Photo-induced arousal response by hornets

When an Oriental hornet Vespa orientalis is subjected to ether anesthesia and then exposed to ultraviolet A light (UVAL) (at a wavelength of 366 nm), it commences showing signs of awakening by starting to move its limbs. While in the process of waking the voltage on its body surface surges sharply from 17-180 mV (median = 71.0) to a level of 93-570 mV (median = 327.5). This elevated level is maintained for several minutes but subsequently drops sharply to starting level. The increase in voltage is throughout accompanied by fluttering of the wings and movements of the legs, as well as attempts to extricate itself from the bindings to the electrodes. These movements by the awakening hornet persist for several minutes even after the irradiation source is turned off but shortly after the switch-off the hornet lapses into sleep again. The described scenario is generally similar in worker, queen and drone hornets, and may even occur in decapitated specimens. The same type of awakening can be repeated in the same fashion after a while, but then the increase in voltage will be smaller than the first time. Continuous UV irradiation of an anesthetized hornet results in a generalized and protracted awakening which, however, is significantly shorter than in a hornet left anesthetized in the dark.