Field release and reproductive success in the lab of Laricobius osakensis, a predatory beetle of the hemlock woolly adelgid (Adelges tsugae)

The hemlock woolly adelgid, a non-native insect introduced into the eastern United States from Japan, feeds on young branches and twigs of both eastern hemlock (Tsuga Canadensis) and Carolina hemlock (Tsuga caroliniana). There numerous ways to combat this pest in landscape environments, but most are ineffective in the forest setting and thus, establishment of biological control agents is necessary. One predator of primary interest is Laricobius osakensis, a predator also from Japan. These beetles are being reared in lab insectaries for the purpose of field release. A major area of concern for mass rearing is maintaining the health of HWA prey on the hemlock branches. To deal with this issue of health quality, four different foliage additives and a control of water are included in water baths where cut hemlock foliage is placed. Adelgid samples are processed quantifying total nitrogen, total carbon and carbohydrates in conjunction with prescribed treatment. Reproductive improvements are monitored for each life stage and compared with previous years’ data. Results from the first year’s work show that there are definitive changes to the health of the adelgids but the treatments did not impact Laricobius reproduction. Two field releases of L. osakensis occurred in the fall of 2012 with two more in the fall of 2013. Colonization at these field sites has been monitored throughout the winter and spring months. Initial results show that the beetles and their offspring have been recovered through two field seasons even with the dramatic winter temperatures in the winter of 2013.