Ary A Hoffmann

University of Melbourne, Melbourne, Victoria, Australia

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Publications (269)1004.83 Total impact

  • Aston L. Arthur, Ary A. Hoffmann, Paul A. Umina
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    ABSTRACT: BackgroundA key component for spray decision-making in IPM programmes is the establishment of economic injury levels (EIL) and economic thresholds (ET). We aimed to establish an EIL for the redlegged earth mite (Halotydeus destructor Tucker) on canola.ResultsComplex interactions between mite numbers, feeding damage and plant recovery were found, highlighting the challenges in linking H. destructor numbers to yield. A guide of 10 mites per plant was established at the 1st true leaf stage; however simple relationships were not evident at other crop development stages, making it difficult to establish reliable EILs based on mite number. Yield was however strongly associated with plant damage and plant densities, reflecting the impact of mite feeding damage and indicating a plant-based alternative for establishing thresholds for H. destructor. Drawing on data from multiple field trials, we show that plant densities below 30–40 per m2 could be used as a proxy for mite damage when reliable estimates of mite densities are not possible.Conclusion This plant-based threshold provides a practical tool that avoids the difficulties of accurately estimating mite densities. The approach may be applicable to other situations where production conditions are unpredictable and interactions between pests and plant hosts are complex.
    Pest Management Science 12/2014; · 2.74 Impact Factor
  • Aston L. Arthur, Ary A. Hoffmann, Paul A. Umina
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    ABSTRACT: Development of sampling techniques to effectively estimate invertebrate densities in the field is essential for effective implementation of pest control programs, particularly when making informed spray decisions around economic thresholds. In this article, we investigated the influence of several factors to devise a sampling strategy to estimate Halotydeus destructor Tucker densities in a canola paddock. Direct visual counts were found to be the most suitable approach for estimating mite numbers, with higher densities detected than the vacuum sampling method. Visual assessments were impacted by the operator, sampling date, and time of day. However, with the exception of operator (more experienced operator detected higher numbers of mites), no obvious trends were detected. No patterns were found between H. destructor numbers and ambient temperature, relative humidity, wind speed, cloud cover, or soil surface conditions, indicating that these factors may not be of high importance when sampling mites during autumn and winter months. We show further support for an aggregated distribution of H. destructor within paddocks, indicating that a stratified random sampling program is likely to be most appropriate. Together, these findings provide important guidelines for Australian growers around the ability to effectively and accurately estimate H. destructor densities.
    Journal of Economic Entomology 12/2014; 107(6). · 1.60 Impact Factor
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    ABSTRACT: The bacterial endosymbiont Wolbachia blocks the transmission of dengue virus by its vector mosquito Aedes aegypti, and is currently being evaluated for control of dengue outbreaks. Wolbachia induces cytoplasmic incompatibility (CI) that results in the developmental failure of offspring in the cross between Wolbachia-infected males and uninfected females. This increases the relative success of infected females in the population, thereby enhancing the spread of the beneficial bacterium. However, Wolbachia spread via CI will only be feasible if infected males are sufficiently competitive in obtaining a mate under field conditions. We tested the effect of Wolbachia on the competitiveness of A. aegypti males under semi-field conditions. In a series of experiments we exposed uninfected females to Wolbachia-infected and uninfected males simultaneously. We scored the competitiveness of infected males according to the proportion of females producing non-viable eggs due to incompatibility. We found that infected males were equally successful to uninfected males in securing a mate within experimental tents and semi-field cages. This was true for males infected by the benign wMel Wolbachia strain, but also for males infected by the virulent wMelPop (popcorn) strain. By manipulating male size we found that larger males had a higher success than smaller underfed males in the semi-field cages, regardless of their infection status. The results indicate that Wolbachia infection does not reduce the competitiveness of A. aegypti males. Moreover, the body size effect suggests a potential advantage for lab-reared Wolbachia-males during a field release episode, due to their better nutrition and larger size. This may promote Wolbachia spread via CI in wild mosquito populations and underscores its potential use for disease control.
    PLoS neglected tropical diseases. 12/2014; 8(12):e3294.
  • Rachel Slatyer, Michael Nash, A. A. Hoffmann
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    ABSTRACT: Alpine species are distributed across steep environmental gradients and turnover of closely related species along these clines is common. Thermal tolerance is frequently inferred as a proximal driver of both high- and low-elevation range limits across a wide range of species, as temperature decreases rapidly with elevation. Furthermore, locally adaptive genetic variation within species can be maintained where populations exist along an environmental gradient. Three species of alpine-endemic grasshopper (Kosciuscola genus) occupy overlapping elevation zones in the mountains of southeastern Australia. We explored role of thermal tolerance in shaping distribution patterns of the Kosciuscola in the NSW alpine region, and the potential for local adaptation in thermal limits. All species showed remarkable thermal tolerance ranges of over 50°C, reflecting the highly variable and unpredictable climate of the Australian alpine region. There were marked differences in cold tolerance between species but little variation in upper thermal limits. Species occupied thermal environments close to their cold-tolerance limit, suggesting a role for thermal adaptation in shaping patterns of species turnover. Within species, however, high-elevation populations showed greater heat tolerance than low-elevation populations. Contrasting patterns of between- and within-species thermal tolerance variation point to different selective forces acting at the two ecological scales.
    Entomological Society of America Annual Meeting 2014; 11/2014
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    ABSTRACT: The rate of biological invasions is expected to increase as the effects of climate change on biological communities become widespread. Climate change enhances habitat disturbance which facilitates the establishment of invasive species, which in turn provides opportunities for hybridization and introgression. These effects influence local biodiversity that can be tracked through genetic and genomic approaches. Metabarcoding and metagenomic approaches provide a way of monitoring some types of communities under climate change for the appearance of invasives. Introgression and hybridization can be followed by the analysis of entire genomes so that rapidly changing areas of the genome are identified and instances of genetic pollution monitored. Genomic markers enable accurate tracking of invasive species’ geographic origin well beyond what was previously possible. New genomic tools are promoting fresh insights into classic questions about invading organisms under climate change, such as the role of genetic variation, local adaptation and climate pre-adaptation in successful invasions. These tools are providing managers with often more effective means to identify potential threats, improve surveillance, and assess impacts on communities. We provide a framework for the application of genomic techniques within a management context, and also indicate some important limitations in what can be achieved.This article is protected by copyright. All rights reserved.
    Evolutionary Applications 11/2014; · 4.15 Impact Factor
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    ABSTRACT: Background Mountain landscapes are topographically complex, creating discontinuous `islands¿ of alpine and sub-alpine habitat with a dynamic history. Changing climatic conditions drive their expansion and contraction, leaving signatures on the genetic structure of their flora and fauna. Australia¿s high country covers a small, highly fragmented area. Although the area is thought to have experienced periods of relative continuity during Pleistocene glacial periods, small-scale studies suggest deep lineage divergence across low-elevation gaps. Using both DNA sequence data and microsatellite markers, we tested the hypothesis that genetic partitioning reflects observable geographic structuring across Australia¿s mainland high country, in the widespread alpine grasshopper Kosciuscola tristis (Sjösted).ResultsWe found broadly congruent patterns of regional structure between the DNA sequence and microsatellite datasets, corresponding to strong divergence among isolated mountain regions. Small and isolated mountains in the south of the range were particularly distinct, with well-supported divergence corresponding to climate cycles during the late Pliocene and Pleistocene. We found mixed support, however, for divergence among other mountain regions. Interestingly, within areas of largely contiguous alpine and sub-alpine habitat around Mt Kosciuszko, microsatellite data suggested significant population structure, accompanied by a strong signature of isolation-by-distance.Conclusions Consistent patterns of strong lineage divergence among different molecular datasets indicate genetic breaks between populations inhabiting geographically distinct mountain regions. Three primary phylogeographic groups were evident in the highly fragmented Victorian high country, while within-region structure detected with microsatellites may reflect more recent population isolation. Despite the small area of Australia¿s alpine and sub-alpine habitats, their low topographic relief and lack of extensive glaciation, divergence among populations was on the same scale as that detected in much more extensive Northern hemisphere mountain systems. The processes driving divergence in the Australian mountains might therefore differ from their Northern hemisphere counterparts.
    BMC Evolutionary Biology 10/2014; 14(1):204. · 3.29 Impact Factor
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    ABSTRACT: Australia's ecosystems are the basis of our current and future prosperity, and our national well-being. A strong and sustainable Australian ecosystem science enterprise is vital for understanding and securing these ecosystems in the face of current and future challenges. This Plan defines the vision and key directions for a national ecosystem science capability that will enable Australia to understand and effectively manage its ecosystems for decades to come. The Plan's underlying theme is that excellent science supports a range of activities, including public engagement, that enable us to understand and maintain healthy ecosystems. Those healthy ecosystems are the cornerstone of our social and economic well-being. The vision guiding the development of this Plan is that in 20 years' time the status of Australian ecosystems and how they change will be widely reported and understood, and the prosperity and well-being they provide will be secure. To enable this, Australia's national ecosystem science capability will be coordinated, collaborative and connected. The Plan is based on an extensive set of collaboratively generated proposals from national town hall meetings that also form the basis for its implementation. Some directions within the Plan are for the Australian ecosystem science community itself to implement, others will involve the users of ecosystem science and the groups that fund ecosystem science. We identify six equal priority areas for action to achieve our vision: (i) delivering maximum impact for Australia: enhancing relationships between scientists and end-users; (ii) supporting long-term research; (iii) enabling ecosystem surveillance; (iv) making the most of data resources; (v) inspiring a generation: empowering the public with knowledge and opportunities; (vi) facilitating coordination, collaboration and leadership. This shared vision will enable us to consolidate our current successes, overcome remaining barriers and establish the foundations to ensure Australian ecosystem science delivers for the future needs of Australia.
    Austral Ecology 10/2014; · 1.74 Impact Factor
  • Isabel Valenzuela, Ary A Hoffmann
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    ABSTRACT: We review yield effects caused by aphid feeding and associated virus injury to cereal, oilseed and pulse crops, and estimate the potential economic loss caused by aphids in Australia. Potential yield reduction due to aphids was determined through a survey of quantitative data from experiments that assessed aphids' effect on grain yield. In cereals, four aphids caused damage; on barley, feeding injury caused by Rhopalosiphum padi + Rhopalosiphum maidis was most damaging in terms of yield reduction (25.5%) with an economic loss of $19/ha. Barley yellow dwarf virus transmitted by R. padi + Sitobion miscanthi was more damaging than direct feeding, causing a yield reduction of 39% and economic loss of $21/ha for wheat. On canola, beet western yellow virus transmitted by Myzus persicae caused the highest yield reduction of 34% and economic loss of $115/ha, although this was measured through artificial inoculations. Feeding injury was high in Brevicoryne brassicae which caused an average yield reduction of 34% and associated economic loss of $88.5/ha, while Lipaphis erysimi and M. persicae had negligible economic effects but more data are needed. On pulses, the most economically damaging (unidentified) aphids feeding on lupins caused a yield reduction of 43% and economic loss of $24/ha. The aphids M. persicae + Aphis craccivora + Acyrthosiphon kondoi reduced lupin yields by 13% and economic returns by $7.40/ha. On field peas, a 14% reduction in yield was caused by transmitted viruses such as pea seed-borne mosaic virus which caused economic losses of $20.50/ha. In total, feeding and virus injuries resulted in potential economic costs of $241 and $482 million/year, respectively. Although this review provides estimates of potential yield and economic losses due to aphids, few data were available for some crops, aphid species or regions (e.g. oats). Nevertheless, economic costs associated with aphids appear substantial.
    Austral Entomology. 10/2014;
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    ABSTRACT: The wMel infection of Drosophila melanogaster was successfully transferred into Aedes aegypti mosquitoes where it has the potential to suppress dengue and other arboviruses. The infection was subsequently spread into two natural populations at Yorkeys Knob and Gordonvale near Cairns, Queensland in 2011. Here we report on the stability of the infection following introduction and we characterize factors influencing the ongoing dynamics of the infection in these two populations. While the Wolbachia infection always remained high and near fixation in both locations, there was a persistent low frequency of uninfected mosquitoes. These uninfected mosquitoes showed weak spatial structure at both release sites although there was some clustering around two areas in Gordonvale. Infected females from both locations showed perfect maternal transmission consistent with patterns previously established pre-release in laboratory tests. After >2 years under field conditions, the infection continued to show complete cytoplasmic incompatibility across multiple gonotrophic cycles but persistent deleterious fitness effects, suggesting that host effects were stable over time. These results point to the stability of Wolbachia infections and their impact on hosts following local invasion, and also highlight the continued persistence of uninfected individuals at a low frequency most likely due to immigration.
    PLoS Neglected Tropical Diseases 09/2014; 8(9):e3115. · 4.57 Impact Factor
  • Ian M. Smith, Ary A. Hoffmann, Linda J. Thomson
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    ABSTRACT: Hymenopteran parasitoids are important natural enemies of pest species in many agricultural crops, including grapes, and there is increasing interest in using habitat manipulation to enhance populations.In the present study, we investigated which vegetation variables of shelterbelts are associated with increased hymenopteran family abundance by screening 60 shelterbelts adjacent to vineyards or pasture near Melbourne, Australia.Associations between vegetation characteristics and parasitoid abundance, sampled five times at monthly intervals using canopy sticky traps, were investigated.The presence of vineyard or pasture adjacent to the shelterbelt had no impact on hymenopteran family abundance within the shelterbelt. The availability of floral resources influenced a single family; the abundance of the Trichogrammatidae was doubled by the presence of canopy floral resources. By contrast, an increased abundance of some large Hymenoptera families was associated with a decreasing leaf litter depth and the proportion of introduced ground cover, an increased grass height and the amount of ground with vegetated cover.These findings suggest that specific manipulations of shelterbelts could increase populations of beneficials to some degree, with potential effects on pests.
    Agricultural and Forest Entomology 09/2014; · 1.47 Impact Factor
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    ABSTRACT: Environmental stimuli can induce plastic changes in life history traits, and stimuli experienced by parents can be transmitted to the next generation ("transgenerational") through the inheritance of factors unrelated to changes in DNA sequences. Transgenerational effects are common in species living in habitats subjected to recurrent stressful events, such as fluctuating resource availability. In a previous study, the nutritional status of the midge Chironomus tepperi has been reported to influence life history traits of the offspring. In this study we investigated whether they also alter sensitivity of offspring to zinc. Offspring of parents reared under low food conditions had a shorter development time and lower reproductive output compared to offspring of parents raised under excess food. While zinc exposure decreased the survival of offspring generally, the interaction between parental food level and zinc exposure did not influence the relative sensitivity of offspring toward zinc. Parental nutritional stress therefore triggered transgenerational effects, potentially acting as confounding factors in ecotoxicological studies, but they did not directly affect the susceptibility of offspring to zinc.
    Ecotoxicology and Environmental Safety 08/2014; 110C:1-7. · 2.20 Impact Factor
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    ABSTRACT: AimComparative phylogeographic analyses of alpine biota from the Northern Hemisphere have linked patterns of genetic diversification to glacial expansion and contraction events in the Pliocene and Pleistocene. Furthermore, the extent of diversification across species groups appears to be associated with vagility. In this study we test whether these patterns apply to a geologically stable system from eastern Australia with comparatively shallow elevational gradients and minimal influence from historical glacial activity.LocationThe Australian Alps, Victoria, eastern Australia.Methods We considered phylogeographic patterns across five alpine invertebrate species based on mitochondrial and nuclear DNA sequence data. Bayesian inference methods were used to estimate species phylogenies and divergence times among lineages. GIS tools were used to map interpopulation genetic divergence and intrapopulation genetic diversity estimates and to visualize spatial patterns across species, providing insights into patterns of endemism and demographic history.ResultsPhylogeographic patterns and the timing of lineage diversification were consistent across taxonomic groups. Mountain summits harbour highly differentiated haplogroups, including summits connected by high-elevational plateaus, pointing to diversifications being maintained since the early to mid-Pleistocene. These findings are consistent with previous studies of alpine mammals and reptiles, demonstrating a high degree of endemism in this region, regardless of species vagility.Main conclusionsThe fine spatial scales at which deep genetic differentiation among alpine communities was observed in this study are unprecedented. This suggests that glacial periods have had less of an impact on species distributions and genetic diversity than they have in alpine systems in the Northern Hemisphere. Historical gene flow among sky-island populations has been limited despite connecting snowlines during glacial periods, suggesting that factors other than snow cover have influenced patterns of gene flow in this region. These findings emphasize the unique phylogeographic history affecting Victorian alpine biodiversity, and the importance of conserving biodiversity from multiple mountain summits in this region of high endemism.
    Journal of Biogeography 08/2014; · 4.86 Impact Factor
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    ABSTRACT: Aedes aegypti, Aedes notoscriptus and Aedes albopictus are important vectors of many arboviruses implicated in human disease such as dengue fever. Genetic markers applied across vector species can provide important information on population structure, gene flow, insecticide resistance and taxonomy, however, robust microsatellite markers have proven difficult to develop in these species and mosquitoes generally. Here we consider the utility and transferability of fifteen Ribosome protein (Rp) Exon-Primed Intron-Crossing (EPIC) markers for population genetic studies in these three Aedes species. Rp EPIC markers designed for Ae. aegypti also successfully amplified populations of the sister species, Ae. albopictus, as well as the distantly related species, Ae. notoscriptus. High SNP and good indel diversity in sequenced alleles plus support for amplification of the same regions across populations and species were additional benefits of these markers. These findings point to the general value of EPIC markers in mosquito population studies.This article is protected by copyright. All rights reserved.
    Insect Science 06/2014; · 1.79 Impact Factor
  • Ary A Hoffmann
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    ABSTRACT: Following the recent transfer of Wolbachia from Drosophila to Aedes aegypti mosquitoes, the wMel Wolbachia infection now has been introduced successfully into natural A. aegypti populations in northern Queensland with likely suppressive effects on the transmission of dengue and other arboviruses. However, the introduction of other Wolbachia strains that might affect the population dynamics of A. aegypti and/or provide almost complete blockage of virus transmission like wMelPop remains challenging given the strong fitness costs of these strains for their hosts. Here, the different approaches that might be followed in facilitating introductions of such strains, including ways to suppress populations prior to release stains, interventions during release to boost the fitness of released strains and timing of releases to provide an initial boost in infection frequencies are reviewed. Suppression of a single mosquito life stage prior to release is likely to have little impact on invasion success, whereas suppression of populations of uninfected mosquitoes at all life stages provides a promising strategy for invasion. Implementation of these approaches requires a detailed understanding of the local ecology of mosquito populations, as well as an understanding of the level of isolation of a local population, particularly when the Wolbachia infection results in population suppression as well as strong blockage of virus transmission.
    Australian Journal of Entomology 05/2014; · 0.88 Impact Factor
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    ABSTRACT: The intracellular endosymbiont Wolbachia has been artificially transinfected into the dengue vector Aedes aegypti, where it is being investigated as a potential dengue biological control agent. Invasion of Wolbachia in natural populations depends upon the fitness of Wolbachia-infected Ae. aegypti relative to uninfected competitors. Although Wolbachia infections impose fitness costs on the adult host, effects at the immature stages are less clear, particularly in competitive situations. We look for effects of two Wolbachia infections, wMel and wMelPop, on intra-strain and inter-strain larval competition in Ae. aegypti. Development of Wolbachia-infected larvae is delayed in mixed cohorts with uninfected larvae under crowded-rearing conditions. Slow developing wMelPop-infected larvae have reduced adult size compared with uninfected larvae, and larvae with the wMel infection are somewhat larger and have greater viability relative to uninfected larvae when in mixed cohorts. Implications for successful invasion by these Wolbachia infections under field conditions are considered.
    The American journal of tropical medicine and hygiene 04/2014; · 2.53 Impact Factor
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    ABSTRACT: Genetic markers are widely used to understand the biology and population dynamics of disease vectors, but often markers are limited in the resolution they provide. In particular, the delineation of population structure, fine scale movement and patterns of relatedness are often obscured unless numerous markers are available. To address this issue in the major arbovirus vector, the yellow fever mosquito (Aedes aegypti), we used double digest Restriction-site Associated DNA (ddRAD) sequencing for the discovery of genome-wide single nucleotide polymorphisms (SNPs). We aimed to characterize the new SNP set and to test the resolution against previously described microsatellite markers in detecting broad and fine-scale genetic patterns in Ae. aegypti. We developed bioinformatics tools that support the customization of restriction enzyme-based protocols for SNP discovery. We showed that our approach for RAD library construction achieves unbiased genome representation that reflects true evolutionary processes. In Ae. aegypti samples from three continents we identified more than 18,000 putative SNPs. They were widely distributed across the three Ae. aegypti chromosomes, with 47.9% found in intergenic regions and 17.8% in exons of over 2,300 genes. Pattern of their imputed effects in ORFs and UTRs were consistent with those found in a recent transcriptome study. We demonstrated that individual mosquitoes from Indonesia, Australia, Vietnam and Brazil can be assigned with a very high degree of confidence to their region of origin using a large SNP panel. We also showed that familial relatedness of samples from a 0.4 km2 area could be confidently established with a subset of SNPs. Using a cost-effective customized RAD sequencing approach supported by our bioinformatics tools, we characterized over 18,000 SNPs in field samples of the dengue fever mosquito Ae. aegypti. The variants were annotated and positioned onto the three Ae. aegypti chromosomes. The new SNP set provided much greater resolution in detecting population structure and estimating fine-scale relatedness than a set of polymorphic microsatellites. RAD-based markers demonstrate great potential to advance our understanding of mosquito population processes, critical for implementing new control measures against this major disease vector.
    BMC Genomics 04/2014; 15(1):275. · 4.40 Impact Factor
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    ABSTRACT: Background Genetic markers are widely used to understand the biology and population dynamics of disease vectors, but often markers are limited in the resolution they provide. In particular, the delineation of population structure, fine scale movement and patterns of relatedness are often obscured unless numerous markers are available. To address this issue in the major arbovirus vector, the yellow fever mosquito (Aedes aegypti), we used double digest Restriction-site Associated DNA (ddRAD) sequencing for the discovery of genome-wide single nucleotide polymorphisms (SNPs). We aimed to characterize the new SNP set and to test the resolution against previously described microsatellite markers in detecting broad and fine-scale genetic patterns in Ae. aegypti. Results We developed bioinformatics tools that support the customization of restriction enzyme-based protocols for SNP discovery. We showed that our approach for RAD library construction achieves unbiased genome representation that reflects true evolutionary processes. In Ae. aegypti samples from three continents we identified more than 18,000 putative SNPs. They were widely distributed across the three Ae. aegypti chromosomes, with 47.9% found in intergenic regions and 17.8% in exons of over 2,300 genes. Pattern of their imputed effects in ORFs and UTRs were consistent with those found in a recent transcriptome study. We demonstrated that individual mosquitoes from Indonesia, Australia, Vietnam and Brazil can be assigned with a very high degree of confidence to their region of origin using a large SNP panel. We also showed that familial relatedness of samples from a 0.4 km2 area could be confidently established with a subset of SNPs. Conclusions Using a cost-effective customized RAD sequencing approach supported by our bioinformatics tools, we characterized over 18,000 SNPs in field samples of the dengue fever mosquito Ae. aegypti. The variants were annotated and positioned onto the three Ae. aegypti chromosomes. The new SNP set provided much greater resolution in detecting population structure and estimating fine-scale relatedness than a set of polymorphic microsatellites. RAD-based markers demonstrate great potential to advance our understanding of mosquito population processes, critical for implementing new control measures against this major disease vector.
    BMC Genomics 04/2014; 15(275). · 4.40 Impact Factor
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    ABSTRACT: The wheat curl mite (WCM), Aceria tosichella Keifer (Trombidiformes: Eriophyidae), is a major pest in cropping regions of the world and is recognised as the primary vector of several yield-reducing pathogens, primarily affecting wheat. Management of WCM is complicated due to several aspects of the mite's biology and ecology; however, commercially viable mite resistant wheat varieties may offer practical long-term management options. Unfortunately, mite populations have adapted to previously identified sources of resistance, highlighting the need for further sources of resistance and the value of stacking different resistances to give greater degrees and longevity of control. In this study we assessed the susceptibility of 42 wheat-derived genotypes to mite population growth using a new experimental method that overcomes methodological limitations of previous studies. Experimental wheat lines included a variety of wheat genotypes, related Triticeae species, wheat-alien chromosome amphiploids, and chromosome addition or substitution lines. From these we identify new promising sources of WCM resistance associated with Thinopyrum intermedium, Th. ponticum and Hordeum marinum chromosomes. More specifically we identify group 1J and 5J chromosomes of the L3 and L5 wheat-Th. intermedium addition lines as new sources of resistance that could be exploited to transfer resistance onto homoeologous wheat chromosomes. This study offers new methods for reliable in situ estimations of mite abundance on cereal plants, and new sources of WCM resistance that may assist management of WCM and associated viruses in wheat.
    Experimental and Applied Acarology 04/2014; · 1.85 Impact Factor
  • Fernando Díaz, Nancy M. Endersby, Ary A. Hoffmann
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    ABSTRACT: The whitefly Bemisia tabaci (Gennadius) is one of the most important pests causing economic losses in a variety of cropping systems around the world. This species was recently found in a coastal region of Colombia and has now spread inland. To investigate this invasive process, the genetic structure of B. tabaci was examined in eight sampling locations from two infested regions (coastal, inland) using nine microsatellite markers and the mitochondrial COI gene. The mitochondrial analysis indicated that only the invasive species of the B. tabaci complex Middle East–Asia Minor 1 (MEAM 1 known previously as biotype B) was present. The microsatellite data pointed to genetic differences among the regions and no isolation by distance within regions. The coastal region in the Caribbean appears to have been the initial point of invasion, while the inland region in the Southwest showed genetic variation among populations most likely reflecting founder events and ongoing changes associated with climatic and topographical heterogeneity. These findings have implications for tracking and managing B. tabaci.This article is protected by copyright. All rights reserved.
    Insect Science 04/2014; · 1.79 Impact Factor
  • Philippa C Griffin, Ary A Hoffmann
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    ABSTRACT: Background and AimsWhile molecular approaches can often accurately reconstruct species relationships, taxa that are incompletely differentiated pose a challenge even with extensive data. Such taxa are functionally differentiated, but may be genetically differentiated only at small and/or patchy regions of the genome. This issue is considered here in Poa tussock grass species that dominate grassland and herbfields in the Australian alpine zone.Methods Previously reported tetraploidy was confirmed in all species by sequencing seven nuclear regions and five microsatellite markers. A Bayesian approach was used to co-estimate nuclear and chloroplast gene trees with an overall dated species tree. The resulting species tree was used to examine species structure and recent hybridization, and intertaxon fertility was tested by experimental crosses.Key ResultsSpecies tree estimation revealed Poa gunnii, a Tasmanian endemic species, as sister to the rest of the Australian alpine Poa. The taxa have radiated in the last 0·5-1·2 million years and the non-gunnii taxa are not supported as genetically distinct. Recent hybridization following past species divergence was also not supported. Ongoing gene flow is suggested, with some broad-scale geographic structure within the group.Conclusions The Australian alpine Poa species are not genetically distinct despite being distinguishable phenotypically, suggesting recent adaptive divergence with ongoing intertaxon gene flow. This highlights challenges in using conventional molecular taxonomy to infer species relationships in recent, rapid radiations.
    Annals of Botany 03/2014; · 3.45 Impact Factor

Publication Stats

5k Citations
1,004.83 Total Impact Points

Institutions

  • 2003–2014
    • University of Melbourne
      • • Department of Genetics
      • • Centre for Environmental Stress and Adaptation
      • • Department of Zoology
      Melbourne, Victoria, Australia
  • 2013
    • Chinese Academy of Agricultural Sciences
      • State Key Lab for Biology of Plant Disease & Insect Pests
      Peping, Beijing, China
    • James Cook University
      Townsville, Queensland, Australia
  • 2005–2013
    • Victoria University Melbourne
      Melbourne, Victoria, Australia
    • Melbourne Water
      Melbourne, Victoria, Australia
  • 2012
    • Fordham University
      • Department of Biological Sciences
      United States
    • Deakin University
      Geelong, Victoria, Australia
  • 2007–2012
    • Aarhus University
      • • Department of Bioscience
      • • Department of Genetics and Biotechnology
      • • Department of Ecology and Genetics
      Aars, Region North Jutland, Denmark
    • The University of Manchester
      • Faculty of Life Sciences
      Manchester, ENG, United Kingdom
  • 2002–2011
    • Monash University (Australia)
      • School of Biological Sciences, Clayton
      Melbourne, Victoria, Australia
  • 1995–2011
    • La Trobe University
      • Department of Genetics
      Melbourne, Victoria, Australia
  • 2009–2010
    • Catholic University of Louvain
      • Earth and Life Institute
      Louvain-la-Neuve, WAL, Belgium
    • C.E.S.A.R.
      Arrecife, Pernambuco, Brazil
  • 2006–2010
    • University of Western Australia
      • School of Animal Biology
      Perth, Western Australia, Australia
  • 2004
    • University of Texas at Austin
      • Department of Integrative Biology
      Texas City, TX, United States
    • Bogor Agricultural University
      • Faculty of Agriculture
      Bogor, Provinsi Banten, Indonesia