Bark-Beetle Parasitoids Population Surveys Following Storm Damage in Spruce Stands in the Vosges Region (France) |
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Authors: | Evelyne Hougardy Jean-Claude Grégoire |
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Affiliation: | (1) Laboratoire de Biologie animale et cellulaire, CP 160/12, Université Libre de Bruxelles, 50 av. F.D. Roosevelt, 1050 Bruxelles, Belgium;(2) Fonds pour la Formation à la Recherche dans l'Industrie et dans l'Agriculture (FRIA), 5 rue d'Egmont, 1000 Bruxelles, Belgium;(3) Present address: Insect Biology, University of California, Wellman Hall 201, Berkeley, CA 94720-3112, USA;(4) Fonds National de la Recherche Scientifique (FNRS), 5 rue d'Egmont, 1000 Bruxelles, Belgium |
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Abstract: | This paper presents the results of a long-term study designed to follow the population dynamics of hymenopteran parasitoids associated with Ips typographus L. (Coleoptera: Scolytidae) in northeastern France (Alsace and Vosges) in spruce stands devastated by the December 1999 storms. Population densities were estimated by periodic samplings in the pre-emerging insect populations developing under the bark of attacked trees. Data were collected between July 2000 and October 2001. I. typographus population density (per m2) increased respectively by 28%, 105%, and 212% in one year in the three sites surveyed. Six hymenopteran ectoparasitoids were found: Coeloides bostrichorum Giraud and Dendrosoter middendorffi Ratzeburg (Hymenoptera: Braconidae); Rhopalicus tutela (Walker), Roptrocerus xylophagorum (Ratzeburg), Roptrocerus mirus (Walker) and Dinotiscus eupterus (Walker) (Hymenoptera: Pteromalidae). After two years, the parasitoid populations increased in terms of average density but parasitism rates remained at a relatively low level, ranging from 0% to 40%, with 60% of the trees having a parasitism rate below 5%. Data outlined the recurrent coexistence of competing parasitoid species. |
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Keywords: | Ips typographus natural enemies parasitoids Coeloides bostrichorum Rhopalicus tutela Roptrocerus xylophagorum Roptrocerus mirus |
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