Tomáš Hamřík

Spinosad is one of the world's most widely applied natural bioinsecticides and its use has been growing rapidly in the past decade. Biologically based plant protection products can also have unexpected effects on beneficial arthropods. Previous studies examining the lethal and sublethal effects of spinosad on different groups of spiders have shown widely diverging results. This work aims at an extension of knowledge related to the effects of spinosad on the generalist predator of genus Pardosa. We focused on the effects of fresh wet, fresh dry, and dry 3-day-old residues of the commercial plant protection product Spintor®. We examined changes in predatory activity at different prey densities after contacts with those residues and also on the mortality of spiders. For the density of six prey (flies), we found differences in spiders' predatory activity in the short term and the long term after their 1 hr contact with fresh wet residue. The fresh wet residues significantly decrease the number of killed flies. There was no significant effect of treatment on the mortality of spiders over short periods. Over long periods, the fresh wet residues caused a significant increase in spider mortality while dry residue had no effects.

The aim of this study was to investigate the effect of selective logging on species richness, composition, and conservation value of epigeic spider community. We studied an initial stage of abandoned coppice restoration in the Děvín National Nature Reserve (Czech Republic). We sampled experimental plots in forest stands with three canopy thinning intensities: strong, moderate, and nonintervention as a control. Altogether, we collected 3,683 adult spiders representing 21 families, 70 genera, and 116 species including 23 red-listed and threatened species. The species richness and degree of rareness significantly increased with the intensity of canopy thinning. Ordination analyses showed that species of conservation concern inclined towards plots with strong canopy thinning. However, some conservation-valuable species tended to be associated with non-intervention plots. Our results suggest that the best silviculture practice for spider diversity conservation is a combination of various thinning intensities on a small scale. Such management would support high species richness with the presence of rare and threatened species. Accordingly, we argue that using selective logging and a partial return to traditional coppicing management can be an appropriate strategy for biodiversity conservation in lowland woodlands.

Arachnologický průzkum na Mostecku a Chomutovsku byl doposud soustředěn zejména na Krušné hory (BUCHAR a HAJER 1999, 2005, 2010. ROUŠAR 2011. RŮŽIČKA a HAJER 2002, 2003), jednotlivé sběry z okolí jsou také zahrnuty v katalogu pavouků ČR (BUCHAR a RŮŽIČKA 2002), na Chomutovsku je známo také několik publikovaných sběrů Antonína Roušara (ROUŠAR 2009, 2015, 2016). Přesto údaje o výskytu pavouků z mnoha lokalit scházejí. Proto od 1. do 4. června 2017 uspořádalo Oblastní muzeum v Mostě arachnologické exkurze do nejbližšího okolí Mostu a Chomutova, kterých se zúčastnili členové České arachnologické společnosti. Jako cílové byly zvoleny lokality, na kterých se systematicky pavoukovci dosud nesbírali, ale i lokality, které by vzhledem ke svým přírodním hodnotám mohly být v budoucnu zařazeny mezi zvláště chráněná území. Tento článek předkládá seznam všech druhů pavouků, kteří byli během akce zjištěni.