THE SPATIAL DYNAMICS OF NATIVE AND INTRODUCED BLOWFLIES (DIPT, CALLIPHORIDAE)

The spatial dynamics of three blowfly species was investigated using a spatially extended model of density-dependent population growth and t he results indicate an overall stabilizing effect. Introduction of dif fusive dispersal induced a quantitative effect of damping variation in population size on the route to a one-fixed point equilibrium in the native species, Cochliomyia macellaria. On the other hand, diffusive d ispersal caused qualitative shifts in the dynamics of two invading spe cies, Chrysomya megacephala and Chrysomya putoria. In both species dif fusive dispersal can produce a qualitative shift from a two-point limi t cycle to a one fixed-point dynamics. Quantitatively, dispersal also has the effect of damping oscillations in population size in the invad ing species.