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The European red click beetle, Elater ferrugineus L., is associated with wood mould in old hollow deciduous trees. As a result of severe habitat fragmentation caused by human disturbance, it is threatened throughout its distribution range. A new pheromone-based survey method, which is very efficient in detecting the species, was used in the present study to relate the occurrence of E. ferrugineus to the density of deciduous trees. The latter data were from a recently completed regional survey in SE Sweden recording >120,000 deciduous trees. The occurrence of E. ferrugineus increased with increasing amount of large hollow and large non-hollow trees in the surrounding landscape. Quercus robur (oak) was found to be the most important substrate for E. ferrugineus, whereas two groups of tree species (Carpinus betulus, Fagus sylvatica, Ulmus glabra, vs. Acer platanoides, Aesculus hippocastanum, Fraxinus excelsior, Tilia cordata) were less important but may be a complement to oak in sustaining populations of the beetle. The occurrence of E. ferrugineus was explained by the density of oaks at two different spatial scales, within the circle radii 327 m and 4658 m. In conclusion, priority should be given to oaks in conservation management of E. ferrugineus, and then to the deciduous trees in the genera listed above. Conservation planning at large spatial and temporal scales appears to be essential for long-term persistence of E. ferrugineus. We also show that occurrence models based on strategic sampling might result in pessimistic predictions. This study demonstrates how pheromone-based monitoring make insects excellent tools for sustained feedback to models for landscape conservation management.

The rare beetle Elater ferrugineus was sampled at 47 sites in the county of Östergötland, Sweden by means of pheromone-baited traps to assess its value as an indicator species for hollow oak stands rich in rare saproxylic beetle species. In addition, Osmoderma eremita was also sampled with pheromone baits. These data were then compared against species survey data collected at the same sites by pitfall and window traps. Both species co-occur with many Red Listed saproxylic beetles, with E. ferrugineus being a somewhat better indicator for the rarest species. The conservation value of a site (measured as Red List points or number of Red Listed species) increased with the number of specimens of E. ferrugineus and O. eremita caught. Accuracy of sampling by means of pheromone trapping turned out to be radically different for the two model species. E. ferrugineus traps put out during July obtained full accuracy after only 6 days, whereas O. eremita traps needed to be out from early July to mid-August in order to obtain full accuracy with one trap per site. By using E. ferrugineus, or preferably both species, as indicator species, accuracy would increase and costs decrease for saproxylic biodiversity sampling, monitoring and identification of hotspots.

The sawfly species Athalia rosae (L.) (Hymenoptera: Tenthredinidae) is phytophagous on plants of the family Brassicaceae and thus needs to cope with the plant defence, the glucosinolate-myrosinase system. The larvae sequester glucosinolates in their haemolymph. We investigated how these compounds are metabolized by this specialist. When larvae were fed with ([(14) C]-labelled) benzylglucosinolate, one major degradation metabolite, with the same sum formula as benzylglucosinolate, was defecated. This metabolite was also found in the haemolymph along with desulfobenzylglucosinolate, which continuously increased in concentration. NMR spectroscopy in conjunction with LC-TOF-MS measurements revealed the major degradation metabolite to be desulfobenzylglucosinolate-3-sulfate, probably converted from desulfobenzylglucosinolate after sulfation at the sugar moiety. The enzymes responsible must be located in the haemolymph. Additionally, a putative sulfotransferase forms benzylglucosinolate sulfate in the gut from intact, non-sequestered glucosinolate. The corresponding desulfoglucosinolate sulfates were also detected in faeces after feeding experiments with phenylethylglucosinolate and prop-2-enylglucosinolate, which indicates a similar degradation mechanism for various glucosinolates in the larvae. This is the first report on glucosinolate metabolism of a glucosinolate-sequestering insect species.

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