Title of talk: Host-parasite molecular crosstalks: progress, pitfalls and future prospects. David G. Biron, Ph. D., FLS, HDR email : email@example.com Abstract __________ Many parasite taxa are capable of altering a wide range of phenotypic traits of their hosts in ways that seem to improve the parasite’s chance of completing its life cycle. Alteration in host behaviour are classically seen as compelling illustrations of the “extended phenotype” concept suggesting that some parasite genes have phenotype effects on the host. There are many impressive examples of such phenomena. For instance, several anecdotal reports in the literature have suggested that arthropods parasitized by hairworms and mermithids commit ’suicide’ by jumping into an aquatic environment needed by the adult worms for the continuation of their life cycle. Despite increasing evidence of host phenotypic manipulation by parasites, the underlying mechanisms causing infected hosts to act in ways that benefit the parasite remain generally enigmatic. Also, the host-parasite crosstalks involved during the manipulative process of a host by its parasite are still poorly understood. Lately proteomics have been used to lay the foundations of the understanding of some aspects of manipulation by parasites (i.e. proximate mechanisms, crosstalk and evolutive convergence) by using some arthropod host-parasite systems. These pioneer studies reveal new candidate genes and biochemical pathways potentially involved in the manipulative process of a host by its parasite. In this talk, the parasite manipulation hypothesis will be briefly presented. Secondly, the pioneer proteomics results obtained on the manipulative process will be pointed out. Future work should build upon this promising start. I will present some additional considerations to move this work forwards. For instance, I will show a new integrated approach to overcome some pitfalls of previous studies. Finally, I will present future prospects for a new discipline in proteomics, the population proteomics, to study the molecular crosstalk at population scale. The population proteomics could be used, for instance, to decipher from the molecule to the habitat (i) the taking-decisions to choice a microclimate by injurious and beneficial insects living alone or in association and (ii) the behavioural strategies used to reach microclimates in an habitat.