Determining changes in the distribution and abundance of a Rhyzopertha dominica phosphine resistance allele in farm grain storages using a DNA marker

BACKGROUND: The lesser grain borer, Rhyzopertha dominica (F.), is a highly destructive pest of stored grain that is strongly resistant to the fumigant phosphine (PH3). Phosphine resistance is due to genetic variants at the rph2 locus that alter the function of the dihydrolipoamide dehydrogenase (DLD) gene. This discovery now enables direct detection of resistance variants at the rph2 locus in field populations. RESULTS: A genotype assay was developed for direct detection of changes in distribution and frequency of a phosphine resistance allele in field populations of R. dominica. Beetles were collected from ten farms in south-east Queensland in 2006 and resampled in 2011. Resistance allele frequency increased in the period from 2006 to 2011 on organic farms with no history of phosphine use, implying that migration of phosphine-resistant R. dominica had occurred from nearby storages. CONCLUSION: Increasing resistance allele frequencies on organic farms suggest local movement of beetles and dispersal of insects from areas where phosphine has been used. This research also highlighted for the first time the utility of a genetic DNA marker in accurate and rapid determination of the distribution of phosphine-resistant insects in the grain value chain. Extending this research over larger landscapes would help in identifying resistance problems and enable timely pest management decisions. © 2013 Society of Chemical Industry © 2013 Society of Chemical Industry 69 6 June 2013 10.1002/ps.3514 Rapid Report Rapid Report © 2013 Society of Chemical Industry.

Individual-based modelling of the efficacy of fumigation tactics to control lesser grain borer (Rhyzopertha dominica) in stored grain

Increasing resistance to phosphine (PH 3) in insect pests, including lesser grain borer (Rhyzopertha dominica) has become a critical issue, and development of effective and sustainable strategies to manage resistance is crucial. In practice, the same grain store may be fumigated multiple times, but usually for the same exposure period and concentration. Simulating a single fumigation allows us to look more closely at the effects of this standard treatment.We used an individual-based, two-locus model to investigate three key questions about the use of phosphine fumigant in relation to the development of PH 3 resistance. First, which is more effective for insect control; long exposure time with a low concentration or short exposure period with a high concentration? Our results showed that extending exposure duration is a much more efficient control tactic than increasing the phosphine concentration. Second, how long should the fumigation period be extended to deal with higher frequencies of resistant insects in the grain? Our results indicated that if the original frequency of resistant insects is increased n times, then the fumigation needs to be extended, at most, n days to achieve the same level of insect control. The third question is how does the presence of varying numbers of insects inside grain storages impact the effectiveness of phosphine fumigation? We found that, for a given fumigation, as the initial population number was increased, the final survival of resistant insects increased proportionally. To control initial populations of insects that were n times larger, it was necessary to increase the fumigation time by about n days. Our results indicate that, in a 2-gene mediated resistance where dilution of resistance gene frequencies through immigration of susceptibles has greater effect, extending fumigation times to reduce survival of homozygous resistant insects will have a significant impact on delaying the development of resistance. © 2012 Elsevier Ltd.

Dosage consistency is the key factor in avoiding evolution of resistance to phosphine and population increase in stored-grain pests

BACKGROUND Control of pests in stored grain and the evolution of resistance to pesticides are serious problems worldwide. A stochastic individual-based two-locus model was used to investigate the impact of two important issues, the consistency of pesticide dosage through the storage facility and the immigration rate of the adult pest, on overall population control and avoidance of evolution of resistance to the fumigant phosphine in an important pest of stored grain, the lesser grain borer. RESULTS A very consistent dosage maintained good control for all immigration rates, while an inconsistent dosage failed to maintain control in all cases. At intermediate dosage consistency, immigration rate became a critical factor in whether control was maintained or resistance emerged. CONCLUSION Achieving a consistent fumigant dosage is a key factor in avoiding evolution of resistance to phosphine and maintaining control of populations of stored-grain pests; when the dosage achieved is very inconsistent, there is likely to be a problem regardless of immigration rate. © 2012 Society of Chemical Industry

Constructing a new individual-based model of phosphine resistance in lesser grain borer (Rhyzopertha dominica): do we need to include two loci rather than one?

In this article, we describe and compare two individual-based models constructed to investigate how genetic factors influence the development of phosphine resistance in lesser grain borer (R. dominica). One model is based on the simplifying assumption that resistance is conferred by alleles at a single locus, while the other is based on the more realistic assumption that resistance is conferred by alleles at two separate loci. We simulated the population dynamic of R. dominica in the absence of phosphine fumigation, and under high and low dose phosphine treatments, and found important differences between the predictions of the two models in all three cases. In the absence of fumigation, starting from the same initial frequencies of genotypes, the two models tended to different stable frequencies, although both reached Hardy-Weinberg equilibrium. The one-locus model exaggerated the equilibrium proportion of strongly resistant beetles by 3.6 times, compared to the aggregated predictions of the two-locus model. Under a low dose treatment the one-locus model overestimated the proportion of strongly resistant individuals within the population and underestimated the total population numbers compared to the two-locus model. These results show the importance of basing resistance evolution models on realistic genetics and that using oversimplified one-locus models to develop pest control strategies runs the risk of not correctly identifying tactics to minimise the incidence of pest infestation.

Microbial quality of hemp (Cannabis sativa L.) and flax (Linum usitatissimum L.) from plants to thermal insulation

Flax and hemp have traditionally been used mainly for textiles, but recently interest has also been focused on non-textile applications. Microbial quality throughout the whole processing chain of bast fibres has not previously been studied. This study concentrates on the microbial quality and possible microbial risks in the production chain of hemp and flax fibres and fibrous thermal insulations. In order to be able to utilize hemp and flax fibres, the bast fibres must be separated from the rest of the plant. Non-cellulosic components can be removed with various pretreatment processes, which are associated with a certain risk of microbial contamination. In this study enzymatic retting and steam explosion (STEX) were examined as pretreatment processes. On the basis of the results obtained in this study, the microbial contents on stalks of both plants studied increased at the end of the growing season and during the winter. However, by processing and mechanical separation it is possible to produce fibres containing less moulds and bacteria than the whole stem. Enzymatic treatment encouraged the growth of moulds in fibres. Steam explosion reduced the amount of moulds in fibres. Dry thermal treatment used in this study did not markedly reduce the amount of microbes. In this project an emission measurement chamber was developed which was suitable for measurements of emissions from both mat type and loose fill type insulations, and capable of interdisciplinary sampling. In this study, the highest amounts of fungal emissions were in the range of 10^3 10^5 cfu/m^3 from the flax and hemp insulations at 90% RH of air. The fungal emissions from stone wool, glass wool and recycled paper insulations were below 10^2 cfu/m^3 even at 90% RH. Equally low values were obtained from bast fibrous materials in lower humidities (at 30% and 80% RH of air). After drying of moulded insulations at 30% RH, the amounts of emitted moulds were in all cases higher compared to the emissions at 90% RH before drying. The most common fungi in bast fibres were Penicillium and Rhizopus. The widest variety of different fungi was in the untreated hemp and linseed fibres and in the commercial loose-fill flax insulation. Penicillium, Rhizopus and Paecilomyces were the most tolerant to steam explosion. According to the literature, the most common fungi in building materials and indoor air are Penicillium, Aspergillus and Cladosporium, which were all found in some of the bast fibre materials in this study. As organic materials, hemp and flax fibres contain high levels of nutrients for microbial growth. The amount of microbes can be controlled and somewhat decreased by the processing methods presented.

Strong resistance to phosphine in the rusty grain beetle, Cryptolestes ferrugineus (Stephens) (Coleoptera: Laemophloeidae): its characterisation, a rapid assay for diagnosis and its distribution in Australia

BACKGROUND: The recent development of very high resistance to phosphine in rusty grain beetle, Cryptolestes ferrugineus (Stephens), seriously threatens stored-grain biosecurity. The aim was to characterise this resistance, to develop a rapid bioassay for its diagnosis to support pest management and to document the distribution of resistance in Australia in 20072011. RESULTS: Bioassays of purified laboratory reference strains and field-collected samples revealed three phenotypes: susceptible, weakly resistant and strongly resistant. With resistance factors of > 1000 x , resistance to phosphine expressed by the strong resistance phenotype was higher than reported for any stored-product insect species. The new time-to-knockdown assay rapidly and accurately diagnosed each resistance phenotype within 6 h. Although less frequent in western Australia, weak resistance was detected throughout all grain production regions. Strong resistance occurred predominantly in central storages in eastern Australia. CONCLUSION: Resistance to phosphine in the rusty grain beetle is expressed through two identifiable phenotypes: weak and strong. Strong resistance requires urgent changes to current fumigation dosages. The development of a rapid assay for diagnosis of resistance enables the provision of same-day advice to expedite resistance management decisions. (c) 2012 Commonwealth of Australia. Published by John Wiley & Sons, Ltd.

Quality of life after early enteral feeding versus standard care for proven or suspected advanced epithelial ovarian cancer: Results from a randomised trial

Background Malnutrition is common in patients with advanced epithelial ovarian cancer (EOC), and is associated with impaired quality of life (QoL), longer hospital stay and higher risk of treatment-related adverse events. This phase III multi-centre randomised clinical trial tested early enteral feeding versus standard care on postoperative QoL. Methods From 2009 to 2013, 109 patients requiring surgery for suspected advanced EOC, moderately to severely malnourished were enrolled at five sites across Queensland and randomised to intervention (n = 53) or control (n = 56) groups. Intervention involved intraoperative nasojejunal tube placement and enteral feeding until adequate oral intake could be maintained. Despite being randomised to intervention, 20 patients did not receive feeds (13 did not receive the feeding tube; 7 had it removed early). Control involved postoperative diet as tolerated. QoL was measured at baseline, 6 weeks postoperatively and 30 days after the third cycle of chemotherapy. The primary outcome measure was the difference in QoL between the intervention and the control group. Secondary endpoints included treatment-related adverse event occurrence, length of stay, postoperative services use, and nutritional status. Results Baseline characteristics were comparable between treatment groups. No significant difference in QoL was found between the groups at any time point. There was a trend towards better nutritional status in patients who received the intervention but the differences did not reach statistical significance except for the intention-to-treat analysis at 7 days postoperatively (11.8 intervention vs. 13.8 control, p 0.04). Conclusion Early enteral feeding did not significantly improve patients' QoL compared to standard of care but may improve nutritional status.

Leaders' personal wisdom and leader-member exchange quality: The role of individualized consideration

Business scholars have recently proposed that the virtue of personal wisdom may predict leadership behaviors and the quality of leader–follower relationships. This study investigated relationships among leaders’ personal wisdom—defined as the integration of advanced cognitive, reflective, and affective personality characteristics (Ardelt, Hum Dev 47:257–285, 2004)—transformational leadership behaviors, and leader–member exchange (LMX) quality. It was hypothesized that leaders’ personal wisdom positively predicts LMX quality and that intellectual stimulation and individualized consideration, two dimensions of transformational leadership, mediate this relationship. Data came from 75 religious leaders and 1–3 employees of each leader (N = 158). Results showed that leaders’ personal wisdom had a positive indirect effect on follower ratings of LMX quality through individualized consideration, even after controlling for Big Five personality traits, emotional intelligence, and narcissism. In contrast, intellectual stimulation and the other two dimensions of transformational leadership (idealized influence and inspirational motivation) did not mediate the positive relationship between leaders’ personal wisdom and LMX quality. Implications for future research on personal wisdom and leadership are discussed, and some tentative suggestions for leadership development are outlined.

Microbes in the tailoring of barley malt properties

Microbes have a decisive role in the barley-malt-beer chain. A major goal of this thesis was to study the relationships between microbial communities and germinating grains during malting. Furthermore, the study provided a basis for tailoring of malt properties with natural, malt-derived microbes. The malting ecosystem is a dynamic process, exhibiting continous change. The first hours of steeping and kilning were the most important steps in the process with regard to microbiological quality. The microbial communities consisting of various types of bacteria, yeasts and filamentous fungi formed complex biofilms in barley tissues and were well-protected. Inhibition of one microbial population within the complex ecosystem led to an increase of non-suppressed populations, which must be taken into account because a shift in microbial community dynamics may be undesirable. Both bacterial and fungal communities should be monitored simultaneously. Using different molecular approaches we showed that the diversity of microbes in the malting ecosystem was greater than expected. Even some new microbial groups were found in the malting ecosystem. Suppression of Gram-negative bacteria during steeping was advanategous for grain germination and malt brewhouse performance. Fungal communities including both filamentous fungi and yeasts significantly contributed to the production of microbial beta-glucanases and xylanases, and were also involved in proteolysis. Well-characterized lactic acid bacteria (Lactobacillus plantarum VTT E-78076 and Pediococcus pentosaceus VTT E-90390) proved to be an effective way of balancing the microbial communities in malting. Furthermore, they had positive effects on malt characteristics and notably improved wort separation. Previously the significance of yeasts in the malting ecosystem has been largely underestimated. This study showed that yeast community was an important part of the industrial malting ecosystem. Yeasts produced extracellular hydrolytic enzymes with a potentially positive contribution to malt processability. Furthermore, several yeasts showed strong antagonistic activity against field and storage moulds. Addition of a selected yeast culture (Pichia anomala VTT C-04565) into steeping restricted Fusarium growth and hydrophobin production and thus prevented beer gushing. Addition of P. anomala C565 into steeping water tended to retard wort filtration, but the filtration was improved when the yeast culture was combined with L. plantarum E76. The combination of different microbial cultures offers a possibility to use ther different properties, thus making the system more robust. Improved understanding of complex microbial communities and their role in malting enables a more controlled process management and the production of high quality malt with tailored properties

QTL associated with barley (Hordeum vulgare) feed quality traits measured through in situ digestion

Barley (Hordeum vulgare) is a major feed source for the intensive livestock industry. Competitiveness against other cereal grains depends largely on the price per unit of expressed feed quality. The traits which contribute to feed quality in barley are largely quantitative in nature but little is known about their genetic control. A study to identify the quantitative trait loci (QTLs) associated with feed quality was performed using a F6-derived recombinant inbred barley population. Samples from each line were incubated in the rumen of fistulated cattle, recovered, washed and dried for determination of in situ dry matter digestibility. Additionally, both pre- and post-digestion samples were analysed to quantify the content of key quality components relating to acid detergent fibre, total starch and protein. The data was used to identify trait-associated QTLs. Genetic analysis identified significant QTLs on chromosomes 2H, 5H and 7H. Genetic markers linked to these QTL should provide an effective tool for the selection and improvement of feed barley in the future.

The Relationship Between the Stay-Green Trait and Grain Yield in Elite Sorghum Hybrids Grown in a Range of Environments

The stay-green drought adaptation mechanism has been widely promoted as a way of improving grain yield and lodging resistance in sorghum [Sorghum bicolor (L.) Moench] and as a result has been the subject of many physiological and genetic studies. The relevance of these studies to elite sorghum hybrids is not clear given that they sample a limited number of environments and were conducted using inbred lines or relatively small numbers of experimental F-1 hybrids. In this study we investigated the relationship between stay-green and yield using data from breeding trials that sampled 1668 unique hybrid combinations and 23 environments whose mean yields varied from 2.3 to 10.5 t ha(-1). The strength and direction of the association between stay-green and grain yield varied with both environment and genetic background (male tester). The majority of associations were positive, particularly in environments with yields below 6 t ha(-1). As trial mean yield increased above 6 t ha(-1) there was a trend toward an increased number of negative associations; however, the number and magnitude of the positive associations were larger. Given that post-flowering drought is very commonly experienced by sorghum crops world wide and average yields are 1.2 and 2.5 t ha(-1) for the world and Australia, respectively, our results indicate that selection for stay-green in elite sorghum hybrids may be broadly beneficial for increasing yield in a wide range of environments.