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Sulfoximines, the next generation systemic insecticides developed to replace neonicotinoids, have been shown to negatively impact pollinator development and reproduction. However, field-realistic studies on sulfoximines are few and consequences on pollination services unexplored. Moreover, the impacts of other agrochemicals such as fungicides, and their combined effects with insecticides remain poorly investigated. Here, we show in a full factorial semi-field experiment that spray applications of both the product Closer containing the insecticide sulfoxaflor and the product Amistar containing the fungicide azoxystrobin, negatively affected the individual foraging performance of bumblebees (Bombus terrestris). Insecticide exposure further reduced colony growth and size whereas fungicide exposure decreased pollen deposition. We found indications for resource limitation that might have exacerbated pesticide effects on bumblebee colonies. Our work demonstrates that field-realistic exposure to sulfoxaflor can adversely impact bumblebees and that applications before bloom may be insufficient as a mitigation measure to prevent its negative impacts on pollinators. Moreover, fungicide use during bloom could reduce bumblebee foraging performance and pollination services.

Recent synthesis studies have shown inconsistent responses of crop pests to landscape composition, imposing a fundamental limit to our capacity to design sustainable crop protection strategies to reduce yield losses caused by insect pests. Using a global dataset composed of 5242 observations encompassing 48 agricultural pest species and 26 crop species, we tested the role of pest traits (exotic status, host breadth and habitat breadth) and environmental context (crop type, range in landscape gradient and climate) in modifying the pest response to increasing semi-natural habitats in the surrounding landscape. For natives, increasing semi-natural habitats decreased the abundance of pests that exploit only crop habitats or that are highly polyphagous. On the contrary, populations of exotic pests increased with an increasing cover of semi-natural habitats. These effects might be related to changes in host plants and other resources across the landscapes and/or to modified top-down control by natural enemies. The range of the landscape gradient explored and climate did not affect pests, while crop type modified the response of pests to landscape composition. Although species traits and environmental context helped in explaining some of the variability in pest response to landscape composition, the observed large interspecific differences suggest that a portfolio of strategies must be considered and implemented for the effective control of rapidly changing communities of crop pests in agroecosystems.

1. In agricultural landscapes, arthropods provide essential ecosystem services such as biological pest control and pollination. Intensified crop management practices and homogenization of landscapes have led to declines among such organisms. Semi-natural habitats, associated with high numbers of these organisms, are increasingly lost from agricultural landscapes but diversification by increasing crop diversity has been proposed as a way to reverse observed arthropod declines and thus restore ecosystem services. However, whether or not an increase in the diversity of crop types within a landscape promotes diversity and abundances of pollinating and predaceous arthropods, and how semi-natural habitats might modify this relationship, are not well understood. 2. To test how crop diversity and the proportion of semi-natural habitats within a landscape are related to the diversity and abundance of beneficial arthropod communities , we collected primary data from seven studies focusing on natural enemies (carabids and spiders) and pollinators (bees and hoverflies) from 154 crop fields in Southern Sweden between 2007 and 2017. 3. Crop diversity within a 1-km radius around each field was positively related to the Shannon diversity index of carabid and pollinator communities in landscapes rich in semi-natural habitats. Abundances were mainly affected by the proportion of semi-natural habitats in the landscape, with decreasing carabid and increasing pollinator numbers as the proportion of this habitat type increased. Spiders showed no response to either crop diversity or the proportion of semi-natural habitats.

Plant diversity is impacted by multiple global change drivers but also by altered biotic interactions with antagonist and mutualist organisms that can potentially affect species coexistence. With a 2‐year, outdoor mesocosm experiment in realistic mesic grassland communities, we explored the role of insect herbivory in impacting plant community dynamics under contrasting levels of water availability simulating altered rainfall regimes. We selected a grasshopper species (Calliptamus italicus L.) feeding predominantly on forbs while avoiding grasses. High water availability reduced species coexistence, boosting productivity while decreasing individual plant survival. At the community level, herbivores were not able to promote species coexistence but asymmetrically influenced grasses and forbs, reducing forb biomass under high water availability. Herbivores shaped individual plant responses to both abiotic conditions and individual‐neighbours’ interactions. Herbivores influenced focal plant survival by altering the effect of neighbouring plants, mitigating the negative effect of high neighbour biomass at low water availability and exacerbating it at high level of water availability. Synthesis. Altered rainfall has the capacity to change the relative strength of plant–plant interactions and also to determine the effects of herbivores on grassland communities. The complexity of the interactions between plants and herbivores and the observed context dependence indicate the need to incorporate multiple biotic and abiotic drivers to fully understand the mechanisms underlying plant dynamics and species coexistence in a changing world.

Agricultural intensification and climate change are expected to affect pest performance through excessive inputs of chemical fertilizers and increased probability of extreme drought events. Potential interactive effects of fertilization and water availability on aboveground pest performance may depend on soil fertility because of its effect on nutrient availability. In a greenhouse experiment, we examined the effects of inorganic fertilization on the performance of the grain aphid (Sitobion avenae, F.), an important pest of wheat, under different conditions of soil fertility and water availability. We found soil fertility and water availability to influence the positive effects of inorganic fertilizers on aphid growth, i.e. fertilization promoted faster aphid development time and higher fecundity and biomass under low fertility and under well-watered conditions. Moreover, although increased soil fertility favored aphid growth under well-watered conditions, it simultaneously sustained plant development. The current practices promoting soil fertility do not have direct negative consequence on crop protection under conventional cropping systems.

Insect pollination is a well-studied ecosystem service that supports production in 75% of globally important crops. Although yield is known to be sustained and regulated by a bundle of ecosystem services and management factors, the contribution of pollination to yield has been mostly studied in isolation. Here, we compiled and reviewed research on the contribution of pollination to crop yield under different environmental conditions, where the potential interaction between pollination and other factors contributing to yield, such as nutrient availability and control of pests, was tested. Specifically, we explored whether pollination displayed synergistic, compensatory or additive effects with concomitant factors. The literature search resulted in 24 peer-reviewed studies for a total of 39 individual tests of interactions. Studies examined responses in 13 crops testing interactions both at the local and the landscape scale. Interactions between pollination and other factors influencing yield were observed for several crops and mostly displayed positive-synergistic relationships. Crop life-history traits such as pollination dependency were found to affect the plant response to variations in resource and pollen availability. Soil properties and crop pests might affect contribution of pollination to yield by altering the amount of resources a plant can allocate to reproduction, independently of the amount of pollen provided. Current management strategies to enhance pollinators might fail to increase pollination benefits in landscapes characterized by poor soil resources or ineffective pest control. We propose that our understanding of the effects of crop-pollinator interactions will benefit by focusing on plant traits and physiological responses. Combining knowledge from plant physiology and ecology with technological advances in agriculture is needed to design novel management strategies to maximize pollination benefits and support yields and reduce environmental impacts of food production.

The meadow spittlebug, Philaenus spumarius (Hemiptera: Aphrophoridae; Linnaeus, 1758), is considered the main vector in the ongoing Xylella fastidiosa outbreak in the olive groves of southern Italy. Identifying the factors driving the spatial distribution of P. spumarius is of primary importance to determine X. fastidiosa infection risk in healthy olive groves. Here, we investigated the local and landscape factors shaping the occurrence and abundance of P. spumarius by sampling 182 olive groves over 2 years in the Abruzzo region. We found the occurrence and abundance of the vector to be positively associated with the proportion of olive groves in the landscape and negatively with the cover of vineyards. Philaenus spumarius best responded to landscape processes at small spatial scale (125–250 m) confirming the available information regarding its dispersal ability. At the local scale, soil management and pesticide application did not affect the vector probably because both interventions were not timed according to the vector biology and ecology. Our findings suggest that the management of agricultural landscape mosaics can drive the spatial distribution of P. spumarius. In particular, the landscape composition of the close surrounding of the olive groves may potentially influence the emergence probability of local X. fastidiosa epidemics through its effects on the vector spatial distribution and activity.

The idea that noncrop habitat enhances pest control and represents a win–win opportunity to conserve biodiversity and bolster yields has emerged as an agroecological paradigm. However, while noncrop habitat in landscapes surrounding farms sometimes benefits pest predators, natural enemy responses remain heterogeneous across studies and effects on pests are inconclusive. The observed heterogeneity in species responses to noncrop habitat may be biological in origin or could result from variation in how habitat and biocontrol are measured. Here, we use a pest-control database encompassing 132 studies and 6,759 sites worldwide to model natural enemy and pest abundances, predation rates, and crop damage as a function of landscape composition. Our results showed that although landscape composition explained significant variation within studies, pest and enemy abundances, predation rates, crop damage, and yields each exhibited different responses across studies, sometimes increasing and sometimes decreasing in landscapes with more noncrop habitat but overall showing no consistent trend. Thus, models that used landscape-composition variables to predict pest-control dynamics demonstrated little potential to explain variation across studies, though prediction did improve when comparing studies with similar crop and landscape features. Overall, our work shows that surrounding noncrop habitat does not consistently improve pest management, meaning habitat conservation may bolster production in some systems and depress yields in others. Future efforts to develop tools that inform farmers when habitat conservation truly represents a win–win would benefit from increased understanding of how landscape effects are modulated by local farm management and the biology of pests and their enemies., This work was supported through the National Socio-Environmental Synthesis Center (SESYNC) National Science Foundation Award DBI-1052875 for the project “Evidence and Decision-Support Tools for Controlling Agricultural Pests with Conservation Interventions” organized by D.S.K. and R.C.-K

Yield production in flowering crops depends on both nutrient availability and pollination, but their relative roles and potential interactions are poorly understood. We measured pollination benefits to yield in sunflower, combining a gradient in insect pollination (0, 25, 50, 100%) with a continuous gradient in nitrogen (N) fertilization (from 0 to 150 kg N ha −1 ) in an experiment under realistic soil field conditions. We found that pollination benefits to yield were maximized at intermediate levels of N availability, bolstering yield by approximately 25% compared with complete pollinator exclusion. Interestingly, we found little decrease in yield when insect visits were reduced by 50%, indicating that the incremental contribution of pollination by insects to yield is greater when the baseline pollination service provision is very low. Our findings provide strong evidence for interactive, nonlinear effects of pollination and resource availability on seed production. Our results support ecological intensification as a promising strategy for sustainable management of agroecosystems. In particular, we found optimal level of pollination to potentially compensate for lower N applications.

There is increasing evidence showing that microbes can influence plant-insect interactions. In addition, various studies have shown that aboveground pathogens can alter the interactions between plants and insects. However, little is known about the role of soil-borne pathogens in plant-insect interactions. It is also not known how environmental conditions, that steer the performance of soil-borne pathogens, might influence these microbe-plant-insect interactions. Here, we studied effects of the soil-borne pathogen Rhizoctonia solani on aphids (Sitobion avenae) using wheat (Triticum aestivum) as a host. In a greenhouse experiment, we tested how different levels of soil organic matter (SOM) and fertilizer addition influence the interactions between plants and aphids. To examine the influence of the existing soil microbiome on the pathogen effects, we used both unsterilized field soil and sterilized field soil. In unsterilized soil with low SOM content, R. solani addition had a negative effect on aphid biomass, whereas it enhanced aphid biomass in soil with high SOM content. In sterilized soil, however, aphid biomass was enhanced by R. solani addition and by high SOM content. Plant biomass was enhanced by fertilizer addition, but only when SOM content was low, or in the absence of R. solani. We conclude that belowground pathogens influence aphid performance and that the effect of soil pathogens on aphids can be more positive in the absence of a soil microbiome. This implies that experiments studying the effect of pathogens under sterile conditions might not represent realistic interactions. Moreover, pathogen-plant-aphid interactions can be more positive for aphids under high SOM conditions. We recommend that soil conditions should be taken into account in the study of microbe-plant-insect interactions.

Agroecosystems are principally managed to maximize food provisioning even if they receive a large array of supporting and regulating ecosystem services (ESs). Hence, comprehensive studies investigating the effects of local management and landscape composition on the provision of and trade-offs between multiple ESs are urgently needed. We explored the effects of conservation tillage, nitrogen fertilization and landscape composition on six ESs (crop production, disease control, soil fertility, water quality regulation, weed and pest control) in winter cereals. Conservation tillage enhanced soil fertility and pest control, decreased water quality regulation and weed control, without affecting crop production and disease control. Fertilization only influenced crop production by increasing grain yield. Landscape intensification reduced the provision of disease and pest control. We also found tillage and landscape composition to interactively affect water quality regulation and weed control. Under N fertilization, conventional tillage resulted in more trade-offs between ESs than conservation tillage. Our results demonstrate that soil management and landscape composition affect the provision of several ESs and that soil management potentially shapes the trade-offs between them.

Summary Biological pest control is a key ecosystem service, and it depends on multiple factors acting from the local to the landscape scale. However, the effects of soil management on biological control and its potential interaction with landscape are still poorly understood. In a field exclusion experiment, we explored the relative effect of tillage system (conservation vs. conventional tillage) on aphid biological control in 15 pairs of winter cereal fields (barley and wheat) selected along a gradient of landscape complexity. We sampled the abundance of the main natural enemy guilds, and we evaluated their relative contribution to aphid predation and parasitism. Conservation tillage was found to support more abundant predator communities and higher aphid predation (16% higher than in the fields managed under conventional tillage). In particular, both the abundance and the aphid predation of vegetation- and ground-dwelling arthropods were increased under conservation tillage conditions. Conservation tillage also increased the parasitism rate of aphids. A high proportion of semi-natural habitats in the landscape enhanced both aphid parasitism and predation by vegetation-dwelling organisms but only in the fields managed under conventional tillage. The better local habitat quality provided by conservation tillage may compensate for a low-quality landscape. Synthesis and applications. Our study stresses the importance of considering both soil management and landscape composition when planning strategies to maximize biological control services in agro-ecosystems, highlighting the role played by conservation tillage in supporting natural enemy communities. In simple landscapes, the adoption of conservation tillage will locally improve biological control provided by both predators and parasitoids mitigating the negative effects of landscape simplification. Moreover, considering the small scale at which both predation and parasitism responded to landscape composition, a successful strategy to improve biological control would be to establish a fine mosaic of crop and non-crop areas such as hedgerows, tree lines and small semi-natural habitat patches.

Pollination and soil fertility are important ecosystem services to agriculture but their relative roles and potential interactions are poorly understood. We explored the combined effects of pollination and soil fertility in sunflower using soils from a trial characterized by different long-term input management in order to recreate plausible levels of soil fertility. Pollinator exclusion was used as a proxy for a highly eroded pollination service. Pollination benefits to yield depended on soil fertility, i.e., insect pollination enhanced seed set and yield only under higher soil fertility indicating that limited nutrient availability may constrain pollination benefits. Our study provides evidence for interactions between above- and belowground ecosystem services, highlighting the crucial role of soil fertility in supporting agricultural production not only directly, but also indirectly through pollination. Management strategies aimed at enhancing pollination services might fail in increasing yield in landscapes characterized by high soil service degradation. Comprehensive knowledge about service interactions is therefore essential for the correct management of ecosystem services in agricultural landscapes.

In a factorial field plot experiment, high and low levels of inorganic nitrogen and of insect pollinators visiting the crop were manipulated and their combined effects on oilseed rape yield were quantified. A third factor was also included, testing whether different cultivars responded differently to the tested factors. Insect pollination was required to reach high yield and seed quality (oil content). Final benefits of pollination service were, however, greatly modified by cultivar, where the seed yield of the open-pollinated cultivar largely depended on insect pollination whereas the two hybrid cultivars did not. A near significant interaction between nitrogen input and insect pollination was also found, i.e. benefits to crop yield from insect pollination seemed to increase with decreased nitrogen levels. The differential response of the three cultivars suggested opportunities to use cultivars that are less dependent on insect pollination in landscapes where this service has been deteriorated. Increased access of nitrogen seems to partly compensate yield losses from poor insect pollination. Integrating conservation, environmental and agronomic sciences is therefore crucial to sustain agriculture productions through optimized management of agronomic inputs and biodiversity-based ecosystem services.