Temporal and Spatial Distribution of Imidacloprid and the Arthropod Fauna Associated with Eastern Hemlock, Tsuga canadensis (L.) Carr

Abstract

Eastern hemlock, Tsuga canadensis (L.) Carr (Pinales: Pinaceae), is an important component of both the urban and forest landscape of the eastern United States. Eastern hemlock has been heavily impacted by the introduction of the hemlock woolly adelgid, Adelges tsugae (Annand) (Hemiptera: Adelgidae). Two goals of this research were (1) to determine the effect of treatment timing (spring versus fall) and application method (tree injection versus soil injection) on the spatial and temporal distribution of imidacloprid the primary insecticide used to treat A. tsugae and (2) to assess the impact of application method and timing of imidacloprid treatments on the arthropods associated with eastern hemlock. The results of this study showed that xylem fluid concentrations of imidacloprid were significantly (P < 0.05) higher for spring applications than for fall applications, and for trunk injections than soil injections in the first year post treatment. A diverse group of arthropods, making up 393 species, were collected by branch beating the lower crowns of TABLE OF CONTENTS

Imidacloprid Bark Treatment for Hemlock Woolly Adelgid (Adelges tsugae)

“…This study found basal bark applications 52 produce imidacloprid and olefin tissue concentrations similar to those associated with soil injections. In addition, concentrations were similar to those found in other studies, despite different application methods (Turcotte 2015, Cowles and Lagalante 2009, Benton et al 2016.…”

“…Research exploring the effects of imidacloprid applications on arthropods is contradictory. Of the 484 arthropods investigated by Turcotte (2015), no difference in mean population levels were found when compared to the untreated control. Dilling (2009) conducted in particular phyotophygus and transient insect communities.…”

“…Tests of water use dosages proved to be more efficient than the current diameter method (Ford et al 2010). Future research linking water usage to crown volume could make use of the findings by producing technicians friendly dosage tables for inclusion in the manufacturer's instructions (Turcotte et al 2015).…”

“…Fourhundred eighty-four arthropods have been associated with Tsuga canadensis (Turcotte 2015). Research exploring the effects of imidacloprid applications on arthropods is contradictory.…”

Spatial and Temporal Distribution of Imidacloprid Within the Crown of Eastern Hemlock

“…To ensure all hemlock trees were A. tsugae free, stand-wide surveys of hemlock trees to check the presence of A. tsugae at each site were conducted in 2004–2006. In addition, bi-weekly visual surveys of the distal 45 cm of one randomly selected branches from each tree were conducted (ground level to ∼3 m above ground) on all study trees from May to October in 2005 and 2006 ( Costa 2005 , Costa and Onken 2006 , Turcotte 2016 ).…”