Development of a barcoding database for the UK Collembola: early results

We report early results from a project to accumulate COI barcodes from UK Collembola to conrm taxonomy and explore their status at an international level. We validated COI sequences for 48 species of Collembola, ranging from 335–670 bp. Of these, seventeen species matched public sequences of the same name, six species were identiable but the molecular identity disagreed with the morphological identication, and twenty ve species gave no reliable match. The successful matches included accurate matches to BINs from countries far from the UK, including Canada, South Africa and Russia. We suggest that, in many cases, these may have been accidentally transported with horticultural materials

The Molecular and behavioural ecology of click beetles (Coleoptera: Elateridae) in agricultural land

The larvae (wireworms) of some click beetle genera inhabit the soil in agricultural land and are crop pests. In the UK, a pest complex of Agriotes species, A. obscurus, A. sputator and A. lineatus, has been identified as the cause of the majority of damage. However, studies on their ecology are lacking, despite knowledge of this being important for the development of sustainable risk assessment and pest management strategies, in part due to the morphologically cryptic nature of wireworms. The ecology of economically important click beetle species was investigated, focusing on UK Agriotes species. The relationship between sex pheromone trapped male Agriotes adults and wireworms, identified using a molecular tool (T‐RFLP), was influenced by sampling method, and some environmental variables significantly correlated with species distributions. Scale of sampling influenced the observed distribution of wireworms and other soil insect larvae. Other wireworm species were trapped together with Agriotes species, but mitochondrial 16S rRNA sequences could not be matched to those of other UK species. Sequences from Canadian wireworm samples revealed possible cryptic species. Differences in adult movement rates were found in laboratory tests (A. lineatus > A. obscurus > A. sputator). Molecular markers (AFLPs) were developed to assess dispersal in adult male Agriotes but further protocol optimisation is required. The results show the importance of identifying wireworms to species for assessing adult and wireworm distributions, since the Agriotes pest complex may not be present or as 3 widespread as previously assumed. Sex pheromone trapping of adults may not be appropriate for risk assessment as the relationship between aboveground adult and belowground wireworm species distribution is not straightforward. The differences observed in Agriotes species’ ecology have implications for the implementation of pest management strategies. The techniques used here can be applied in future studies to provide information on other economically important click beetle species worldwide

Molecular approaches for studying root herbivores

The use of molecular techniques in insect ecology has expanded rapidly, allowing ever more challenging questions to be addressed. Compared to their aboveground equivalents, root herbivore molecular ecology has received less attention, despite essentially the same ecological questions being of importance in both the above- and belowground ecosystems. Studies so far have concentrated on economically important taxa, using mitochondrial and nuclear DNA sequencing and a variety of markers to investigate the species identity and relationships, population dynamics and dispersal, distribution, feeding behaviour and interactions with other organisms. Although this has proved useful for elucidating these aspects of their ecology, there remains a need to focus on the functioning of root herbivores in the soil ecosystem. Application of new and emerging technologies developed for aboveground systems will increasingly be applied to those belowground, allowing a focus on root herbivore biology and ecology in the context of ecosystem processes and systems ecology. For the foreseeable future, however, the use of molecular techniques is likely to remain dominated by the need to address pragmatic research questions about specific taxa, notably pests. © 2013 Elsevier Ltd

The distribution of soil insects across three spatial scales in agricultural grassland

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

Walking behaviour in the ground beetle, Poecilus cupreus: dispersal potential, intermittency and individual variation

Dispersal is a key ecological process affecting community dynamics and the maintenance of populations. There is increasing awareness of the need to understand individual dispersal potential to better inform population-level dispersal, allowing more accurate models of the spread of invasive and beneficial insects, aiding crop and pest management strategies. Here, fine-scale movements of Poecilus cupreus, an important agricultural carabid predator, were recorded using a locomotion compensator and key movement characteristics were quantified. Net displacement increased more rapidly than predicted by a simple correlated random walk model with near ballistic behaviour observed. Individuals displayed a latent ability to head on a constant bearing for protracted time periods, despite no clear evidence of a population level global orientation bias. Intermittent bouts of movement and non-movement were observed, with both the frequency and duration of bouts of movement varying at the inter- and intra-individual level. Variation in movement behaviour was observed at both the inter- and intra- individual level. Analysis suggests that individuals have the potential to rapidly disperse over a wider area than predicted by simple movement models parametrised at the population level. This highlights the importance of considering the role of individual variation when analysing movement and attempting to predict dispersal distances

New frontiers in belowground ecology for plant protection from root-feeding insects

Herbivorous insect pests living in the soil represent a significant challenge to food security given their persistence, the acute damage they cause to plants and the difficulties associated with managing their populations. Ecological research effort into rhizosphere interactions has increased dramatically in the last decade and we are beginning to understand, in particular, the ecology of how plants defend themselves against soil-dwelling pests. In this review, we synthesise information about four key ecological mechanisms occurring in the rhizosphere or surrounding soil that confer plant protection against root herbivores. We focus on root tolerance, root resistance via direct physical and chemical defences, particularly via acquisition of silicon-based plant defences, integration of plant mutualists (microbes and entomopathogenic nematodes, EPNs) and the influence of soil history and feedbacks. Their suitability as management tools, current limitations for their application, and the opportunities for development are evaluated. We identify opportunities for synergy between these aspects of rhizosphere ecology, such as mycorrhizal fungi negatively affecting pests at the root-interface but also increasing plant uptake of silicon, which is also known to reduce herbivory. Finally, we set out research priorities for developing potential novel management strategies