Insecticidal toxicity of ω-Atypitoxin-Cs1a and its inhibitory effects on insect voltage-gated calcium channels.

Background: Excessive use of chemical insecticides raises concerns about insecticide resistance, urging the development of novel insecticides. Peptide neurotoxins from spider venom are an incredibly rich source of ion channel modulators with potent insecticidal activity. A neurotoxin U1-Atypitoxin-Cs1a from the spider Calommata signata was annotated previously. It was of interest to investigate its insecticidal activity and potential molecular targets.
Results: Cs1a was heterologously expressed, purified and pharmacologically characterized here. The recombinant neurotoxin inhibited high-voltage-activated calcium channel currents with an median inhibitory concentration (IC ₅₀ ) value of 0.182 ± 0.026 μm on cockroach DUM neurons and thus was designated as ω-Atypitoxin-Cs1a. The recombinant Cs1a was toxic to three insect pests of agricultural importance, Nilaparvata lugens, Spodoptera frugiperda and Plutella xylostella with median lethal concentration (LD ₅₀ ) values of 0.121, 0.172 and 0.356 nmol g ^-1 , respectively, at 24 h postinjection. Cs1a was equivalently toxic to both insecticide-susceptible and -resistant insects. Cs1a exhibited low toxicity to Danio rerio with an LD ₅₀ of 2.316 nmol g ^-1 .
Conclusion: Our results suggest that ω-Atypitoxin-Cs1a is a potent Ca _V channel inhibitor and an attractive candidate reagent for pest control and resistance management. © 2023 Society of Chemical Industry.
(© 2023 Society of Chemical Industry.)