Proteolytic stabilization of a spider venom peptide results in an orally active bioinsecticide

The toxin peptide U1-AGTX-Ta1b from the Hobo spider, Eratigena agrestis (Walckenaer, 1802), was studied to determine its potential to serve as a bioinsecticide.

U1-AGTX-Ta1b has insecticidal potencies similar to commercial insecticides when injected directly into insect hemolymph but lacks activity when ingested by lepidopterans due to trypsin-like gut proteases. Alanine scanning identified an arginine and lysine rich patch on the peptide's surface that is critical for bioactivity. Targeted stability studies on these basic residues identified a single site, R9, to be the rate limiting site in U1-AGTX-Ta1b proteolysis. Mutation of position R9 to glutamine was sufficient to stabilize the peptide and render the toxin orally active with the additional benefit of enhanced temperature stability. Further refinement of the peptide to remove an O-linked glycosylation site and prevent exoprotease activity during expression in yeast led to a final peptide sequence suitable for commercialization as a bioinsecticide. This peptide displayed activity comparable to commercial insecticides in a range of crop/pest combinations.

A novel, peptide-based bioinsecticide derived from spider venom was developed to be stable and active by ingestion by lepidopteran pests. The peptide, U1-AGTX-Ta1b-QA, can replace or reduce the use of chemical insecticides and has been approved by the United States Environmental Protection Agency. © 2025 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.