The effects of specific environmental factors on abundance and distribution of some individual soil insect taxa is known, but how scale influences spatial distribution is less well evaluated, particularly at the community level. However, given that many soil insects are pests or beneficial natural enemies, and that collectively they play a role in soil processes, this information is of potential value for predictive modeling and in furthering our understanding of soil ecology and management. The objectives of this study were to characterize the spatial distribution, relative population sizes, effect of sampling scale and taxa co-occurrence on a range of soil insects at the family level over 2 years. Soil cores were taken from agricultural grassland soils across three different sampling scales (farm, field, and core) using a systematic sampling approach. Spatial distribution was assessed using the variance-to-mean (VMR) ratio and taxa distribution plots and the contribution of scale, spatial (geographical location), and biotic (presence-absence of other species) factors determined using deviance partitioning. Tipulid larvae (leatherjackets) were the most abundant taxa in both years, but the composition of other Dipteran and Coleopteran taxa varied between years. The VMRs revealed differences in spatial distribution between taxa across scales and years, showing a range of underlying distributional patterns. Scale was the most important factor influencing species distributions, but a large proportion of deviance remained unexplained and there was much variation between taxa, suggesting biological and scale-specific factors are driving distributions, in agreement with a previous study.

1 DNA barcoding is useful for the identification of morphologically cryptic invertebrates. An important application is for pest species, for which it is critical to determine the distribution, biology and ecology of damaging life stages in order to target management effectively. 2 Tipula paludosa (Meigen) and Tipula oleracea (Linnaeus) leatherjackets, the larvae of crane flies (Diptera: Tipulidae), are pests of agricultural grassland in Europe and the U.S.A. and are difficult to distinguish morphologically. 3 We used cytochrome c oxidase subunit I (COI) barcoding to identify leatherjackets from 19 permanent grassland fields over 2 sampling seasons on the Rothamsted Research North Wyke Farm Platform, south west UK, to assess species-level distribution and genetic diversity. 4 Most larvae (94%) were found to be T. paludosa, comprising 18 haplotypes that were spread across the sampling site in a panmictic population. However, T. oleracea were found in low abundance (3% of larval samples) and only in the second year of sampling. Other morphologically similar Dipteran larvae (3%) were also found. 5 This dominance of one species suggests that there may be underlying differences in species biology, such as choice of oviposition site and dispersal ability, which is in agreement with other studies and has implications for monitoring and management.