Host-symbiont interactions and insect communities provide ideal models for investigating diverse evolutionary and ecological processes. I started to investigate these topics during the course of my PhD. I tried to explain the observed variations in prevalence and penetrance of a Wolbachia infection in different butterfly populations. Since my interest for the understanding of the Dynamics, Ecology and Evolution of host-symbiont interactions has grown further. Currently I am interested in investigating how symbiotic micro-organisms may influence insect communities and food-webs, and how the diverse interactions between species of insect communities may facilitate the horizontal transfer of their endosymbionts.