Organic Farming Can Promote Weed Seed Predation by Invertebrates in Tea Fields

ABSTRACT Postdispersal weed seed predation by invertebrates, an important ecosystem service in farmlands, has not yet been quantified in tea ( Camellia sinensis ) fields. Recently, organic farming has been promoted in Japanese tea production, and changes in farm management can affect seed predation. To sustainably utilize this service in tea cultivation, it is essential to quantify seed predation and evaluate the effects of farm management. Hence, in this study, we investigated the temporal variability in invertebrate seed predation and activity densities of seed predators (crickets, ground beetles, and pill bugs) in organic and conventional tea fields in Japan from June to October 2020 and 2021. Seed predation rates were investigated for Lolium multiflorum in 2020 and for L. multiflorum , Digitaria ciliaris , Eleusine indica , Bidens pilosa var. pilosa , and Erechtites hieraciifolius in 2021. Organic farming increased invertebrate seed predation and the activity densities of crickets and pill bugs. The average rates of weed seed predation biweekly were 42.8%–80.5% in the organic fields and 21.7%–59.6% in the conventional fields. This study shows that invertebrate seed predation can significantly influence weed seedbanks in tea fields and that organic farming can foster the potential of biological weed control due to seed predation.