Measurement of post-dispersal invertebrate seed predation of some relevant weed species in maize fields in Hungary: An ecosystem service provided in crop fields contributing to weed management

Invertebrate seed predation is a potential ecosystem service that substantially reduces weed seeds in crop fields, decreasing the seedling emergence and, thus, limiting the weed competition next season. It may, thus, be considered as a natural component of the long-term weed management toolbox. This study aimed to measure the post-dispersal invertebrate seed predation levels of the following relevant weed species in Hungarian maize fields: Ambrosia artemisiifolia, Datura stramonium, Chenopodium album, and Echinochloa crus-galli, and to compare the predation levels among them. We hypothesised that invertebrate seed predators will predate weed seeds, but the predation levels may vary with the weed species. Two sampling rounds were performed, in November 2019 and October 2020, in Gödöllő, Hungary. A total of 100 seed cards/round were placed on the soil surface inside a maize field prior to harvest, 10 m from the field's edge, along 25 transects, with four cards/transect. A distance of 10 m was set between the transects and 1 m between the cards. Twenty seeds of each weed species were glued onto sandpaper (25 × 10 cm, P-60), and a wire mesh was used to exclude vertebrate predators. The seed removal was calculated every 24 h, for seven days in 2019 and for five days in 2020, and then the seed predation was measured using the number of removed seeds on each card. The results showed high seed predation levels on all the seed cards, with an overall average of 85.9 ± 13.7%. Besides, there was a decrease in the % of remaining seeds on the cards starting from the first day after exposure due to seed predation in both years. The optimum exposure period for measuring the seed predation was found to be three to four days, though the number of predated seeds on days 3 and 4 significantly differed between years (P < 0.001), with higher predation rates in 2020 than in 2019. However, no differences were detected in the predation rates among the weed species (P = 0.962, 0.079). These findings indicate the potential contribution of seed predation by invertebrates to weed management in Hungarian maize fields.