1,721,011 research outputs found
Geneflow from GM plants - towards a more quantitative risk assessment
No full textAssessing the risks associated with geneflow from GM crops to wild relatives is a significant scientific challenge. Most researchers have focused on assessing the frequency of gene flow, too often on a localized scale, and ignoring the hazards caused by geneflow. To quantify risk, multi-disciplinary research teams need to unite and scale up their studies
Comparison of glass vessels and plastic bags for enclosing living plant parts for headspace analysis
No full textPlants release volatile chemicals into their surrounding air space that can affect the physiology of neighboring plants and influence the behavior of insects. In studying these interactions, it is desirable to collect volatiles from plants that have not been excised and are growing under as natural conditions as possible. We compared a vessel of borosilicate glass and Nylon-6 or polyester [poly(ethyleneterephthalate) or PET] cooking bags for enclosing plants during collection of volatiles. A push–pull airflow system was used, and volatiles were trapped on Tenax TA and analyzed by gas chromatography after thermal desorption. Low levels of impurities were found for the glass vessel and polyester bags. Nylon bags contained higher levels and more impurities. Recoveries of standards of 10 plant volatiles were measured in static and dynamic systems. In a static air system, there was good recovery only from the glass vessel. In a dynamic system, there was generally good recovery from both the glass vessel and polyester bags. Recoveries of ?-pinene and (Z)-jasmone were poor throughout. The former was shown to have a very low breakthrough volume on the Tenax TA adsorbent, and the latter may be strongly adsorbed on glass. All three materials were essentially transparent in the IR and visible (photosynthetic) range but with significantly different absorptions in the UV range. In a simulated dynamic entrainment in full sunlight, internal vessel temperatures were higher than ambient by up to 9.5°C in the glass vessel and 7.5°C in the polyester bag. Lower increases in temperature relative to ambient (<1°C) were recorded when entrainments were conducted in the shade. In a field trial, the profiles of volatiles collected from an apple tree infested with rosy apple aphid using a glass vessel and a polyester bag were similar. Polyester bags are recommended as more convenient than glass vessels for the enclosure of plants during the collection of volatiles
Does host-feeding on GNA-intoxicated aphids by Aphelinus abdominalis affect their longevity and/or fecundity?
No full textTransgenic potatoes have been transformed with a gene coding the snowdrop lectin Galanthus nivalis agglutinin (GNA) and they have been shown to be partially resistant to aphids. GNA binds to insect gut cells, including those of aphids, consequently inducing disruption of nutrient assimilation. Aphid parasitoids are important natural biocontrol agents of aphids and some species such as Aphelinus abdominalis are commercially available. Aphid parasitoids are endoparasitoids during their larval stages and free-living insects as adults. They could be directly or indirectly affected by GNA during both these stages. In this work, we present data on the potential direct and indirect effects of GNA on adult A. abdominalis.Aphelinus abdominalis is a synovigenic species (eggs are matured throughout the adult life) which needs a diet relatively rich in proteins and amino-acids to produce anhydropic eggs (large, yolk-rich eggs that do not expand in the host during embryonic stages). Adult A. abdominalis females feed on aphid haemolymph and they may be directly exposed to the entomotoxin or indirectly affected by a change in aphid haemolymph quality due to intoxication by GNA. We conducted a first tier experiment to investigate this potential risk. A. abdominalis females were offered either aphids reared on control diet or aphids reared on GNA 0.1% diet as hosts (i.e., as food and oviposition sites). No trace of GNA was found in females fed with GNA-aphids but no GNA could be detected in the haemolymph of aphids fed a 0.1% GNA diet. Longevity and fecundity were not affected suggesting that the quality of the haemolymph necessary for A. abdominalis egg maturation and production was not significantly altered.<br/
The breakdown of trust in decision making about GM crops in a knowledge deficit
No full textIn a society that is becoming increasingly sceptical of scientific innovation, any novel technological advance which has the potential to dramatically alter some aspect of society will face criticism. Biotechnology is no exception. Trust is crucial for its acceptance, as society lacks both broad scientific understanding and specific. biotechnological knowledge. In recent years, society’s trust in science and scientific regulation has been severely dented. Questions of scientific independence and credibility, the negative impacts of previous innovations, and the contrasting views of experts and society, have all played their part in the diminution of society’s trust of scientific innovation, and the capacity of those charged with regulating these innovations. When it comes to regaining trust, one-way dialogue ‘informing’ society of the regulatory steps taken to ensure safety has been shown not to work. We suggest a more inclusive approach, which incorporates societal concerns within the regulatory assessment in a transparent an explicit way, is needed to rebuild societal trust. While the regulatory process only includes the concerns of scientific experts, there will always be criticisms of its scope and the impartiality of experts and the validity of the underlying science
Effects of Bt maize-fed prey on the generalist predator Poecilus cupretis L. (Coleoptera : Carabidae)
No full textWe investigated the effects of transgenic maize (Zea mays) expressing Bacillus thuringienses toxin (Bt maize) on larval and adult Poecilus cupreus carabid beetles in laboratory studies. In no-choice trials, neonate P. cupreus larvae were fed exclusively with Spodoptera littoralis caterpillars, which had been raised on Bt maize. S. littoralis raised on conventional maize or "high quality" Calliphora sp. pupae were fed to the beetle larvae in two control treatments. Bt-maize-fed caterpillar prey increased mortality to 100 within 40 days. The experiment was repeated with 10-day-old beetle larvae. Bt treatment resulted in fewer pupae than in both controls, and in a higher mortality than in the Calliphora control. S. littoralis was suitable as exclusive prey in no-choice tests, at least for 40 days, although prey quality seemed to be low compared to Calliphora pupae. The observed effects are most likely indirect effects due to further reduced nutritional prey quality. However, direct effects cannot be excluded. In the second part of the study, exposure of P. cupreus to Bt intoxicated prey was examined in paired-choice tests. Adult beetles were offered a choice between different prey conditions (frozen and thawed, freshly killed or living), prey types (S. littoralis caterpillars, Calliphorasp. pupae, cereal aphids) and prey treatments (raised on Bt or conventional maize). Living prey was preferred to frozen and dead prey. Caterpillars were only preferred to fly pupae and aphids when living. Prey treatment seemed to be least important for prey selection. The tests showed that P. cupreus ingested caterpillars readily and there was no evidence of them avoiding Bt containing prey, which means exposure in the field could occur. The presented protocols are a first step towards ecological risk assessment for carabid beetles
Effects of Bt maize on the herbivore Spodoptera littoralis (Lepidoptera: Noctuidae) and the parasitoid Cotesia marginiventris (Hymenoptera: Braconidae)
No full textRecent studies have shown that transgenic insect resistant plants can have negative effects on non-target herbivores as well as on beneficial insects. The studyof tritrophic interactions gives insight into the complex mechanisms of food webs in the field and can easily be incorporated into a tiered risk assessment framework. We investigated the effects of transgenic maize (Zea mays) expressing insecticidal proteins derived from Bacillus thuringiensis (Bt maize) on Spodoptera littoralis, a non-target herbivore, and on the hymenopteran parasitoid Cotesia marginiventris. In a laboratory study, S. littoralis larvae were reared for their whole lifespan on a mixture of leaves and stems from 2–4-week old Bt maize plants. S. littoralis survival, developmental times and larval weights were significantly affected by Bt maize diet. However, adult moths, which survived development on Bt maize, were the same size as the adults from the control group. C. marginiventris survival, developmental times and cocoon weights were significantly negatively affected if their S. littoralis host larva had been fed Bt maize. ELISA tests confirmed that S. littoralis larvae ingest high amounts of Cry1A(b) toxin while feeding on Bt maize. In S. littoralis pupae and in C. marginiventris cocoon silk, only traces of the toxin could be detected. No toxin was found in S. littoralis and C. marginiventris adults. Thus the toxin is not accumulating in the trophic levels and in fact appears to be excreted. Our results suggest that the effects on C. marginiventris when developing in susceptible S. littoralis larvae are indirect (host mediated). The biological relevance of those results and the significance of this study in risk assessment are discussed
The usability of digestate in organic farming
No full textAs organic farming prohibits the use of synthetic fertilisers, animal slurries and manures must be used. Digestate offers an alternative to these and this study reports on three experiments conducted to determine its usability in terms of: (1) the effect on earthworm populations, (2) its fertilising effects on Italian Ryegrass and wild Creeping Thistle, and (3) the suppression effects digestate has on weed emergence. The results for digestate application to field plots were intermediate between slurry and no treatment for earthworm attraction and wild thistle suppression. In glasshouse trials it led to increased ryegrass growth compared with undigested slurry. Analysis showed that the digestate had improved nitrogen availability, leading to increased plant growth, but a reduced organic matter content compared with the slurry, leading to a positive though less beneficial impact on the earthworms. Digestate therefore provides a suitable fertiliser for organic farming. This suitability could be improved by drying or separation to increase the OM content making its properties closer to those of slurry whilst still retaining the higher content of plant available nitrogen
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Suitability of Arabidopsis thaliana as a model for host plant-Plutella xylostella-Cotesia plutellae interactions
No full textSuccessful pest management is often hindered by the inherent complexity of the interactions of a pest with its environment. The use of genetically characterized model plants can allow investigation of chosen aspects of these interactions by limiting the number of variables during experimentation. However, it is important to study the generic nature of these model systems if the data generated are to be assessed in a wider context, for instance, with those systems of commercial significance. This study assesses the suitability of Arabidopsis thaliana (L.) Heynh. (Brassicaceae) as a model host plant to investigate plant-herbivore-natural enemy interactions, with Plutella xylostella (L.) (Lepidoptera: Plutellidae), the diamondback moth, and Cotesia plutellae (Kurdjumov) (Hymenoptera: Braconidae), a parasitoid of P. xylostella. The growth and development of P. xylostella and C. plutellae on an A. thaliana host plant (Columbia type) were compared to that on Brassica rapa var. pekinensis (L.) (Brassicaceae), a host crop that is widely cultivated and also commonly used as a laboratory host for P. xylostella rearing. The second part of the study investigated the potential effect of the different A. thaliana background lines, Columbia and Landsberg (used in wider scientific studies), on growth and development of P. xylostella and C. plutellae. Plutella xylostella life history parameters were found generally to be similar between the host plants investigated. However, C. plutellae were more affected by the differences in host plant. Fewer adult parasitoids resulted from development on A. thaliana compared to B. rapa, and those that did emerge were significantly smaller. Adult male C. plutellae developing on Columbia were also significantly smaller than those on Landsberg A. thaliana
Attack rate and success of the parasitoid Diaeretiella rapae on specialist and generalist feeding aphids
No full textLipaphis erysimi (Kaltenbach) is a specialist crucifer feeding aphid and Myzus persicae (Sulzer) is a generalist feeding aphid. The foraging behavior of Diaeretiella rapae (McIntosh), a parasitoid with the ability to parasitize both of these species, was assessed using a series of attack rate and success bioassays, with turnip, Brassica rapa var rapifera, as the host plant. The attack rate of D. rapae was significantly greater on L. erysimi than on M. persicae when aphids were feeding on turnip leaf discs in Petri dishes, irrespective of the aphid species upon which the parasitoids were originally reared. Attack rate bioassays with leaf discs absent, using both satiated and starved aphids, revealed that background chemistry and internal aphid chemistry may have small effects on attack rate. Excision of D. rapae pupae from mummy cases and subsequent use of the fully developed adults in attack rate bioassays showed that cues received by D. rapae at the time of adult emergence provide cues that prime D. rapae to attack L. erysimi at a greater rate than M. persicae. However, the relative success of D. rapae on these two aphid species, in terms of the percentage of attacks resulting in a successful adult parasitoid, was not significantly different
Are fecundity and longevity of female Aphelinus abdominalis affected by development in GNA-dosed Macrosiphum euphorbiae?
No full textSnowdrop lectin (Galanthus nivalis agglutinin, GNA) confers partial resistance to several aphid species when incorporated into an artificial diet and/or expressed in transgenic potato. First-tier laboratory-scale experiments were conducted to assess the potential effect of GNA on the longevity and fecundity of female parasitoid Aphelinus abdominalis (Dalman) that had developed in Macrosiphum euphorbiae (Thomas) fed artificial diet containing 0.1% GNA (w/v). In a previous study it was shown that GNA ingested by A. abdominalis larvae is not acutely toxic. It was also shown that GNA has a host-size mediated effect on parasitoid sex ratio and larval development, but no apparent direct effect. In this study, we report that A. abdominalis larvae that developed in GNA-dosed aphids that were smaller than control aphids of the same age, produced smaller adults with a reduced longevity and fecundity. Aphelinus abdominalis larvae that developed in GNA-dosed aphids older than the control but of the same size, produced adults of similar size that lived as long as the control but had a reduced fecundity. Our results suggest that GNA fed to aphids in artificial diet has both a host-mediated effect (via aphid-size) and a direct effect on adult parasitoid fecundity. It is not known how GNA affects parasitoid larval development and subsequently adult fecundity, but it is hypothesized that GNA acted as an antifeedant to parasitoid larvae, thus disturbing nutrient assimilation and conversion necessary for egg maturation
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