Quambalaria species associated with plantation and native eucalypts in Australia

This study aimed to determine which species of Quambalaria are associated with shoot blight symptoms on Corymbia spp. An additional aim was to determine the presence and impact of quambalaria shoot blight on Eucalyptus species used in plantation development in subtropical and tropical regions of eastern Australia. Surveys identified three Quambalaria spp. -Q. pitereka, Q. eucalypti and Q. cyanescens - from native and plantation eucalypts, as well as amenity plantings, including the first confirmed report of Q. eucalypti from Eucalyptus plantations in Australia. Symptom descriptions and morphological studies were coupled with phylogenetic studies using ITS rDNA sequence data. Quambalaria pitereka was the causal agent of blight symptoms on species and hybrids in the Corymbia complex. Quambalaria eucalypti was identified from Eucalyptus species and a single Corymbia hybrid. Quambalaria cyanescens was detected from native and plantation Corymbia spp.

Rainfall and streamflow response to El Niño Southern Oscillation: a case study in a semiarid catchment, Australia.

This paper aims to compare the shift in frequency distribution and skill of seasonal climate forecasting of both streamflow and rainfall in eastern Australia based on the Southern Oscillation Index (SOI) Phase system. Recent advances in seasonal forecasting of climate variables have highlighted opportunities for improving decision making in natural resources management. Forecasting of rainfall probabilities for different regions in Australia is available, but the use of similar forecasts for water resource supply has not been developed. The use of streamflow forecasts may provide better information for decision-making in irrigation supply and flow management for improved ecological outcomes. To examine the relative efficacy of seasonal forecasting of streamflow and rainfall, the shift in probability distributions and the forecast skill were evaluated using the Wilcoxon rank-sum test and the linear error in probability space (LEPS) skill score, respectively, at three river gauging stations in the Border Rivers Catchment of the Murray-Darling Basin in eastern Australia. A comparison of rainfall and streamflow distributions confirms higher statistical significance in the shift of streamflow distribution than that in rainfall distribution. Moreover, streamflow distribution showed greater skill of forecasting with 0-3 month lead time, compared to rainfall distribution.

Light environment and tree development of young Acacia melanoxylon in mixed-species regrowth forest, Tasmania, Australia

Blackwood (Acacia melanoxylon R. Br.) is a valuable leguminous cabinetwood species which is commonly found as a canopy or subcanopy tree in a broad range of mixed-species moist forests on tablelands and coastal escarpments in eastern Australia. This paper reports on the competitive light environment of a commercially valuable multi-species regrowth forest in NW Tasmania, in order to define some of the functional interactions and competitive dynamics of these stands. Comparative observations were made of the internal forest light environment in response to small-gap silvicultural treatments, in a young regenerative mix of three codominant tree species. Light measurements were made during periods of maximum external irradiance of the regrowth Eucalyptus obliqua/A. melanoxylon forest canopy at age 10.5 years. This was at a time of vigourous stand development, 4.5 years following the application of three experimental silvicultural treatments whose effects were observed in comparison with an untreated canopy sample designed as a control. Minimal irradiance was observed within and beneath the dense subcanopy of the native nurse species (Pomaderris apetala) which closely surrounds young blackwood regeneration. Unlike current plantation nurse systems, the dense foliage of the native broadleaved Pomaderris all but eliminated direct side-light and low-angle illumination of the young blackwood, from the beginning of tree establishment. The results demonstrated that retention of these densely stocked native codominants effectively suppressed both size and frequency of blackwood branches on the lower bole, through effective and persistent interception of sunlight. Vigorous young blackwood crowns later overtopped the codominant nurse species, achieving a predictable height of branch-free bole. This competitive outcome offers a valuable tool for management of blackwood crown dynamics, stem form and branch habit through manipulation of light environment in young native regrowth systems. Results demonstrate that effective self-pruning in the lower bole of blackwood is achieved through a marked reduction in direct and diffuse sunlight incident on the lower crown, notably to less than 10-15% of full sunlight intensity during conditions of maximum insolation. The results also contain insights for the improved design of mixed-species plantation nurse systems using these or functionally similar species' combinations. Based on evidence presented here for native regrowth forest, plantation nurse systems for blackwood will need to achieve 85-90% interception of external side-light during early years of tree development if self-pruning is to emulate the results achieved in the native nurse system.

Population genetic structure of the brown tiger prawn, Penaeus esculentus, in tropical northern Australia

Eight polymorphic microsatellite loci were analysed in six population samples from four locations of the Australian endemic brown tiger prawn, Penaeus esculentus. Tests of Hardy-Weinberg equilibrium were generally in accord with expectations, with only one locus, in two samples, showing significant deviations. Three samples were taken in different years from the Exmouth Gulf. These showed no significant heterogeneity, and it was concluded that they were from a single panmictic population. A sample from Shark Bay, also on the west coast of Australia, showed barely detectable differentiation from Exmouth Gulf (F (ST) = 0 to 0.0014). A northeast sample from the Gulf of Carpentaria showed low (F (ST) = 0.008) but significant differentiation from Moreton Bay, on the east coast. However, Exmouth Gulf/Shark Bay samples were well differentiated from the Gulf of Carpentaria/Moreton Bay (F (ST) = 0.047-0.063). The data do not fit a simple isolation by distance model. It is postulated that the east-west differentiation largely reflects the isolation of east and west coast populations that occurred at the last glacial maximum when there was a land bridge between north-eastern Australia and New Guinea.

Using morphological traits to identify persistent lucernes for dryland agriculture in NSW, Australia

This paper reports on several studies conducted to better understand the variability between lucerne cultivars and lines, and use this to predict persistence in dryland grazing pastures in eastern Australia. Morphological traits of 20 cultivars/lines were measured in irrigated and dryland spaced plant experiments. Studies were also conducted to describe variation among lucernes in their utilisation of starch and responses to water deficit, pests and diseases. Multiple regression analyses were used to develop simple models where the measured traits could be used to predict persistence of lucerne lines in dryland evaluation experiments. Although there was significant variation among cultivars/lines in most measured traits, no single trait reliably predicted persistence of cultivars/lines in dryland evaluation experiments. However, variation in persistence at both sites could be explained by models developed by multiple regression using differences in the mean lengths of the longest stems at 10% flower in summer and winter. Persistent lucernes were those that had relatively long stems in summer and short stems in winter. Water use efficiencies, starch utilisation patterns and resistances to pests and diseases of different lucernes provided some improvement to this simple model, but these improvements were not consistent.

An overview of integrated pest management (IPM) in north-eastern Australian grain farming systems: Past, present and future prospects

The authors overview integrated pest management (IPM) in grain crops in north-eastern Australia, which is defined as the area north of latitude 32°S. Major grain crops in this region include the coarse grains (winter and summer cereals), oilseeds and pulses. IPM in these systems is complicated by the diversity of crops, pests, market requirements and cropping environments. In general, the pulse crops are at greatest risk, followed by oilseeds and then by cereal grains. Insecticides remain a key grain pest management tool in north-eastern Australia. IPM in grain crops has benefited considerably through the increased adoption of new, more selective insecticides and biopesticides for many caterpillar pests, in particular Helicoverpa spp. and loopers, and the identification of pest-crop scenarios where spraying is unnecessary (e.g. for most Creontiades spp. populations in soybeans). This has favoured the conservation of natural enemies in north-eastern Australia grain crops, and has arguably assisted in the management of silverleaf whitefly in soybeans in coastal Queensland. However, control of sucking pests and podborers such as Maruca vitrata remains a major challenge for IPM in summer pulses. Because these crops have very low pest-damage tolerances and thresholds, intervention with disruptive insecticides is frequently required, particularly during podfill. The threat posed by silverleaf whitefly demands ongoing multi-pest IPM research, development and extension as this pest can flare under favourable seasonal conditions, especially where disruptive insecticides are used injudiciously. The strong links between researchers and industry have facilitated the adoption of IPM practices in north-eastern Australia and augers well for future pest challenges and for the development and promotion of new and improved IPM tactics.

Infection with Menangle virus in flying foxes (Pteropus spp.) in Australia

Objective: To examine flying foxes (Pteropus spp.) for evidence of infection with Menangle virus. Design: Clustered non-random sampling for serology, virus isolation and electron microscopy (EM). Procedure: Serum samples were collected from 306 Pteropus spp. in northern and eastern Australia and tested for antibodies against Menangle virus (MenV) using a virus neutralisation test (VNT). Virus isolation was attempted from tissues and faeces collected from 215 Pteropus spp. in New South Wales. Faecal samples from 68 individual Pteropus spp. and four pools of faeces were examined by transmission EM following routine negative staining and immunogold labelling. Results: Neutralising antibodies (VNT titres ≥ 8) against MenV were detected in 46% of black flying foxes (P. alecto), 41% of grey-headed flying foxes (P. poliocephalus), 25% of spectacled flying foxes (P. conspicillatus) and 1% of little red flying foxes (P. scapulatus) in Australia. Positive sera included samples collected from P. poliocephalus in a colony adjacent to a piggery that had experienced reproductive disease caused by MenV. Virus-like particles were observed by EM in faeces from Pteropus spp. and reactivity was detected in pooled faeces and urine by immunogold EM using sera from sows that had been exposed to MenV. Attempts to isolate the virus from the faeces and tissues from Pteropus spp. were unsuccessful. Conclusion: Serological evidence of infection with MenV was detected in Pteropus spp. in Australia. Although virus-like particles were detected in faeces, no viruses were isolated from faeces, urine or tissues of Pteropus spp.

Biology and host range of Ophiomyia camarae Spencer (Diptera: Agromyzidae), a potential biocontrol agent for Lantana spp. (Verbenaceae) in Australia

The life history and host range of the herringbone leaf-mining fly Ophiomyia camarae, a potential biological control agent for Lantana spp., were investigated. Eggs were deposited singly on the underside of leaves. Although several eggs can be laid on a single leaf and a maximum of three individual mines were seen on a single leaf, only one pupa per leaf ever developed. The generation time (egg to adult) was about 38 days. Females (mean 14 days) lived longer than males (mean 9 days) and produced about 61 mines. Oviposition and larval development occurred on all five lantana phenotypes tested. Eleven plant species representing six families were tested to determine the host range. Oviposition and larval development occurred on only lantana and another nonnative plant Lippia alba (Verbenaceae), with both species supporting populations over several generations. A CLIMEX model showed that most of the coastal areas of eastern Australia south to 30°16' S (Coffs Harbour) would be suitable for O. camarae. O. camarae was approved for release in Australia in October 2007 and mines have been observed on plants at numerous field sites along the coast following releases.

Reproductive ecology of invasive Ochna serrulata (Ochnaceae) in south-eastern Queensland

We investigated aspects of the reproductive ecology of Ochna serrulata (Hochst.) Walp., an invasive plant in eastern Australia. O. serrulata drupes were similar in size to fleshy fruits of other local invasive plants, but showed some distinct differences in quality, with a very high pulp lipid content (32.8% of dry weight), and little sugar and water. Seeds were dispersed by figbirds, Sphecotheres viridis Vieillot, a locally abundant frugivore, and comprised between 10 and 50% of all non-Ficus spp. fruit consumed during October and November. The rate of removal of O. serrulata drupes was greater in bushland than suburban habitats, indicating that control in bushland habitats should be a priority, but also that suburban habitats are likely to act as significant seed sources for reinvasion of bushland. Germination occurred under all seed-processing treatments (with and without pulp, and figbird gut passage), suggesting that although frugivores are important for dispersal, they are not essential for germination. Recruitment of buried and surface-sown seed differed between greenhouse and field experiments, with minimal recruitment of surface-sown seed in the field. Seed persistence was low, particularly under field conditions, with 0.75% seed viability after 6 months and 0% at 12 months. This provides an opportunity to target control efforts in south-eastern Queensland in spring before fruit set, when there is predicted to be few viable seeds in the soil.

The stock structure of grey mackerel Scomberomorus semifasciatus in Australia as inferred from its parasite fauna

The scombrid Scomberomorus semifasciatus is an important component of inshore fisheries in tropical Australia. Data on the parasite fauna of 593 fish from areas off northern and eastern Australia were examined for evidence of discrete fish populations. The parasites used were juveniles of Pterobothrium pearsoni, Callitetrarhynchus gracilis, Anisakis simplex (sensu latu) and Terranova sp. Tukey Kramer pairwise comparisons gave significant differences in the abundances of two or more parasites between fish from the east coast, the eastern Gulf of Carpentaria and the remainder of northern Australia. Multivariate analysis gave further evidence of differences and the results suggest that at least 4 populations or stocks of grey mackerel occur along the northern and eastern coastline of Australia.

The adoption of sustainable grazing land management practices in the Burdekin Rangelands of northern Australia.

The Burdekin Rangelands is a diverse area of semi-arid eucalypt and acacia savannah covering six million hectares in north eastern Australia. The major land use is cattle grazing on 220 commercial cattle properties (average size 26,000 ha) each carrying on average 2600 adult equivalents. Production was the focus of the beef industry and support agencies prior to the mid 1980's. Widespread land degradation during the 1980's led to a grassroots realisation that environmental impacts, including water quality had to be addressed for the beef industry to attain sustainability. The formation of a series of producer based landcare gropus and the support of several Queensland and Australian government research and extension agencies led to a greater awareness and adoption of sound grazing land management practices (Shepherd 2005).

The impacts and management of foxes Vulpes vulpes in Australia

1. The successful introduction of the red fox Vulpes vulpes into Australia in the 1870s has had dramatic and deleterious impacts on both native fauna and agricultural production. Historical accounts detail how the arrival of foxes in many areas coincided with the local demise of native fauna. Recent analyses suggest that native fauna can be successfully reintroduced to their former ranges only if foxes have been controlled, and several replicated removal experiments have confirmed that foxes are the major agents of extirpation of native fauna. Predation is the primary cause of losses, but competition and transmission of disease may be important for some species. 2. In agricultural landscapes, fox predation on lambs can cause losses of 1–30%; variation is due to flock size, health and management, as well as differences in the timing and duration of lambing and the density of foxes. 3. Fox control measures include trapping, shooting, den fumigation and exclusion fencing; baiting using the toxin 1080 is the most commonly employed method. Depending on the baiting strategy, habitat and area covered, baiting can reduce fox activity by 50–97%. We review patterns of baiting in a large sheep-grazing region in central New South Wales, and propose guidelines to increase landholder awareness of baiting strategies, to concentrate and coordinate bait use, and to maximize the cost-effectiveness of baiting programs. 4. The variable reduction in fox density within the baited area, together with the ability of the fox to recolonize rapidly, suggest that current baiting practices in eastern Australia are often ineffective, and that reforms are required. These might include increasing landholder awareness and involvement in group control programs, and the use of more efficient broadscale techniques, such as aerial baiting.

Variation in ecophysiology and carbon economy of invasive and native woody vines of riparian zones in south-eastern Queensland

Exotic and invasive woody vines are major environmental weeds of riparian areas, rainforest communities and remnant natural vegetation in coastal eastern Australia, where they smother standing vegetation, including large trees, and cause canopy collapse. We investigated, through glasshouse resource manipulative experiments, the ecophysiological traits that might facilitate faster growth, better resource acquisition and/or utilization and thus dominance of four exotic and invasive vines of South East Queensland, Australia, compared with their native counterparts. Relative growth rate was not significantly different between the two groups but water use efficiency (WUE) was higher in the native species while the converse was observed for light use efficiency (quantum efficiency, AQE) and maximum photosynthesis on a mass basis (Amax mass). The invasive species, as a group, also exhibited higher respiration load, higher light compensation point and higher specific leaf area. There were stronger correlations of leaf traits and greater structural (but not physiological) plasticity in invasive species than in their native counterparts. The scaling coefficients of resource use efficiencies (WUE, AQE and respiration efficiency) as well as those of fitness (biomass accumulated) versus many of the performance traits examined did not differ between the two species-origin groups, but there were indications of significant shifts in elevation (intercept values) and shifts along common slopes in many of these relationships – signalling differences in carbon economy (revenue returned per unit energy invested) and/or resource usage. Using ordination and based on 14 ecophysiological attributes, a fair level of separation between the two groups was achieved (51.5% explanatory power), with AQE, light compensation point, respiration load, WUE, specific leaf area and leaf area ratio, in decreasing order, being the main drivers. This study suggests similarity in trait plasticity, especially for physiological traits, but there appear to be fundamental differences in carbon economy and resource conservation between native and invasive vine species.

Scalloped Hammerhead microsatellite genotypes (eight loci) representing five regions on Australia's east coast and one location in central Indonesia.

Biodiversity of sharks in the tropical Indo-Pacific is high, but species-specific information to assist sustainable resource exploitation is scarce. The null hypothesis of population genetic homogeneity was tested for scalloped hammerhead shark (Sphyrna lewini, n=244) and the milkshark (Rhizoprionodon acutus, n=209) from northern and eastern Australia, using nuclear (S. lewini, eight microsatellite loci; R. acutus, six loci) and mitochondrial gene markers (873 base pairs of NADH dehydrogenase subunit 4). We were unable to reject genetic homogeneity for S. lewini, which was as expected based on previous studies of this species. Less expected were similar results for R. acutus, which is more benthic and less vagile than S. lewini. These features are probably driving the genetic break found between Australian and central Indonesian R. acutus (F-statistics; mtDNA, 0.751 to 0.903; microsatellite loci, 0.038 to 0.047). Our results support the spatially-homogeneous management plan for shark species in Queensland, but caution is advised for species yet to be studied.

Quambalaria species: increasing threat to eucalypt plantations in Australia

Spotted gum (Corymbia citriodora subsp. variegata and C. maculata) is a valuable source of commercial timber and suitable for a wide range of different soil types in eastern Australia. The main biological constraint to further expansion of spotted gum plantations is Quambalaria shoot blight caused by the fungus Quambalaria pitereka. Surveys conducted to evaluate the impact of Quambalaria shoot blight have shown that the disease is present in all spotted gum plantations and on a range of Corymbia species and hybrids in subtropical and tropical regions surveyed in eastern Australia. More recently, Q. eucalypti has also been identified from a range of Eucalyptus species in these regions. Both pathogens have also been found associated with foliage blight and die-back of amenity trees and Q. pitereka in native stands of Corymbia species, which is the probable initial infection source for plantations. Infection by Q. pitereka commonly results in the repeated destruction of the growing tips and the subsequent formation of a bushy crown or death of trees in severe cases. In comparison, Q. eucalypti causes small, limited lesions and has in some cases been associated with insect feeding. It has not been recorded as causing severe shoot and stem blight. A better understanding of factors influencing disease development and host-pathogen interactions is essential in the development of a disease management strategy for these poorly understood but important pathogens in the rapidly expanding eucalypt (Corymbia and Eucalyptus spp.) plantation industry in subtropical and tropical eastern Australia.