Semi-natural habitats are key components of rural landscapes because they shelter a significant number of overwintering arthropods that are beneficial to agriculture. However, woodlots are semi-natural habitats with high patch-level heterogeneity and this aspect has been poorly studied. The purpose of this study was to determine the influence of woodlot heterogeneity on overwintering ground beetles. Woodlot heterogeneity was characterized in terms of distance from the woodlot boundary and date of the most recent logging operation. We used emergence traps to quantify the population density of ground beetles that overwintered in the different parts of the woodlot. In woodlot edges the densities and species richness of ground beetles were significantly higher than in the rest of the woodlot. Ground beetles that are active in crop fields overwintered in the edges but not in the inner zone of the woodlot. Species assemblages of ground beetles overwintering in the edges were highly diverse. The date of the most recent logging operation did not explain the distribution of ground beetles that overwintered in the woodlot. Our results show that woodlots, and in particular their edges, are used as a winter shelter by ground beetles that spend part of their life in crops, which potentially favours biological control in adjacent crop fields. and Anthony Roume, Annie Ouin, Laurent Raison, Marc Deconchat.
This study in Lithuania showed that the abundance dynamics of the common dormouse (Muscardinus avellanarius) populations were comparatively “smooth”, without outbreaks and crashes. Decreases and increases of abundance continued for some years, and abundance differed no more than three-fold in two successive years. A close negative correlation was revealed between spring population density and percentage of juveniles in the autumnal population. The last parameter is a consequence of reproduction success, which determined the scale of population increase in autumn and was due to several factors. Among them, proportion of breeding adult females had the greatest significance and was inversely proportional to population density in spring. Some young-of-the-year females usually joined the breeding process, when population density was low. The proportion of late breeding cases, when juveniles were born in September, was also negatively correlated with spring population density. The number of litters produced by one female during the season, and the average litter size also influenced reproduction success. The negative correlation between population density and reproduction success shows the presence of a reproduction success based pattern of density dependent self-regulation in M. avellanarius in the populations investigated.
The abundance of Coleoptera, Diptera and Collembola on different species of fungi was investigated in relation to the size and abundance of fungal resources at different spatial scales; i.e., the size of the fungal fruiting body, the quality of resource in terms of number of conspecific sporophores growing within a radius of 50 cm, crowding of the clumps of fruiting bodies, and the quality of resource within a plot (20 m × 30 m). Multiple linear regression analyses showed that the influential spatial scale varied among the arthropod orders. The amount of resource at the scale of a clump made a significant contribution to the abundance of Coleoptera, and the fruiting body size significantly affected the abundance of Diptera on each fungal species. Collembolan abundance was significantly affected by the crowding of the clumps of fruiting bodies and the number of fruiting bodies per plot. These results suggest that the spatial distribution of fungal fruiting bodies may determine whether they are selected by arthropods visited.
The impact of transgenic Bt-maize, expressing the Cry1Ab protein, on aphids, leafhoppers, cutworms and wireworms was evaluated at the farm scale by comparing their abundance on Bt-plots and those sown with the isogenic variety over three consecutive growing seasons. The impact of Bt-maize was different on each of the three-herbivore groups. There were significantly more aphids on the Bt-maize but in terms of aphid species, the difference was only statistically significant for Sitobion avenae and not for the other three most abundant species (Metopolophium dirhodum, Rhopalosiphum padi and Macrosiphum euphorbiae). The analysis of aphid age structure showed consistently more individuals on Bt-plots; differences were significant for alates, apterous adults and young nymphs of R. padi, apterous adults and apterous fourth instar nymphs of S. avenae, alates, apterous adults and apterous fourth instar nymphs of M. dirhodum. Leafhoppers (Zyginidia scutellaris), particularly mature nymphs, were also more abundant on the Bt-maize. In spite of this there was no difference in leafhopper damage to Bt and non Bt-maize. The reasons for this are unclear but may be due to changes in Bt-maize that favoured aphids and leafhoppers. Differences in aphid and leafhopper densities were not high enough to affect yield. However, they may have affected the availability of prey for polyphagous predators such as Orius sp. The Bt-maize did not affect the incidence of cutworms (Agrotis segetum) or wireworms (Agriotes lineatus). These results indicate that Bt-maize does not have a negative impact on the non-target maize biocenosis at the farm scale.
Mezi významné aktivity Ústavu pro jazyk český AV ČR patří již od jeho vzniku služby veřejnosti. Jazyková poradna, jejíž provoz zaštiťuje oddělení jazykové kultury, je jediným bohemistickým pracovištěm v České republice, které poskytuje soustavné jazykové poradenství a jazykové expertizy nejrůznějším uživatelům českého jazyka. O radu může prostřednictvím internetových stránek nebo telefonické linky požádat každý. Na základě dotazů adresovaných jazykové poradně vydalo nyní Nakladatelství Academia dvě publikace: Akademickou příručku českého jazyka a dotisk knihy Jsme v češtině doma? and Markéta Pravdová.