Mode of action of an insecticidal peptide toxin from the venom of a weaving spider (Diguetia canities).

A recently discovered spider toxin (DTX9.2) induced a rapid paralysis when injected into insects. In neurophysiological experiments, DTX9.2 elevated spike discharges in sensory nerves and at the neuromuscular junction, and also caused a depolarization of the membrane potential in cockroach giant axons. All these effects were reversed by treatment with the specific sodium channel blocker, tetrodotoxin. These findings suggest that DTX9.2 acts upon the voltage-dependent sodium channels of insect nerve membrane.