SPATIAL DYNAMICS OF HELICOVERPA POPULATIONS IN AUSTRALIA - SIMULATIONMODELING AND EMPIRICAL-STUDIES OF ADULT MOVEMENT

Two species of Helicoverpa (Lepidoptera: Noctuidae) are major pests of agricultural crops in Australia. The population ecology of these inse cts is dominated by their wide host range and the mobility of adults. In an effort to improve Helicoverpa management in high value crops suc h as cotton, a comprehensive population dynamics model (HEAPS - HElico verpa Armigera and Punctigera Simulation) has been developed which inc orporates the spatial structure of the habitat and pest population and explicitly simulates adult movement within a regional cropping system . HEAPS includes modules for the spatial representation of the region, moth movement, oviposition, pest and crop development and pest mortal ity. The structure and current state of development of the model is de scribed. A key aspect of the model is moth movement. Empirical studies to quantify aspects of adult behaviour and to provide parameters for HEAPS have included mark-recapture experiments in which natural, high density populations have been artificially labelled with strontium as larvae and then recaptured as adults in a widespread network of pherom one traps. The results of one such experiment are presented to highlig ht differences in the mobility of the two species of Helicoverpa and i ndicate the difficulties inherent in validation of the movement routin es of the model.