HIPV concentration field (herbivore-specific) Mechanical damage dust (no signal) Caterpillar (herbivore) Parasitoid wasp

Herbivore-Induced Plant Volatiles Simulator (2D)

This 2D counterpart models the same tritrophic chemical-ecology interaction as a real reaction-diffusion-advection system rather than a particle animation. A feeding caterpillar injects a herbivore-induced plant volatile (HIPV) source term into a wind-advected concentration grid, which diffuses and decays over time exactly like an airborne chemical plume. A parasitoid wasp released downwind runs a genuine cast-and-surge odor-plume-tracking algorithm — zig-zag casting crosswind until concentration rises, then a straight upwind surge — the same strategy real insects use to find a scent source in turbulent air. Switch to mechanical wind damage to confirm that identical leaf tearing injects nothing into the field: no plume gradient ever forms, and the wasp has nothing to track.