Weak blocker of vertebrate P/Q-, N- and L-type voltage-gated calcium channels (Cav1 and Cav2). Is both paralytic and lethal when injected into lepidopteran larvae. Is not toxic to mice. Expressed by the venom gland. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. PD(50) is 5.0 +- 0.3 nmol/g on lepidopteran larvae (Spodoptera litura). The primary structure of the mature peptide is identical to that of omega-oxotoxin-Ot1a from Oxyopes takobius (AC P83288). Belongs to the spiderine family. Spiderine subfamily.