An individual-based model for sex-pheromone-oriented flight patterns of male moths in a local area

We constructed an individual-based model for pheromone-oriented flight patterns of male moths to analyze the spatial distribution of males and the efficacy of synthetic-sex-pheromone traps in a local area. Our model allows individual male moths to move around in a two-dimensional virtual arena in the center of which a pheromone source (a lure in a trap) was placed, Changes in the wind direction were incorporated into the model so that the pheromone plume could meander. The model demonstrated that males clustered around the lure. This clustering phenomenon was caused by the zigzag flight of the males in their attempt to track a pheromone plume as the wind direction changed. The changing wind direction and the male zigzag flight behavior were essential for the clustering to occur. Many males gathered around the trap when the variation (SD) of the wind angle changed between 22.5 and 67.5. Although the clustering tendency was strengthened with an increase in the number of zigzags per moth, this did not significantly affect the number of trap catches. Increasing the density of pheromone sources did not result in a greater catch of males but made the clustering distribution more prominent, The positive and negative effects of cluster-formation on the control of moth pests are discussed. (C) 2002 Elsevier Science B.V. All rights reserved.