"Spite is one of four fundamental categories of social evolution (alongside selfishness, altruism and mutualism). It is costly to both actor and recipient, and puzzles evolutionary biologists. Historically, conditions favouring spite were thought to be narrow, which resulted in relativelylittle research interest. This assumption has been recently challenged by theoretical work that shows that spite is likely to be widespread in nature. The unusual biology of the parasitic wasp Copidosoma floridanum will enable me to test recently identified factors predicted to favour spite in its specialised soldier larval caste. During the Fellowship, I will conduct several novel experiments to measure the relative importance of potential adaptive functions of spite in this species. These include the mediation of competition and conflict over sex ratio. This training will greatly enhance my future career prospects and open up to me many opportunities for future projects. Working in a top UK university will extend and consolidate my existing experience, knowledge, and skills base, and will enable me to develop a new suite of professional qualities. Moreover, the intended international collaborations will add further to these factors, which will all help me to realise my goal of becoming an independent researcher. The resulting data from this Fellowship will further general understanding of social evolution and will be applicable to other non-biological disciplines. In Europe, social evolution is mainly centred on ‘traditional’ model systems such as social insects, not those with unusual life-histories such as C. floridanum. The few spite studies on C. floridanum have all involved researchers based in the USA, who have agreed to cooperate with this project. This proposal will thus bring focus and highlight international cooperation in exploring a neglected but fundamental branch of social evolution, and will increase the profile and attractiveness of the European Research Area."