Plant Species Loss Affects Life-History Traits of Aphids and Their Parasitoids

The consequences of plant species loss are rarely assessed in a multi-trophic context and especially effects on life-history traits of organisms at higher trophic levels have remained largely unstudied. We used a grassland biodiversity experiment and measured the effects of two components of plant diversity, plant species richness and the presence of nitrogen-fixing legumes, on several life-history traits of naturally colonizing aphids and their primary and secondary parasitoids in the field. We found that, irrespective of aphid species identity, the proportion of winged aphid morphs decreased with increasing plant species richness, which was correlated with decreasing host plant biomass. Similarly, emergence proportions of parasitoids decreased with increasing plant species richness. Both, emergence proportions and proportions of female parasitoids were lower in plots with legumes, where host plants had increased nitrogen concentrations. This effect of legume presence could indicate that aphids were better defended against parasitoids in high-nitrogen environments. Body mass of emerged individuals of the two most abundant primary parasitoid species was, however, higher in plots with legumes, suggesting that once parasitoids could overcome aphid defenses, they could profit from larger or more nutritious hosts. Our study demonstrates that cascading effects of plant species loss on higher trophic levels such as aphids, parasitoids and secondary parasitoids begin with changed life-history traits of these insects. Thus, life-history traits of organisms at higher trophic levels may be useful indicators of bottom-up effects of plant diversity on the biodiversity of consumers

Retrospective HRMS Screening and Dedicated Target Analysis Reveal a Wide Exposure to Pyrrolizidine Alkaloids in Small Streams

Pyrrolizidine alkaloids (PAs) are found to be toxic pollutants emitted into the environment by numerous plant species, resulting in contamination. In this article, we investigate the occurrence of PAs in the aquatic environment of small Swiss streams combining two different approaches. Pyrrolizidine alkaloids (PAs) are toxic secondary metabolites produced by numerous plant species. Although they were classified as persistent and mobile and found to be emitted into the environment, their occurrence in surface waters is largely unknown. Therefore, we performed a retrospective data analysis of two extensive HRMS campaigns each covering five small streams in Switzerland over the growing season. All sites were contaminated with up to 12 individual PAs and temporal detection frequencies between 36 and 87%. Individual PAs were in the low ng/L range, but rain-induced maximal total PA concentrations reached almost 100 ng/L in late spring and summer. Through PA patterns in water and plants, several species were tentatively identified as the source of contamination, with Senecio spp. and Echium vulgare being the most important. Additionally, two streams were monitored, and PAs were quantified with a newly developed, faster, and more sensitive LC–MS/MS method to distinguish different plant-based and indirect human PA sources. A distinctly different PA fingerprint in aqueous plant extracts pointed to invasive Senecio inaequidens as the main source of the surface water contamination at these sites. Results indicate that PA loads may increase if invasive species are sufficiently abundant.ISSN:0013-936XISSN:1520-585

Preface: Special Issue on Probing the Open Ocean With the Research Sailing Yacht Eugen Seibold for Climate Geochemistry

The 72‐foot sailing yacht Eugen Seibold is a new research platform for contamination‐free sampling of the water column and atmosphere for biological, chemical, and physical properties, and the exchange processes between the two realms. Ultimate goal of the project is a better understanding of the modern and past ocean and climate. Operations started in 2019 in the Northeast Atlantic, and will focus on the Tropical Eastern Pacific from 2023 until 2025. Laboratories for air and seawater analyses are equipped with down‐sized and automated state‐of‐the‐art technology for a comprehensive description of the marine carbon system including CO 2 concentration in the air and sea surface, pH, macro‐, and micro‐nutrient concentration (e.g., Fe, Cd), trace metals, and calcareous plankton. Air samples are obtained from ca. 13 m above sea surface and analyzed for particles (incl. black carbon and aerosols) and greenhouse gases. Plankton nets and seawater probes are deployed over the custom‐made A‐frame at the stern of the boat. Near Real‐Time Transfer of underway data via satellite connection allows dynamic expedition planning to maximize gain of information. Data and samples are analyzed in collaboration with the international expert research community. Quality controlled data are published for open access. The entire suite of data facilitates refined proxy calibration of paleoceanographic and paleoclimate archives at high temporal and spatial resolution in relation to seawater and atmospheric parameters. Plain Language Summary The new research sailing yacht Eugen Seibold ( ES ) enables clean, contamination‐free sampling of air and seawater to better understand the interactions between ocean and climate. For example, the oceans remove increasingly less carbon dioxide (CO 2 ) from the atmosphere the more saturated they are with CO 2 (ocean acidification). However, a detailed systematic understanding of air‐sea exchange processes remains to be developed. We analyze air and seawater as well as the exchange of greenhouse gases and other substances such as aerosols and soot (black carbon) between air and seawater at high resolution using modern materials and technologies. Scaled‐down, energy‐efficient, and automated probes developed over the past decade are being used to measure around 50 different characteristics of the marine environment. The work deck at the stern of the boat allows the use of custom‐made water samplers and plankton nets to study the ocean to below 1,000 m depth. In addition, the new data enables a better understanding of past ocean archives, such as the marine plankton accumulated in seafloor sediments, to reconstruct past climate changes. From 2019 to 2022, the S/Y ES sailed in the eastern North Atlantic and will operate in the tropical eastern Pacific until 2025. Key Points New research platform for contamination‐free sampling of the water column and atmosphere of biological, chemical, and physical properties Comprehensive marine geochemical analyzes including carbon (e.g., CO 2 ) in air and sea surface Proxy calibration of paleoclimate archives at high temporal and spatial resolution in relation to seawater and atmospheric parameter