Gesine Pufal

Cross-pollination benefits differ among oilseed rape varieties.

Winter oilseed rape ( Brassica napus ) is an important crop for human consumption and biofuel production and its production is increasing worldwide. It is generally assumed that cross-pollination by insects increases oilseed rape yield but testing of this has been restricted to a few rapeseed varieties and produced varying results. The present study determines whether cross-pollination benefits a number of oilseed rape varieties by comparing yield in the presence and absence of insects. Four rapeseed varieties (Sherlock, Traviata, Treffer and Visby) were used with ten individuals each in four pollination treatments: (1) supplementary hand-pollination, (2) open pollination with insects able to access the flowers, (3) wind pollination and (4) autonomous self-pollination. Across all four varieties, open and supplementary hand-pollination treatments resulted in higher fruit set, numbers of seeds per pod and seed yield compared with wind and self-pollination. The cross-pollination benefits, however, differed among rapeseed varieties: Treffer and Visby had a higher dependence on open (insects) and supplementary cross-pollination than Sherlock and Traviata. Across all four varieties, seed weight compensated for reduced fruit set and was highest when plants were self-pollinated. The present results highlight the importance of considering varietal differences in crop pollination research. Information on the pollination requirements of crop varieties is required by farmers to optimize management decisions in a world of increasing agropollination deficits.

Spillover of trap-nesting bees and wasps in an urban-rural interface

A mismatch of resource availability in certain periods can lead to spillover of insects between habitats, resulting in temporal differences in insect diversity. Urban gardens are important anthropogenic habitats but it is unknown whether, when and why spillover of beneficial insects occurs between gardens and agricultural habitats. We used trap nests for Hymenoptera to monthly monitor bee and wasp abundance and species richness in 12 gardens and 12 rapeseed fields. Half of the gardens and rapeseed fields were located in the urban–rural interface and bordered each other (a garden paired with a rapeseed field) and the other half were isolated in the rural landscape (isolated rapeseed fields) and in the urban city centre (isolated gardens). In general, gardens in the urban–rural interface comprised the highest richness of bees and wasps. The abundance of bees but not of wasps was highest in paired habitats and peaked at full rapeseed blooming, indicating that mass-flowering rapeseed offers foraging resources for bees nesting in adjacent gardens. Thus, bees nest and increase their populations in both areas, benefiting from the mass-flowering resource in the agricultural habitat as well as the nesting resources from gardens, suggesting spillover of bees but not of wasps between paired gardens and rapeseed fields. Our study highlights the value of gardens in the urban–rural interface for the biodiversity of functionally important insects. Implementing urban gardening and small-scale agriculture in cities and suburban habitats can promote local pollinator populations and benefit adjacent croplands.

Diversity and specificity of host-natural enemy interactions in an urban-rural interface

1. Urbanisation and agricultural intensification cause the replacement of natural ecosystems but might also create novel habitats in urban and rural ecosystems promoting some insect communities by providing food and nesting resources.

Agro‐ecosystem services and dis‐services in almond orchards are differentially influenced by the surrounding landscape

1. The simultaneous influence of specific habitats on agro‐ecosystem services, dis‐services, and their interactions are largely unknown. Natural and semi‐natural habitats surrounding cropland may support ecosystem services and dis‐services and their net balance is important to guide decision‐making in agriculture.

Plant density can increase invertebrate postdispersal seed predation in an experimental grassland community

Abstract Janzen–Connell effects are negative effects on the survival of a plants progeny at high conspecific densities or close to its conspecifics. Although the role of Janzen–Connell effects on the maintenance of plant diversity was frequently studied, only few studies targeted Janzen–Connell effects via postdispersal seed predation in temperate grassland systems. We examined effects of conspecific density (abundance of conspecific adult plants) on postdispersal seed predation by invertebrates of three grassland species (Centaurea jacea, Geranium pratense, and Knautia arvensis) in experimental plant communities. Additionally, we examined the impact of plant species richness and different seed predator communities on total and relative seed predation (= seed predation of one plant species relative to others). We offered seeds in an exclusion experiment, where treatments allowed access for (1) arthropods and slugs, (2) arthropods only, (3) small arthropods only, and (4) slugs only. Treatments were placed in plots covering a gradient of abundance of conspecific adults at different levels of plant species richness (1, 2, 3, 4, 8 species). Two of the plant species (C. jacea and K. arvensis) experienced higher rates of seed predation and relative predation with increasing abundance of conspecific adults. For C. jacea, this effect was mitigated with increasing plant species richness. Differences in seed predator communities shifted seed predation between the plant species and changed the magnitude of seed predation of one plant species relative to the others. We exemplify density‐dependent increase in seed predation via invertebrates in grassland communities shaping both the total magnitude of species‐specific seed predation and seed predation of one species relative to others. Further differences in seed predator groups shift the magnitude of seed predation between different plant species. This highlights the importance of invertebrate seed predation to structure grasslands via density‐dependent effects and differing preferences of consumer groups.

Antibiotics impact plant traits, even at small concentrations

Antibiotics used in livestock industry are released to agricultural fields via grazing animals and manure. From there, they may affect human health due to consumption of antibiotic-exposed crop plants or drinking water. Also they may affect performance of natural occurring non-target species. Our study shows that antibiotics, even in small concentrations, significantly affect plant traits. Cropland species showed delayed germination and lower biomass allocation, indicating possible yield-effects in farmland fertilized with manure containing antibiotics. Antibiotics may also alter the composition of plant species in natural field margins, due to different species-specific responses, with unknown consequences for higher trophic levels.

Elementary School Children Contribute to Environmental Research as Citizen Scientists.

Research benefits increasingly from valuable contributions by citizen scientists. Mostly, participating adults investigate specific species, ecosystems or phenology to address conservation issues, but ecosystem functions supporting ecosystem health are rarely addressed and other demographic groups rarely involved. As part of a project investigating seed predation and dispersal as ecosystem functions along an urban-rural gradient, we tested whether elementary school children can contribute to the project as citizen scientists. Specifically, we compared data estimating vegetation cover, measuring vegetation height and counting seeds from a seed removal experiment, that were collected by children and scientists in schoolyards. Children counted seeds similarly to scientists but under- or overestimated vegetation cover and measured different heights. We conclude that children can be involved as citizen scientists in research projects according to their skill level. However, more sophisticated tasks require specific training to become familiarized with scientific experiments and the development of needed skills and methods.

Crop pollination services at the landscape scale

Managed and wild pollinators of different functional groups can provide pollination services in agricultural landscapes. These pollinators differ in their resource requirements and response to the amount and arrangement of different habitat types, that is, landscape composition and configuration. Most current approaches to test landscape effects on pollinators and pollination services are either applied to central individual crop fields or other landscape elements but rarely consider that pollinators depend on and make use of multiple habitat elements in an entire landscape. To capture these complex spatial and temporal interactions between different pollinators and habitat elements at the landscape scale, we propose to apply a combination of experimental and observational approaches across multiple habitat types and seasons.

Antibiotic-induced effects on scaling relationships and on plant element contents in herbs and grasses

Abstract Plant performance is correlated with element concentrations in plant tissue, which may be impacted by adverse chemical soil conditions. Antibiotics of veterinary origin can adversely affect plant performance. They are released to agricultural fields via grazing animals or manure, taken up by plants and may be stored, transformed or sequestered by plant metabolic processes. We studied the potential effects of three antibiotics (penicillin, sulfadiazine, and tetracycline) on plant element contents (macro‐ and microelements). Plant species included two herb species (Brassica napus and Capsella bursa‐pastoris) and two grass species (Triticum aestivum and Apera spica‐venti), representing two crop species and two noncrop species commonly found in field margins, respectively. Antibiotic concentrations were chosen as to reflect in vivo situations, that is, relatively low concentrations similar to those detected in soils. In a greenhouse experiment, plants were raised in soil spiked with antibiotics. After harvest, macro‐ and microelements in plant leaves, stems, and roots were determined (mg/g). Results indicate that antibiotics can affect element contents in plants. Penicillin exerted the greatest effect both on element contents and on scaling relationships of elements between plant organs. Roots responded strongest to antibiotics compared to stems and leaves. We conclude that antibiotics in the soil, even in low concentrations, lead to low‐element homeostasis, altering the scaling relationships between roots and other plant organs, which may affect metabolic processes and ultimately the performance of a plant.

Relevance of wild and managed bees for human well-being

Wild and managed bees provide pollination services to both crops and wild plants, and a variety of other services from which humans benefit. We summarize the most important and recent findings on bees as providers of provisioning, regulating and cultural ecosystem services. With comprehensive literature searches, we first identified ten important bee species for global pollination of crops, which include wild and managed honey bees, bumble bees, orchard-, cucumber- and longhorn bees. We second summarized bee-dependent ecosystem services to show how bees substantially contribute to food security, medical resources, soil formation or spiritual practices, highlighting their wide range of benefits for human well-being and to identify future research needs.