Mediates visceral muscle contractile activity (myotropic activity). Both CAPA-pyrokinin and CAPA-pyrokinin(2-15) are expressed in CNS, ring gland and abdominal perisympathetic organs (aPSO) but not in midgut or thoracic perisympathetic organs (tPSO) (at protein level). Detected in larvae. Belongs to the pyrokinin family.