No abstract

Resistance to diflubenzuron in the Australian sheep blowfly, Lucilia cuprina , has rendered this insecticide incapable of preventing flystrike in sheep from a few districts in eastern Australia. Wool producers affected by this situation must find suitable alternatives to protect their flocks. Results of laboratory bioassays against one population demonstrated that, despite extremely high diflubenzuron resistance (Resistance Factor > 791), it had only very low (2x) tolerance of cyromazine and dicyclanil. It is unlikely that this level of tolerance would have any practical impact on field control with either insecticide. Consequently, wool producers in districts where diflubenzuron-resistant flies are common can rotate insecticide treatment to either of these compounds to prevent flystrike in their flocks. However, unlike the highly diflubenzuron-resistant field strain, a laboratory strain selected for resistance to diflubenzuron (Resistance Factor = 617) was 10 times more resistant to dicyclanil than a susceptible strain but, like the field strain, was only two times more tolerant of cyromazine. Conversely, a field-derived strain selected in the laboratory for cyromazine resistance was 20 times more resistant to dicyclanil and 362 times more resistant to diflubenzuron than the reference susceptible strain.

This study was carried out with fresh Australian lager beer which was sampled directly off the production line, the same samples aged for 12 weeks at 30 °C, and the vintage beer which was kept at 20 °C for 5 years. Characteristic Australian lager flavour was maintained in the fresh and vintage beers but was lost in the aged beer. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and free thiol group labelling analyses of beer proteins found that this flavour stability correlated with the presence of an unknown 10 kilodaltons (kDa) protein with a higher level of free thiols. The protein was purified by size-exclusion chromatography, then peptide sequencing and database matching identified it as the barley lipid transfer protein (LTP1). Further characterisation using diphenylpicrylhydrazyl (DPPH) free radical scavenging and a Saccharomyces cerevisiae-based antioxidant screening assay demonstrated that the LTP1 protein was active in DPPH reduction and antioxidant activity. The absence of free thiol in the aged beer indicates that the thiol functional groups within the LTP1 protein were saturated and suggests that it is important in the flavour stability of beer by maintaining reduction capacity during the ageing process.

BackgroundBovine theileriosis, caused by the haemoprotozoan Theileria orientalis, is an emerging disease in East Asia and Australasia. Previous studies have demonstrated transplacental transmission of various Theileria spp. but molecular confirmation of transplacental transmission of T. orientalis has never been confirmed in the field. In this study, cow-calf (< 48 h old) pairs were sampled across 3 herds; opportunistic samples from aborted foetuses or stillborn calves were also examined. Molecular (multiplex qPCR) and serological (ELISA) methods were used to determine infection prevalence and the presence of anti-Theileria antibodies in each herd. In addition, pregnant heifers and foetal calves were sampled at abattoir and tested for the presence of T. orientalis by qPCR.ResultsThe qPCR results indicated that, even though there was a high prevalence of T. orientalis infection in cows, the rate of transplacental transmission to their calves was low, with only one newborn calf from one herd and one foetus from the abattoir testing positive for T. orientalis DNA. Five aborted foetuses and stillborn calves, 3 of which were derived from a herd experiencing a high number of clinical theileriosis cases at the time of sampling, all tested negative for T. orientalis by qPCR. This suggests that in utero infection of calves with T. orientalis may not be a major driver of abortions during theileriosis outbreaks. Temporal monitoring of 20 calves born to T. orientalis-positive mothers indicated that T. orientalis was detectable in most calves between 10 and 27 days post-partum, consistent with prior field studies on adult cattle introduced to Theileria-affected herds. There was a positive correlation between the ELISA ratio of newborn calves and their mothers within 48 h of calving; however, maternal antibodies were only detectable in some calves and only for 4–4.5 weeks post-partum. All calves displayed high parasite loads peaking at 4–8 weeks post-partum, with only some calves subsequently mounting a detectable adaptive antibody response.ConclusionsThese findings indicate transplacental transmission of T. orientalis appears to play only a minor role in persistence of T. orientalis infection in the field; however calves are highly susceptible to developing high level T. orientalis infections at 4–8 weeks of age regardless of whether maternal antibodies are present post-partum.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-017-2166-9) contains supplementary material, which is available to authorized users.

In vitro monooxygenase activity (aldrin epoxidation) in 19 field-collected strains of the Australian sheep blowfly Lucilia cuprina (Wiedemann) varied over a 46-fold range. Activities were significantly correlated with toxicological responses to diflubenzuron and diazinon. Relationships between activity and toxicological response were stronger at the LC95 than at the LC50. Toxicological responses to diflubenzuron and diazinon were significantly related, particularly at the LC95. The slope of diflubenzuron concentration-response lines decreased as enzyme activity increased, suggesting that the proportion of the larval population that can tolerate high rates of diflubenzuron increases with increasing mean enzyme levels. Tolerance levels to diflubenzuron among the field strains (relative to a reference susceptible strain) were up to 10-fold at LC50 and 56-fold at LC95. This tolerance appears to be provided, at least in part, by enhanced larval monooxygenase levels.