Optimizing the use of barrier zones to slow the spread of gypsy moth (Lepidoptera: Lymantriidae) in North America

Slowing the expansion of the range of the gypsy moth, Lymantria dispar (L.), in North America will reduce the area affected by gypsy moth populations in the future and hence may be economically justified. The rate of range expansion can be reduced by eradication of isolated gypsy moth infestations in a barrier zone that is located just beyond the expanding population front and is slowly shifted in the direction of population spread. We developed a model to optimize the allocation of resources for monitoring and treatment of isolated colonies in a barrier zone. Model parameters were estimated using data collected in the central Appalachian Mountains. The model predicted that the cost of slowing population spread is minimized when the density of pheromone traps and eradication activity within the barrier zone decrease with increasing distance from the population front. Sensitivity analysis indicated that the output was most sensitive to the change of the maximum distance from the population front at which colonies can become established. The present value of predicted costs of all monitoring and treatment in the barrier zone were <1/4 the present value of expected benefits from slowing the spread of the gypsy moth over 25 yr.