Biology and Impact of Western Pine Shoot Borer, Eucosma sonomana, in the Western United States : Insects Affecting Reforestation. Biology and Damage

1989

S. 102-109

Unselbständiges Werk

200069378

Western pine shoot borer, Eucosma sonomana Kearfott, damages yellow pines in the western United States by mining the pith of elongating terminal shoots causing loss of about 25% of 1 year's vertical growth per attack. Some shoots are killed or weakened and lateral shoots become dominant. The insect occurs at low population levels. Trees are first attacked at 5 to 10 years of age. After trees are 15 to 20 years old, about 50% of terminal shoots are attacked. Recognition of western pine shoot borer as a pest coincides with the development of managed pine plantations. It is an atypical forest pest in that population levels are stable over most of a rotation, damage is chronic, and damage is inconspicuous. Treatment with synthetic pheromone reduces population levels by 75%. Adults mate early in spring. Females select the larger terminal buds for oviposition sites. Larvae hatch from eggs and enter the elongating shoots shortly after bud burst. In mid-summer they chew out, drop to the ground, pupate, and diapause. Insect development correlates with host development and with heat accumulation.