Cardiac activity and the influence of isoflurane on this parameter in Anteos menippe butterflies

Understanding the physiological mechanisms regulating cardiac activity in insects remains a fundamental challenge in comparative physiology. This study investigated the effects of isoflurane anesthesia on the electrocardiographic (ECG) activity of Anteos menippe butterflies during induction and recovery. Six newly emerged adults were exposed to 1 mL of isoflurane vapor, and the latency to loss and recovery of postural reflex was recorded. Nickel–chromium electrodes were implanted in the abdomen to record ECG signals for 30 min in a Faraday-shielded setup. Isoflurane produced smooth and reversible anesthesia with induction and recovery times of 48.5 ± 8.9 s and 117.7 ± 16.2 s, respectively, without excitatory responses. During anesthesia, spike frequency decreased to 35 ± 3.3 min⁻¹, returning to 64.3 ± 3.9 min⁻¹ during recovery, accompanied by progressive amplitude and power increases. Spectral analysis revealed dynamic energy redistribution associated with chronotropic modulation during anesthetic elimination. These findings provide the first direct ECG characterization in Lepidoptera, demonstrating that isoflurane is a safe and effective anesthetic and that the butterfly cardiac system follows conserved electrophysiological mechanisms among insects.