The diversity in different groups of obligate saproxylic beetles was related to ecological variables at three levels of spatial scale in mature spruce-dominated forest. The variables were connected to: (i) decaying wood, (ii) wood-inhabiting fungi, (iii) the level of disturbance, (iv) landscape ecology, and (v) vegetational structure. Several strong relationships were found at medium (1.kin 2) and large scales (4 kin2), while only weak relationships were found at a small scale (0.16 ha; I ha --104 m2). This may be explained by the local variations in habitat parameters and the high mobilities of many beetle species. Factors connected to decaying wood and wood-inhabiting fungi were clearly the most important factors at all scale levels. In particular, the variables diversity of dead treeparts, number of dead trees of large diameter and number of polypore fungi species increased the species richness of many groups and increased the abundance of many species. Eight species were absent below a certain density of decaying wood per i or 4 km 2. Former extensive cutting was a negative factor at large scale, probably because of decreasing recolonization with increasing distance to the source habitats. Thinning reduced the diversity of species associated with birch. The development of guidelines favouring the diversity of saproxylic beetles are discussed below.

Thanasimus formicarius (L.) responds to racemic ipsdienol and ipsenol and less to (S)-cis-verbenol. All three are pheromone components in several bark beetles of the genusIps. Synergistic effects appeared when the components were combined. Methylbutenol alone, the specific pheromone component ofIps typographus, elicited no response, but synergestic effects appeared when methylbutenol was combined withcis-verbenol and ipsdienol. The sympatric speciesThanasimus femoralis (Zett.) responds to (S)-cis-verbenol, while ipsdienol and ipsenol synergize the response.

1 Host tree terpenes can influence attraction of conifer-infesting bark beetles to their aggregation pheromones, and both synergistic and inhibitory effects have been reported. 2 We tested a gradient of ratios of ( -)-␣ -pinene, the predominant monoterpene in Norway spruce, to the pheromone of Ips typographus , a major pest of Norway spruce. 3 Attraction of I. typographus increased as the release rate of ( -)-␣ -pinene increased. The two highest ( -)-␣ -pinene : pheromone ratios (526 : 1 and 2595 : 1) attracted twice as many I. typographus as pheromone alone, whereas low to intermediate ratios (56 : 1, 274 : 1) did not differ from pheromone alone. 4 Our results are in agreement with a proposed model, which suggests that bark beetles display unique response profiles to host terpenes depending on the physiological condition of the host trees that they typically colonize. Ips typographus , which is an aggressive species capable of colonizing and killing healthy trees, showed an increased attraction to monoterpene : pheromone ratios, and this may be high enough to inhibit attraction of less aggressive beetle species typically colonizing dead, dying or stressed trees. 5 Attraction of associates of I. typographus was also modified by ( -)-␣ -pinene. Ips duplicatus , a competitor of I. typographus , showed increased attraction to the pheromone of I. typographus across all concentrations of ( -)-␣ -pinene.

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(1) We document the invertebrate fauna collected from 24 oak canopies in east and west Norway as a contribution to the Norwegian Biodiversity Information Centre’s ‘The Norwegian Taxonomy Initiative’. (2) A snap-shot inventory of the canopies was recorded by means of emitting a mist of natural pyrethrum into the canopies at night using a petrol-driven fogger and collecting the specimens in butterfly nets spread on the ground under the canopy. (3) Almost the entire catch of more than 6800 specimens was identified to 722 species. Out of 92 species new to the Norwegian fauna, 21 were new to science and, additionally, 15 were new to the Nordic fauna. Diptera alone constituted nearly half of the species represented, with 61 new records (18 new species). Additionally, 24 Hymenoptera (one new species), six oribatid mites (two new species) and one Thysanoptera were new to the Norwegian fauna. (4) Our study emphasizes the importance of the oak tree as a habitat both for a specific fauna and occasional visitors, and it demonstrates that the canopy fogging technique is an efficient way to find the ‘hidden fauna’ of Norwegian forests. The low number of red listed species found reflects how poor the Norwegian insect fauna is still studied. Moreover, the implication of the IUCN red list criteria for newly described or newly observed species is discussed.