MOVEMENT OF POTATO MOTH ESTIMATED BY MARK- RECAPTURE EXPERIMENTS

The movement of potato moth, Phthorimaea operculella (Zeller), was investigated using moths marked with fluorescent powder and recaptured with sweep nets and pheromone traps. In a small plot trial sweep netting recovered most marked moths within the release plot, and both sweep and pheromone trap catches declined at distances of 20 and 42 m. In commercial fields, pheromone trap recaptures declined beyond distances of 40 m from the release point, and may have been reduced by natural barriers. Moths were recaptured at approximately 200 m both within the release crop and in separate crops. Use of a standard linear dispersal model with pooled data from all three experiments suggested that only 10% of moths dispersed beyond 200 m, but evidence for this model was not conclusive. These results provide part of the information required for determining suitable locations of susceptible refuge crops which have been proposed for diluting pest resistance to insect-resistant transgenic crops.