We report here on the taxonomic and molecular diversity of 10 929 terrestrial arthropod specimens, collected on four islands of the Society Archipelago, French Polynesia. The survey was part of the 'SymbioCode Project' that aims to establish the Society Islands as a natural laboratory in which to investigate the flux of bacterial symbionts (e.g., Wolbachia) and other genetic material among branches of the arthropod tree. The sample includes an estimated 1127 species, of which 1098 included at least one DNA-barcoded specimen and 29 were identified to species level using morphological traits only. Species counts based on molecular data emphasize that some groups have been understudied in this region and deserve more focused taxonomic effort, notably Diptera, Lepidoptera and Hymenoptera. Some taxa that were also subjected to morphological scrutiny reveal a consistent match between DNA and morphology-based species boundaries in 90% of the cases, with a larger than expected genetic diversity in the remaining 10%. Many species from this sample are new to this region or are undescribed. Some are under description, but many await inspection by motivated experts, who can use the online images or request access to ethanol-stored specimens.

The intensification of agriculture is one of the main drivers of biodiversity loss worldwide. One of the intensification shifts has occurred from cattle grazing on biodiversity-rich semi-natural grasslands to ceased grazing or grazing on cultivated species-poor grasslands. While the effect of different grazing pressure on biodiversity in semi-natural grasslands has been studied extensively, little is known of how current grazing regimes on cultivated grasslands affect biodiversity and ecosystem services in different farming systems. Here, we investigated how arthropod abundance and potential ecosystem services are related to varying grazing pressure on cultivated grasslands at conventional and organic farms with meat or dairy production. We sampled aerial arthropods with sticky tape traps in four land-use types within the farms. Relative arthropod abundance was derived from the tapes using an imagery analysis, and the numbers of pollinators and predators from 4 taxonomic groups were counted. The results showed no difference in the relative arthropod abundance in relation to grazing pressure, but there was weak evidence for higher predator abundance at low and high grazing pressure. The relative arthropod abundance showed a positive trend in organic farms. However, pollinator abundance was higher in conventional farms, and predator abundance did not differ between farming systems. Land-use type was related to the occurrence of predators and pollinators: both groups had the lowest abundance in farmyards compared to cultivated pastures, silage fields, and cereal crop fields. Predator numbers were also higher in silage fields than in the other land-use types. However, there was no significant interaction between land-use types and farming systems in their effect on the arthropod groups. The results suggest that grazing pressure on cultivated grasslands has a minor or negligible impact on arthropod abundance in the two commonest farming systems. However, the effect of farming systems on relative arthropod abundance might be obscured by low sample sizes, high abundance of only a few species, and other variables not included here, such as the use of manure or pesticides. In addition, pollinators included only two taxonomic groups, potentially leading to results not applicable to all pollinators. Consequently, more large-scale studies with higher sample sizes and the inclusion of arthropod diversity and data on the key on-farm practices and landscape structure are needed to disentangle the relationship between biodiversity and grazing on cultivated grasslands in Finland.

The structure of arthropod communities in the forest floor vegetation in four differently managed forest sites (virgin forest, lightly selectively logged, heavily selectively logged, and exotic Pinus caribaea plantation) in Kibale Forest National Park, western Uganda, was studied by sweep net between March and May 1985 and July 1995. For the analysis three (or four) 800 sweeps samples were collected from each habitat. In the samples eight arthropod groups (Araneae, Hymenoptera, Heteroptera, Homoptera, Coleoptera, Orthoptera, Lepidoptera, caterpillars (Lepidoptera larvae)) formed over 95% of all the individuals of the arthropod caught in all habitats. The variation within one habitat was smaller than variation between habitats in samples of the same year. Thus, the arthropod communities in differently managed forests differ from each other after over 20 years of management practices (selective logging and clear-cut plus pine plantation) as well as from adjacent virgin forest, and the differences seem to become greater during the succession in managed sites. Samples taken in the same habitat type, 10 years apart, differed greatly from each other. This is the result of both long-term succession and seasonal variation.