Search

DNA-based diet analysis of natural enemies is a valuable tool for unravelling the food choice of predators in agroecosystems. It enables the rapid identification of potential biocontrol agents of invertebrate pests. Here, we present a new multiplex PCR system for the identification of pest slug species in the diet of their natural enemies such as carabid beetles. It comprises three species-specific primers targeting the mitochondrial cytochrome c oxidase subunit I (COI) gene to detect DNA of the common garden slug, Arion distinctus (Stylommatophora: Arionidae), the Iberian slug, Arion lusitanicus (Stylommatophora: Arionidae) and the grey field slug Deroceras reticulatum (Stylommatophora: Agriolimacidae). We also include (super)family-specific primers for Arionidae and Limacoidea, which amplify parts of the 28S gene for ribosomal RNA (rRNA) in order to identify a wider range of slugs. The amplicons for Arionidae can be assigned to a total of seven Central European slug species of this family and the amplicons for Limacoidea to ten species. The multiplex assay showed high specificity against DNA extracts of field-collected slugs and co-occurring invertebrates. The assay also exhibited high sensitivity, which was confirmed by testing it with 223 dietary samples from field-collected carabids as potential natural enemies of slugs in agroecosystems. This methodology represents a new, cost-effective, highly sensitive and specific approach for the identification of common Central European slug species as well as for analysing trophic interactions to identify natural enemies for further biological control development. It can also be applied in any study where a rapid and reliable identification of slugs is needed. [ABSTRACT FROM AUTHOR]

The arthropod predator community of an organically cultivated 0.3 ha field was sampled by pitfall trapping during 1 year and analysed for small-scale spatial distribution patterns and their seasonal variation. Due to the small size of the study site, most of the investigated species were able to colonise the whole field. Ordination analyses revealed significant differences in community composition (i) between field centre and margin in summer and (ii) between field parts adjacent to meadows or conventionally cultivated arable land in all seasons. Results changed considerably if only adult carabids or spiders were used instead of the whole predator community.During summer the following significant differences in community parameters were found: (i) total catches in the centre were nearly twice as high as near the margin, (ii) predator richness did not differ between centre and margin while significantly more species were found close to meadows and (iii) evenness and heterogeneity were significantly higher at the margin versus the centre.The arthropod predator community even of a small field site showed distinct spatial distribution patterns with seasonal changes. Selecting appropriate taxonomic groups is crucial for the outcome of such studies and should be tailored to the aim of the investigation. [Copyright &y& Elsevier]