Jerome Grant
Wednesday, October 15, 2008 - 10:30-11:00
Hemlock woolly adelgid (HWA), Adelges tsugae, is native to Asia and has caused extensive mortality to native hemlocks throughout the eastern U.S., including the southern Appalachians. A two-year study was conducted to assess its biology and life cycle. This exotic insect feeds by inserting its piercing-sucking mouthparts at the base of needles, causing needle discoloration, needle drop, twig dieback, and tree mortality, usually within four to six years. HWA, which is parthenogenic and produces only females, has a complex life cycle with two generations annually. HWA develops more rapidly in the southern Appalachians than in the northeastern U.S. For example, the overwintering generation (sistens) begins oviposition in February (one month earlier), and the next generation (progrediens) begins oviposition in April (two months earlier). Sistens begin aestivation in July and end in October in both the southern Appalachians and the northeastern U.S. A better understanding of HWA in the south will help researchers to enhance niche exploitation by natural enemies and better time insecticide applications to maximize efficacy and minimize environmental impacts.
Keywords: HEMLOCK WOOLLY ADELGID, BIOLOGICAL CONTROL, INVASIVE SPECIES, BIOLOGY, HEMLOCK