Diversity and abundance of arboreal psocids (Psocoptera) along latitudinal gradients in northern Europe

Abstract

Abstract. Psocids are small insects that feed primarily on fungi, algae, lichens and organic detritus. Although they are relatively common in forest ecosystems, the general patterns in their abundance and diversity in boreal forests are still poorly known. We report records of 20 species of psocids quantitatively collected from four species of woody plants (Pinus sylvestris, Picea abies, Betula pubescens and B. pendula) at 50 sites in northern Europe, located between 59° and 70°N and between 10° and 60°E. Seven species were found only on conifers, seven other species only on birches and six species inhabited both birches and conifers. The overall density of psocids was 18.9 ± 2.9 exx/kg (d.w. of plant material). Densities varied among the studied species of trees, being highest on P. abies and lowest on B. pendula. The species diversity was highest on B. pendula and lowest on B. pubescens. Both diversity and abundance of arboreal psocids in northern Europe decreased with latitude. However, due to the relatively low number of specimens collected, the conclusions about the diversity of psocids should be seen as tentative.

Factors shaping latitudinal patterns in communities of arboreal spiders in northern Europe

“…Our data demonstrated that the average abundance of spiders decreases with latitude much faster than the abundance of their potential prey. While the densities of sap‐ feeding insects (mostly aphids) in the two northernmost sites of each gradient were, on average, 57.7% (Kozlov et al ), the densities of psocids – about 50% (Kanervo and Kozlov ), and the densities of defoliating insects (as indicated by the proportion of the consumed birch foliage) – 31% of the values observed in the two southernmost sites (Kozlov ), the spider densities dropped to as low as 19.9%. Of course Hemiptera, Psocoptera and Lepidoptera (which are the most abundant defoliators in our study region) constitute only a small fraction of spider diets (12.4, 0.2 and 5.3%, respectively: Birkhofer and Wolters ), but the abundance of the most important group of prey, Diptera (31.4% of spiders' diet over the Globe: Birkhofer and Wolters ; about 54% of spider's diet in temperate regions: Pekár et al ), may even increase towards the north (Nilsson et al ).…”

The Arthropod Fauna of Oak (Quercus spp., Fagaceae) Canopies in Norway

“…Its apparent association with oak may rather be an expression of its preference [67,68] for dead leaves lingering on the tree, as commonly found on oaks, or on cut-off branches on the ground. Valenzuela flavidus and Graphopsocus cruciatus (Linnaeus, 1768) are associated with foliage of various deciduous trees [6,69].…”

Nutritional, Gastrointestinal and Endo-Metabolic Traps in the Management of Children with Spinal Muscular Atrophy Type 1

“…Its apparent association with oak may rather be an expression of its preference [58,59] for dead leaves lingering on the tree, as commonly found on oaks, or on cut-off branches on the ground. Valenzuela flavidus and Graphopsocus cruciatus (Linnaeus, 1768) are associated with foliage of various deciduous trees [6,60].…”

“…Complete list of species with numbers per locality. Literature used for the table:[2,6,10,12,25,36,51,53,[55][56][57][58][59][60][61][62]62,69,78,[85][86][87][88][89][90][91][92][93][94][95][96][97][98][99][100][101][102] and personal comments from the authors. The (B) and (S) in the heading under Kvam are Berge and Skeianeset, respectively while the (S) and (D) under Drangedal are Steinknapp and Djupedal, respectively.…”