Local movement in herbivorous insects: applying a passive diffusion model to mark-recapture field experiments.

A simple passive diffusion model is used to analyze the local within-habitat dispersal of twelve species of herbivorous insects. The data comprise field mark-recapture studies in relatively homogeneous habitats. For eight of the species, the cumulative frequency distributions of dispersal distances are consistent with a model of movement by passive diffusion. The observed departures from passive diffusion indicate the directions in which we need to modify our mathematical descriptions of movement if we are to develop realistic models of population dynamics and dispersal. The analyses also synthesize in a standard way the relative dispersal rates of several ecologically similar species. The variation both within and between species in diffusion coefficients is striking-certainly sufficient to generate significant consequences for population dynamics and interactions.