PREDATION AND OVERWINTERING MORTALITY OF THE WHITE-PINE WEEVIL, PISSODES-STROBI, IN PLANTED AND SEEDED JACK PINE

Predation by birds and insects and overwintering mortality of the whit e pine weevil, Pissodes strobi Peck, were examined in planted and seed ed stands of jack pine (Pinus banksiana Lamb.) in northern Ontario to develop recommendations for management. No significant difference was found in weevil damage to the stand and in mortality of weevils due to natural enemies between planted and seeded stands. On average, 7.3 +/ - 0.3 (mean +/- 1 SE) weevils emerged as adults from dead terminals. B irds consumed up to 6.4% of late-larval and pupal weevils in planted s tands and up to 8.9% in seeded stands. More weevils emerged from scree ned than from unscreened leaders, indicating a significant mortality o f larvae and pupae, presumably owing to insect predators and parasitoi ds and high density of pupae. Overwintering mortality of adult weevils was 92% in the planted and 76% in the seeded stand. Mammalian predati on significantly reduced survival of overwintering weevils. Factors re lated to other silvicultural treatments, such as the presence of weeds , may be affecting the survival of Pissodes strobi and the susceptibil ity of Pinus banksiana stands to Pissodes strobi infestation. The mani pulation of both mammalian predation and overwintering sites should be emphasized in the management of P. strobi in Pinus banksiana plantati ons.