Abstract / Summary
Pine wilt disease poses a significant threat to pine ecosystems worldwide. By investigating the interaction between Monochamus alternatus , the primary vector insect of the pine wood nematode, and the parasitoid Dastarcus helophoroides , we construct a reaction–diffusion host–parasitoid model incorporating nonlocal competition, memory diffusion, a Holling type III functional response, and two delays associated with energy conversion and memory. The stability of the positive steady state and the occurrence of Hopf bifurcation are analyzed under different delay conditions, and the normal form is derived using the method of multiple time scales. Numerical simulations show that the energy-conversion delay affects both the critical memory threshold and the critical spatial mode. Near the first Hopf threshold, the memory delay induces stable spatially inhomogeneous periodic solutions. As the memory delay increases, the spatial pattern changes and the temporal dynamics become more complex. A systematic numerical scan further suggests a period-doubling route toward chaos-like dynamics, followed by multi-level periodic or quasiperiodic behavior in the long-memory regime. These results show that the two delays jointly influence the stability and spatiotemporal dynamics of the host–parasitoid system, providing theoretical insight into the role of delayed feedback in forest biological control.