Seasonal abundance and hybridization of native and introduced Laricobius species on eastern hemlock in the southern Appalachians

In 2010, a study was initiated to evaluate the use of emergence traps to assess emergence of Laricobius nigrinus in two locations (Blackberry Farm, Walland, Tennessee and Elkmont, Great Smoky Mountains National Park) where this predatory beetle species was released against hemlock woolly adelgid (Adelges tsugae). The emergence of L. nigrinus was observed from 12 October to 2 December 2010. Also, adults of Laricobius rubidus (a predatory beetle native to the eastern U.S.) were collected from traps at Blackberry Farm and Elkmont. This native species has been documented to hybridize with L. nigrinus in some areas of the eastern U.S. Therefore, the extent of hybridization that occurs between these two species in the study sites will be presented and discussed. Additionally, the effectiveness of traps to assess emergence of L. nigrinus will be presented. Specifically, differences between numbers of L. nigrinus collected from inner vs. outer traps, lower beat samples vs. upper beat samples, numbers of adults of Laricobius species collected in bole traps, and density of L. nigrinus under canopies of study trees will be presented and discussed.