evidence for an optimal level of connectivity for establishment and colonization dispersal is usually associated with the spread of invasive species but it also has two opposing effects one decreasing and the other increasing the probability of establishment indeed dispersal both slows population growth at the site of introduction and increases the likelihood of surrounding habitat being colonized the connectivity of the introduction site is likely to affect dispersal and thus establishment according to the dispersal behaviour of individuals using individualbased models and microcosm experiments on minute wasps we demonstrated the existence of a humpshaped relationship between connectivity and establishment in situations in which individual dispersal resembled a diffusion process these results suggest that there is an optimal level of connectivity for the establishment of introduced populations locally at the site of introduction and regionally over the whole landscape