EN
INTRODUCTION: Cerci mechanoreceptors act as input into the insect escape system. They permit insects to recognize the direction of mechanical stimuli action. Amputation of one cercus elicits a disturbance of space-orientation of the insect and alters its locomotor activity. AIM(S): The aim of the study was: 1) to examine whether untouched one cercus can functionally replace the second one removed, and 2) to determine the influence of electromagnetic field (EMF, 7 mT, 50 Hz, exposition 1 h/day during 3 weeks) on activity of the remaining cercus. METHOD(S): Recordings of the global bioelectrical activity of cercal nerve were performed using tungsten extracellular electrodes. RESULTS: Effect of wind puff stimulation was dependent on a direction of stimulus application. Under control conditions, stimulation of the left cercus from the right side caused ca. 50% smaller response (recorded from cercal nerve) than that of induced by stimulation from the left side. Similar side‑dependent effect was observed for the other (right) cercus – stimulation from the left side induced much lower effect than stimulation from the right side. In the following experiments, the right cercus was removed and observations of cercal nerve bioelectrical activity were performed 24 hours after amputation, and then 1, 2 and 3 weeks later. The ratio of the magnitude of responses following stimulation from the right side to the stimulation from the left side was assessed. Twenty four hours after the amputation, and then 1 and 3 weeks later the ratio in unexposed insects equals 0.37, 0.45 and 0.53, respectively. During exposure to EMF the ratio was 0.54 after 1 week and 0.69 after 3 weeks from amputation. CONCLUSIONS: Results suggest that the function of amputated cercus can be replaced by the other one and exposure to EMF facilitates this process. FINANCIAL SUPPORT: Work was supported by grant of Nicolaus Copernicus University.