Host plant influence on movement patterns and subsequent distribution of the polyphagous herbivore Lygus rugulipennis (Heteroptera: Miridae)

We studied movement patterns of nymphs of a highly polyphagous herbivore, Lygus rugulipennis Poppius (Heteroptera: Miridae) on two host plants, wheat (Triticum aestivum) and scentless mayweed (Tripleurospermum inodorum Schultz). We used the observed movement pat terns to model redistribution of nymphs with an individual based movement model and with a diffusion approximation of random walk, and we tested the predictions of the models by following redistribution of nymphs on small arenas in the laboratory. The nymphs were clearly more mobile on wheat than on T. inodorum, and on the arenas most of nymphs were found on T. inadorum after the period of redistribution. Both the simulation model and the diffusion approximation of random walk predicted the distribution well. The ability of the models to predict equilibrium distribution oft, rugulipennis nymphs in heterogeneous space, even though they were parameterized with data collected in homogenous vegetation, suggests that the observed distribution of individuals may have been caused by the host plant induced differences in movement patterns. The high speed of redistribution predicted by the models suggests that no tactic behavior, e.g., orientation toward T. inodorum, is needed for locating preferred hosts in a heterogeneous vegetation composed of small patches.