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 of the genus Medetera (Diptera: Dolichopodidae), the bark beetles Ips typographus and Pityogenes chalcographus (Coleoptera: Curculionidae: Scolytinae) as prey and Norwegian spruce (Picea abies) as the host plant. Of the nine species of predators collected, only M. setiventris and M. melancholica provided sufficient data for statistical analysis. 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.
A novel method was used to study dispersal in the spruce bark beetle, Ips typographus (L.), under epidemic conditions (rapidly increasing population density) in the Šumava National Park. Infested spruce logs were coated with a fine fluorescent powder and the passively marked emerging beetles were captured in pheromone baited traps located at various distances from these logs. The number of marked beetles captured decreased exponentially with increasing distance from the release point. The sex ratio of the bark beetles was more female biased the further they were recaptured from the logs, being 57% and 60% at distances of up to 50 and 100 m, respectively. The maximum distance flown by a marked beetle recorded in this experiment was 1094 m. A model fitted to the data on dispersal indicates that 10% of the spruce bark beetles dispersed over distances of 55 m and 4 m in spring (overwintered parental generation) and summer (first filial generation), respectively. Differences between spring and summer swarming are briefly discussed., Petr Doležal, Jan Okrouhlík, Markéta Davídková., and Obsahuje bibliografii
Novel microsatellite markers for the spruce bark beetle (Ips typographus L.) are identified and characterized using next generation sequencing technology. 18 polymorphic loci were obtained by screening 10,684 reads and tested on 35 bark beetle samples from different locations in Bavaria, Germany. Allelic richness ranged from two to 38 alleles, observed heterozygosity from 0.03 to 0.66 and expected heterozygosity from 0.08 to 0.97. Four loci showed significant deviation from the Hardy-Weinberg equilibrium and no linkage between loci was detected. The 18 loci, along with another six loci previously described, provide effective analytical tools for analyzing the fine-scale genetic structure of bark beetle populations. The result of this study demonstrates that next generation sequencing technology is a valuable method for isolating microsatellites of a coleopteran species. and Bernhard C. STOECKLE, Ralph KUEHN.
We feature an interview with Pavel Kindlmann, professor of ecology at Charles University in Prague, Czech Republic, who performs research on various aspects of biodiversity as head of the Biodiversity Research Centre in Šumava National Park in the Bohemian Forest. Bark beetles, which have become a heated issue with a political dimension, are the focus of his study. On one side, some experts demand that natural processes be allowed to take their course, even if that menas the bark beetle would destroy most of that forest. On the other side, experts are insisting on intervention. Anti-intervention forces are supporting the Biodiversity Research Centre. and Luděk Svoboda.
Abnormal spermatogenesis in Pityogenes chalcographus (L.) and Ips typographus (L.) results in oversized spermatozoa in all the populations investigated. They can be identified by light microscopy and classified as 2n up to 16n polyploid. The percentage of polyploid sperm increases when allopatric parents are crossed: Parental populations with less than 1% polyploid, result in male F1 with more than 20% polyploid. Wild populations of P. chalcographus and I. typographus have very different percentages of polyploid sperm. Populations from allochthonous sites for the host tree, Picea abies (Karst.), are distinguished by higher rates of sperm polyploidy than those from autochthonous areas. Thus, it is assumed that polyploid sperm indicates populations originating from the mixing of partially incompatible beetles.
This study determined the scale of the phoresy of mesostigmatid mite by Ips typographus. Thirty pheromone traps in the Karkonosze National Park (Poland) caught 10,575 bark beetles on which there were 2,388 mesostigmatid mites belonging to eight species. The most numerous mites were Dendrolaelaps quadrisetus (1076 ind.) and Trichouropoda polytricha (1067 ind.). and Dariusz J. Gwiazdowicz, Jacek Kamczyc, Jerzy Bloszyk.