The aim of this project was to investigate the hypothesis that aphid-infested potato plants produce elevated amounts of the main secondary metabolites that occur in potatoes compared to the amounts produced by non-infested plants. Peach potato aphids <I>Mysuz persicae </I>(Sulzer) (Homoptera: Aphididae) were reared on artificial diets containing the steroidal glycoalkaloids (GAs) α-solanine and α-chaconine in concentrations lower or similar to those observed in potato leaves. The parameters used to measure the aphid performance were the total individual adult cumulative fecundity, diet uptake and mortality the mean relative growth rate (MRGR) and the intrinsic rate of natural increase (IRI). The adults proved to be susceptible to high concentrations (80-160 mg GA /100ml of diet) showing reduced fecundity, diet uptake and increased mortality in comparison to controls. Ingestion of these artificial diets by nymphs delayed maturity and decreased the intrinsic rate of natural increase. GAs in low concentrations marginally stimulated the reproductive performance and diet acceptability of this aphid. The effects of nitrogen fertilisation and pesticide (Aldicarb) application on the foliar total and individual GA production of two potato cultivars King Edward and Maris Piper were examined using a semi-hydroponic culture system. Nitrogen deficient potato plants produced elevated concentrations of GAs. The two cultivars reacted in a different way on pesticide application. Cv. King Edward produced elevated amounts of GAs in the low pesticide treatment when no differences were observed between pesticide treatments on cv. Maris Piper. Glycoalkaloid production of potato plants subjected to stress induced by peach potato aphid <I>M. persicae</I> infestation was investigated in a glasshouse, a plant growth room, and a field experiment. In both glasshouse and plant growth room experiments aphid-infested potato plants produced reduced amounts of total and individual GAs compared to those produced by non-infested plants. This reduction was attributed to a decrease of sugar moities possibly induced to plants heavily infected by aphids.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:651073 |
| Date | January 1999 |
| Creators | Fragoyiannis, Demetrios A. |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/28054 |
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