Peptide neurotoxins affecting insect voltage-gated calcium channels and possessing insecticidal toxicity: Two ω-Atypitoxins from Calommata signata

Abstract

Spider peptide toxins, as potent insecticides, distinguish them from current insecticides, and thus expand the range of viable molecular targets of insecticides in insect pests. This study reports the isolation of two neurotoxic peptides, ω-Atyptoxin-Cs2a (Cs2a) and ω-Atyptoxin-Cs2b (Cs2b), from the venom gland of the burrowing spider Calommata signata. These peptides exhibit strong insecticidal activity against two insect pests with agricultural importance, Nilaparvata lugens and Spodoptera frugiperda. Both toxins demonstrated rapid and significant lethality, with LD₅₀ values of 1.083 ± 0.120 nmol/g and 0.949 ± 0.079 nmol/g for N. lugens and 1.035 ± 0.114 nmol/g and 0.998 ± 0.081 nmol/g for S. frugiperda within 24 h. Using the whole-cell patch-clamp electrophysiology, Cs2a and Cs2b were identified as inhibitors of high-voltage-activated calcium channels in cockroach DUM neurons, with IC₅₀ values of 0.504 ± 0.078 μM and 0.411 ± 0.053 μM, respectively. These findings show that Cs2a and Cs2b are effective calcium channel blockers with potential to develop bioinsecticides, offering selective toxicity toward insect pests.