Adrien Rusch

The contamination of non-target organisms by elements and pesticides can adversely affect biodiversity and key ecosystem services such as pollination. In this study, we used honey bee colonies as sentinels of environmental contamination in four distinct habitats - urban, suburban, forest, and vineyard - and collected bees every three weeks from May to November. Pesticide residues were extracted using an adapted QuEChERS method and analyzed by LC-MS/MS, while inorganic major and trace elements were measured by ICP-MS and ICP-AES. Our results show that land-use and seasonal changes shape contaminant profiles in bees. Bees from vineyards exhibited the highest contaminant diversity and loads, indicating a particularly intense contamination profile in this environment. This reflects exposure to multiple pesticide inputs - such as copper - which can accumulate over time to potentially harmful levels. Pollinators like honey bees provide effective indicators of environmental risk, as their contaminant loads may affect honey bee health and can reveal broader ecological impacts.

Crop diversification is a promising strategy to strengthen pest control services in agricultural landscapes. Diversifying crops may limit pests through host crop dilution or by enhancing top‐down control by their enemies. However, crop diversification may also benefit generalist pests through higher resource continuity. Using a large‐scale dataset encompassing 742 landscapes across 13 countries, we assessed the impact of landscape‐scale crop diversity on the abundance of natural enemies, the potential for biological control, and insect pest abundance. Crop diversification did not increase the overall abundance of natural enemies or the potential for biological pest control. Instead, crop diversity primarily favoured the abundance of specialist natural enemies and pests in highly simplified landscapes, an effect that was reduced in landscapes with high proportions of semi‐natural habitats. Lastly, low proportions of host crops in the landscape were associated with higher abundances of natural enemies. Taken together, our results indicate that crop diversification is not a ‘one size fits all’ strategy to control agricultural pests, and that other landscape characteristics, such as high amounts of semi‐natural habitats, must be considered to enhance biological pest control services.

Landscape heterogeneity, notably the amount of semi‐natural habitats, has been found to enhance natural enemies of crop pests and biological pest control in agricultural landscapes. Moreover, increasing host‐crop areas can directly affect the dynamics of pest or pathogen populations by providing them with more resources. However, the actual beneficial impacts of diversifying agricultural landscapes on pest or pathogen population levels are still poorly demonstrated, limiting farmers' adoption of such approaches. Here, using national‐scale data collected between 2014 and 2019 and Bayesian spatial models, we investigated how land use in the municipality and meteorological context affected the occurrence of two main pest and pathogen in vineyards: downy mildew (632 fields per year) and grape berry moth (225 fields per year). Our analysis revealed that the probability of occurrence of downy mildew and grape berry moth decreased as the percentage of woodland in the municipality increased. Additionally, we found that the probability of occurrence of downy mildew strongly depended on the meteorological context, as the probability of occurrence of downy mildew increased with the mean rainfall during spring and summer. Our analysis revealed no effect of the share of organic farming vineyard in the municipality on pest pressure. Synthesis and applications. Our study demonstrates that diversifying vineyard‐dominated landscapes by increasing the area of woody habitats could limit the occurrence of downy mildew and grape berry moth, which are responsible for most pesticide applications in vineyards. This work provides a significant step forward in the design of pest‐suppressive landscapes that highlight the key role of woody habitat maintenance in vineyard landscapes. Future work should now investigate how such nature‐based solutions could provide other benefits to farmers and the entire society.

The contamination of non-target organisms by elements and pesticides can adversely affect biodiversity and key ecosystem services such as pollination. In this study, we used honey bee colonies as sentinels of environmental contamination in four distinct habitats - urban, suburban, forest, and vineyard - and collected bees every three weeks from May to November. Pesticide residues were extracted using an adapted QuEChERS method and analyzed by LC-MS/MS, while inorganic major and trace elements were measured by ICP-MS and ICP-AES. Our results show that land-use and seasonal changes shape contaminant profiles in bees. Bees from vineyards exhibited the highest contaminant diversity and loads, indicating a particularly intense contamination profile in this environment. This reflects exposure to multiple pesticide inputs - such as copper - which can accumulate over time to potentially harmful levels. Pollinators like honey bees provide effective indicators of environmental risk, as their contaminant loads may affect honey bee health and can reveal broader ecological impacts.

Aim: Ground beetles (Coleoptera: Carabidae) are a highly diverse group of soil‐associated organisms with varied biological functions, diet preferences and mobility. Their diversity has made them a popular focus in urbanisation research. However, studies on urbanisation's impact on Carabid species richness and abundance have yielded inconsistent results, showing negative, positive, neutral and even non‐linear effects. This study aimed to synthesise the existing literature to identify potential non‐linear effects of rural‐to‐urban gradients while accounting for the influence of climatic confounding factors. Location: Global. Methods: We conducted hierarchical meta‐analyses to evaluate non‐linear urbanisation effects on Carabid species richness and abundance. additionally, we examined the moderating roles of climate variables (annual precipitation, precipitation seasonality) and the relative urban heat island (UHI) effect. From 25 relevant studies, we extracted 43 effect sizes for species richness and 46 for assemblage‐level abundance. Results: Our analysis revealed a significant non‐linear relationship between urbanisation and carabid abundance, characterised by an increase from rural to suburban areas, followed by a decline towards city centres. Cities with high precipitation seasonality and elevated relative UHI were associated with a suburban peak in both abundance and species richness, likely due to suburban areas mitigating extreme weather, such as harsh winters and heatwaves. Conversely, in climates with low precipitation seasonality and UHI, suburban areas showed a decline, as these conditions do not provide the mitigating benefits, yet the disadvantages of urbanisation remain. Main Conclusions: Our findings highlight the crucial role of climate as a confounding factor in the non‐linear effects of urbanisation, underscoring the importance of integrating these variables into future research. Moreover, the results suggest that suburban environments in regions with high climatic seasonality and elevated UHI may hold conservation potential, supporting higher carabid abundance and species richness compared to urban cores or rural regions.

Biological pest control is a major ecosystem service and is known to depend on landscape heterogeneity. The composition and configuration of landscapes can affect natural enemy communities, trophic interactions, and pest density within agroecosystems. However, local agricultural management can interfere with natural enemy activity, so the positive effects of landscape heterogeneity may be disrupted by farming practices. Here, we studied the influence of landscape context and management options on the biological control of Lobesia botrana, one of the main insect pests of grapes. We focused on two complementary measures: predation rates, which reflect part of biological control potential, and plant damage, which reflects pest density and the associated infestation. We used a set of sentinel prey (eggs, caterpillars, pupae) to quantify predation rates across different developmental stages of the pest. The study was carried out in a landscape‐scale experimental set‐up consisting of 38 vineyards in Southwestern France. Using structural equation models, we show that predation rates on sentinel prey were affected by both landscape heterogeneity and local management practices. Higher pest predation rates were observed in landscapes with smaller vineyards and in vineyards with low applications of synthetic pesticides. We observed limited relationships between predation rates and grape infestation levels. However, our results suggest that predation rates at the pest pupae stage are significantly shaping infestation levels. Additionally, pest damage in spring and summer was primarily influenced by the intensity of local pesticide use and the grass cover in the field and exacerbated by the decreasing size of vineyards, while semi‐natural habitats had no effect on pest damage. We conclude that links between L. botrana infestation and biological control potential appear tenuous in our study region. This is likely due to the high local management intensity, as evidenced by the negative association observed between pesticide applications and predation rates. Nevertheless, both predation and infestation respond to landscape or field heterogeneity and pesticide use. Reducing the use of pesticides should be combined with multi‐scale diversification measures at field and landscape levels to amplify the predation potential.

Context: Land-use intensification to increase yields is often detrimental to biodiversity undermining the provision of ecosystem services. However, it is questionable if ecosystem service providers contribute to ecological intensification by achieving the same or higher yields than conventional high-intensity agriculture. Objectives: In this study, we aimed to disentangle the effects of local and landscape-scale land-use intensification on arthropod communities and their contribution to ecosystem services and crop yield. A set of meta-analytic structural equation models allowed us to assess direct and indirect relationships in the cascade from land use to yield. Methods: We selected 37 datasets containing information on land use, community composition, levels of pollination and natural pest control services, and crop yield. We quantified functional diversity of communities by collecting trait information for three exemplary groups of service-providers: bees, ground beetles, and spiders. Results: Local land-use intensification reduced the abundance of all arthropod groups. Spiders were the only group whose species richness was negatively related to a higher percentage of arable land in the landscape. High abundance of bees related positively to oilseed rape pollination and crop yields. In the models for the two predator groups, crop yield was strongly determined by land use, independent of the pest control services provided by natural enemies. Conclusions: Our results suggest a potential for ecological intensification mediated by land-use change in crops where pollination benefits yield, but suggest more nuanced effects for pest control. Our study also calls for experiments on multiple taxonomic groups and ecosystem services that apply comparable methods at similar scales.

Promoting natural pest control services through natural enemies in agricultural landscapes offers a sustainable perspective for pest management. Several management options across spatio‐temporal scales enhance natural pest control. However, most studies examining how pest control services respond to environmental changes focused on the magnitude of natural pest control across space and often neglect its temporal stability. Consequently, we lack information on the ecological drivers influencing interannual stability of pest control, which is especially important in perennial cropping systems threatened by multiple pests. Here, we used a landscape‐scale experiment in southwest France to investigate how local management and landscape context affect the mean level and temporal stability of natural pest control. Our design included paired vineyards in 20 landscapes selected along two orthogonal gradients: organic farming proportion and semi‐natural habitat proportion in the landscape. We evaluated natural pest control services annually using eggs of the grape moth Lobesia botrana from 2018 to 2022 (excluding 2020). We predicted that low‐intensity farming, with reduced pesticide application and soil disturbance, would enhance predation rates and its stability by benefiting natural enemy communities. Finally, we expected that more complex landscapes, both in terms of composition and configuration, would benefit natural enemy activities and lead to higher levels of pest control. Our analyses revealed that mean daily pest predation decreased with pesticide use and was lower in less complex landscapes, associated with larger patch sizes. However, farming practices and landscape context did not affect predation rate stability over time. Synthesis and applications. Our results suggest that the magnitude of natural pest control services can be improved by reducing intensive management practices at the field scale and by promoting greater landscape heterogeneity, for example, by reducing the mean patch size. These findings highlight the potential for promoting ecosystem services and limit pesticide use, thereby supporting more sustainable farming systems. However, our results indicate that these management strategies may not necessarily contribute to the temporal stability of pest control across years. This suggests that complementary approaches, such as fostering specific functional groups, might be needed to ensure consistent pest control service over time.