassaui, and the fecundity and oviposition rates fell below the thresholds predicted for a pest paropsine species.
Despite establishment of Tasmanian E. nassaui, hyperparasitism has now rendered this control agent ineffective in New Zealand. Neopolycystus insectifurax offers the best hope for future biological control of paropsine species in New Zealand.

The Enemy Release Hypothesis proposes that introduced species often achieve larger individual sizes and greater population abundance in their introduced range because they have escaped their natural enemies - predators and parasites - that regulate populations in their native range. The main objective of this study is to test the Enemy Release Hypothesis (ERH) by investigating the identity, prevalence and intensity of parasites in two marine species introduced to New Zealand - the recently introduced but spatially restricted Asian portunid crab, Charybdis japonica, and the longer-established Asian nesting mussel, Musculista senhousia. Host choice of a native generalist parasite presented with the non-native and native mussels, and prey selection by a native predator presented with these bivalves will be examined. This is the first study of its kind in New Zealand. The parasite fauna of the only established New Zealand population of C. japonica (Waitemata Harbour, Auckland), was compared to that from (a) a population of C. japonica from its native region (Japan) and (b) to multiple populations of the native New Zealand crab Ovalipes catharus, a native New Zealand portunid. Results showed the introduced crab harboured only one species of endoparasite (a nematode), and two types of melanised lesions. Neither the parasite nor the lesions were present in the native crab populations. The native crab was host to only one parasite species, which occurred at very low prevalence, and was present in only one of the six populations examined from throughout New Zealand. Carapace width in the introduced crab was no larger than that reported in literature from its native are, but was larger than carapace widths of the Japanese sample. M. senhousia was examined from five sites within New Zealand. Parasites in M. senhousia were compared with a sympatric native bivalve, Austrovenus stutchburyi, two native mytilids, (Perna canaliculus and Xenostrobus pulex) and with samples of M. senhousia from Italy and the USA where it is introduced, and Japan where it is native. Two native generalist parasites, the pea crab Pinnotheres novaezelandiae, and a copepod, were found within M. senhousia in New Zealand, but only at low prevalence. A greater array of organisms was associated with the native bivalves. No parasites were recovered from any of the overseas samples of M. senhousia, including the Japanese samples. This may be caused by the preservation medium used, but could be a true reflection of the parasite fauna in these populations. The site where the two native parasites were exploiting M. senhousia was the only site sampled where two native mussels, P. canaliculus and X. pulex, also occurred. Consequently, effects of these two generalist parasites on the three mussel species were examined. In P. canaliculus, presence of native pea crabs was associated with lower tissue dry weight and greater shell depth. Shell width and depth were both greater in the presence of copepods. However, the prevalence of pea crabs and copepods was much lower in M. senhousia compared to the two native mussels, indicating some release from the effects of these parasites for the non-native species. Experimental choice tests showed that the pea crab, P. novaezelandiae, does not actively select M. senhousia as a host, preferring the larger native mussel, P. canaliculus. Rates of infection of M. senhousia are, therefore, likely to remain low in natural habitats where there are large numbers of native hosts. In addition, a generalist predator, the crab O. catharus, showed no preference when foraging on the three mussel species under experimental conditions. Thus, some predation pressure may be exerted on M. senhousia by this native crab in the natural environment. Investigation of multiple populations of both native and non-native species has shown large variation in parasite prevalence and intensity among populations of each species. After examining C. japonica and the comparable native O. catharus, evidence to support the ERH was found to be weak. As the native crab was relatively free of parasites, it seems unlikely that parasite infection is important within native populations and therefore, the success of C. japonica is unlikely to be caused by comparatively greater freedom from parasites (a central tenet of the ERH). There was also no evidence for host-switching by native parasites into the introduced C. japonica population. In contrast, native parasites were present at very low prevalence in the non-native mussel M. senhousia. Length of time since introduction can be an important factor in host switching between native and introduced hosts, but unless prevalence of these parasites is high, the introduced species still escapes from enemies that could control a population. Therefore every non-native species needs to be examined using multiple populations to investigate variation in parasite fauna, prevalence and intensity, as the same species, if introduced numerous times, could potentially show contrasting results for the ERH unless multiple populations are examined.

The purpose of this study is to locate spatial manifestations of power, and acts of agency, by conducting a subversive reading of the female immortal threats in Homer’s Odyssey. With an aim to question preconceived notions on sexuality, gender and power, I draw on the theoretical perspectives of gender theorists J. Butler and J. Halberstam in my reading of non-normative female displays of power. The material in question is the adventures in the Odyssey that present female immortals, functioning as antagonists in the epos’ narrative structure. Space and power make the foundation in the deconstruction of these adventures. I approach the subject using analytical tools from the spatial methodology of K. Knott. Starting with ‘location’ I apply analytical categories such as ‘physical space’, ‘social space’, ‘properties of space’ and ‘spatial aspects’ in order to critically analyze spatial manifestations of power in each adventure. By placing the female immortal in the subject position, this work shows how she utilizes her space in order to dominate the mortal man she encounters. This is conducted through non-normative acts such as isolation and restriction. The study highlights the problem of putting ‘sex’ as the only, or dominant, focus in the reading of these adventures. The female immortals that Odysseus encounters, can by spatial analysis be shown to act autonomously towards mortal intruders that enter their territory.  They present themselves as having the right to take a mortal man for a husband, as well as kill him or keep him as a prisoner. This suggests that their status as immortal exceeds Odysseus’ male gender, whilst still being restricted by the gender hierarchy of her immortal society. The spatial analysis show that the female immortal possesses the agency of the mortal female as well as of the mortal male within in their oikos. The female immortal displays power by sustaining her space, as well as by regulating the movements of the mortal man, in and out of, and sometimes beyond, her space.

An established host-parasitoid-hyperparasitoid system was used to investigate how the physiological and behavioural characteristics of parasitoids influence the outcomes of laboratory-based host specificity tests. The characteristics of the two pteromalid egg parasitoids, Enoggera nassaui (Girault) and Neopolycystus insectifurax Girault, were assessed and interpreted in regard to the particular host specificity testing methods used and the control of the eucalypt defoliating beetle Paropsis charybdis Stål (Chrysomelidae) in New Zealand. The physiology of N. insectifurax was examined to determine how to increase production of female parasitoids that were physiologically capable and motivated to parasitise P. charybdis eggs in laboratory trials. Neopolycystus insectifurax were found to be more synovigenic than E. nassaui. Provisioning them with honey and host stimuli for three days, and allowing females to parasitise hosts in isolation (i.e. in the absence of competition) was an effective means of achieving these goals. No-choice tests were conducted in Petri dish arenas with the four paropsine beetles established in New Zealand. All four were found to be within the physiological host ranges of E. nassaui and N. insectifurax, but their quality as hosts, as indicated by the percent parasitised and offspring sex ratios, varied. The results of paired choice tests between three of the four species agreed with those of no-choice tests in most instances. However, the host Trachymela catenata (Chapuis), which was parasitised at very low levels by E. nassaui in no-choice tests, was not accepted by that species in paired choice tests. A much stronger preference by N. insectifurax for P. charybdis over T. catenata was recorded in the paired choice test than expected considering the latter was parasitised at a high level in the no-choice test. The presence of the target host in paired choice tests reduced acceptance of lower ranked hosts. Both no-choice and choice tests failed to predict that eggs of the acacia feeding beetle Dicranosterna semipunctata (Chapuis) would not be within the ecological host range of E. nassaui and N. insectifurax. Behavioural observations were made of interspecific competition between E. nassaui and N. insectifurax for access to P. charybdis eggs. Two very different oviposition strategies were identified. Neopolycystus insectifurax were characterised by taking possession of, and aggressively guarding host eggs during and after oviposition. They also appeared to selectively oviposit into host eggs already parasitised by E. nassaui, but did not emerge from significantly more multi-parasitised hosts than E. nassaui. Enoggera nassaui did not engage in contests and fled when approached by N. insectifurax. Although often prohibited from ovipositing by N. insectifurax, E. nassaui were able to locate and begin ovipositing more quickly, and did not remain to guard eggs after oviposition. It is hypothesised that although N. insectifurax have a competitive advantage in a Petri dish arena, E. nassaui may be able to locate and parasitise more host eggs in the field in New Zealand, where competition for hosts in is relatively low. The biology of the newly established encyrtid Baeoanusia albifunicle Girault was assessed. It was confirmed to be a direct obligate hyperparasitoid able to exploit E. nassaui but not N. insectifurax. Field and database surveys found that all three parasitoids have become established in many climatically different parts of New Zealand. Physiological characteristics were identified that may allow B. albifunicle to reduced effective parasitism of P. charybdis by E. nassaui to below 10%. However, the fact that hyperparasitism still prevents P. charybdis larvae from emerging, and that B. albifunicle does not attack N. insectifurax, may preclude any significant impact on the biological control of P. charybdis. Overall, parasitoid ovigeny and behavioural interactions with other parasitoids were recognised as key characteristics having the potential to influence host acceptance in the laboratory and the successful biological control of P. charybdis in the field. It is recommended that such characteristics be considered in the design and implementation of host specificity tests and might best be assessed by conducting behavioural observations during parasitoid colony maintenance and the earliest stages of host specificity testing.