Animal contests are widely studied by animal behaviourists and behavioural ecologists and there is a well developed framework for evaluating their functional significance. Parasitoid wasps in the family Bethylidae have proven ideal organisms to test predictive models (all of the predicted major influences on contest outcome-fighting ability, prior ownership and the way that individuals value possession of the contested resource - have now been successfully explored) and also in linking contests to other areas of basic (e.g. clutch size) and applied (e.g. biological pest control) areas of animal behaviour study.The link between nutritional/physiological state and contest behaviour has rarely been fully explored. The purpose of this proposal is to evaluate a range of nutrients derived from diverse food sources (nectar and the parasitoid’s host) and their influences on contest behaviours andoutcomes. It is expected that particular nutrients may affect contest ability (termed Resource Holding Potential) whereas others may influence the value of the resource to a contestant. The relative importance, and interactions between these contrasting effects, will be explored.Identification and manipulation of key nutrients (proteins, lipids, carbohydrates and other metabolites) will be achieved by metabolomic analysis and other analytical and biochemical methods. The influence of nutritional state on contest behaviour will be assessed by behavioralobservations. The cost of fighting behavior as influenced by nutritional state will be evaluated by real–time respirometry. The interdisciplinary approach of the proposed project will provide training opportunities in a range of modern techniques new to the researcher (metabolomics, NMRspectroscopy, biochemical methods) whereas will provide a new dimension to the understanding of dyadic animal contests by investigating the effect of variation in nutritional state between competing individuals