Reproductive interference between honey bee species in artificial sympatry

Reproductive isolation between closely related species is often incomplete. The Western honey bee, Apis mellifera, and the Eastern hive bee, A. cerana have been allopatric for millions of years, but are nonetheless similar in morphology and behaviour. During the last century the two species were brought into contact anthropogenically, providing potential opportunities for interspecific matings. Hybrids between A. mellifera and A. cerana are inviable, so natural interspecific matings are of concern because they may reduce the viability of A. cerana and A. mellifera populations – two of the world's most important pollinators. We examined the mating behaviour of A. mellifera and A. cerana queens and drones from Caoba Basin, China and Cairns, Australia. Drone mating flight times overlap in both areas. Analysis of the spermathecal contents of queens with species-specific genetic markers indicated that in Caoba Basin, 14% of A. mellifera queens mated with at least one A. cerana male, but we detected no A. cerana queens that had mated with A. mellifera males. Similarly, in Cairns, no A. cerana queens carried A. mellifera sperm, but one third of A. mellifera queens had mated with at least one A. cerana male. No hybrid embryos were detected in eggs laid by interspecifically-mated A. mellifera queens in either location. However A. mellifera queens artificially inseminated with A. cerana sperm produced inviable hybrid eggs, or unfertilised drones. This suggests that reproductive interference will impact the viability of honey bee populations wherever A. cerana and A. mellifera are in contact. This article is protected by copyright. All rights reserved.

Germinating the seeds of three species of Pimelea sect. Epallage (Thymelaeaceae)1

Pimelea trichostachya Lindl., P. simplex F.Muell. and P. elongata Threlfall frequently cause pimelea poisoning of cattle. Fresh seeds of these species, belonging to sect. Epallage (Endl.) Benth. of Pimelea Gaertn. (Thymelaeaceae) are strongly dormant for years when in laboratory storage. Common methods of stimulating germination, such as scarification, dry heat and cold stratification, did not remove much of the dormancy. ‘Smoke water’ stimulated some germination but its effect was unpredictable and many seedlings then grew aberrantly. Exposure of imbibed seeds to gibberellic acid greatly and reliably improved the germination of all three species. However, the manner of application and the concentration of gibberellic acid used had to be appropriate or many young seedlings grew abnormally or died suddenly, limiting successful plant establishment rates. The dormancy type involved is non-deep Type 2 physiological. Ten days of good moisture, in addition to gibberellic acid exposure, is required before appreciable laboratory germination occurs at optimal temperatures. Thus, the mechanism by which gibberellic acid stimulates good germination does not appear to be the same as that which primes seeds for the rapid and prolific germination often seen under natural conditions in arid Australia. Seeds of P. simplex subsp. continua (J.M.Black) Threlfall proved most difficult to germinate and those of P. elongata the easiest.

Flying-Fox Species Density-A Spatial Risk Factor for Hendra Virus Infection in Horses in Eastern Australia

Hendra virus causes sporadic but typically fatal infection in horses and humans in eastern Australia. Fruit-bats of the genus Pteropus (commonly known as flying-foxes) are the natural host of the virus, and the putative source of infection in horses; infected horses are the source of human infection. Effective treatment is lacking in both horses and humans, and notwithstanding the recent availability of a vaccine for horses, exposure risk mitigation remains an important infection control strategy. This study sought to inform risk mitigation by identifying spatial and environmental risk factors for equine infection using multiple analytical approaches to investigate the relationship between plausible variables and reported Hendra virus infection in horses. Spatial autocorrelation (Global Moran’s I) showed significant clustering of equine cases at a distance of 40 km, a distance consistent with the foraging ‘footprint’ of a flying-fox roost, suggesting the latter as a biologically plausible basis for the clustering. Getis-Ord Gi* analysis identified multiple equine infection hot spots along the eastern Australia coast from far north Queensland to central New South Wales, with the largest extending for nearly 300 km from southern Queensland to northern New South Wales. Geographically weighted regression (GWR) showed the density of P. alecto and P. conspicillatus to have the strongest positive correlation with equine case locations, suggesting these species are more likely a source of infection of Hendra virus for horses than P. poliocephalus or P. scapulatus. The density of horses, climate variables and vegetation variables were not found to be a significant risk factors, but the residuals from the GWR suggest that additional unidentified risk factors exist at the property level. Further investigations and comparisons between case and control properties are needed to identify these local risk factors.

Cotton bunchy top virus and other relatives

Cotton bunchy top virus (CBTV) and the related Cotton leafroll dwarf virus (CLRDV) have caused sporadic disease outbreaks in most cotton regions of the world. Until recently, little was known about the diversity of CBTV or its natural host range. Seven natural field hosts and one experimental host of CBTV have now been identified. These include cotton, Malva parviflora (Marshmallow weed), Abutilon theophrasti (Velvetleaf), Anoda cristata (Spurred anoda), Hibiscus sabdariffa (Rosella), Sida rhombifolia (Paddy’s lucerne), Chamaesyce hirta (Asthma plant) and Gossypium australe. These are currently the only eight known hosts of CBTV. However the virus may have a wider host range than originally thought and include further non-Malvaceae species like asthma plant (family Euphorbiaceae). There are two distinct strains of CBTV in Australia, -A and -B, which have been detected in cotton from numerous locations across almost all growing regions. From 105 samples of cotton that have been positive for CBTV, 6 were infections of strain A only, 60 were strain B only and 64 were a mixed infection of strains A and B. These results indicate the symptoms of cotton bunchy top disease are closely associated with the presence of strain CBTV-B. A diagnostic assay for Cotton leafroll dwarf virus (CLRDV - cotton blue disease) is being developed and applied successfully for the detection of CLRDV samples from Brazil and Thailand. This is the first confirmation of CLRDV from SE-Asia, which may pose an increased biosecurity threat to the Australian industry.

Quantitative effects of in-line operations on Campylobacter and Escherichia coli through two Australian broiler processing plants

Campylobacter is an important food borne pathogen, mainly associated with poultry. A lack of through-chain quantitative Campylobacter data has been highlighted within quantitative risk assessments. The aim of this study was to quantitatively and qualitatively measure Campylobacter and Escherichia coli concentration on chicken carcasses through poultry slaughter. Chickens (n = 240) were sampled from each of four flocks along the processing chain, before scald, after scald, before chill, after chill, after packaging and from individual caeca. The overall prevalence of Campylobacter after packaging was 83% with a median concentration of 0.8 log10 CFU/mL. The processing points of scalding and chilling had significant mean reductions of both Campylobacter (1.8 and 2.9 log10 CFU/carcase) and E. coli (1.3 and 2.5 log10 CFU/carcase). The concentration of E. coli and Campylobacter was significantly correlated throughout processing indicating that E. coli may be a useful indicator organism for reductions in Campylobacter concentration. The carriage of species varied between flocks, with two flocks dominated by Campylobacter coli and two flocks dominated by Campylobacter jejuni. Current processing practices can lead to significant reductions in the concentration of Campylobacter on carcasses. Further understanding of the variable effect of processing on Campylobacter and the survival of specific genotypes may enable more targeted interventions to reduce the concentration of this poultry associated pathogen.

Impacts of level of utilisation by grazing on an Astrebla (Mitchell grass) grassland in north-western Queensland between 1984 and 2010. 2. Plant species richness and abundance

The occurrence of interstitial species in Astrebla grasslands in Australia are influenced by grazing and seasonal rainfall but the interactions of these two influences are complex. This paper describes three studies aimed at determining and explaining the changes in plant species richness and abundance of the interstitial species in a long-term sheep utilisation experiment in an Astrebla grassland in northern Queensland. In the first study, increasing utilisation increased the frequency of Dactyloctenium radulans (Button grass) and Brachyachne convergens (Downs couch) and reduced that of Streptoglossa adscendens (Mint bush). In the second study, seasonal rainfall variation between 1984 and 2009 resulted in large annual differences in the size of the seed banks of many species, but increasing utilisation consistently reduced the seed bank of species such as Astrebla spp. and S. adscendens and increased that of species such as B. convergens, D. radulans, Amaranthus mitchellii (Boggabri) and Boerhavia sp. (Tar vine). In the third study, the highest species richness occurred at the lightest utilisation because of the presence of a range of palatable forbs, especially legumes. Species richness was reduced as utilisation increased. Species richness in the grazing exclosure was low and similar to that at the heaviest utilisation where there was a reduction in the presence of palatable forb species. The pattern of highest species richness at the lightest grazing treatment was maintained across three sampling times, even with different amounts of seasonal rainfall, but there was a large yearly variation in both the density and frequency of many species. It was concluded that the maintenance of highest species richness at the lightest utilisation was not aligned with other data from this grazing experiment which indicated that the maximum sustainable wool production occurred at moderate utilisation.

Phyllosticta species on orchids (Orchidaceae), introducing Phyllosticta speewahensis sp. nov. (Phyllostictaceae, Ascomycota) from northern Australia

Several species of Phyllosticta (syn. Guignardia) have been described from orchids worldwide. A new species, Phyllosticta speewahensis, is proposed for a specimen isolated from leaf spots on a hybrid Vanda orchid in northern Queensland, Australia. Phylogenetic analysis of the nrDNA internal transcribed spacer region (ITS) and partial translation elongation factor 1-alpha (TEF1) gene sequences showed that P. speewahensis is most closely related to P. hostae. The likelihood that orchids harbour further cryptic species of endophytic and pathogenic Phyllosticta species is discussed.

Panel of real-time PCRs for the multiplexed detection of two tomato-infecting begomoviruses and their cognate whitefly vector species

A new approach for the simultaneous identification of the viruses and vectors responsible for tomato yellow leaf curl disease (TYLCD) epidemics is presented. A panel of quantitative multiplexed real-time PCR assays was developed for the sensitive and reliable detection of Tomato yellow leaf curl virus-Israel (TYLCV-IL), Tomato leaf curl virus (ToLCV), Bemisia tabaci Middle East Asia Minor 1 species (MEAM1, B biotype) and B.tabaci Mediterranean species (MED, Q biotype) from either plant or whitefly samples. For quality-assurance purposes, two internal control assays were included in the assay panel for the co-amplification of solanaceous plant DNA or B.tabaci DNA. All assays were shown to be specific and reproducible. The multiplexed assays were able to reliably detect as few as 10 plasmid copies of TYLCV-IL, 100 plasmid copies of ToLCV, 500fg B.tabaci MEAM1 and 300fg B.tabaci MED DNA. Evaluated methods for routine testing of field-collected whiteflies are presented, including protocols for processing B.tabaci captured on yellow sticky traps and for bulking of multiple B.tabaci individuals prior to DNA extraction. This work assembles all of the essential features of a validated and quality-assured diagnostic method for the identification and discrimination of tomato-infecting begomovirus and B.tabaci vector species in Australia. This flexible panel of assays will facilitate improved quarantine, biosecurity and disease-management programmes both in Australia and worldwide.

Rapid assessment of genotype-by-environment interactions and heritability for growth rate in aquaculture species using in vitro fertilisation and DNA tagging

Commercial environments may receive only a fraction of expected genetic gains for growth rate as predicted from the selection environment. This fraction is result of undesirable genotype-by-environment interactions (GxE) and measured by the genetic correlation (rg) of growth between environments. Rapid estimates of genetic correlation achieved in one generation are notoriously difficult to estimate with precision. A new design is proposed where genetic correlations can be estimated by utilising artificial mating from cryopreserved semen and unfertilised eggs stripped from a single female. We compare a traditional phenotype analysis of growth to a threshold model where only the largest fish are genotyped for sire identification. The threshold model was robust to differences in family mortality differing up to 30%. The design is unique as it negates potential re-ranking of families caused by an interaction between common maternal environmental effects and growing environment. The design is suitable for rapid assessment of GxE over one generation with a true 0.70 genetic correlation yielding standard errors as low as 0.07. Different design scenarios were tested for bias and accuracy with a range of heritability values, number of half-sib families created, number of progeny within each full-sib family, number of fish genotyped, number of fish stocked, differing family survival rates and at various simulated genetic correlation levels.

The minute, fungus-feeding species of Sophiothrips (Thysanoptera, Phlaeothripinae) from Australia and New Zealand

Five new species of Sophiothrips are described from mainland Australia, of which one is widespread in the eastern part of the continent, with a second widespread across the northern tropical zone. These species appear to be members of the breviceps species-group from the Old World tropics. One of these five is particularly unusual within the genus in that the maxillary stylets are retracted into the head anterior to the postoccipital ridge. A sixth new species is described from Australia that is known only from Norfolk Island, but this is closely related to two species that are endemic to New Zealand. A key is provided to the nine species recognised.

Impacts on nontarget avian species from aerial meat baiting for feral pigs

Bait containing sodium fluoroacetate (1080) is widely used for the routine control of feral pigs in Australia. In Queensland, meat baits are popular in western and northern pastoral areas where they are readily accepted by feral pigs and can be distributed aerially. Field studies have indicated some levels of interference and consumption of baits by nontarget species and, based on toxicity data and the 1080 content of baits, many nontarget species (particularly birds and varanids) are potentially at risk through primary poisoning. While occasional deaths of species have been recorded, it remains unclear whether the level of mortality is sufficient to threaten the viability or ecological function of species. A series of field trials at Culgoa National Park in south-western Queensland was conducted to determine the effect of broadscale aerial baiting (1.7 baits per km2) on the density of nontarget avian species that may consume baits. Counts of susceptible bird species were conducted prior to and following aerial baiting, and on three nearby unbaited properties, in May and November 2011, and May 2012. A sample of baits was monitored with remote cameras in the November 2011 and May 2012 trials. Over the three baiting campaigns, there was no evidence of a population-level decline among the seven avian nontarget species that were monitored. Thirty per cent and 15% of baits monitored by remote cameras in the November 2011 and May 2012 trials were sampled by birds, varanids or other reptiles. These results support the continued use of 1080 meat baits for feral pig management in western Queensland and similar environs.

Coordination and plasticity in leaf anatomical traits of invasive and native vine species

Premise of the study: Plant invasiveness can be promoted by higher values of adaptive traits (e.g., photosynthetic capacity, biomass accumulation), greater plasticity and coordination of these traits, and by higher and positive relative influence of these functionalities on fitness, such as increasing reproductive output. However, the data set for this premise rarely includes linkages between epidermal–stomatal traits, leaf internal anatomy, and physiological performance.• Methods: Three ecological pairs of invasive vs. noninvasive (native) woody vine species of South-East Queensland, Australia were investigated for trait differences in leaf morphology and anatomy under varying light intensity. The linkages of these traits with physiological performance (e.g., water-use efficiency, photosynthesis, and leaf construction cost) and plant adaptive traits of specific leaf area, biomass, and relative growth rates were also explored.• Key results: Except for stomatal size, mean leaf anatomical traits differed significantly between the two groups. Plasticity of traits and, to a very limited extent, their phenotypic integration were higher in the invasive relative to the native species. ANOVA, ordination, and analysis of similarity suggest that for leaf morphology and anatomy, the three functional strategies contribute to the differences between the two groups in the order phenotypic plasticity > trait means > phenotypic integration.• Conclusions: The linkages demonstrated in the study between stomatal complex/gross anatomy and physiology are scarce in the ecological literature of plant invasiveness, but the findings suggest that leaf anatomical traits need to be considered routinely as part of weed species assessment and in the worldwide leaf economic spectrum.

Evaluating pasture species for less fertile soils in a subtropical aseasonal low rainfall zone

Grasses, legumes, saltbushes and herbs were evaluated at 6 sites in southern inland Queensland to identify potential pasture and forage plants for use on marginal cropping soils. The region experiences summer heat waves and severe winter frosts. Emphasis was on perennial plants, and native species were included. Seedlings were transplanted into the unfertilized fields in either summer or autumn to suit the growing season of plants, and watered to ensure estab-lishment. Summer-growing grasses were the most successful group, while cool season-growing perennials mostly failed. Summer legumes were disappointing, with Stylosanthes scabra and Indigofera schimperi performing best. Some lines such as I. schimperi and the Eragrostis hybrid cv. Cochise were assessed as potential weeds owing to low animal acceptance. Native Rhynchosia minima grew well at some sites and deserves more study. Cenchrus ciliaris was always easy to establish and produced the highest yields. Persistence of some Digitaria and Bothriochloa species, Eragrostis curvula and Fingerhuthia africana at specific sites was encouraging, but potential weediness needs careful assessment. Standard species were identified to represent the main forage types, such as Austrostipa scabra for cool season-growing grasses, for incorporation into future trials with new genetic materials. The early field testing protocol used should be considered for use elsewhere, if unreliable rainfall poses a high risk of establishment failure from scarce seed.

Issues and solutions for researching weed eradication target species

Species biology drives the frequency, duration and extent of survey and control activities in weed eradication programs. Researching the key biological characters can be difficult when plants occur at limited locations and are controlled immediately by field crews who are dedicated to preventing reproduction. Within the National Four Tropical Weeds Eradication Program and the former National Siam Weed Eradication Program, key information needed by the eradication teams has been obtained through a combination of field, glasshouse and laboratory studies without jeopardising the eradication objective. Information gained on seed longevity, age to reproductive maturity, dispersal and control options has been used to direct survey and control activities. Planned and opportunistic data collections will continue to provide biological information to refine eradication activities.

Estimates of genetic parameters for growth and wood properties in Eucalyptus pellita F. Muell. to support tree breeding in Vietnam

Key message Eucalyptus pellita demonstrated good growth and wood quality traits in this study, with young plantation grown timber being suitable for both solid and pulp wood products. All traits examined were under moderate levels of genetic control with little genotype by environment interaction when grown on two contrasting sites in Vietnam. Context Eucalyptus pellita currently has a significant role in reforestation in the tropics. Research to support expanded of use of this species is needed: particularly, research to better understand the genetic control of key traits will facilitate the development of genetically improved planting stock. Aims This study aimed to provide estimates of the heritability of diameter at breast height over bark, wood basic density, Kraft pulp yield, modulus of elasticity and microfibril angle, and the genetic correlations among these traits, and understand the importance of genotype by environment interactions in Vietnam. Methods Data for diameter and wood properties were collected from two 10-year-old, open-pollinated progeny trials of E. pellita in Vietnam that evaluated 104 families from six native range and three orchard sources. Wood properties were estimated from wood samples using near-infrared (NIR) spectroscopy. Data were analysed using mixed linear models to estimate genetic parameters (heritability, proportion of variance between seed sources and genetic correlations). Results Variation among the nine sources was small compared to additive variance. Narrow-sense heritability and genetic correlation estimates indicated that simultaneous improvements in most traits could be achieved from selection among and within families as the genetic correlations among traits were either favourable or close to zero. Type B genetic correlations approached one for all traits suggesting that genotype by environment interactions were of little importance. These results support a breeding strategy utilizing a single breeding population advanced by selecting the best individuals across all seed sources. Conclusion Both growth and wood properties have been evaluated. Multi-trait selection for growth and wood property traits will lead to more productive populations of E. pellita both with improved productivity and improved timber and pulp properties.