Growth reduction of Scots pine, Pine sylvestris, caused by the larger pine shoot beetle, Tomicus piniperda (Coleoptera, Scolytidae), in New York State.
Dendrochronological techniques were used to (1) estimate the impact of shoot feeding by the exotic bark beetle Tomicus piniperda in an unmanaged 35-year old Scots pine, Pinus sylvestris, stand in New York State and (2) back-date the probable time of arrival of this beetle to the study site. Increment cores were taken from overstorey trees with severe and moderate crown damage, as no undamaged or lightly damaged trees were present in the study site. In 1989, average growth patterns of both damage classes began to diverge, and in 1995 the average annual basal area increment of trees with severely damaged crowns was 50% less than that of trees with moderately damaged crowns. Over the last 7 years (1989-95) the mean periodic basal area increment of trees with severely damaged crowns was 37% less than that of trees with moderately damaged crowns. This is the first report of growth loss of Scots pine caused by T. piniperda in North America. Tree-ring data suggest that T. piniperda arrived in the stand possibly prior to 1982 and unquestionably before 1989. This was further supported by the growth patterns of hardwood species sampled throughout the study site. This is the first attempt to estimate the time of arrival of this beetle to North America. The damage to Scots pine estimated in this study, together with preferences for certain North American pine species, indicates a potential for serious damage as T. piniperda spreads to major pine-growing regions throughout North America.