Stan Fenwick

The microscopic examination of naturally infected plant material for the presence of Phytophthora cinnamomi can be problematic as structures such as hyphae, hyphal swellings, chlamydospores, and oospores are often indistinguishable from those of other oomycetes or fungi. Frequently, it would be useful to be able to clearly differentiate P. cinnamomi from other microorganisms, especially when trying to determine how the pathogen is surviving in plant material particularly in harsh environments. Consequently, the lack of stains that can clearly and definitively localise hyphae and reproductive structures of P. cinnamomi within plant material is a limitation in increasing our understanding of the biology of the pathogen in susceptible and tolerant plant species in different ecosystems. This study demonstrates that a P. cinnamomi specific, fluorescently labelled DNA probe can be used to specifically detect and visualise P. cinnamomi in plant material using fluorescent in situ hybridization (FISH) without damage to plant or pathogen cell integrity. The method will allow us to more accurately study plant‐P. cinnamomi interactions in plants, and to be particularly useful in naturally infected material.

Viewing of Phytophthora cinnamomi by microscopic examination in planta is often difficult as structures such as hyphae, chlamydospores and oospores are often indistinguishable from those of other fungi with histological stains not enabling species differentiation. This lack of staining specificity makes the localisation of P. cinnamomi hyphae and reproductive structures within plant tissue difficult, especially in woody tissues. This study demonstrates that utilising a species-specific fluorescently labelled DNA probe allowed P. cinnamomi to be specifically detected and visualised using fluorescent in situ hybridisation (FISH) without damage to plant or pathogen cell integrity. This approach provides a new application of FISH with potential use in the study of plant-pathogen interactions in planta.

Feral pigs have long been implicated as vectors in the spread of the plant pathogen Phytophthora cinnamomi. The wallowing and rooting activities of feral pigs predispose them to the transport of infested soil. These activities not only disturb the soil structure but also reduce leaf litter and vegetation cover which can lead to an increased susceptibility of an area to colonisation with P. cinnamomi. The non-fastidious diet and use of rub and tusk trees by feral pigs may also represent an avenue of pathogen spread. However, there is very little evidence to support these ideas. Replicated feeding trials using P. cinnamomi inoculated millet seed, fine roots and pine have shown that the pathogen can survive passage through the pig gut, in some instances for up to seven days before being passed. The study is also investigating the home range of pigs within the forest and potential distances over which spread is likely to occur. The controlled experiments and field work from this research will be presented and the implications for the management of feral pig populations as an important component of P. cinnamomi management will be discussed.

The movements and habitat use of feral pigs in the northern jarrah forest of Western Australia were examined using GPS tracking collars over a 12 month period. Collars were fitted to six feral pigs (3 male, 3 female) trapped from within the same river valley system, incorporating both private property and state forest. Home range sizes varied from 13.5 km2 (dominant boar) to 0.5 km2 (nursing sow) (minimum convex polygon method). Home range size, overlap and habitat use by each of the collared pigs was investigated for seasonal and temporal variation. Management implications for this population are discussed.

Ectoparasite biodiversity across a range of Western Australian threatened mammals is being described as part of a larger project examining the presence and impact of parasites in fauna. Fleas, ticks, mites and lice are collected in animals that are trapped across the State as part of the Department of Environment and Conservation's threatened mammal monitoring programs, an Australian Research Council funded project and the Woylie Conservation Research Programme. Most of the published work on ectoparasite biodiversity was done in the first half of the last century and is based on drawings of morphological features. These monographs have been found to be inadequate and many rare mammals have no records of their parasite fauna described. New methods utilising PCR and scanning electron microscopes are being used to help describe species of ectoparasite. A tick found on the woylie may prove to be a new species. PCR is also being used to examine the role of ectoparasites as vectors of disease. The presence of introduced ectoparasites such as the rat flea Xenopsylla cheopis underlines the risks to Australian fauna of novel vector-borne diseases. Results to date will be discussed and it is hoped that the work will contribute to wildlife management decisions as well as biodiversity research.

Feral pigs have been widely implicated in the spread of dieback disease, caused by Phytophthora cinnamomi, via the transport of infected soil material. P. cinnamomi is an important introduced plant pathogen with a wide host range which is widespread throughout much of Australia. This pathogen currently threatens many unique and diverse natural ecosystems throughout the south-west corner of Western Australia, both in areas where feral pigs are present and absent. The disruption of native ecosystems caused by the rooting and wallowing activities of feral pigs are believed to increase their susceptibility to dieback infections. As such, feral pigs may play an important role in the spread of P. cinnamomi as well as the re-introduction of new infections to previously exposed areas. This study aims to determine the role of feral pigs in the spread of Phytophthora dieback through the transport of infected soil as well as investigating the potential for disseminating the pathogen via passage of infected plant material through their gastrointestinal tract. A new detection technique, fluorescent in situ hybridisation (FISH) targeting conserved 16S rRNA allows for easier sample processing and visualisation of the pathogen in situ within root fragments

The Gilbert's potoroo (Potorous gilbertii) is Australia's most critically endangered mammal with an estimated population of less than 30 individuals. There has been a long history of balanoposthitis (inflammation of the penis and prepuce) in individuals from both wild and captive populations of this species. Clinically, this is evident as crusty green tenacious preputial exudates with associated ulceration. Bacteriologic examination has revealed a number of potential pathogens amongst the mixed bacteria isolated. The most significant is a Treponema like organism. Sequencing results from these spirochetes identified a 164 nucleotide segment of 16S ribosomal RNA, which had 92% similarity to Treponema species. Prevalence of infection with the Treponema-like organism was 17/26 (65.38%).