Winter Moth (Operophtera brumata): Biological control and population dynamics in the Northeastern United States

The winter moth, Operophtera brumata: a leaf-feeding geometrid native to Europe, has recently invaded eastern New England and is causing widespread defoliation. Previous invasions by this species in Nova Scotia and British Columbia have been suppressed by the introduction of two parasitoids from Europe, the tachinid Cyzenis albicans and the ichneumonid, Agrypon flaveolatum. As a result of these introductions, low-density populations of winter moth now persist indefinitely in these regions similar to those that exist in Europe.  Over the past nine years we have introduced C. albicans at 32 locations in Massachusetts, Connecticut, Rhode Island and Maine. We focus our efforts on C. albicans because it specializes on winter moth and it is thought to be the agent primarily responsible for the decline of winter moth densities in Canada, As of this year we have established C. albicans at 7 sites and parasitism levels have been increasing steadily at these sites. We have also documented yearly changes of density and survival of winter moth life stages at these sites and so that we can explain the yearly fluctuations of density that we have observed and the impact of C. albicans  with respect to the other sources of mortality in this system.