The winter moth, Operophtera brumata L, a native of Europe, invaded the northeastern United States in the late 1990s and became a major defoliator of forests and shade trees, as well as a serious pest of blueberries. Beginning in 2005, we collected the tachinid parasitoid Cyzenis albicans each year from Vancouver Island, where it had been released to control the winter moth invasion in the late 1970s. As of 2018, we have released the fly at a total 44 locations from coastal Maine to southeast Connecticut. Beginning in 2004 we established six widely-spaced sites across this region to monitor yearly changes in winter moth density and parasitism by C. albicans. We also measured the rate of spread of C. albicans along six 10 km transects in Wellesley, Massachusetts and sequenced the CO1 gene of the fly to prove that the flies we recovered match those that we had released.
Results/Conclusions
As of 2017, we have established the fly at 32 of the 44 release locations. Parasitism by C albicans has increased to 20 to 50% at all six of our long-term study sites and winter moth densities have declined by about two orders of magnitude. Widespread defoliation of trees by winter moth no longer occurs. The flies spread at the rate of about 4 km per year in our Wellesley’s transect and have now occupied nearly all of the high-density winter moth populations in the northeastern United States. In short, we believe we have converted winter moth to a non-pest status. This success mirrors earlier biological control projects in Nova Scotia and Vancouver island. Our DNA analyses confirmed that the fly we established matches exactly the flies that were originally collected in Germany and established in Nova Scotia and Vancouver island.