Biology and distribution of chafers (Coleoptera, Scarabaeidae) living in hollow trees in Sweden.
Publikation/Tidskrift/Serie: Entomologisk tidskrift
Dokumenttyp: Artikel i tidskrift
Förlag: Sveriges Entomologiska Förening
We review the ecology and distributions of the chafers Liocola marmorata (F.), Gnorimus nobilis (L.) and Gnorimus variabilis (L.) in Sweden based on museum and several large private collections. These species live in hollow deciduous trees, in Sweden especially in oaks. The former and recently documented localities are shown on maps. More than 100 years ago, all the species as well as their habitats were more common in Sweden than today. One problem when interpreting old finds is that hollow trees do not seem to have been examined by entomologists, except during the last 50 years. However, Gnorimus nobilis, which often visits flowers, was frequently found in former times. In the province of Skane, which has been most intensively studied among Swedish provinces, the number of known localities for Gnorimus nobilis has decreased from 13 before 1975 to 6 after that year, despite more intensive studies during the last 25 years. Of the studied species, Liocola marmorata has had the largest contraction of its range in Sweden. It has disappeared from the southwestern part, but occurs still in many localities in the provinces of Ostergotland and Uppland. In Uppland, the absence of Osmoderma eremita, which has a similar niche, may decrease the competition in tree hollows and favour L. marmorata. Gnorimus varibilis has a preference for sun-exposed oaks, and can live in downed dead trees long after the trunk has fallen. It has been found at about 30 localities in Sweden during the last 25 years. We suggest that Gnorimus variabilis is a globally threatened species and that Sweden has a strong responsibility to preserve this species. There are still seven localities in southeastern Sweden where all three species as well as Osmoderma eremita occur. All these localities harbour a high number of threatened saproxylic beetles. We discuss the chafers living in hollow trees as indicator species and propose conservation measures for them. The highest priority should be given to increase the survival rate and number of very old trees, especially oaks, in and near stands which inhabit the species and contains a large number of suitable hollow trees.
- ISSN: 0013-886X