Seasonal Assessment of Supercooling Points for Two Introduced and One Native spp. (Coleoptera: Derodontidae), Predators of Adelgidae.

The hemlock woolly adelgid, Annand, is an invasive insect that threatens hemlock species in eastern North America. Several species from the genus are predators of in its native areas of Asia and the western United States. Two species have been released as biological control agents: Fender, and Montgomery and Shiyake. LeConte is an adelgid predator native to the Eastern United States, where it can feed and complete development on opportunistically. Laboratory assays were conducted to assess the cold hardiness of these three species, including two distinct populations of , by measuring the supercooling points of each species from November 2016 through March 2017. This information may be useful for choosing the best-suited biological control agent for a particular region to control . There was a significant difference between the overall mean supercooling point of compared to the other spp. There were also significant differences of supercooling points between and both strains of in January, and significant differences between and all other strains in February. appear better adapted to cold extremes in the eastern U.S. than imported spp.