Integrating Biodiversity Benefits of Weeds into the Economic Threshold Concept

Abstract Weeds on arable land present a double-edged sword: they negatively influence the quantity and qualities of cash crops, but they can also provide biodiversity benefits. The benefits are categorized into use (support for predators/parasitoids, pollinators, herbivores, and granivores) and non-use values (existence value) based on examples from the literature. Recognizing the potential benefits of weeds, it is important to integrate these aspects into weed control decision-making process. Building upon the traditional economic threshold model for insect pests, this paper presents a first step toward upgrading the economic threshold for arable weeds by incorporating biodiversity benefits of weeds. To determine the traditional threshold, a tool estimating crop yield loss caused by weeds was used. This tool also incorporates the intra- and inter-specific competition among weed plants. Due to the data limitation, we focus on the existence value of weeds in a case study for winter wheat in Germany. We estimated the weed economic thresholds incorporating existence values for three weed scenarios varying in species and densities. The results indicate that the updated weed thresholds would generally increase. This study highlights the importance to consider biodiversity benefits of weeds when developing a more holistic, agroecological approach to weed management.