Conserving and restoring semi-natural habitat, i.e. enhancing landscape complexity, is one of the main strategies to mitigate pollinator decline in agricultural landscapes. However, we still have ...limited understanding of how landscape complexity shapes pollinator communities in both crop and non-crop habitat, and whether pollinator responses to landscape complexity vary with their association with mass-flowering crops. Here, we surveyed pollinator communities on mass-flowering leek crops and in nearby semi-natural habitat in landscapes of varying complexity. Surveys were done before and during crop bloom and distinguished between pollinators that visit the crop frequently (dominant), occasionally (opportunistic), or not at all (non-crop). Forty-seven per cent of the species in the wider landscape were also observed on leek flowers. Crop pollinator richness increased with local pollinator community size and increasing landscape complexity, but relationships were stronger for opportunistic than for dominant crop pollinators. Relationships between pollinator richness in semi-natural habitats and landscape complexity differed between groups with the most pronounced positive effects on non-crop pollinators. Our results indicate that while dominant crop pollinators are core components of crop pollinator communities in all agricultural landscapes, opportunistic crop pollinators largely determine species-richness responses and complex landscapes are local hotspots for both biodiversity conservation and potential ecosystem service provision.
•Ozone modulates the effect of pesticide exposure on crop pollinators.•Interacting effects between ozone and pesticide differed between Apis and non-Apis.•Ozone negatively impacts the contribution of ...pollinators to crop production.•Ozone should be considered for environmental policies in favor of biodiversity.
Human driven environmental changes increase the concentrations of polluting reactive compounds in the troposphere, such as ozone and nitrogen oxides. These changes lead to biodiversity losses and alter plant physiology and plant-pollinator interactions, essential for pollination services, with potential consequences for agricultural production. Here we used 133 unique sampling events from NW Europe to investigate how air pollution (ozone and nitrogen oxides) and other sources of nitrogen is related to pollinator visitation rate and their contribution to agricultural production, also considering possible interactive effects with landscape quality and pesticide input. We showed that ozone modulates the effect of pesticide exposure and temperature on crop pollinators, increasing the probability of negative impacts on crop pollination. Indeed, when ozone levels are highest, the strength of the effect of pesticide on pollinators is more than double then when ozone levels are intermediate. This indicates that air pollution should be considered in management plans and policies aiming to safeguard biodiversity and promote more sustainable food production practices.
•Drosophila suzukii and parasitoid wasp abundance increase with landscape complexity.•Pesticide effectiveness might be reduced in highly complex agroecosystems.•High mobility of D. suzukii across ...agricultural landscapes.•Low impact of conservation biological control (CBC) on D. suzukii management.•Long-term effects of CBC practices on invasive pest species remain unexplored.
Agricultural landscapes rich in natural and semi-natural habitats promote biodiversity and important ecosystem services for crops such as pest control. However, semi-natural habitats may fail to deliver these services if agricultural pests are disconnected from the available pool of natural enemies, as may be the case with invasive species. This study aimed to provide insights into the relationship between landscape complexity and the abundance of the recently established invasive pest species Drosophila suzukii and a group of natural enemies (parasitoid wasps), which contain species that parasitize D. suzukii in native and invaded ecosystems. The importance of landscape complexity was examined at two spatial scales. At the field scale, the response to introduction of wildflower strips was analysed, while the relationship with forest cover was assessed at the landscape scale. Half of the surveys were done next to blueberry crops (Vaccinium corymbosum), the other half was done in landscapes without fruit crops to examine effects of D. suzukii host presence. As expected, the number of observed parasitoid wasps increased with amount of forest surrounding the blueberry fields, but the number of D. suzukii individuals likewise increased with forest cover. Establishment of wildflower strips did not significantly affect the abundance of D. suzukii or parasitoid wasps and insect phenology was similar in landscapes with and without blueberry crops. This suggests that D. suzukii is enhanced by landscape complexity and is largely unlinked from the species group that, in its native range, hosts key natural enemies. Although management practices that rely on enhancing natural enemies through habitat manipulations can contribute to the long-term stability of agroecosystems and to control agricultural pests, other control measures may still be necessary in the short term to counteract the benefits obtained by D. suzukii from natural habitats.
Abstract Over the last two decades, ecological and conservation studies on pollinator insects have increased significantly. However, scientific evidence alone is not enough to translate knowledge ...into policy and into changes in behaviour. To reduce the gap between scientific knowledge on conservation actions and their actual uptake, one should understand the socio‐psychological drivers of people's willingness to undertake these actions. Here, we investigated the socio‐psychological factors influencing individual behaviour in favour of conservation interventions for pollinators in rural versus urban environments across three European countries: Germany, Italy and the Netherlands. We administered an online questionnaire to 4541 respondents stratified by nationality, environment, age and gender. Despite regional differences in socio‐cultural and economic conditions, individuals from Germany, Italy and the Netherlands living in both rural or urban environments shared similar socio‐psychological drivers to protect pollinators. People intended to take action to protect pollinators when they felt morally obliged to, when their social environment supported pollinator protection, when they believed their individual behaviour had an impact, and when they engaged frequently in outdoor activities. Interestingly, specific values held towards pollinators, such as their right to exist, seemed much more important predictors of activating norms that promote conservation actions compared to increasing general environmental concern. In all countries, among the conservation actions, the most likely to be implemented was planting flowers, while one of the most unlikely was participating in monitoring activities. Synthesis and applications . People from three contrasting European countries living in both rural and urban landscapes were mostly driven by the same socio‐psychological factors to help pollinator insects. Therefore, our results offer several practical recommendations to promote pollinator conservation across Europe. First, conservation practitioners interested in pollinator conservation should pay greater attention to values specific to pollinators, as they seemed more important behaviour predictors than general care for the environment. Second, engaging people in conservation efforts can be accomplished by increasing awareness about the vital roles that pollinators play within ecosystems. Lastly, promoting simple nature‐based activities such as wildlife observation, and gardening can help foster a sense of connection to and appreciation for pollinators and pollination. Read the free Plain Language Summary for this article on the Journal blog.
Read the free Plain Language Summary for this article on the Journal blog.
Thorny shrubs play a crucial role for the diversity and dynamics in wood pastures: they protect non-defended plants from large herbivores and thus facilitate tree establishment in the landscape ...through associational resistance. How thorny shrubs themselves establish in wood pastures – the main bottleneck for a dynamic shifting of grassland – shrub – woodland mosaics – is an essential unanswered question. We studied post-primary dispersal seed fate – i.e. removal, predation, secondary dispersal and survival of seeds after primary dispersal – of the thorny shrub blackthorn (
Prunus spinosa) in an ancient wood pasture in the Netherlands. Blackthorn seeds are primarily dispersed by frugivorous birds and may secondarily be dispersed by scatter-hoarding rodents.
We performed two cafeteria-style experiments with blackthorn seeds placed on dishes in the dominant vegetation types. In the first we monitored seed removal in grassland, swards or blackthorn shrubs and determined rodent species abundance by live-trapping. In the second we followed tagged blackthorn seeds under shrubs and in swards to determine seed removal, predation, survival and secondary dispersal patterns. Tagged seeds were retrieved using a metal detector and by visual means. We recorded dispersal direction and distance, vegetation type, seed handling (burial, consumption) and rodent species responsible via bite marks.
Seed removal and number of live-trapped rodents differed between vegetation types, with higher removal and rodent captures under shrubs than in swards and grassland. All retrieved seeds were depredated, predominantly by the wood mouse (
Apodemus sylvaticus). Disproportionally high seed numbers were retrieved in the vegetation type where originally placed (shrubs or swards).
Our study suggests that rodents play an important role for blackthorn in wood pastures, predominantly as seed predators rather than secondary seed dispersers. Predation is particularly high under blackthorn shrubs, suggesting that primary seed dispersal by birds away from shrubs into grassland or swards is a prerequisite for blackthorn recruitment in wood pastures.
► Post-primary dispersal seed fate of a thorny shrub was studied in a wood-pasture. ► Rodent seed removal and dispersal was monitored in different vegetation types. ► Seed removal was higher under shrubs than in swards and grasslands. ► All retrieved tagged seeds were depredated by rodents. ► Establishment of thorny shrubs requires primary seed dispersal away from shrubs.
Land-use change and global warming are important factors driving bee decline, but it is largely unknown whether these drivers have resulted in changes in the life-history traits of bees. Recent ...studies have shown a stronger population decline of large- than small-bodied bee species, suggesting there may have been selective pressure on large, but not on small species to become smaller. Here we test this hypothesis by analyzing trends in bee body size of 18 Dutch species over a 147-year period using specimens from entomological collections. Large-bodied female bees shrank significantly faster than small-bodied female bees (6.5% and 0.5% respectively between 1900 and 2010). Changes in temperature during the flight period of bees did not influence the size-dependent shrinkage of female bees. Male bees did not shrink significantly over the same time period. Our results could imply that under conditions of declining habitat quantity and quality it is advantageous for individuals to be smaller. The size and sex-dependent responses of bees point towards an evolutionary response but genetic studies are required to confirm this. The declining body size of the large bee species that currently dominate flower visitation of both wild plants and insect-pollinated crops may have negative consequences for pollination service delivery.
Species distribution models (SDM) are increasingly used to understand the factors that regulate variation in biodiversity patterns and to help plan conservation strategies. However, these models are ...rarely validated with independently collected data and it is unclear whether SDM performance is maintained across distinct habitats and for species with different functional traits. Highly mobile species, such as bees, can be particularly challenging to model. Here, we use independent sets of occurrence data collected systematically in several agricultural habitats to test how the predictive performance of SDMs for wild bee species depends on species traits, habitat type, and sampling technique. We used a species distribution modeling approach parametrized for the Netherlands, with presence records from 1990 to 2010 for 193 Dutch wild bees. For each species, we built a Maxent model based on 13 climate and landscape variables. We tested the predictive performance of the SDMs with independent datasets collected from orchards and arable fields across the Netherlands from 2010 to 2013, using transect surveys or pan traps. Model predictive performance depended on species traits and habitat type. Occurrence of bee species specialized in habitat and diet was better predicted than generalist bees. Predictions of habitat suitability were also more precise for habitats that are temporally more stable (orchards) than for habitats that suffer regular alterations (arable), particularly for small, solitary bees. As a conservation tool, SDMs are best suited to modeling rarer, specialist species than more generalist and will work best in long‐term stable habitats. The variability of complex, short‐term habitats is difficult to capture in such models and historical land use generally has low thematic resolution. To improve SDMs’ usefulness, models require explanatory variables and collection data that include detailed landscape characteristics, for example, variability of crops and flower availability. Additionally, testing SDMs with field surveys should involve multiple collection techniques.
Species distribution models (SDM) are becoming increasingly used to understand the factors that regulate variation in biodiversity patterns and to help plan conservation strategies. but are rarely validated with independent data. Here we use independent data to test how the predictive performance of SDMs constructed to predict wild bee distributions depends on species traits, habitat type, and sampling technique. We conclude that, as a conservation tool, SDMs are best suited to modelling rarer, specialist species than more generalist species and will be most useful in long‐term stable habitats.
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