PREDICTION AND MANIPULATION OF MOVEMENT BY POLYPHAGOUS, HIGHLY MOBILEPESTS

The population dynamics of certain types of pests are particularly dri ven by movement behavior, i.e., highly mobile, polyphagous pests. The development of species-specific integrated pest management (IPM) progr ams for such pests depends on event forecasting, predicted density cha nges, and manipulation of colonization rates. Research on potato leafh opper, Empoasca fabae (Harris), is presented to illustrate the develop ment of such IPM programs. First, based on first detection of spring m igrants, local temperature patterns, and established developmental req uirements of the leafhopper, phenological prediction of expected popul ation increase is shown to serve to alert IPM scouts when to begin fie ld-based sampling. Second, observed densities of adults and predicted densities from a model simulating within-field dynamics demonstrates t hat both within-field factors as well as landscape-level factors influ ence densities. Finally, intercropping of oats and alfalfa is shown to reduce colonization of adults as a function of oat density, illustrat ing the potential of crop modification as a means to reduce pest colon ization. Although landscape-level management programs have been employ ed for some highly mobile, polyphagus pests, current lack of knowledge of potato leafhopper regional dynamics prevents such program developm ent at present. Yet, within-field management may significantly reduce colonization rates, thus leading to reduced crop susceptibility to pes t-induced damage.