Some liver functions in the Oriental hornet (Vespa orientalis) are performed in its cuticle: Exposure to UV light influences these activities

The Oriental hornet Vespa orientalis (Hymenoptera, Vespinae) coordinates its daily activities (e.g. flights out of the nest associated with digging activities and removal of the dug soil from the nest) with the amount of insolation. Thus, the stronger the insolation, the more intense the flight activity and vise versa. The hornet's cuticle bears a few yellow stripes interposed among brown parts of the gastral cuticle. These yellow stripes are composed of two elements, namely, a transparent cuticle and underneath it a layer of yellow granules. When the hornets are exposed to UV light, the layer containing the yellow granules is less active than in hornets kept in the dark. This diminished activity entails a lower production of glucose as well as of several enzymes prevalent also in the liver of mammals, like creatine kinase, alanine aminotransferase, aspartate transaminase. Thus solar irradiation stimulates and produces a change in the metabolic activities of the hornet. The fact that hornets link their flight activity with the insolation leads us to speculate that the sun contributes energetically to the hornet's activity.