SIMULATION OF HOST-PARASITE-LANDSCAPE INTERACTIONS - INFLUENCE OF SEASON AND HABITAT ON CATTLE FEVER TICK (BOOPHILUS SP) POPULATION-DYNAMICS IN ROTATIONAL GRAZING SYSTEMS

Explicit consideration of spatial and temporal factors regulating host -parasite-landscape interactions is basic to understanding systems per spectives for the management of animal parasites. A simulation model o f cattle fever tick, Boophilus annulatus and B. micropulus, population dynamics on rangelands of the northeastern Mexico-United States borde r region was modified to examine spatial and temporal dynamics of tick s in rotational grazing systems, Five short-duration grazing rotations in an eight-pasture system were evaluated on rangeland landscapes dom inated by uncanopied grass, mesquite canopied grass and mixed-brush ca nopied grass. Infestations of the grazing system were initiated by int roducing infested cattle in either fall or spring, Grazing system infe stations in mesquite and mixed brush canopied grass persisted longer t han those in uncanopied grass and were characterized by more frequent reinfestations of both pastures and cattle over the two-year simulatio ns. Infestations initiated in fall were generally of longer duration t han those initiated in spring due in part to longer incubation periods for tick eggs. Temporal dynamics of infestations by pasture were eval uated numerically and graphically. These analyses show that gaps and d iscontinuities of infestations within individual pastures over the cou rse of the fall- and spring-initiated simulations reflect host-parasit e-landscape interactions affecting tick distribution and survival. (C) 1997 Elsevier Science B.V.