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Keywords:

  • Papilio polyxenes;
  • black swallowtail;
  • electrophysiology;
  • contact chemoreception;
  • tarsal sensilla;
  • oviposition stimulants;
  • luteolin 7-0-(6“-0-malonyl)-β-D-glucopyranoside;
  • trans-chlorogenic acid;
  • Daucus carota;
  • Brassica oleracea;
  • sensory codes.

Abstract Tarsal contact chemoreceptors of the black swallowtail butterfly Papilio polyxenes (Lepidoptera: Papilionidae) were stimulated with leaf-surface extracts and ethanolic extracts of whole leaves of a host-plant (Daucus carota) and a non-host (Brassica oleracea). Both leaf extracts evoked large numbers of spikes but stimulated different receptor neurones. It is concluded that a large difference exists between the sensory responses to host and non-host extracts. Two chemicals, luteolin 7-0-(6“-0-malonyl)-β-D-glucopyranoside and trans-chlorogenic acid, known to be present in the host and known oviposi-tion stimulants for P.polyxenes, were also tested and shown to be active. No responses were found to luteolin 7-O-β-D-glucoside or to luteolin 7-O-β-D-glucuronide. These flavonoids occur in D.carota foliage, but do not stimulate oviposition.