The disulfide linkage of HWTX-II was assigned as Cys4-Cys18, Cys8-Cys29 and Cys23-Cys34, forming a 1-3,2-5 and 4-6 disulfide connectivity. The three-dimensional structure of HWTX II contains two beta-turns (Cys4-Ser7 and Lys24-Trp27) and a double stranded antiparallel beta-sheet (Tryp27-Cys29 and Cys34-Lys36). HWTX-II was able to reversibly paralyze cockroaches for several hours, with a median knockdown dose ED50 of 127 ± 54 µg/g. HWTX-II blocks neuromuscular transmission in the isolated mouse nerve diaphragm preparation and acts cooperatively to potentiate the activity of HWTX I. The toxin can paralyze cockroaches. HWTX-III is a selective inhibitor of insect voltage-gated Na+ channels. It has a natural mutant named HWTX-IIIa, the sequence of which is only truncated a tryptophan (Trp33) residue from C-terminal of HWTX-III  This mutant does not have the same effects as HWTX-III, suggesting that Trp33 is an important residue related to the biological function of HWTX-III. HWTX III contains 33 residues, including six cysteine residues, which form three disulfide bridges. It has a molecular weight of 3853 Da.  HWTX-III inhibits voltage-gated Na+ channels on dorsal unpaired median (DUM) neurons (concentration of toxin at half-maximal inhibition (IC50) ≈1.106 µmol/L) in a similar way as tetrodotoxin (TTX). HWTX-III has no effect on the kinetics of activation and inactivation. HWTX-III showed no effect on the activation and inactivation kinetics of the insect neuron VGSCs, and also no change in the ion selectivity of the channels. However, it can reversibly paralyze cockroaches, depressing the amplitude of the Na+ currents on cockroach DUM neurons. HWTX-III is able to enhance smooth muscle reactions elicited by nerve stimulation of the isolated rat vas deferens. HWTX-IV is an inhibitor of tetrodotoxin (TTX) -sensitive voltage-gated Na+ channels.