Metabolic consequences of feeding and fasting on nutritionally different diets in the wolf spider Pardosa prativaga.
We investigated whether spiders fed lipid-rich rather than protein-rich prey elevate metabolism to avoid carrying excessive lipid deposits, or whether they store ingested lipids as a buffer against possible future starvation. We fed wolf spiders (Pardosa prativaga) prey of different lipid:protein compositions and measured the metabolic rate of spiders using closed respirometry during feeding and fasting. After a 16-day feeding period, spider lipid:protein composition was significantly affected by the lipid:protein composition of their prey. Feeding caused a large and fast increase in metabolism. The cost of feeding and digestion was estimated to average 21% of the ingested energy irrespective of diet. We found no difference in basal metabolic rate between dietary treatments. During starvation V ₀₂ and V(CO)₂decreased gradually, and the larger lipid stores in spiders fed lipid-rich prey appeared to extend survival of these spiders under starvation compared to spiders fed protein-rich prey. The results show that these spiders do not adjust metabolism in order to maintain a constant body composition when prey nutrient composition varies. Instead, lipids are stored efficiently and help to prepare the spiders for the long periods of food deprivation that may occur as a consequence of their opportunistic feeding strategy.
Department of Zoology, University of Oxford, Oxford, UK. kim.jensen@zoo.ox.ac.uk
Kim
K
Jensen
David
D
Mayntz
Tobias
T
Wang
Stephen J
SJ
Simpson
Johannes
J
Overgaard
D000704:Analysis of Variance; D000824:Animal Nutritional Physiological Phenomena / Q000502:physiology*; D000818:Animals; D001481:Basal Metabolism; D001823:Body Composition / Q000502:physiology*; D001837:Body Weights and Measures; D002245:Carbon Dioxide / Q000378:metabolism; D003718:Denmark; D004041:Dietary Fats / Q000378:metabolism; D004044:Dietary Proteins / Q000378:metabolism; D004734:Energy Metabolism / Q000502:physiology*; D005215:Fasting / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology; D013112:Spiders / Q000502:physiology*
D004041:Dietary Fats; D004044:Dietary Proteins; D002245:Carbon Dioxide