Composition and seasonal variation of epigeic arthropods in field margins of NW Portugal

Abstract

Field margins act as shelters for different arthropod taxa in agricultural fields. Several factors may promote seasonal changes in arthropod communities, especially in regions with marked seasonality, such as Mediterranean areas. Epigeic arthropods were sampled from the margins of fields located in northwestern Portugal during 2 contrasting seasons, spring and autumn. Organisms were identified to family or order level and seasonal variation in arthropod communities was evaluated. Abundance, group richness, and feeding guild parameters were affected by sampling season, with both abundance and richness being higher in spring. Of the groups captured in both seasons, most evidenced either higher abundance in spring or similar abundance between seasons. Ants constituted one of the most abundant trophic guilds in spring but one of the least captured in autumn, while catches of parasitoids and parasites were not affected by sampling season. Results indicate that the higher taxa approach is useful to distinguish seasonally distinct communities.