Exploitation of kairomones and synomones by Medetera spp. (Diptera: Dolichopodidae), predators of spruce bark beetles
Hulcr, J.(Jihoceska Univ., Ceske Budejovice (Czech Republic). Biologicka Fakulta)E-mail:[email protected] | Pollet, M.(University of Ghent (Belgium). Research Group Terrestrial Ecology) | Ubik, K.(Akademie Ved, Prague (Czech Republic). Ustav Organicke Chemie a Biochemie) | Vrkoc, J.(Akademie Ved, Prague (Czech Republic). Ustav Organicke Chemie a Biochemie)
The semiochemical relationships in a predator-prey-host plant system were studied by a series of multiple-choice field assays. The studied system included predatory flies Medetera setiventris and M. melancholica, Ips typographus and Pityogenes chalcographus as prey and Picea abies as the host plant. The response of the predators to monoterpenic products of the host (alpha-pinene, limonene, camphor), pheromone compounds of I. typographus (S-cis-verbenol and 2-methyl-3-buten-2-ol) and a mixture of the pheromones of I. typographus and P. chalcographus were investigated. Our field trials revealed that tree volatiles plus pheromones of the prey, and a pheromone mixture of both prey species were considerably more attractive to M. setiventris and M. melancholica than the individual chemicals. Medetera seem to respond to the stage of tree decay and the intensity of bark beetle infestation via the ratios of tree volatiles and/or prey pheromones.
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