Identification of zoonotic Giardia genotypes in marsupials in Australia

A total of 421 fecal samples from a variety of captive and wild marsupial hosts in Western Australia, Victoria and South Australia were screened for the presence of Giardia species/genotypes using PCR and sequence analysis of a fragment of the 18S rRNA gene. Giardia spp. were identified in 13.4% (28/209) of samples from captive marsupials and 13.7% (29/212) of samples from wild marsupials. Sequence analysis at the 18S locus identified the zoonotic Giardia duodenalis Genotypes A and B in both captive and wild marsupials. Eight isolates were typed as genotype B3 and B4 at the gdh locus, although 7/8 were typed as genotype A at the 18S rRNA locus. The possible reasons for this discordance are discussed. This is the first report of genotype B and only the second report of genotype A in marsupials. As some of the genotype B isolates were identical to human-derived Giardia gdh sequences, these results suggest that marsupials in catchments may pose a public health risk and therefore warrant further investigation.     

Severe malaria in children and pregnancy: an update and perspective

This review summarizes progress in preventing and treating severe malaria, which has been accompanied by advances in our understanding of the pathogenesis of severe malaria complications. New drugs such as intravenous artesunate and oral artemisinin combinations, with increased access to insecticide-treated bed nets, are improving outcomes and decreasing malaria deaths. Several groups are beginning to identify characteristics of parasite var genes associated with cerebral malaria. Understanding of the interactions between malaria and other diseases in causing severe anaemia and cerebral malaria has increased substantially, and at the cellular level, the disturbances leading to coma or other complications are becoming clearer.     

Positive effects of cyanogenic glycosides in food plants on larval development of the common blue butterfly

Cyanogenesis is a widespread chemical defence mechanism in plants against herbivory. However, some specialised herbivores overcome this protection by different behavioural or metabolic mechanisms. In the present study, we investigated the effect of presence or absence of cyanogenic glycosides in birdsfoot trefoil (Lotus corniculatus, Fabaceae) on oviposition behaviour, larval preference, larval development, adult weight and nectar preference of the common blue butterfly (Polyommatus icarus, Lycaenidae). For oviposition behaviour there was a female-specific reaction to cyanogenic glycoside content; i.e. some females preferred to oviposit on cyanogenic over acyanogenic plants, while other females behaved in the opposite way. Freshly hatched larvae did not discriminate between the two plant morphs. Since the two plant morphs differed not only in their content of cyanogenic glycoside, but also in N and water content, we expected these differences to affect larval growth. Contrary to our expectations, larvae feeding on cyanogenic plants showed a faster development and stronger weight gain than larvae feeding on acyanogenic plants. Furthermore, female genotype affected development time, larval and pupal weight of the common blue butterfly. However, most effects detected in the larval phase disappeared for adult weight, indicating compensatory feeding of larvae. Adult butterflies reared on the two cyanogenic glycoside plant morphs did not differ in their nectar preference. But a gender-specific effect was found, where females preferred amino acid-rich nectar while males did not discriminate between the two nectar mimics. The presented results indicate that larvae of the common blue butterfly can metabolise the surplus of N in cyanogenic plants for growth. Additionally, the female-specific behaviour to oviposit preferably on cyanogenic or acyanogenic plant morphs and the female-genotype-specific responses in life history traits indicate the genetic flexibility of this butterfly species and its potential for local adaptation.     

Arabidopsis thaliana and the Robin Hood parasite: a chivalrous oomycete that steals fitness from fecund hosts and benefits the poorest one?

Are parasites always harmful to their hosts? By definition, indeed, but in a few cases and particular environments, hosts experience higher fitness in the presence than in the absence of their parasites. Symbiotic associations form a continuum of interactions, from deleterious to beneficial effects on hosts. In this paper, we investigate the outcome of parasite infection of Arabidopsis thaliana by its natural pathogen Hyaloperonospora arabidopsis. This system exhibits a wide range of parasite impact on host fitness with, surprisingly, deleterious effects on high fecundity hosts and, at the opposite extreme, seemingly beneficial effects on the least fecund one. This phenomenon might result from varying levels of tolerance among host lines and even overcompensation for parasite damage analogous to what can be observed in plant–herbivore systems.     

Stream macroinvertebrate assemblage uniformity and drivers in a tropical bioregion

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Enemy release but no evolutionary loss of defence in a plant invasion: an inter-continental reciprocal transplant experiment

Plant chemical defenses and escape from natural enemies have been postulated to select for dietary specialization in herbivorous insects. In field and laboratory bioassays, we evaluated the effectiveness of intact and chemically modified larval shield defenses of the generalist Chelymorpha alternans and the specialists Acromis sparsa and Stolas plagiata (Chrysomelidae: Cassidinae) against three natural predators, using larvae reared on two morning glory (Convolvulaceae) species. We assessed whether: (1) specialists were better defended than generalists when both were fed and assayed on the same plant; (2) larval shield defenses were chemical, physical, or both; and (3) specialists exploit chemistry better than generalists. Live specialist larvae survived at higher rates than did generalists in predator bioassays with the bug Montina nigripes (Reduviidae), but there were no differences among groups against two species of Azteca ants (Hymenoptera: Dolichoderinae). Solvent leaching by H₂O or MeOH significantly reduced shield efficacy for all species compared to larvae with intact shields. In contrast, freshly killed specialist larvae exhibited significantly lower capture rates and frequencies than the generalists. Although solvent leaching significantly reduced overall shield efficacy for freshly killed larvae of all species, the pattern of leaching effects differed between specialists and generalists, with H₂O-leaching having a greater impact on the specialists. The overall vulnerability of the generalists appears due to lower chemical protection, which is ameliorated by increased escape behaviors, suggesting a selective trade-off between these defensive components. These experiments indicate that shield defenses are essential for larval survival and that specialists are superior at exploiting plant compounds residing in the aqueous fraction. Our results support the hypothesis that diet-specialized herbivorous insects have more effective defenses than generalists when both feed on the same plant due to the differential ability to exploit defensive precursors obtained from the host. The evolution of dietary specialization may therefore confer the advantage of enhanced enemy-free space.     

Decision analysis for the planning and assessment of ex situ management: An application to the endangered mahogany glider

Ex situ (‘off-site’) management refers to keeping species in artificial conditions away from their natural habitat and includes captive breeding facilities, botanical gardens and seed banks. There is scope for ex situ programmes to be more commonly used for supplementing or establishing wild populations. However, undertaking ex situ management comes with risks, costs and uncertainties, which must be assessed in the context of available in situ (‘on-site’) management options. The PACES (Planning and Assessment for Conservation through Ex situ management) tool tailors the principles of structured decision-making to the specific problem of assessing and comparing ex situ and in situ management options. We applied the PACES tool to the mahogany glider (Petaurus gracilis), a threatened arboreal marsupial endemic to north Queensland, Australia. Through an expert elicitation process, we predicted the likely benefits of an ex situ and two in situ management options, as compared to a baseline ‘do-nothing’ scenario. The ‘in situ plus’ alternative (where extra resources are dedicated to in situ management) was predicted to result in the largest population increase according to the participants' best estimates. However, this benefit came at a much larger cost than the ex situ alternative, and without the benefit of an ex situ insurance population. The PACES tool assessment allowed the Mahogany Glider Recovery Team to document and plan the financial costs, risks and benefits of potential future management options for the mahogany glider, laying a transparent basis for future assessment and decision-making.     

Expression of snowdrop lectin (GNA) in transgenic rice plants confers resistance to rice brown planthopper

Snowdrop lectin ( Galanthus nivalis agglutinin; GNA) has been shown previously to be toxic towards rice brown planthopper ( Nilaparvata lugens ; BPH) when administered in artificial diet. BPH feeds by phloem abstraction, and causes ‘hopper burn’, as well as being an important virus vector. To evaluate the potential of the gna gene to confer resistance towards BPH, transgenic rice ( Oryza sativa L.) plants were produced, containing the gna gene in constructs where its expression was driven by a phloem-specific promoter (from the rice sucrose synthase RSs1 gene) and by a constitutive promoter (from the maize ubiquitin ubi1 gene). PCR and Southern analyses on DNA from these plants confirmed their transgenic status, and that the transgenes were transmitted to progeny after self-fertilization. Western blot analyses revealed expression of GNA at levels of up to 2.0% of total protein in some of the transgenic plants. GNA expression driven by the RSs1 promoter was tissue-specific, as shown by immunohistochemical localization of the protein in the non-lignified vascular tissue of transgenic plants. Insect bioassays and feeding studies showed that GNA expressed in the transgenic rice plants decreased survival and overall fecundity (production of offspring) of the insects, retarded insect development, and had a deterrent effect on BPH feeding. gna is the first transgene to exhibit insecticidal activity towards sap-sucking insects in an important cereal crop plant.     

Invertebrate biodiversity in apple orchards: agrichemical sprays as explanatory variables for inter‐orchard community differences

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Relationships between management practices and ground‐active invertebrate biodiversity in New Zealand kiwifruit orchards

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