Forage Production and Grassland Systems, Agroscope, 8046, Zurich, Switzerland.
Department of Biology/Ecology and Evolution, University of Fribourg, 1700, Fribourg, Switzerland.
Sci Rep. 2023 Oct 28;13(1):18508. doi: 10.1038/s41598-023-45609-y.
Outcomes of weed biological control projects are highly variable, but a mechanistic understanding of how top-down and bottom-up factors influence the success of weed biological control is often lacking. We grew Rumex obtusifolius, the most prominent native weed in European grasslands, in the presence and absence of competition from the grass Lolium perenne and subjected it to herbivory through targeted inoculation with root-boring Pyropteron spp. To explore whether the interactive effects of competition and inundative biological control were size-dependent, R. obtusifolius was planted covering a large range of plant sizes found in managed grasslands. Overall, competition from the grass sward reduced aboveground biomass and final root mass of R. obtusifolius about 62- and 7.5-fold, respectively, and increased root decay of R. obtusifolius from 14 to 58%. Herbivory alone increased only root decay. However, grass competition significantly enhanced infestation by Pyropteron spp. and, as a consequence, enhanced the impact of herbivory on aboveground biomass and final root mass. The synergistic effect was so strong that R. obtusifolius plants grown from initially smaller roots did no longer develop. Inoculating R. obtusifolius with Pyropteron species in grasslands should be further pursued as a promising inundative biological control strategy in the weed's native range.
杂草生物防治项目的结果高度可变，但人们往往缺乏对上下因子如何影响杂草生物防治成功的机制理解。我们在存在和不存在来自草地黑麦草竞争的情况下种植了欧洲草原上最突出的本地杂草皱叶酸模，并通过靶向接种蛀根 Pyropteron 种来对其进行食草性处理。为了探索竞争和泛滥生物防治的相互作用是否取决于植物大小，我们种植了覆盖管理草地中发现的各种大小的皱叶酸模。总的来说，草丛的竞争分别使皱叶酸模的地上生物量和最终根质量减少了约 62 倍和 7.5 倍，并将皱叶酸模的根腐烂率从 14%增加到 58%。单独的食草性处理仅增加了根腐烂率。然而，草竞争显著加剧了 Pyropteron 种的侵染，从而增强了食草性对地上生物量和最终根质量的影响。协同作用非常强烈，以至于从最初较小的根生长的皱叶酸模不再发育。在草地中用 Pyropteron 种接种皱叶酸模应该作为该杂草原生范围内有前途的泛滥生物防治策略进一步研究。
