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Samples of carabids were collected from two study areas in southern Finnish coniferous forest using continuous pitfall trapping throughout the breeding season. These were compared with samples from combinations of early and late season sampling periods (5+5, 10+10 or 14+14 days in each combination). The same species were abundart in both the smaller samples from combinations of periods and in the whole season samples. There was considerable variation in the total catch of carabids among the 10-day samples (5+5 days) which mainly reflected fluctuation in catch of the abundant species in the early season. About 42% of the total number of species was caught in every 10-day sample, 52% in every 20-day sample, and 61% and 77% in every 28-day sample. Most species not caught during the shorter trapping periods were scarce in the whole season sample (<10 individuals). We suggest that samples obtained by trapping periods of 20 days or more were similar enough to the whole season sample to be used in several types of ecoiogical studies.

Background: Modern lifestyle and urbanization have been associated with a raised risk for atopic diseases whereas early and long-term exposure to a farm environment confers protection against atopic sensitization. Immunomodulatory potential and microbiological characteristics of settled airborne dust from an urban house and a barn were examined. Methods: Pulmonary inflammation was induced in mice by repeated intranasal administration of dusts. Monocyte-derived human dendritic cells (moDCs) were exposed to dusts followed by coculture with purified naïve T cells. Cytokine/chemokine mRNA and protein levels were analyzed by real-time polymerase chain reaction, enzyme-linked immunosorbent assay and flow cytometry. The dusts were analyzed by cloning and sequencing of 16S rRNA genes (290 sequences) for DNA, lipids, endotoxin and β-glucan, by live-dead staining, viable counting, isolation and identification of pure cultures (n = 76). Results: Repeated exposure to house dust elicited pulmonary eosinophilia in mice whereas exposure to barn dust elicited neutrophilic and lymphocytic airway inflammation. Stimulation of moDCs with urban house dust elicited expression of Th2-promoting OX40L and Jagged-1 costimulatory molecules. Dendritic cells (DCs) exposed to house dust directed naïve T cells towards Th2 responses. Exposure of DCs to barn dust elicited the development of Th1-dominated immune responses. Urban house dust contained bacterial debris almost exclusively of human commensal species (corynebacteria, streptococci) whereas barn dust comprised mainly intact, viable bacteria of high diversity and no commensal species. Conclusion: Contact to debris originating from human commensal bacteria in urban house dust elicited a Th2-type response whereas barn dust with high bacterial diversity directed the cells towards a Th1 response.

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