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Astrid Jankielsohn   Dr.  Other 
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Astrid Jankielsohn published an article in November 2015.
6
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11
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Distribution of Articles published per year 
(2011 - 2015)
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3
 
Publications
Article 1 Read 0 Citations Erratum to: The Hidden Cost of Eating Meat in South Africa: What Every Responsible Consumer Should Know Astrid Jankielsohn Published: 18 November 2015
Journal of Agricultural and Environmental Ethics, doi: 10.1007/s10806-015-9583-6
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Article 0 Reads 1 Citation The Hidden Cost of Eating Meat in South Africa: What Every Responsible Consumer Should Know Astrid Jankielsohn Published: 27 October 2015
Journal of Agricultural and Environmental Ethics, doi: 10.1007/s10806-015-9581-8
DOI See at publisher website
Article 0 Reads 0 Citations Host Associations of Diuraphis noxia (Homoptera: Aphididae) Biotypes in South Africa Astrid Jankielsohn Published: 01 December 2013
Journal of Economic Entomology, doi: 10.1603/EC13274
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Article 0 Reads 0 Citations Host associations of Diuraphis noxia (Homoptera: Aphididae) biotypes in South Africa. Astrid Jankielsohn Published: 01 December 2013
Journal of Economic Entomology,
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The incidence and host associations of Russian wheat aphid were investigated in the wheat-growing areas of South Africa from 2009 to 2011. Most Russian wheat aphid samples were collected on dryland wheat, while few samples were collected on irrigation wheat. Volunteer wheat and rescue grass were the preferred alternative host plants to cultivated wheat for all three biotypes. No RWASA1 samples were collected from oats, but RWASA2 seemed to be able to survive successfully on oats, with 12.26% of the total RWASA2 samples collected on oats and 2.83% RWASA2 samples on wild oats. The intrinsic rate of population increase (rm) has often been used as an index of herbivore performance, and alternative host suitability can be quantified using growth rate parameters, such as the intrinsic rate of increase. The rm was determined for the three South African biotypes-RWASA1, RWASA2, and RWASA3--on seven different host plants. Russian wheat aphid biotypes showed a positive intrinsic rate of increase on all host plants tested, indicating that these host plants were all suitable hosts to support populations of all three biotypes. The rm on TugelaDn, which is resistant to RWASA1 but susceptible to RWASA2 and RWASA3, was significantly higher for RWASA3 and lowest for RWASA1. The rm for RWASA2 and RWASA3 was significantly lower on TugelaDn5, which is resistant to these two biotypes. The rm for RWASA2 and RWASA3 was significantly higher than for RWASA1 on both oats and wild oats. Aphid infestation of winter wheat in the spring may be directly influenced by their success and abundance in noncultivated host plants between harvest and emergence of the cultivated wheat. Therefore, it is important to consider the success of different Russian wheat aphid biotypes on host plant alternatives to cultivated cereals when planning a management strategy for Russian wheat aphid in an area.
Article 0 Reads 11 Citations Distribution and Diversity of Russian Wheat Aphid (Hemiptera: Aphididae) Biotypes in South Africa and Lesotho Astrid Jankielsohn Published: 01 October 2011
Journal of Economic Entomology, doi: 10.1603/EC11061
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Article 0 Reads 0 Citations Distribution and diversity of Russian wheat aphid (Hemiptera: Aphididae) biotypes in South Africa and Lesotho. Astrid Jankielsohn Published: 01 October 2011
Journal of Economic Entomology,
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Russian wheat aphid, Diuraphis noxia (Kurdjumov) (Hemiptera: Aphididae) was recorded for the first time in South Africa in 1978. In 2005, a second biotype, RWASA2, emerged, and here we report on the emergence of yet another biotype, found for the first time in 2009. The discovery of new Russian wheat aphid biotypes is a significant challenge to the wheat, Triticum aestivum L., industry in South Africa. Russian wheat aphid resistance in wheat, that offered wheat producers a long-term solution to Russian wheat aphid control, may no longer be effective in areas where the new biotypes occur. It is therefore critical to determine the diversity and extent of distribution of biotypes in South Africa to successfully deploy Russian wheat aphid resistance in wheat. Screening of 96 Russian wheat aphid clones resulted in identification of three Russian wheat aphid biotypes. Infestations of RWASA1 caused susceptible damage symptoms only in wheat entries containing the Dn3 gene. Infestations of RWASA2 caused susceptible damage symptoms in wheat entries containing Dn1, Dn2, Dn3, and Dn9 resistant genes. Based on the damage-rating scores for the seven resistance sources, a new biotype, which caused damage rating scores different from those for RWASA1 and RWASA2, was evident among the Russian wheat aphid populations tested. This new biotype is virulent to the same resistance sources as RWASA2 (Dn1, Dn2, Dn3, and Dn9), but it also has added virulence to Dn4, whereas RWASA2 is avirulent to this resistance source.