Mass Spectrometry-Based Characterization and Functional Evaluation of Paralytic Peptides From Bracon brevicornis...

Parasitoid wasp venoms contain diverse bioactive molecules that manipulate host physiology, most notably by inducing rapid paralysis, yet the paralytic components of many agriculturally important species remain uncharacterized. Bracon brevicornis, an ectoparasitoid of lepidopteran pests, induces rapid and sustained paralysis in its insect hosts, but the molecular basis of this effect remains unknown. Using LC-MS/MS analysis of venom gland extracts, we identified five peptides derived from the C-terminal region of a putative paralytic protein. Two representative peptides-Peptide 1 (946.48 Da; GLFDFIVH) and an N-acetylated Peptide 2 (1,791.93 Da; QAAAQAAAAGIQLPSKPAS)-were validated by LC-ESI-QToF MS/MS analysis, synthesized, and subjected to functional assays. Bioassays revealed dose-dependent paralysis induced by both synthetic peptides, confirming that they retain intrinsic paralytic activity. However, the onset of paralysis was consistently slower than that caused by the crude venom extract, suggesting that additional venom constituents act synergistically to enhance or accelerate the paralytic response. Overall, our findings identify Peptides 1 and 2 as active fragments of the B. brevicornis paralytic protein and indicate that venom activity arises from multiple interacting components. This work provides the first molecular insight into B. brevicornis venom-mediated paralysis and establishes a foundation for mechanistic and applied studies.