Supercooling Points (SCPs) of Social Hymenopterans, Apis mellifera (Hymenoptera: Apidae) and Vespa velutina(Hymenoptera: Vespidae)

Abstract

Apis mellifera (Hymenoptera: Apidae) is an important pollinator but being threatened by Vespa velutina (Hymenoptera: Vespidae), an invasive predator in South Korea. Supercooling point (SCP) is one of indicators of cold tolerance but SCP has not studied for both A. mellifera and V. velutina. Morphological factors like body traits influence fitness of insects in terms of their thermal tolerance. Therefore, we determined SCPs of honey bee, A. mellifera workers, and wasps, V. velutina workers and V. velutina queens, and analyzed the influence of body traits; body size and body mass on SCPs of these species. This is the first report of SCPs of V. velutina queen and worker. The SCPs of A. mellifera workers, V. velutina workers, and V. velutina queens were -6.1, -6.5, and -11.3°C, respectively. Both A. mellifera and V. velutina have unimodal distribution of their SCPs. Neither body size nor body mass influenced the SCPs of A. mellifera and V. velutina. This study showed that SCPs of social insects, A. mellifera and V. velutina were much lower than those of solitary overwintering insects, and differed relative to the caste of the same species.