Lynch, Margaret EmmaInterspecific competition has seen a renaissance over the last several decades and has become recognized as an important force influencing the structure of phytophagous insect communities. This research examined interspecific competition, mediated through a shared host plant, between the potato leafhopper (PLH) and the Colorado potato beetle (CPB), two important pests on potatoes. In Maryland, PLH colonize fields in advance of CPB due to management practices and differences in the migration behavior of these two herbivores. Results show that previous feeding by PLH adversely affected oviposition preference and larval performance of CPB in both greenhouse and field-cage experiments. Results suggest that these two herbivores compete through feeding-induced changes in plant physiology or morphology. This research has important implications for the management of agricultural pests such that higher densities of PLH should be tolerated before controls are instigated due to the benefits of CPB reduction that accrue via leafhopper-induced plant resistance.en-USThesisBiology, EntomologyBiology, Ecologyinduced resistanceinterspecific competitionColorado potato beetlepotato leafhopperintegrated pest managementspecies interactions