The phyllosphere microbiome in Tsuga canadensis: Possible relationships with resistance to the insect Adelges tsugae and effects of the pesticide dinotefuran.
Eastern hemlock (Tsuga canadensis) is an important forest tree species in North America, but it has been subject to threats from invasive insects; primarily hemlock woolly adelgid (HWA - Adelges tsugae) and elongate hemlock scale (EHS - Fiorinia externa). Both insect species are native to Asia and Tsuga sp. from this region are typically resistant to damage caused by these insects. In this study, we examined the phyllosphere microbiome of two hemlock species native to North America and susceptible to HWA (T. canadensis and T. caroliniana), as well as two species native to Asia and resistant to HWA (T. chinensis and T. diversifolia). Since pesticide application is often used to treat native hemlock species impacted by HWA and EHS, we also examined the response of the microbiome and overall plant physiology to the pesticide dinotefuran in T. canadensis.