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Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài:" spread of Rhizophagus grandis Gyll (Coleoptera: Rhizophagidae) 6 years after release in the Forêt domaniale du Mézenc (France). | Ann Sci For 1995 52 243-250 Elsevier INRA 243 Original article Establishment and spread of Rhizophagus grandis Gyll Coleoptera Rhizophagidae 6 years after release in the Foret domaniale du Mezenc France A van Averbeke JC Gregoire Laboratoire de biologie animale et cellulaire CP 160 12 université libre de Bruxelles 50 av FD-Roosevelt B-1050 Brussels Belgium Received 11 March 1994 accepted 9 August 1994 Summary Sampling was carried out in August 1993 in a Norway spruce stand Foret domaniale du Mezenc Haute-Loire France heavily infested by the bark beetle Dendroctonus micans and where the predatory beetle Rhizophagus grandis had been released in 1987. Three circular plots 20 m in diameter were marked out in the vicinity of the release area and all trees within were examined. All D micans brood chambers below 2 m were opened and their contents analysed. Three similar plots were created 800 m or so away from the release area. In addition a number of brood chambers were sampled at the release area s limit and at distances of about 800-900 m and 1 090 m. There was a significant inverse relationship between local tree density and proportion of attacked trees r2 0.91 p 0.01 . However there was a significant direct relationship between local tree density and absolute numbers of attacked trees r2 0.92 p 0.01 . Adults and lan ae of the predator were found along the whole transect. Only prey brood chambers containing 5th instar larvae or older stages were colonised by R grandis. The R grandis D micans ratio counting all individuals in each brood chamber significantly decreased as distance increased r2 0.18 p 0.05 . These findings suggest an effective but slow spread in predators released from a limited spot in a densely attacked stand. They fit well with earlier information from other release sites in the Massif Central. Rhizophagus grandis Dendroctonus micans I biological control dispersal I Scolytidae I Rhizophagidae Resume Établissement et dispersion de Rhizophagus grandis .
