PARENT SESSION
Poster Session #4: Invasions.
Monday, August 6, 2001. Presentation from 10:30 AM to 12:00 PM. Exhibition Hall

Introduced tachinid parasitoid explains the enigmatic disappearance of the invasive browntail moth.

ELKINTON, JOSEPH¹, PARRY, DYLAN¹, BOETTNER, GEORGE¹, ¹

ABSTRACT- The browntail moth Euproctis chrysorrhoea, was introduced to North America near Boston from Europe in 1897. It became an important defoliator of many tree species throughout New England and was also a human health hazard due to severe skin rashes caused by urticating hairs from the larvae. Beginning around 1915, however, browntail populations receded gradually to coastal enclaves at the tip of Cape Cod and on islands in Casco Bay in Maine, where high densities have persisted ever since. Until now little research of any kind has been done on browntail moth in North America and no studies have explained why it declined and why it persists in coastal enclaves. We present evidence that the cause of the decline was the generalist tachinid parasitoid Compsilura concinnata, which was introduced to North America in 1906 to control gypsy moths. We have recently implicated this species as a major cause for the decline of silk moths in North America. Analysis of historical data revealed high levels of parasitism of browntail moth by this species, but low levels in coastal areas. We confirm this pattern experimentally by creating artificial browntail populations at both inland and coastal locations on Cape Cod. C. concinnata decimated the browntail moth populations at the inland site but was virtually nonexistent in the coastal sites where browntail moth is now abundant.

KEY WORDS: invasive species, population dynamics, biological control