Article

Journal of Chemical Ecology

, Volume 27, Issue 1, pp 33-43

First online:

Response of the Ladybird Parasitoid Dinocampus coccinellae to Toxic Alkaloids from the Seven-spot Ladybird, Coccinella septempunctata

  • S. Al AbassiAffiliated withDepartment of Entomology, Swedish University of Agricultural Sciences
  • , M. A. BirkettAffiliated withDepartment of Biological and Ecological Chemistry, IACR-Rothamsted
  • , J. PetterssonAffiliated withDepartment of Entomology, Swedish University of Agricultural Sciences
  • , J. A. PickettAffiliated withDepartment of Biological and Ecological Chemistry, IACR-Rothamsted
  • , L. J. WadhamsAffiliated withDepartment of Biological and Ecological Chemistry, IACR-Rothamsted
  • , C. M. WoodcockAffiliated withDepartment of Biological and Ecological Chemistry, IACR-Rothamsted

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Abstract

Electrophysiological and behavioral responses of the ladybird parasitoid Dinocampus coccinellae to volatiles from the seven-spot ladybird, Coccinella septempunctata, were investigated to identify semiochemicals involved in host location. Coupled gas chromatography–electroantennography (GC-EAG) with D. coccinellae located a small peak of prominent activity in an extract of volatiles from adult C. septempunctata. The active compound was identified by coupled GC-mass spectrometry and by comparison with an authentic sample as the free-base alkaloid precoccinelline, which forms part of the toxic defense of this ladybird. Behavioral studies in an olfactometer showed that D. coccinellae was significantly attracted to the volatile extract and also to the alkaloid. Myrrhine, a stereoisomer of precoccinelline found in low amounts in C. septempunctata and in other ladybird species, was shown to be electrophysiologically active and significantly attractive. Perception of ladybird alkaloids by D. coccinellae is a rare example of toxicants acting as aerially transmitted cues for interactions between the third and fourth trophic levels.

Seven-spot ladybird Coccinella septempunctata Coleoptera Coccinellidae electroantennogram behavior Dinocampus coccinellae Hymenoptera Braconidae alkaloid precoccinelline myrrhine hippodamine volatile semiochemical