Venom Peptide Repertoire of the European Myrmicine Ant <i>Manica rubida</i>: Identification of Insecticidal Toxins

Abstract

Using an integrated transcriptomic and proteomic approach, we characterized the venom peptidome of the European red ant, <i>Manica rubida</i>. We identified 13 "myrmicitoxins" that share sequence similarities with previously identified ant venom peptides, one of them being identified as an EGF-like toxin likely resulting from a threonine residue modified by <i>O-</i>fucosylation. Furthermore, we conducted insecticidal assays of reversed-phase HPLC venom fractions on the blowfly <i>Lucilia caesar</i>, permitting us to identify six myrmicitoxins (i.e., U₃-, U₁₀-, U₁₃-, U₂₀-MYRTX-Mri1a, U₁₀-MYRTX-Mri1b, and U₁₀-MYRTX-Mri1c) with an insecticidal activity. Chemically synthesized U₁₀-MYRTX-Mri1a, -Mri1b, -Mri1c, and U₂₀-MYRTX-Mri1a irreversibly paralyzed blowflies at the highest doses tested (30-125 nmol·g^-1). U₁₃-MYRTX-Mri1a, the most potent neurotoxic peptide at 1 h, had reversible effects after 24 h (150 nmol·g^-1). Finally, U₃-MYRTX-Mri1a has no insecticidal activity, even at up to 55 nmol·g^-1. Thus, <i>M. rubida</i> employs a paralytic venom rich in linear insecticidal peptides, which likely act by disrupting cell membranes.