Reprint of: Seasonal changes in the composition of storage and membrane lipids in overwintering larvae of the codling moth,Cydia pomonella |
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| Institution: | 1. Institute of Entomology, Biology Centre of the Academy of Sciences of the Czech Republic, České Budějovice, Czech Republic;2. Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic;1. Antarctic Climate Ecosystems CRC, University of Tasmania, Private Bag 80, Hobart, 7001, Australia;2. School of Geography and Environmental Studies, University of Tasmania, Private Bag 78 Hobart, 7001, Australia;3. Department of Biological Sciences, Macquarie University, North Ryde, NSW, 2109, Australia;1. Área de Edafoloxía e Química Agrícola, Departamento de Bioloxía Vexetal e Ciencias do Solo, Facultade de Ciencias, Universidad de Vigo, 32004, Ourense, Spain;2. Department of Agroecology, Faculty of Science and Technology, Aarhus University, Blichers Allé 20, P.O. Box 50, 8830, Tjele, Denmark;1. INRA, UR1115, PSH, Plantes & Systèmes de cultures Horticoles, 84000 Avignon, France;2. CTIFL, Centre Interprofessionnel des Fruits & Légumes, Balandran, 30127 Bellegarde, France;3. INRA, UR546, BioSP, Biostatistiques & Processus Spatiaux, 84000 Avignon, France |
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| Abstract: | The codling moth (Cydia pomonella) is a major insect pest of apples worldwide. It overwinters as a diapausing fifth instar larva. The overwintering is often a critical part of the insect life-cycle in temperate zone. This study brings detailed analysis of seasonal changes in lipid composition and fluidity in overwintering larvae sampled in the field. Fatty acid composition of triacylglycerol (TG) depots in the fat body and relative proportions of phospholipid (PL) molecular species in biological membranes were analyzed. In addition, temperature of melting (Tm) in TG depots was assessed by using differential scanning calorimetry and the conformational order (fluidity) of PL membranes was analyzed by measuring the anisotropy of fluorescence polarization of diphenylhexatriene probe in membrane vesicles. We observed a significant increase of relative proportion of linoleic acid (C18:2n6) at the expense of palmitic acid (C16:0) in TG depots during the larval transition to diapause accompanied with decreasing melting temperature of total lipids, which might increase the accessibility of depot fats for enzymatic breakdown during overwintering. The fluidity of membranes was maintained very high irrespective of developmental mode or seasonally changing acclimation status of larvae. The seasonal changes in PL composition were relatively small. We discuss these results in light of alternative survival strategies of codling moth larvae (supercooling vs. freezing), variability and low predictability of environmental conditions, and other cold tolerance mechanisms such as extending the supercooling capacity and massive accumulation of cryoprotective metabolites. |
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| Keywords: | Triacylglycerols Phospholipids Fatty acids Homeoviscous adaptation Membrane fluidity Cold tolerance |
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