Pine shoot beetles, Tomicus piniperda, are native to North Africa, Europe, and Asia. They were first discovered in Ohio in July 1992. This beetle was considered a minor or “regulatory” pest when it attacked Christmas trees in the Great Lakes region. As a result, strict quarantines were established to restrict the movement of the beetle and infested material. However, it appears that the beetle is spreading outside the suspected quarantine zone into Canada.
Pine shoot beetle adults overwinter in the bark at the base of pine trees. They emerge in early spring and fly to newly killed or cut pine trees, stumps, logs, and pine slash. Adult females lay eggs beneath the bark. Larvae that emerge from eggs feed and develop within the sapwood. Adults emerge in early summer and feed in tunnels in shoots of live pines after which they move to overwintering sites before the onset of winter. The beetle’s impact depends on adult numbers and management of Christmas tree plantations.
Surveys have been conducted in the United States and Canada since 1993. In summer 1998, pine shoot beetles were captured in two traps in Quebec. These were the first catches since the trapping program started in 1993. In addition, 24 counties in Quebec were found infested with this beetle. In North America, pine shoot beetles were reported attacking Scots, red, white, and jack pine. Tree susceptibility to attack by pine shoot beetles may be influenced by drought, disease, overstocking, and poor management practices (that is, slash left on the ground). These factors, along with the ability of adult females to reproduce more than once, may have led to high beetle populations. The beetle’s potential spread into northern, western, and southern pine forests is a major concern.
Surveys this year have found pine shoot beetles in seven regions of Quebec. In the United States, the USDA Animal, Plant, Health, Inspection Service (APHIS) has surveyed Maine, Vermont, and New Hampshire. Pine shoot beetles were detected in two Vermont counties and in one county in New Hampshire. These new infested areas are not near the Great Lakes region, which is the center of pine shoot beetle infestations.
Pine shoot beetles have been found in 25 counties in Illinois, including Woodford County, where they were detected by the APHIS trapping program this year. The complete list of infested Illinois counties includes Boone, Bureau, Champaign, Cook, DeKalb, DuPage, Grundy, Iroquois, Kane, Kankakee, Kendall, Lake, LaSalle, Lee, Livingston, McHenry, McLean, Ogle, Piatt, Putnam, Stephenson, Vermilion, Will, Winnebago, and Woodford. Indiana now has 45 infested counties, and Wisconsin has three known infested counties.
In response to survey findings, APHIS and Canadian regulatory agencies are promoting research on the biology of the beetle and reviewing current survey methods. In addition, APHIS and agencies in Canada are trying to establish cooperative programs to strengthen pine shoot beetle regulations. They are currently determining regulatory windows to restrict commodity movement. This involves examining the life cycle of the pine shoot beetle to determine how it is influenced by different geographic locations.
APHIS and Canada are also evaluating the current compliance program. The compliance program has been effective with nursery stock and Christmas tree farms, but there are several concerns. First, lack of intensive management in forests and woodlots results in the presence of logs with bark, which act as a reservoir for pine shoot beetles. Second, logging procedures that allow fallen logs and slash to be left on the ground attract pine shoot beetles and may act as breeding sites. Finally, the difficulties of regulating the movement of logs may increase the spread of the pine shoot beetle beyond the infestation area.
Part of the information for this article comes from the United States/Canada guidelines for pine shoot beetle surveys, August 10, 1999.