Reversed-Phase LC Isolates Potent Insecticidal Protein From Tarantula

A novel orally active insecticidal peptide (OAIP-1) has been isolated from the venom of one of Australia’s largest spiders, the Australian tarantula (Selenotypus plumipes) using reversed-phase liquid chromatography (reversed-phase LC) coupled with mass spectrometry (MS). The study was recently published in the journal PLOS ONE.¹

Insect pests are an affliction on the agricultural industry, reducing world crops by 10–14% annually. Margaret Hardy of the University of Queensland, Australia, told The Column that there is a need to develop new environmentally friendly insecticides, driven by the increasing levels of insecticide resistance. Recently developed insecticides are highly selective and specific, often targeting a small number of molecular targets. Evolution of these targets over time eventually renders the insecticide ineffective. Hardy added that “green” insecticides need to be included in integrated pest management (IPM) programmes to limit their environmental impact.

The tarantula injects venom into its prey using a needle-like fang, and so it has been assumed that it is not a source of orally‑active peptides, which are effective when ingested by insects. The group has previous experience with spider venom peptides with insecticidal activity, but this was the first time they had performed this method. “The manuscript describes the first instance of a directed-discovery programme that successfully isolated a novel, orally-active insecticide,” said Hardy.

Venom was collected from Australian tarantulas and subsequently lypophilized. Reversed-phase LC coupled with MS was performed to isolate and analyse toxins within the venom. Around 50 peaks resulted, with one elution faction displaying oral insecticidal action against tested specimens (including mealworms and termites). A 34-residue orally active insecticidal peptide (OAIP‑1) was identified. The structure of the peptide, was determined by nuclear magnetic resonance (NMR) spectroscopy and indicated high thermal and chemical stability. According to the paper, this suggests the potential to produce the peptide via a synthetic pathway.

“Our results are significant because it describes the discovery of the most potent insecticidal peptide published to date; the insecticide shows synergism with another, currently used conventional insecticide; and, because the peptide could be used as part of an IPM programme,“ said Hardy.Hardy added that the group has already filed patents on the technology used and that future work will focus on determining the safety of the peptide for non-targeted species. - B.D.

Reference

M.C. Hardy et al., PLoS ONE8(9), e73136 (2013).

This story originally appeared in The Column. Click here to view that issue.