Factors affecting the occurrence of the endangered saproxylic beetle Osmoderma eremita (Scopoli, 1763) (Coleoptera : Cetoniidae) in an agricultural landscape.

International audienceAgricultural landscapes structured by trees are substitution habitats for some species that inhabited mature trees of primeval forest. Those agricultural landscapes have a complex heterogeneous structure that changes over centuries. These dynamics could affect the persistence of such relict species.We studied factors affecting the occurrence of the endangered habitat-tracking beetle Osmoderma eremita in a landscape structured by hedgerows and orchards. By surveying the mature trees in 2003 and the change of landscape features between 1947 and 2003 in a 16-km2 area in northwestern France,we tested several hypotheses. The first hypothesis was that the occupancy rate of microhabitat would be affected by tree species. The second was that landscape openness and microhabitat density would influence the occurrence of O. eremita. Third, the spatio-temporal change of landscape features after land consolidation was tested as a predictor of O. eremita presence.We showed that O. eremita preferred apple trees of orchards and pollard oaks of hedgerows in the most open parts of the landscape. Short range microhabitat density and aggregation of populations were significantly highest in orchards. Populations subsisted in areas where few changes occurred with time in hedgerow density, revealing the sensitivity of this habitat tracking species to landscape changes in a complex human made landscape. All these results should be considered for conservation planning of this endangered species