Electroantennogram responses of the southern pine beetle parasitoidDinotiscus dendroctoni (Ashmead) (Hymenoptera: Pteromalidae) to potential semiochemicals.

In two studies using the electroantennogram (EAG) technique, bark beetle- and tree-produced semiochemicals were presented toDinotiscus dendroctoni (Ashmead), a larval parasitoid ofDendroctonus frontalis Zimm. In the first study, 20 test compounds and a standard mixture of oxygenated monoterpenes were presented individually at one concentration to the parasitoids. In the second study, the nine compounds that elicited the greatest EAGs in study 1 were then tested as serial dilutions of 10 to 0.0001μg/ul. The individual compounds did not elicit responses greater than the standard mixture of oxygenated monoterpenes. Males and females exhibited similar dose responses, although females showed lower thresholds of response than males to frontalin, terpinen-4-ol,E,Z-chalcogran, andexo-brevicomin. In both studies, pino-/isopinocamphone elicited the greatest responses at high concentrations. Tests of different ratios of the camphone mixture indicated that pinocamphone elicited the greatest response. Most of the test compounds elicited similar responses which suggests that several of the compounds may be used together byD. dendroctoni in habitat and/or host community location.