MORTALITY OF THE WHITE-PINE WEEVIL ASSOCIATED WITH SILVICULTURAL PRACTICES IN JACK PINE PLANTATIONS

A synthesis of white pine weevil (Pissodes strobi Peck) mortality caus ed by predation (insects, birds, and mammalian predators), crowding of pupae, and abiotic factors, acting under different stand conditions g iven by the type of reforestation, depth of the duff, distance from wo ody debris, and presence of competing vegetation is presented, based o n a four-year study conducted in northeastern Ontario. The type of ref orestation (planted vs. aerial seeding) did not influence mortality to immature weevils in the leaders from either bird predation, insect pr edators and parasitoids or crowding of pupae, but 16% more weevils die d during winter in a planted than in a seeded stand suggesting that th ere was an effect of site condition or small mammal predation on overw intering adults in the duff. Over all conditions, overwintering mortal ity averaged 76-92% with small mammal predation representing about 5-1 3%. Site conditions which augmented small mammal populations and preda tion, such as proximity to woody debris and presence of competing vege tation, had no effect on overwintering mortality of the weevils. The m ost important factor influencing ovenwintering mortality was likely th e depth of duff where an inverse relationship was observed between mor tality and depth. Forest managers should address conditions of duff de pth and small mammal predation to increase the already significant ove rwintering mortality of adult weevils in young jack pine stands.