Exergonic reactions involving the catabolism of lipids, in particular the fatty acid moieties of triacylglycerols, provide Nasonia vitripennis Walker (Hymenoptera: Pteromalidae) with a major part of the energy required during metamorphosis, odgenesis, host deprivation, and diapause. Flight muscle development is described and flight muscle mitochondriogenesis probably accounts for the increase in phosphoglycerides during the pupal stage and the marked sexual dimorphism in phosphoglyceride metabolism of the flightless male, and the female insect. Palmitic, palmitoleic and oleic acids are preferentially deposited in the triacylglycerols of N. vitripennis and these fatty acids are selectively utilised during metamorphosis, oogenesis, host deprivation and diapause. Phosphoglycerides contain a preponderance of polyunsaturated fatty acids, and in the female insect, large quantities of branched-chain fatty acids. It is thought that the latter are important constituents of flight muscle mitochondria or egg lipids, and may perform functions normally attributed to long chain polyunsaturates. Fatty acid metabolism is markedly influenced by the environment. Parasitoids reared at extremes of temperature contain more unsaturated fatty acids. This is probably a reflection of temperature-dependent anabolic, catabolic and desaturation enzyme systems, but increased unsaturation of membrane lipids at low temperatures would be beneficial and counteract a tendency of decreasing membrane fluidity. Fatty acid composition is also influenced by diet. Certain fatty acids are selectively accumulated or excluded from the tissue lipids of N. vitripennis while the parasitoid duplicates host levels of palmitic, palmitoleic, linolenic and arachidic acids. The degree to which the parasitoid can adapt to its host's fatty acid metabolism, as a factor governing host suitability is discussed. Lipid is accumulated prior to entry into diapause and it is suggested that the accumulation of w 6 series fatty acids, normally excluded from the tissue lipids of N. vitripennis, may be an important factor in diapause induction and maintenance.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:636070 |
| Date | January 1980 |
| Creators | Beeby, J. |
| Publisher | Swansea University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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