Assessing flower‐visiting arthropod diversity in apple orchards through metabarcoding of environmental DNA from flowers and visual census

Abstract

AbstractArthropods are essential in maintaining healthy and productive agricultural ecosystems. Agricultural crops such as apples are typically pollinated by domesticated honey bees, but wild bees and other arthropod flower visitors also contribute to pollination. Flower visitors can also be natural enemies of crop‐pests or herbivores. Biodiversity is under pressure and knowledge of wildflower visitors is an important tool in designing orchards that can support high functional biodiversity. In our study, we assessed the diversity of arthropod flower visitors in four Danish apple orchards using both molecular and nonmolecular techniques to study arthropod communities in agricultural ecosystems. Arthropod DNA collected from apple flowers was analyzed using a DNA metabarcoding approach using the mitochondrial COI marker, while arthropod pollinators were recorded through visual assessment surveys. These complementary techniques resulted in a total of 19 arthropod taxa detected. Nonbee arthropods constituted a large proportion of arthropods detected by both methods (84%, 16 taxa). Metabarcoding detected 12 taxa and had 83% species resolution. Visual census recovered flower visiting groups to the order level (Coleoptera, Diptera, Hymenoptera and Lepidoptera) but not species level and also provided relative abundance data, which is not possible with molecular methods. We demonstrated that by utilizing both molecular and nonmolecular techniques to assess arthropod communities, we are able to obtain a broader overview of the arthropod fauna present. The methodology used and the outcome of this study can be used to inform and tailor suitable arthropod‐pest management practices in orchards to increase crop yield and maintain healthy agricultural systems.