DIGITALNA ARHIVA ŠUMARSKOG LISTA
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| ŠUMARSKI LIST 9-10/2018 str. 23 <-- 23 --> PDF |
Influence of predator abundance and winter mortality on reproduction of bivoltine populations of Ips typographus L. (Coleoptera: Curculionidae) Utjecaj gustoće predatora i zimskog mortaliteta na reprodukciju bivoltnih populacija smrekovog potkornjaka Ips typographus L. (Coleoptera: Curculionidae) Luka Kasumović, A/sup>ke Lindelöw, Boris Hrašovec Summary The study was aimed at evaluating the influence of winter mortality and predator larvae abundance on breeding performance of bivoltine populations of Ips. typographus colonizing felled spruce trees in Croatia. A low colonization density of I. typographus expressed as a number of maternal galleries per square meter of bark, usually reflects high reproductive success, defined as a number of daughters per mother beetle (♀/♀). Regarding this study, the mean gallery density on felled trees varied between 27 and 146 per m2 of bark, while the lowest reproduction rate was only 0.5 ♀/♀. Althought differently suggested by previous findings, the cause of such a low reproduction rate can be explained by high abundance of predator larvae and high winter mortality of larvae, pupae and callow beetles. The results suggest that predators, primarily long-legged flies-of the genus Medetera (Fischer von Waldheim) (Diptera: Dolichopodidae), have huge ecological impact on bark beetle populations at endemic levels. At low attack densities, the majority of males (74%) copulate with two females, following the evolutionary trait of avoiding intraspecific larval competition. Key words: breeding, low attack, gallery, intraspecific, Medetera INTRODUCTION Uvod Most bark beetle species (Coleoptera, Curculionidae, Scolytinae) colonize recently dead trees, but some species are able to attack and kill living trees to reproduce (Lindelöw and Schroeder, 2002; Hedgren, 2004). Ips typographus (Linnaeus) (Coleoptera: Curculionidae: Ipini) is the most severe and destructive spruce pest in Europe (Christiansen and Bakke, 1988; Grégoire and Evans, 2004; Wermelinger, |