  In this paper we are interested in propagation phenomena for nonlocal
reaction-diffusion equations of the type: $\delta_tu = J \times u - u + f (x,
u) t \in R^+, x \in R^N$, where J is a probability density and f is a KPP
nonlinearity periodic in the x variables. Under suitable assumptions we
establish the existence of pulsating fronts describing the invasion of the 0
state by a heterogeneous state. We also give a variational characterization of
the minimal speed of such pulsating fronts and exponential bounds on the
asymptotic behavior of the solution.
