Gerardo Fracasso, Robert Poulin, Barbara Tschirren
A vast body of literature has investigated the direct and indirect effects of parasites on hosts. While the key role of among-individual variation of host traits has long been acknowledged, individual parasite variation has mostly been overlooked due to the difficulties in studying individual parasites. This has hampered advances in our understanding of fundamental parasite biology as well as progress in the development of novel control strategies. Here, we show how recent technological and methodological innovations, coupled with an improved theoretical understanding, allow for a paradigm shift towards individual-based approaches in parasite-related research and highlight potential breakthroughs across fields. We suggest that ectoparasites-due to their life history as well as medical and veterinary importance-are ideal model systems for the study of individual parasite variation.