Evaluation of two environmental DNA (eDNA) approaches for monitoring hemlock woolly adelgid (HWA).

Abstract

Eastern hemlocks ( Tsuga canadensis) are experiencing significant mortality due to the invasive insect, hemlock wooly adelgid (HWA) ( Adelges tsuga) . Common monitoring methods for HWA detection include visual assessment of hemlock trees for the presence of ovisac material. However, this method requires time and resources to survey large areas. We compared two methods, ball sampling coupled with genetic analysis and passive environmental DNA (eDNA) sampling, and evaluated their ability to detect HWA in infested and high-risk areas using qPCR. We found that the two methods were equally effective at detecting HWA and could serve as supplemental methods for early HWA monitoring.