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 j unction, and also caused a depolarization of the membrane potential in cockroach giant axons. All these effects were reversed by treatment w ith the specific sodium channel blocker, tetrodotoxin. These findings suggest that DTX9.2 acts upon the voltage-dependent sodium channels of insect nerve membrane. Copyright (C) 1996 Elsevier Science Ltd