Electrophysiological activity of the Sirex noctilio ovipositor: You know the drill?

• The Sirex woodwasp (Sirex noctilio) assesses tree quality with the ovipositor.
• The Sirex ovipositor is electrophysiologically active.
• The Sirex ovipositor detects ethanol and chemical components in timber extracts.

Sirex woodwasp (Sirex noctilio F: Hymenoptera: Siricidae) is a major worldwide pest of pine (Pinus) species. The female woodwasp undertakes exploratory drills with the ovipositor prior to egg-laying to assess tree suitability. Previous work has shown that this behaviour is associated with assessing the osmotic pressure of the tree. Here we show that, in addition, the ovipositor is electrophysiologically active and capable of detecting ethanol and chemical components of solvent extracts of pine needles and bark. Scanning electron micrographs of the ovipositor show the presence of structures which may have a chemoreceptive function. Our research expands our knowledge of the role that the Sirex ovipositor plays in egg-laying site selection.

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