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Hu Z.-Q.,Northwest University, China | Zhao H.-Y.,Northwest University, China | Thieme T.,BTL Bio Test Labor GmbH Sagerheide
Environmental Entomology | Year: 2013

The effects of enhanced UV-B radiation on the biology of green and brown morphs of Sitobion avenae (F.) (Hemiptera: Aphididae) were tested under laboratory conditions. The two S. avenae morphs were exposed directly to different doses (0, 216, 432, and 864 kJ/m2) of artificial UV-B. Under low doses of UV-B (216 kJ/m2), the nymphal development period was significantly shorter, whereas mean relative growth, total fecundity, and gross reproductive rate were significantly higher for both aphid morphs compared with those morphs under control treatments (0 kJ/m2). Under high doses of UV-B (432 kJ/m2 and/or 864 kJ/m2), the nymphal development period was significantly longer, whereas the reproductive period, postreproductive period, difference in weight, mean relative growth, and life table parameters were significantly reduced for both aphid morphs. Moreover, the nymphal development period was significantly shorter and the differences in weight, mean relative growth, total fecundity, and life table parameters were significantly higher for the brown morph under high doses of UV-B compared with the green morph. The results showed that enhanced UV-B affects the performance of the green and brown S. avenae morphs from positively to negatively. The brown morph exhibited stronger adaptability than the green morph at high doses of UV-B. © 2013 Entomological Society of America.

Schubert J.,Institute for Biosafety in Plant Biotechnology | Habekuss A.,Institute for Resistance Research and Stress Tolerance | Wu B.,Chinese Academy of Agricultural Sciences | Thieme T.,BTL Bio Test Labor GmbH Sagerheide | Wang X.,Chinese Academy of Agricultural Sciences
Virus Genes | Year: 2014

Recently, the importance of the Geminiviruses infecting cereal crops has been appreciated, and they are now being studied in detail. Barley and wheat strains of Wheat dwarf virus are recorded in most European countries. Information on complete sequences of isolates from the United Kingdom, Spain, and Austria are reported here for the first time. Analysis revealed that their sequences are very stable. Recombination between strains was recorded only for the barley strain. We identified several defective forms of the barley strain from barley and wheat, which do not influence symptom expression. Sequences of barley isolates infecting wheat were obtained that did not differ from the isolates from barley. Based on specific features of the SIR of the barley strains, it is suggested that they are assigned to one of the two proposed new clusters, A1 or A2. © Springer Science+Business Media New York 2013.

Thieme T.,BTL Bio Test Labor GmbH Sagerheide | Dixon A.F.G.,Academy of Sciences of the Czech Republic | Dixon A.F.G.,University of East Anglia
Journal of Applied Entomology | Year: 2015

Aphid taxa are characterized by a number of biological features, such as their feeding behaviour and host selection, which it is generally accepted are affected by keeping them for several generations under standard conditions in a laboratory. Analyses of three strains of the green pea aphid, Acyrthosiphon pisum (Harris, 1776), reared in culture for long periods, indicate that other characters are also affected. For example, the response of these aphids to alarm pheromone is dramatically reduced. This raises an interesting question regarding the mechanism by which it occurs and has consequences when aphids from laboratory cultures are used for studies in ecology and applied biology and especially the long-term effectiveness of crop plants genetically engineered to produce EBF as a means of controlling aphids. © 2015 Blackwell Verlag GmbH.

Hu Z.-Q.,Northwest University, China | Zhao H.-Y.,Northwest University, China | Thieme T.,BTL Bio Test Labor GmbH Sagerheide
Insect Science | Year: 2014

Life tables of brown and green color morphs of the English grain aphid, Sitobion avenae (Fabricius) reared on barley under laboratory conditions at 20 ± 1°C, 65% ± 5% relative humidity and a photoperiod of 16 : 8 h (L : D) were compared. The plants were either: (i) infected with the Barley yellow dwarf virus (BYDV); (ii) not infected with virus but previously infested with aphids; or (iii) healthy barley plants, which were not previously infested with aphids. Generally, both color morphs of S. avenae performed significantly better when fed on BYDV-infected plants than on plants that were virus free but had either not been or had been previously infested with aphids. Furthermore, when fed on BYDV-infected plants, green S. avenae developed significantly faster and had a significantly shorter reproductive period than the brown color morph. There were no significant differences in this respect between the two color morphs of S. avenae when they were reared on virus-free plants that either had been or not been previously infested with aphids. These results indicate that barley infected with BYDV is a more favorable host plant than uninfected barley for both the color morphs of S. avenae tested, particularly the green color morph. © 2013 Institute of Zoology, Chinese Academy of Sciences.

Huhnlein A.,Julius Kuhn Institute | Schubert J.,Julius Kuhn Institute | Zahn V.,Plant Protection Office | Thieme T.,BTL Bio Test Labor GmbH Sagerheide
European Journal of Plant Pathology | Year: 2016

Over the last 30 years the importance of Potato leaf roll virus (PLRV) in commercial potato and seed potato production has decreased considerably. Since PLRV is transmitted by aphids in a persistent manner it can be controlled by applying a systemic insecticide. However, the development of insecticide resistance in the main vectors of PLRV Myzus persicae, Aulacorthum solani, Rhopalosiphoninus latysiphon, Aphis fabae, A. nasturtii, A. frangulae and Macrosiphum euphorbiae, and the development of isolates of PLRV that do not induce visible symptoms in some potato cultivars may lead to a resurgence in the significance of PLRV. Isolates of this type were found repeatedly during growing-on tests in Lower Saxony, Germany. In this study we examined such a symptomless isolate. The visible symptoms induced by this isolate in different potato cultivars were compared with those induced by isolates causing typical symptoms of a PLRV infection. By using quantitative real-time PCR the quantifiable amount of viral RNA was determined. Under climate chamber conditions all the isolates tested induced similar symptoms and did not differ in viral RNA content. Complete sequences for the tested isolates were obtained and used in a phylogenetic analysis. All the PLRV isolates compared were very similar at the molecular level. Several motifs that could play a role in symptom expression were analyzed, but none of them were correlated with the absence of symptoms in potato plants during growing-on tests. The discrepancy between the observations recorded in the growing-on tests and our experiments are discussed. © 2016 Koninklijke Nederlandse Planteziektenkundige Vereniging

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