Global Geographic Distribution and Host Range of Fusarium circinatum, the Causal Agent of Pine Pitch Canker

Fusarium circinatum, the causal agent of pine pitch canker (PPC), is currently one of the most important threats of Pinus spp. globally. This pathogen is known in many pine-growing regions, including natural and planted forests, and can affect all life stages of trees, from emerging seedlings to mature trees. Despite the importance of PPC, the global distribution of F. circinatum is poorly documented, and this problem is also true of the hosts within countries that are affected. The aim of this study was to review the global distribution of F. circinatum, with a particular focus on Europe. We considered (1) the current and historical pathogen records, both positive and negative, based on confirmed reports from Europe and globally; (2) the genetic diversity and population structure of the pathogen; (3) the current distribution of PPC in Europe, comparing published models of predicted disease distribution; and (4) host susceptibility by reviewing literature and generating a comprehensive list of known hosts for the fungus. These data were collated from 41 countries and used to compile a specially constructed geo-database. A review of 6297 observation records showed that F. circinatum and the symptoms it causes on conifers occurred in 14 countries, including four in Europe, and is absent in 28 countries. Field observations and experimental data from 138 host species revealed 106 susceptible host species including 85 Pinus species, 6 non-pine tree species and 15 grass and herb species. Our data confirm that susceptibility to F. circinatum varies between different host species, tree ages and environmental characteristics. Knowledge on the geographic distribution, host range and the relative susceptibility of different hosts is essential for disease management, mitigation and containment strategies. The findings reported in this review will support countries that are currently free of F. circinatum in implementing effective procedures and restrictions and prevent further spread of the pathogen

Worldwide diversity of endophytic fungi and insects associated with dormant tree twigs

International trade in plants and climate change are two of the main factors causing damaging tree pests (i.e. fungi and insects) to spread into new areas. To mitigate these risks, a large-scale assessment of tree-associated fungi and insects is needed. We present records of endophytic fungi and insects in twigs of 17 angiosperm and gymnosperm genera, from 51 locations in 32 countries worldwide. Endophytic fungi were characterized by high-throughput sequencing of 352 samples from 145 tree species in 28 countries. Insects were reared from 227 samples of 109 tree species in 18 countries and sorted into taxonomic orders and feeding guilds. Herbivorous insects were grouped into morphospecies and were identified using molecular and morphological approaches. This dataset reveals the diversity of tree-associated taxa, as it contains 12,721 fungal Amplicon Sequence Variants and 208 herbivorous insect morphospecies, sampled across broad geographic and climatic gradients and for many tree species. This dataset will facilitate applied and fundamental studies on the distribution of fungal endophytes and insects in trees

Health problems of the Western Australian dhufish

The purpose of this project was to describe and investigate health problems in captive West Australian dhufish, Glaucosoma hebraicum. The dhufish is a potential aquaculture species due to its popularity as an edible species and fishing pressure on wild fisheries. The two most significant health problems apparent in captive dhufish were exophthalmos in otherwise apparently normal fish and infestation of gills with a monogenean parasite, Haliotrema abaddon. Several other health problems were also described and investigated during the project. Exophthalmic lesions were described, followed by investigations into the aetiology and pathogenesis of the condition. Epidemiological data were gathered to identify risk factors that may increase the pre-disposition of dhufish to the development of exophthalmos. The anatomical arrangement of vasculature supplying the eye was described and the haemoglobin-oxygen transport properties of dhufish blood that pre-dispose dhufish to exophthalmos were studied. Oxygen partial pressure in the normal retina and oxygen content of gas bubbles in exophthalmic eyes were recorded. Risk factors for the development of exophthalmos were investigated in an experiment using unaffected fish, variable water temperature, fright- induction and exercise regimes. Gas and haemorrhage was present in the choroid of exophthalmic eyes, with haemorrhage in retrobulbar tissues resulting from perforation of the sclera in some eyes. Oxygen content of gas in eyes with recently developed exophthalmos was high (up to 73%). In some eyes with retrobulbar haemorrhage, oxygen tension approached zero, indicating severe disruption of blood supply to the eye. Oxygen tension at the retinal-vitreal junction of normal dhufish eyes was high (344 ± 26 mm Hg), with oxygenated blood supplied to the choroid body from the gills via the pseudobranch. The finding of a single haemoglobin with pronounced Root and Bohr effects in dhufish was significant and may contribute to the susceptibility of the species to exophthalmos. Investigations suggest that exophthalmos is physiological in origin and is related to the environmental differences between the natural habitat of the fish and the conditions that are experienced in aquaculture. Dhufish appear to be highly adapted to a relatively inactive life-style with relatively constant environmental conditions at high hydrostatic pressure. Rapid changes of temperature or blood acid-base characteristics may precipitate the development of exophthalmos. The monogenean parasite, Haliotrema abaddon, was described and stages of its life-cycle identified. As the parasite was troublesome in captive fish, potential treatments were investigated using in vitro and in vivo studies. Praziquantel was identified as the most effective ‘in water’ treatment of fish infested with H. abaddon. Other useful but less effective and safe treatments were low salinity baths (<1.5 ppt for ninety minutes) and 0.5 mg L-1 trichlorphon for 36 hours. Life in tanks appears stressful for many dhufish, resulting in health problems such as exophthalmos and disease outbreaks, including severe H. abaddon infestation and bacterial and fungal diseases. Multiple risk factors appear to pre-dispose the fish to these conditions. They include environment al factors such as water temperature, depth and physico-chemical composition, diet and stocking density; host factors such as physiological and social adaptation to a relatively solitary, sedentary lifestyle in a deepwater habitat and pathogen factors such as increased fecundity and decreased generation time in warmer water temperatures. Decreasing fish stress and maintaining environmental conditions close to those in the natural habitat, including increasing tank depth and decreasing light intensity are expected to improve the overall health of captive dhufish

Treatments to control Haliotrema abaddon in the West Australian dhufish, Glaucosoma hebraicum

Haliotrema abaddon is a significant monogenean parasite of the gills of maricultured Western Australian dhufish, Glaucosoma hebraicum, and can cause severe gill pathology. A series of trials was undertaken using infested fish in 120-l glass aquaria to assess the safety and efficacy of some potential “in water” treatments, including trichlorphon, praziquantel, formalin, toltrazuril and a freshwater bath. Treatment efficacy was established by assessment of the number of parasites found in tank sediment immediately following treatment and by examination of gills for parasites using a gill biopsy technique. Praziquantel bathes, 2 mg l−1 of 30-h duration, were the most safe and effective treatment. Freshwater bathes of below 2‰ salinity for 90 min were effective but highly stressful for the fish. Trichlorphon 0.5 mg l−1 for 30 h was safe and relatively effective. Formalin, 25 ppm, and toltrazuril, 12.5 mg l−1, were safe but resulted in the removal of insufficient parasites to recommend it as a treatment for dhufish infested with H. abaddon

Haemoglobin and oxygen transport of the West Australian dhufish, Glaucosoma hebraicum Richardson, and other species

To better understand the possible role of deoxygenation of haemoglobin in the pathogenesis of exophthalmos in the West Australian dhufish, Glaucosoma hebraicum Richardson, some oxygen transport properties of haemoglobin from this species were determined and compared with haemoglobin from black bream, Acanthopagrus butcheri (Munro), snapper, Pagrus auratus (Bloch & Schneider) and King George whiting, Sillaginodes punctata (Cuvier). Dhufish had a single haemoglobin with a pronounced Root effect. Snapper and black bream blood had six and five types of haemoglobin, respectively. The magnitude of the Root effect of haemoglobins in the haemolysate was demonstrated by comparing oxygenation and total deoxygenation at pH 8 with relative deoxygenation at pH 6.9. Dhufish haemoglobin demonstrated a large Root effect, with the Root effect of King George whiting, snapper and black bream being of lesser magnitude. Deoxygenation of all haemolysates was more pronounced in the presence of adenosine triphosphate (ATP). Seasonal changes in haematological parameters and ATP content of dhufish blood were not evident. The Root effect is discussed in the context of its possible role in oxygen supply to the retina and adaptation to the fish's habitat and the environment

Achieving a reuse perspective within a component recovery process: an industrial scale case study

Identifying elements of existing software that are reused within a system may provide maintainers with valuable insights during system evolution. This paper evaluates an extension of software reconnaissance that can be used to analyse reuse across features in a system, as part of a component recovery process proposed in [18]. We illustrate and evaluate retrieval of reuse information in this fashion using a large, commercial ERP and warehousing application. Results suggest that the approach scales well in terms of reuse information across features in existing software, providing maintainers with a valuable new perspective on the software system in question