Release-recovery in the field and reproductive success in the lab of Laricobius osakensis, a predatory beetle of the hemlock woolly adelgid (Adelges tsugae)

The hemlock woolly adelgid (HWA) is a non-native insect introduced into the eastern U.S. from Japan.  It severely impacts eastern hemlock (Tsuga canadensis L. Carrière) and Carolina hemlock (Tsuga caroliniana Engelman) by their feeding on young branches and twigs, usually at the base where the needles attach. Establishment of biological control predators is critical in the control of this pest. One predator of interest is Laricobius osakensis, a beetle native to the same location HWA in the eastern United States originated from. This beetle has shown a high functional and numerical response and has a synchronous life cycle with HWA. These beetles are currently being reared in the lab for the purposes of field release, though several factors may be limiting our full potential to mass rear them. Two field releases of L. osakensis occurred in the fall of 2012 and colonization at these field sites was monitored throughout the winter and spring. Preliminary results show that the beetle population survived through one field season and larvae were present on release and adjacent trees, showing that they are reproducing. To improve fecundity and health of the lab reared beetles, four different foliage additives were used in water baths holding cut hemlock infested with adelgid that serves as food for the beetles. Carbon-nitrogen elemental analysis and sugar assays will show any changes in health of adelgids and beetle emergence in the fall will be noted and compared with previous years data to determine if there is any improvement in rearing success.