Insecticidal toxin that acts, at least partially, by inhibiting insect voltage-gated sodium (NaV) channels of several insect species. The toxin binds to the voltage sensor in NaV channel domain II and inhibits channel opening by shifting the threshold for channel activation to more positive voltages. The toxin binding is sensitive to residues in the S1-S2 loop of the domain II voltage sensor. In vivo, the recombinant toxin causes paralysis and/or death to two dipteran species (Lucilia cuprina and Drosophila melanogaster). In contrast, the toxin does not show paralytic or lethal effect on the cotton bollworm Helicoverpa armigera and the triatomine bug Rhodinius prolixus. Expressed by the venom gland. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. Monoisotopic mass. PD(50) is 0.96 nmol/g in Lucilia cuprina (at 0.5-1 hour post-injection). No paralytic or lethal effects are observed 24 hours post-injection. Injection of recombinant toxin into Drosophila melanogaster induces irreversible paralysis leading to death. PD(50) is 0.285 nmol/g (at 3 hours post-injection). PD(50) is 1.9 nmol/g (at 24 hours post-injection). LD(50) is 4.3 nmol/g (at 24 hours post-injection). The recombinant toxin has no effect on american cockroach Nav channels and on the human voltage-gated sodium channel Nav1.5/SCN5A. Belongs to the neurotoxin 10 (Hwtx-1) family. 47 subfamily.