Contributions to biodiversity and integrated pest management from arable margins in Ireland evaluated through carabid populations

Abstract: As an island, Ireland has a restricted diversity of insects in comparison to Britain and continental Europe. As such, there is a research gap on the effects of measures introduced to promote biodiversity. This study aims to evaluate five different grass and perennial wildflower mixtures in comparison with a cereal control using a field scale experiment replicated across five sites. Treatments were established in 2016 and 2017, and sampled for insect populations in May 2018 and 2019. Carabid beetles were selected as a representative family. The total abundance, abundance of functional groups by feeding preferences, diversity, and species richness of adult carabids are used to infer how each mixture supported insect populations in the margin and crop and the potential for pest control. Parallel sampling provided information on whether the populations within the adjacent cereal crop were influenced by composition of the margin. The abundance of general predator carabids was higher in the cereal control than the alternative mixes of the margin. However, no difference in abundance, diversity or richness of all carabids specific to margin composition was evident. Diversity indices differed between the margin and adjacent crop, and richness was greater in the crop than grass margin.