Biology of the parasitic wasp nest beetle, Metoecus paradoxus (Coleoptera: Ripiphoridae), in Finland

Parasitoids and predators can cause marked mortality in their host species. I studied the occurrence, abundance, and biology of the wasp nest beetle Metoecus paradoxus (Ripiphoridae), inhabiting the nests of the common wasp Vespula vulgaris (Vespidae) in Central Finland. I also compiled phenological data of the species in Finland. The proportion of parasitized nests was 80%. The abundance of the beetle was generally some tens of individuals (max. = 130) per nest, and the parasitism rate 1–18% of the sealed cells, which are typical for the species in temperate Europe. The beetle occurred in several combs but was absent or rare in the oldest and newest combs. Sex ratio was female biased. Females were larger than males, and individuals from large cells were larger than from small cells. Adult beetles were observed rather steadily from early August to late September. The study shows that M. paradoxus is a common inhabitant of V. vulgaris nests in Central Finland, but due to a low frequency of parasitized cells its impact on wasp populations is likely to be minor

Ground-dwelling true bugs (Heteroptera) in afforested fields

Former agricultural lands may host peculiar biota, because agriculture activities have changed the physical, chemical and biological features of the soil; however, biodiversity in afforested fields is poorly known. The aim of this study was to investigate the diversity of ground-dwelling true bugs (Heteroptera) in early successional afforested fields in central Finland. We used a large-scale field experiment, in which agricultural land had been afforested 25 years ago by planting monocultures of birch, pine and spruce trees. Pitfall traps caught a total of 224 heteropteran individuals representing 20 species. The community was numerically dominated by Lygaeidae, Drymus brunneus being the most abundant species. Birch plots hosted about the double the number of individuals and species in spruce and pine plots. The near-threatened Teloleuca pellucens (Saldidae) was recorded from a birch plot. Although T. pellucens is suggested to require old-growth forests, our observation indicates that the species can occur also in other types of forests. In conclusion, more studies on Heteroptera in different environments are needed to better understand their distribution, abundance and habitat affinities

Redescription and biology of Trichosia (Baeosciara) sinuata Menzel & Mohrig (Diptera: Sciaridae)

Trichosia (Baeosciara) sinuata Menzel & Mohrig, previously known only from the holotype from Austria, is redescribed and its biology discussed. Individuals of the species were reared from an old-growth forest bracket fungus Fomitopsis rosea (Alb. & Schw.:Fr.) P. Karst from eastern Finland. We suggest that B. sinuata might be parasitised by the ichneumonid wasp Stenomacrus curvulus (Thomson)

Uusekosysteemit – melua tyhjästä?

Uusekosysteemit ovat kaikkialla. On arvioitu, että noin kolmasosa maaekosysteemeistä on uusia. Uusekosysteemeistä on kirjoitettu satoja tieteellisiä artikkeleita kymmenen viime vuoden aikana. Mutta ovatko hylätyt soramontut, ojitetut suot ja metsitetyt pellot uusekosysteemejä? Onko uusekosysteemejä ylipäätään olemassa? Määrittelykamppailu käy kiivaana soveltavassa ekologiassa. Samalla käytännön toimija seuraa sanailua ymmällään ja pohtii, tarvitseeko hän edes koko käsitettä

Luonnon Tutkija uudistuu

Pääkirjoitus 1/202

Lajintuntemuksen renesanssi

Pääkirjoitus 2/2023: Lajintuntemuksen renesanss

Uuden päätoimittajan esittely

Luonnon Tutkija -lehden päätoimittajana aloitti vuoden 2021 lopulla FT Pasi Reunanen. Pasilla on monipuolinen tutkija- ja kirjoittajatausta, mutta vastailkoon hän itse omin sanoin toimitusneuvoston esittämiin kysymyksiin

Insects inhabiting two old-growth forest polypore species

This paper describes insect communities inhabiting two old-growth forest polypores Amylocystis lapponica and Fomitopsis rosea (Polyporaceae). Basidiocarps of both species were collected from old-growth forests in southern and eastern Finland and Russia. Samples of A. lapponica and F. rosea basidiocarps revealed insect communities of more than 50 species each, including many rare old-growth forest species. Here we report the rearing results and discuss the biology of the beetle Hallomenus sp. (Melandryidae) inhabiting A. lapponica and the beetle Cis dentatus (Cisidae), the moth Agnathosia mendicella (Tineidae) and the fly Elfia cingulata (Tachinidae) inhabiting F. rosea. Distribution maps of C. dentatus and A. mendicella in Finland are given

Insect assemblage associated with the polypore Fomitopsis pinicola: a comparison across Fennoscandia

We compiled the data on the insect assemblage occurring within the polypore Fomitopsis pinicola from six regions in Finland, Sweden and Norway. The species composition and diversity of the primary fungivorous beetles (Cisidae and Anobidae) were similar across Fennoscandia. The beetles Cis glabratus Mellié (Cisidae) and C. quadridens Mellié were the most frequent species occurring in 70% and 23% of the fruiting bodies on average. Sulcacis fronticornis (Panzer) and Ennearthron cornutum (Gyllenhal) were relatively common in southern Sweden, while absent from the study regions in Norway and Finland. Similarly, Cis bidentatus (Olivier) and Cis dentatus Mellié were rather common inNorway, but almost absent from the Finnish samples. Species relative abundances in the six study regions exhibit more variation, which to some extent corresponds the biogeographical zones. Our results on the high similarity in species composition indicate deterministic nature of the F. pinicola-associated insect assemblage over large spatial scales. On the other hand, climatic factors probably have an impact on the relative abundance of species

Dead wood profile of a semi-natural boreal forest - implications for sampling

Dead wood profile of a forest is a useful tool for describing forest characteristics and assessing forest disturbance history. Nevertheless, there are few studies on dead wood profiles, including both coarse and fine dead wood, and on the effect of sampling intensity on the dead wood estimates. In a semi-natural boreal forest, we measured every dead wood item over 2 cm in diameter from 80 study plots. From eight plots, we further recorded dead wood items below 2 cm in diameter. Based on these data we constructed the full dead wood profile, i.e. the overall number of dead wood items and their distribution among different tree species, volumes of different size and decay stage categories. We discovered that while the number of small dead wood items was immense, their number dropped drastically from the diameter below 1 cm to diameters 2-3 cm. Different tree species had notably different abundance-diameter distribution patterns: spruce dead wood comprised most strikingly the smallest diameter fractions, whereas aspen dead wood comprised a larger share of large-diameter items. Most of the dead wood volume constituted of large pieces (>10 cm in diameter), and 62% of volume was birch. The variation in the dead wood estimates was small for the numerically dominant tree species and smallest diameter categories, but high for the sub-dominant tree species and larger size categories. In conclusion, the more the focus is on rare tree species and large dead wood items, the more comprehensive should the sampling be.Peer reviewe