SPATIAL DYNAMICS OF HELICOVERPA POPULATIONS IN AUSTRALIA - SIMULATION MODELING 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 insects is dominated by their wide host range and the mobility of adults. In an effort to improve Helicoverpa management in high value crops such as cotton, a comprehensive population dynamics model (HEAPS - HElicoverpa Armigera and Punctigera Simulation) has been developed which incorporates 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 mortality. The structure and current state of development of the model is described. 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 pheromone traps. The results of one such experiment are presented to highlight differences in the mobility of the two species of Helicoverpa and indicate the difficulties inherent in validation of the movement routines of the model.