Tomicus piniperda (Coleaoptera: Scolytidae) Within and Between Tree Movement When Migrating to Overwintering Sites
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The Great Lakes Entomologist 35(2):183-192
Tomicus piniperda (L.) (Coleoptera: Scolytidae) is a univoltine bark beetle that conducts maturation feeding inside shoots of pine (Pinus) trees during summer and fall. In the northern portion of its range, where freezing winter temperatures occur, adults overwinter in the outer bark at the base of live pine trees. In the present study, we investigated how adults move to their overwintering sites. We collected infested shoots in late October 2001, applied fluorescent powder to the entrance holes of the feeding tunnels, and attached about 50 shoots to each of 8 test trees in early November. We installed interception traps around the trunks of four test trees, and placed barrier pitfall traps in the soil around the other four test trees. The eight test trees were cut 10 days later and an additional neighboring trees, 4 trees per test tree, were cut in late November. Another "control" trees, which were 8-17 m from any test tree, were cut in early December. We debarked the lower trunk of each cut tree, collected all overwintering adults, and inspected them for powder, using a dissecting microscope and ultraviolet light. Overall, we recovered 56% of the estimated number of released beetles (221 of 392) on the eight test trees. Powder was present on 97% of the 221 recovered beetles. The trunk traps intercepted 66% of all adults recovered on the four trees with trunk traps. No adults were recovered in the pitfall traps. On the 32 nearby trees, 6 of the recovered 129 overwintering adults had powder. No powder was found on any of the 53 overwintering adults recovered from the 22 control trees. There were significantly more overwintering adults found on the 32 trees that neighbored the 8 test trees (4.0 adults/tree) compared with the 22 control trees that were further away (2.5 adults/tree). The sex ratios of overwintering adults were similar among the three groups of trees. Daily maximum temperatures exceeded the flight threshold of T. piniperda (10-12?C) on each day during the 10-day field study. Results indicate that most adults overwinter on the same tree where they last shoot fed, but some adults will fly to nearby trees to overwinter when temperatures exceed the flight threshold of T. piniperda.
Hui, Ye; Haack, Robert A.; Petrice, Toby R. 2002. Tomicus piniperda (Coleaoptera: Scolytidae) Within and Between Tree Movement When Migrating to Overwintering Sites. The Great Lakes Entomologist 35(2):183-192