Persistence of imidacloprid and olefin in eastern hemlock: Seven years of suppression of hemlock woolly adelgid
Monday, March 3, 2014: 1:40 PM
Greenbrier (Embassy Suites Greenville Golf & Conference Center)
Elizabeth P. Benton
,
Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN
Carla I. Coots
,
Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN
Richard Cowles
,
Connecticut Agricultural Experiment Station, Windsor, CT
R. Jesse Webster
,
Great Smoky Mountains National Park, National Park Service, Gatlinburg, TN
Anthony Lagalante
,
Villanova University, Villanova, PA
Jerome F. Grant
,
Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN
Hemlock woolly adelgid (HWA),
Adelges tsugae (Annand), has severely impacted eastern hemlock,
Tsuga canadensis (L.) Carriére, populations in the eastern U.S. Since HWA was detected in the Great Smoky Mountains National Park (GRSM) in 2002, park personnel have conducted an aggressive integrated pest management program to protect hemlock resources. One main management tactic is the use of systemic imidacloprid treatments. A retrospective study was conducted to assess longevity of HWA suppression due to basal drench imidacloprid treatments, focusing on persistence of olefin, an imidacloprid metabolite.
Treatments (0.8 or 1.6 gai/2.54 cm dbh) were applied four to seven years before sampling was initiated at three different sites. Branchlet samples (0.5 m long) were collected during winter 2012 and 2013. HWA were counted on each branchlet. Liquid chromatography-mass spectrometry determined imidacloprid and olefin foliar concentrations (ppb). Chemical data were analyzed by a generalized linear model (p<0.05). HWA data were analyzed using ANOVA and LSD (p<0.05).
Imidacloprid and olefin persists four to seven years after a single imidacloprid treatment while HWA population suppression is maintained. Increased understanding of the longevity of imidacloprid treatments enhance GRSM’s HWA control program by treating hemlocks less frequently and obtaining sufficient HWA control with low-dose treatments.
