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Post-dispersal predation of weed seeds in a pampas agroecosystem, Argentina

Abstract:

Predation causes significant seed losses from the epigeal and hypogeal seedbanks. In the present work, three weed species predation by insects, rodents and birds was evaluated in a closed area covered by high vegetation and in the adjacent farmland area. The study was carried out at the JF. Villarino Experimental Field (FCA-UNR), Zavalla town, Santa Fe, Argentina. Plastic trays were placed at the level of the soil surface, where 100 seeds (total of 300 seeds) of three weed plants (i.e Commelina erecta, Echinochloa colona and Chenopodium album) were placed. Each tray represented a predation treatment. On the surface of each tray, woven wires of different mesh sizes and with different architecture were placed, so that the predation factors (TOT – Total; I&R – Insects and Rodents; INS – Insects only; SPR – Without predation) were isolated. The daily seed predation rate was calculated based on the data obtained, i.e.P=100(1−r1/t). Bird records of 41% and 33% were corresponding to Passer domesticus and Zenaida auriculata, respectively, with seeds being their main source of food. The predation of weed seeds was highly variable; the most preyed seeds were found to be Echinochloa colona and Chenopodium album. Insects and rodents were the predominant predators. Enhancing environmentally friendly and more sustainable practices, i.e. seed predation, is able to reduce reliance on chemical weed control.