Venom chemistry underlying the painful stings of velvet ants (Hymenoptera: Mutillidae)

Velvet ants (Hymenoptera: Mutillidae) are a family of solitary parasitoid wasps that are renowned for their painful stings. We explored the chemistry underlying the stings of mutillid wasps of the genus Dasymutilla Ashmead. Detailed analyses of the venom composition of five species revealed that they are composed primarily of peptides. We found that two kinds of mutillid venom peptide appear to be primarily responsible for the painful effects of envenomation. These same peptides also have defensive utility against invertebrates, since they were able to incapacitate and kill honeybees. Both act directly on cell membranes where they directly increase ion conductivity. The defensive venom peptides of Dasymutilla bear a striking similarity, in structure and mode of action, to those of the ant Myrmecia gulosa (Fabricius), suggesting either retention of ancestral toxins, or convergence driven by similar life histories and defensive selection pressures. Finally, we propose that other highly expressed Dasymutilla venom peptides may play a role in parasitisation, possible in delay or arrest of host development. This study represents the first detailed account of the composition and function of the venoms of the Mutillidae.

Automated summary

This study investigates the composition and function of the venom of mutillid wasps in the genus Dasymutilla, revealing that their venom is primarily composed of peptides. These peptides play a key role in causing the painful effects of envenomation and defending against invertebrates. The defensive venom peptides of Dasymutilla share structural and functional similarities with those of the ant Myrmecia gulosa, suggesting either retention of ancestral toxins or convergence due to similar life histories and defensive selection pressures.