Proctolin is a neuropeptide that plays a significant role in the regulation of muscle contraction in invertebrates, particularly insects. It is widely used in research to study the neuromuscular systems of these organisms, providing insights into how neuropeptides control muscle activity. In entomology, proctolin is applied to investigate the physiological mechanisms of insect locomotion, feeding, and other muscle-dependent behaviors. Additionally, it serves as a valuable tool in pharmacological studies to explore potential targets for pest control, as manipulating proctolin signaling can disrupt essential functions in insects. Its application extends to comparative neurobiology, where it helps in understanding the evolution of neuropeptide functions across species.