Measurement and Interpretation of Salinity Tolerance in Four Perennial Grasses

Whilst the topic of soil salinity has received a substantive research effort over the years, the accurate measurement and interpretation of salinity tolerance data remain problematic. The tolerance of four perennial grass species (non-halophytes) to sodium chloride (NaCl) dominated salinity was determined in a free-flowing sand culture system. Although the salinity tolerance of non-halophytes is often represented by the threshold salinity model (bent-stick model), none of the species in the current study displayed any observable salinity threshold. Further, the observed yield decrease was not linear as suggested by the model. On re-examination of earlier datasets, we conclude that the threshold salinity model does not adequately describe the physiological processes limiting growth of non-halophytes in saline soils. Therefore, the use of the threshold salinity model is not recommended for non-halophytes, but rather, a model which more accurately reflects the physiological response observed in these saline soils, such as an exponential regression curve.

Impacts and management of wild pigs Sus scrofa in Australia

Globally, wild or feral pigs Sus scrofa are a widespread and important pest. Mitigation of their impacts requires a sound understanding of those impacts and the benefits and limitations of different management approaches. Here, we review published and unpublished studies to provide a synopsis of contemporary understanding of wild pig impacts and management in Australia, and to identify important shortcomings. Wild pigs can have important impacts on biodiversity values, ecosystem functioning and agricultural production. However, many of these impacts remain poorly described, and therefore, difficult to manage effectively. Many impacts are highly variable, and innovative experimental and analytical approaches may be necessary to elucidate them. Most contemporary management programmes use lethal techniques to attempt to reduce pig densities, but it is often unclear how effective they are at reducing damage. We conclude that greater integration of experimental approaches into wild pig management programmes is necessary to improve our understanding of wild pig impacts, and our ability to manage those impacts effectively and efficiently.

Biology and Management of Psocids Infesting Stored Products

Previously regarded as minor nuisance pests, psocids belonging to the genus Liposcelis now pose a major problem for the effective protection of stored products worldwide. Here we examine the apparent biological and operational reasons behind this phenomenon and why conventional pest management seems to be failing. We investigate what is known about the biology, behavior, and population dynamics of major pest species to ascertain their strengths, and perhaps find weaknesses, as a basis for a rational pest management strategy. We outline the contribution of molecular techniques to clarifying species identification and understanding genetic diversity. We discuss progress in sampling and trapping and our comprehension of spatial distribution of these pests as a foundation for developing management strategies. The effectiveness of various chemical treatments and the availability and potential of nonchemical control methods are critically examined. Finally, we identify research gaps and suggest future directions for research.

Human-associated fluoroquinolone-resistant Escherichia coli clonal lineages, including ST354, isolated from canine feces and extraintestinal infections in Australia

Phylogenetic group D extraintestinal pathogenic Escherichia coli (ExPEC), including O15:K52:H1 and clonal group A, have spread globally and become fluoroquinolone-resistant. Here we investigated the role of canine feces as a reservoir of these (and other) human-associated ExPEC and their potential as canine pathogens. We characterized and compared fluoroquinolone-resistant E. coli isolates originally identified as phylogenetic group D from either the feces of hospitalized dogs (n = 67; 14 dogs) or extraintestinal infections (n = 53; 33 dogs). Isolates underwent phylogenetic grouping, random amplified polymorphic DNA (RAPD) analysis, virulence genotyping, resistance genotyping, human-associated ExPEC O-typing, and multi-locus sequence typing. Five of seven human-associated sequence types (STs) exhibited ExPEC-associated O-types, and appeared in separate RAPD clusters. The largest subgroup (16 fecal, 26 clinical isolates) were ST354 (phylogroup F) isolates. ST420 (phylogroup B2); O1-ST38, O15:K52:H1-ST393, and O15:K1-ST130 (phylogroup D); and O7-ST457, and O1-ST648 (phylogroup F) were also identified. Three ST-specific RAPD sub-clusters (ST354, ST393, and ST457) contained closely related isolates from both fecal or clinical sources. Genes encoding CTX-M and AmpC β-lactamases were identified in isolates from five STs. Major human-associated fluoroquinolone-resistant ± extended-spectrum cephalosporin-resistant ExPEC of public health importance may be carried in dog feces and cause extraintestinal infections in some dogs.

First detection of extended-spectrum cephalosporin- and fluoroquinolone-resistant Escherichia coli in Australian food-producing animals

This study aimed to define the frequency of resistance to critically important antimicrobials (CIAs) [i.e. extended-spectrum cephalosporins (ESCs), fluoroquinolones (FQs) and carbapenems] among Escherichia coli isolates causing clinical disease in Australian food-producing animals. Clinical E. coli isolates (n = 324) from Australian food-producing animals [cattle (n = 169), porcine (n = 114), poultry (n = 32) and sheep (n = 9)] were compiled from all veterinary diagnostic laboratories across Australia over a 1-year period. Isolates underwent antimicrobial susceptibility testing to 18 antimicrobials using the Clinical and Laboratory Standards Institute disc diffusion method. Isolates resistant to CIAs underwent minimum inhibitory concentration determination, multilocus sequence typing (MLST), phylogenetic analysis, plasmid replicon typing, plasmid identification, and virulence and antimicrobial resistance gene typing. The 324 E. coli isolates from different sources exhibited a variable frequency of resistance to tetracycline (29.0–88.6%), ampicillin (9.4–71.1%), trimethoprim/sulfamethoxazole (11.1–67.5%) and streptomycin (21.9–69.3%), whereas none were resistant to imipenem or amikacin. Resistance was detected, albeit at low frequency, to ESCs (bovine isolates, 1%; porcine isolates, 3%) and FQs (porcine isolates, 1%). Most ESC- and FQ-resistant isolates represented globally disseminated E. coli lineages (ST117, ST744, ST10 and ST1). Only a single porcine E. coli isolate (ST100) was identified as a classic porcine enterotoxigenic E. coli strain (non-zoonotic animal pathogen) that exhibited ESC resistance via acquisition of blaCMY-2. This study uniquely establishes the presence of resistance to CIAs among clinical E. coli isolates from Australian food-producing animals, largely attributed to globally disseminated FQ- and ESC-resistant E. coli lineages.

Chemical containment and eradication of screw− worm incursions in Australia

Screwworms are obligate, invasive parasites of warm-blooded animals. The female flies lay batches of eggs at the edge of wounds or other lesions. These eggs hatch to larvae or screw-worms which feed on affected animals for 6-7 days, burrowing deeply into subcutaneous tissues and causing severe trauma to animals, production loss and potentially death. Susceptible sites include wounds resulting from management practices such as castration, de-horning and ear tagging and lesions caused by the activities of other parasites such as buffalo flies and ticks. The navels of the new born and the vulval region of their mothers following parturition are highly susceptible and body orifices such as nose and ears are also frequent targets for ovipositing screwworm flies. The Old World screw-worm, Chrysomya bezziana (OWS) is considered one of the most serious exotic insect pest threatening Australia's livestock industries and is endemic in a number of our closest neighbouring countries. New World screwworm (NWS), Cochliomyia hominivorax, endemic to South America, has also entered Australia on at least 2 occasions. Many tropical and subtropical areas of Australia are suitable for the establishment of OWS and the potential range is expected to increase with climate change. The Australian screwworm preparedness strategy indicates a program of containment with chemical treatments followed by eradication of OWS using sterile male release and parasiticides. However, there is no longer an operational OWS sterile insect screw-worm facility anywhere in the world and establishing a large scale production facility would most optimistically take at least 2 years. In the interim, containment would be almost totally dependent on the availability of effective chemical controls. A review of chemical formulations available for potential use against OWS in Australia found that currently only one chemical, ivermectin administered by subcutaneous injection (s.c.) is registered for use against OWS and that many of the chemicals previously shown to be effective against OWS were no longer registered for animal use in Australia.18 From this review a number of Australian-registered chemicals were recommended as a priority for testing against OWS. The Australian Pesticides and Veterinary Medicines Authority (APVMA) can issue an emergency use permit for use of pesticides if they are registered in Australia for other animal uses and shown to be effective against OWS. This project tested the therapeutic and prophylactic efficacy of chemicals with potential for use in the treatment and control of OWS.