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Landscape simplification decreases wild bee pollination services to strawberry

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... Natural or non-crop land in agriculture (e.g., forest, riparian vegetation, and fallow fields) acts as reservoirs for biodiversity and provides resources for bees and wasps [10,[12][13][14]. Wild bee abundance and richness is lower in farms with little natural land use, resulting in lower flower visitation and crop yields [13,14]. ...
... Natural or non-crop land in agriculture (e.g., forest, riparian vegetation, and fallow fields) acts as reservoirs for biodiversity and provides resources for bees and wasps [10,[12][13][14]. Wild bee abundance and richness is lower in farms with little natural land use, resulting in lower flower visitation and crop yields [13,14]. Similarly, wasp diversity, abundance, and activity in fields can decrease with increasing distance to, or between patches of natural vegetation [10,12]. ...
... Sites consisted of natural forests dominated by an overstorey of Eucalyptus and Corymbia species (four sites) or orchards that consisted of a complex matrix of commercial macadamia plantings (Macadamia integrifolia Maiden and Betche × M. tetraphylla Johnson) and forest fragments (three sites, Figure 1). We measured landscape simplification with the following metrics: dominant land use, plant richness, percentage of land cover type (forest and orchard), and distance to forest [13,19] ( Table 1). Study sites selected had ≥75% of target forest or orchard cover [38]. ...
Presentation
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Trap nests or “bee hotels” have been used to manage solitary bees since the 1950s in agriculture, research and, more recently, for urban conservation. Various designs are available for different purposes and target species, however, site characteristics such as land use also need to be considered. In this study, we test the performance of a hybrid design of timber and cobb trap nests in macadamia orchards and eucalypt forests around south-east Queensland. Overall, average occupation rates were similar in orchards and forests, with higher occupation in summer across all nesting substrates. Surprisingly, wasps (62%) were more likely to occupy timber substrates than bees (37%), particularly in orchards. Over 20 species of bee and wasp occupants were identified, including some parasitoid and cleptoparasitic species. Future research will identify key plants in the pollen diets and nest materials of bee occupants, which can be used to inform targeted approaches to habitat restoration.
... In terms of which scale should be used in future works that address how landscape features affect agricultural plots (e.g. Avelino et al., 2012;Connelly et al., 2015;Poveda et al., 2012), we found no optimal scale for the landscape level metrics. For the class level metrics, a grain size below 60 m is recommended, while the change of extent shows a pattern in which the metrics stabilize for all classes from 300 km 2 onwards. ...
... It has been shown that these differences in compositional and configurational heterogeneity can impact agricultural management practices (e.g. biological control strategies: Avelino et al., 2012;Connelly et al., 2015;Poveda et al., 2012;Thies and Tscharntke, 1999), persistence and conservation of native biodiversity (Burel, 1989;Chust et al., 2003;Connelly et al., 2015;Fahrig, 2003;Franklin and Lindenmayer, 2009;Gallé et al., 2019;Katayama et al., 2014;Ramos et al., 2018;Reis Madeiros et al., 2019;Rundlöf and Smith, 2006;Smith et al., 2010), agrobiodiversity reproduction (Avelino et al., 2012;Connelly et al., 2015;Weibull, 2003) and ecosystem services such as water availability, soil quality, qualityfood provisioning and overall human well-being (e.g. Gallé et al., 2019;Ickowitz et al., 2014;Laudon et al., 2016;Mora Van Cauwelaert, 2016). ...
... It has been shown that these differences in compositional and configurational heterogeneity can impact agricultural management practices (e.g. biological control strategies: Avelino et al., 2012;Connelly et al., 2015;Poveda et al., 2012;Thies and Tscharntke, 1999), persistence and conservation of native biodiversity (Burel, 1989;Chust et al., 2003;Connelly et al., 2015;Fahrig, 2003;Franklin and Lindenmayer, 2009;Gallé et al., 2019;Katayama et al., 2014;Ramos et al., 2018;Reis Madeiros et al., 2019;Rundlöf and Smith, 2006;Smith et al., 2010), agrobiodiversity reproduction (Avelino et al., 2012;Connelly et al., 2015;Weibull, 2003) and ecosystem services such as water availability, soil quality, qualityfood provisioning and overall human well-being (e.g. Gallé et al., 2019;Ickowitz et al., 2014;Laudon et al., 2016;Mora Van Cauwelaert, 2016). ...
... Por ejemplo, Liao y colaboradores (2016) encontraron que ciertas configuraciones pueden compensar la pérdida de hábitat y reducir los riesgos de extinción. Desde la perspectiva agrícola, existen estudios que demuestran que el tipo de paisaje que rodea las zonas agrícolas tiene un fuerte impacto en la polinización, la herbivoría, la fertilidad y la productividad de las parcelas (Fahrig, 2003;Tscharntke et al., 2005;Poveda et al., 2012;Connelly et al., 2015;Boesing et al., 2017). ...
... El paisaje de Zaachila, y probablemente muchos otros paisajes campesinos en nuestro país, tiene una mayor diversidad, complejidad y conectividad que los paisajes agrícolas en Estados Unidos (Urrutia et al., 2020). Este es un buen ejemplo de las diferencias que pueden existir entre los paisajes en zonas agrícolas de América Latina, manejados por campesinos, y los paisajes agrícolas que han sido el foco de los estudios de heterogeneidad del paisaje agrícola hasta el momento (Wu et al., 2002;McGarigal y Cushman, 2002;Wu, 2004;Peters et al., 2007;Poveda et al. 2012;Connelly et al. 2015). Así, esta comparación destaca la importancia de estudiar y caracterizar paisajes en los trópicos para poder entender los procesos socioecológicos que ahí ocurren y, enúltima instancia, discutir y diseñar estrategias acordes al contexto local. ...
... ;Avelino et al., 2012;Poveda et al., 2012;Ickowitz et al., 2014;Connelly et al., 2015;Karp et al., 2018;Gallé et al., 2019;Reis Madeiros et al., 2019) ...
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La Agroecología y las Ciencias de la Complejidad surgieron en la segunda mitad del siglo XX. En tanto campos académicos en construcción y de frontera, ambas enfrentan los retos de continuar reflexionando sobre sus bases epistémicas, explorar enfoques metodológicos novedosos y robustecer sus corpus a través de casos de estudio de distinta naturaleza. Este libro representa un primer esfuerzo por integrar un conjunto de trabajos desde la experiencia mexicana que, de alguna manera u otra, buscan tejer puentes entre la Agroecología y las Ciencias de la Complejidad respecto a los retos señalados. El eje conductor que subyace a la obra es la tesis central de que bajo cualquier acepción que se tenga sobre la ‘Agroecología’, esta involucrará constitutivamente procesos ecológicos, agrícolas, tecnológicos, socioeconómicos y políticos que se intersectan entre sí de múltiples maneras dando como resultado dinámicas emergentes y comportamientos inestables frecuentemente situados entre el orden y el desorden. Los entendimientos e interpelaciones de dichos procesos no pueden ni deben ser sobresimplificados por las miradas reduccionistas, sino por el contrario, requieren ser abordados de manera integral, entre otros enfoques, por las perspectivas filosóficas y las herramientas metodológicas heterodoxas propias de las Ciencias de la Complejidad. Algunas de las preguntas detonadoras que motivan la obra, son las siguientes: ¿Cuáles son las singularidades y aportes de reconocer y aproximarnos a la complejidad agroecológica? ¿Cómo dotarnos como agroecólogas y agroecólogos de nuevos andamiajes y herramientas de investigación? ¿Cómo dialoga la complejidad agroecológica con otras agroecologías, actores y sectores no académicos? ¿Qué rasgos tendría la complejidad agroecológica para el caso mexicano concretamente? ¿Cómo lidiar con la supuesta objetividad/neutralidad de los modelos desarrollados comúnmente en el marco de ciencias de la complejidad y llevar la complejidad agroecológica hacia la construcción participativa?
... Dans les paysages dominés par les grandes cultures par exemple, une faible diversité de plantes spontanées et de pollens est clairement observée au sein des parcelles cultivées comme dans les éléments semis-naturels en bordure des champs . Or les pollinisateurs sauvages sont des insectes particulièrement sensibles à ces pertes de diversité florale (Connelly et al., 2015;Hass et al., 2018;Wood et al., 2019). En conséquence, les abeilles oligolectiques (c'est-à-dire spécialisées sur une famille ou un genre botanique), plus vulnérables face à la diminution des ressources florales, voient leur population fortement impactée, ce qui conduit au final à une homogénéisation des communautés d'insectes observées (Danforth et al., 2019;Rowe et al., 2020;Wood et al., 2016). ...
... Nous sommes donc dépendants des services de pollinisation rendus par les pollinisateurs, car ils sont responsables à hauteur de 30 % de la production alimentaire (Klein et al., 2007). Les abeilles et les syrphes ont en particulier un rôle majeur dans la production alimentaire en qualité et en quantité (Blitzer et al., 2016;Burkle et al., 2013;Connelly et al., 2015;Gallai et al., 2009;Garibaldi et al., 2013). ...
... En effet, plusieurs études ont montré que le service de pollinisation augmente avec l'abondance et la diversité des abeilles sauvages (Fründ et al., 2013;Garibaldi et al., 2014), et que l'abeille domestique à elle seule n'est pas la meilleure pollinisatrice pour toutes les cultures (Javorek et al., 2002;Martin, 2015;Vicens et Bosch, 2000). Si on prend en compte l'ensemble des cultures entomophiles à l'échelle d'un paysage, c'est la complémentarité entre les différentes espèces d'abeilles qui fait leur efficacité dans la pollinisation : présence étalée dans le temps, taille du corps, longueur de la langue, mode d'alimentation (Blitzer et al., 2016;Connelly et al., 2015;Holzschuh et al., 2012). La diversité de ces traits écologiques et morphologiques permet de s'adapter à toutes les espèces de plantes et toutes les formes de fleurs (Loreau et Hector, 2001;Wood et al., 2017) et donc de permettre une pollinisation optimale. ...
Thesis
The intensification of agriculture with intensive use of inputs, simplification of the landscape, and reduction of semi-natural habitats, is known to contribute to the decline of arthropods. However, arthropods provide essential ecosystem functions and services in agroecosystems and for agricultural activities such as natural regulation of pests and weeds, and pollination. Increasing plant diversity in cultivated fields through the implementation of agroecological practices and infrastructures is a promising approach to promote the presence of arthropods and their associated ecosystem services. The overall objective of the thesis project was to design and experiment an innovative agroecological practice in maize cropping systems, which is easy to insert into existing cropping systems, and which provides an undisturbed habitat for ground-dwelling arthropods and supplementary floral resources for pollinators. The idea of the proposed practice was to capitalize on an already well known practice, the implementation of winter cover crops, by keeping a strip of a winter cover crop in the middle of the field during the whole maize cultivation period. Therefore, two research objectives were defined: i) to measure the impact of the practice on activity-density and diversity of ground-dwelling arthropods, on their dispersion in the cultivated area (spillover), and on the potential pest regulation in the adjacent cultivated area, and ii) to measure the interest of the practice for the conservation of wild pollinators in intensively cultivated landscapes. Field experiments took place on 12 commercial fields of volunteer farmers in 2019 and 2020, in order to take into account the technical and regulatory constraints of farmers in a conventional arable cropping system. Different species groups were surveyed: communities of ground-dwelling arthropods (carabids, spiders, staphylinids and harvestmen), slugs (the main maize pest in the study area), and pollinating insects (bees and hoverflies). Spatio-temporal dynamics of the different natural enemy groups were analysed, predation rates measured with sentinel prey, and the composition of carabid and wild bee communities investigated. Results show that the undestroyed cover crop strips constitute reservoirs of biodiversity, in particular for carabids, spiders, and bees. In the cropped area, no clear effect of the distance from the strip was detected for the different groups of ground-dwelling arthropods, thus no indication of a potential spillover of arthropods into the crop. However, two main carabid species (Poecilus cupreus and Pterostichus melanarius) were more abundant in the vicinity of the strip (10 meters), but not inside the strip, indicating a potential phenomenon of aggregation of these species towards the strip. Predation rates were higher in the strip and seemed to decrease with increasing distance from the strip into the cropped area. Moreover, carabid and bee communities showed to be different from one habitat to another, as well as the distribution of their ecological traits. Thus, the strips can provide complementary habitat and resources for natural enemies and pollinators. Finally, the spontaneous plants of field margins appeared to be essential for oligolectic and less common bees. The results of this thesis show that the conservation of a cover crop strip in the middle of cropped fields can be an effective practice for the conservation of beneficial arthropods in agricultural landscapes, but can also enhance ecosystem services such as pest regulation. Additionally, the results highlight the importance of preserving or even extending perennial semi-natural habitats such as field margins to contribute to biodiversity conservation in arable cropping systems and landscapes.
... Natural or non-crop land in agriculture (e.g., forest, riparian vegetation, and fallow fields) acts as reservoirs for biodiversity and provides resources for bees and wasps [10,[12][13][14]. Wild bee abundance and richness is lower in farms with little natural land use, resulting in lower flower visitation and crop yields [13,14]. ...
... Natural or non-crop land in agriculture (e.g., forest, riparian vegetation, and fallow fields) acts as reservoirs for biodiversity and provides resources for bees and wasps [10,[12][13][14]. Wild bee abundance and richness is lower in farms with little natural land use, resulting in lower flower visitation and crop yields [13,14]. Similarly, wasp diversity, abundance, and activity in fields can decrease with increasing distance to, or between patches of natural vegetation [10,12]. ...
... Sites consisted of natural forests dominated by an overstorey of Eucalyptus and Corymbia species (four sites) or orchards that consisted of a complex matrix of commercial macadamia plantings (Macadamia integrifolia Maiden and Betche × M. tetraphylla Johnson) and forest fragments (three sites, Figure 1). We measured landscape simplification with the following metrics: dominant land use, plant richness, percentage of land cover type (forest and orchard), and distance to forest [13,19] ( Table 1). Study sites selected had ≥75% of target forest or orchard cover [38]. ...
Article
Full-text available
(1) Background: Landscape simplification is a major threat to bee and wasp conservation in the tropics, but reliable, long-term population data are lacking. We investigated how community composition, diversity, and abundance of tropical solitary bees and wasps change with landscape simplification (plant diversity, plant richness, distance from forest, forest cover, and land use type) and season. (2) Methods: We installed 336 timber and cob trap nests in four complex forests and three simplified orchards within the subtropical biodiversity hotspot of south-east Queensland, Australia. Trap nests were replaced every season for 23 months and all emergents identified. (3) Results: We identified 28 wasp species and 13 bee species from 2251 brood cells. Bee and wasp community composition changed with landscape simplification such that large, ground-nesting, and spider-hunting species were present in all landscapes, while those with specialist resource requirements and (clepto) parasitoids were present only in complex landscapes. Abundance and diversity of bees and wasps were unaffected by landscape simplification but increased with rainfall. (4) Conclusions: This study highlights the need for multi-year studies incorporating nuanced measures such as composition with a focus on functional diversity to detect changes bee and wasp populations.
... Blitzer et al., 2016;Garibaldi et al., 2013;Garratt et al., 2014;Klein et al., 2007;Miñarro and Twizell, 2015;Nicholson and Ricketts, 2019), pollination in the orchard context is still one of the least understood management factors (Goodwin, 2012). In this context, there is a number of potentially interacting factors influencing the levels of pollen limitation such as crop species or variety, degree of dependence on cross pollination and on pollinator communities' diversity and abundance, landscape context and climate conditions (Connelly et al., 2015;Klein et al., 2007). Understanding pollination needs within the orchard is key to determine if this service is optimal or if it can be improved. ...
... These overall patterns may suggest a contrasting success of natural pollination in these regions. The large kiwifruit orchards, largely concentrated over a single region within New Zealand (Testolin and Ferguson, 2009), leading to landscape simplification, are expected to have significantly lower pollinator communities, resulting in poor natural pollination, as shown for other crops (e.g., strawberry, apple; Connelly et al., 2015;Martins et al., 2015) and in significant increments after supplementary (hand or mechanical) pollination (Connelly et al., 2015;King and Ferguson, 1991;Martins et al., 2015;Tacconi et al., 2016). In contrast, orchards in our study region are small and integrated within a heterogeneous landscape which may provide abundant pollinator communities (Gaspar, 2020;Castro et al., submitted). ...
... These overall patterns may suggest a contrasting success of natural pollination in these regions. The large kiwifruit orchards, largely concentrated over a single region within New Zealand (Testolin and Ferguson, 2009), leading to landscape simplification, are expected to have significantly lower pollinator communities, resulting in poor natural pollination, as shown for other crops (e.g., strawberry, apple; Connelly et al., 2015;Martins et al., 2015) and in significant increments after supplementary (hand or mechanical) pollination (Connelly et al., 2015;King and Ferguson, 1991;Martins et al., 2015;Tacconi et al., 2016). In contrast, orchards in our study region are small and integrated within a heterogeneous landscape which may provide abundant pollinator communities (Gaspar, 2020;Castro et al., submitted). ...
Article
Despite the key role of pollination in the production of many crops, this is still one of the least understood factors in the orchard context. Pollen limitation, and impacts on crop production, is influenced by several potentially interacting factors such as crop or crop variety degree of dependence on cross pollination and on pollinators, diversity and abundance of the pollinator communities, landscape context and climate conditions. Understanding the pollination needs within an orchard is key to determine if the pollination is optimal or if it needs improvement. In some crops, such as kiwifruit, artificial pollination may be required where and when natural pollination cannot be improved or there is lack of pollen. In this study we quantified improvements to productivity resulting from artificial pollination and the efficiency of the technique for kiwifruit production and monetary gain on seven orchards distributed over the production range of this crop in Portugal. For that, we quantified orchard yield under 1) current natural pollination services, including pollination provided by wind and naturally occurring pollinator communities, 2) after artificial pollination and 3) under optimal pollination services. We characterized fruit production and key fruit traits such as fruit weight, size and caliber, and used production values, fruit caliber and respective market values to calculate the economic impact of pollination improvement. Results showed that pollen supply improved kiwifruit production in most orchards, either by changes in fruit set, fruit weight or both, and/or changes in fruit distribution by caliber and category. However, artificial pollination was not always efficient and/or needed. Contrarily to the expected, the artificial pollination treatment did not increase fruit weight but, in some orchards, it resulted in higher proportion of high-quality market fruits and/or lower proportion of unmarketable fruits. The changes in fruit traits translated into a tendency towards a small to moderate increase in monetary gain in four out of the seven orchards. This study reinforces the need to understand the current status of pollination services within the orchard context and to look at artificial pollination as a management tool in kiwifruit production. We conclude that pollination services in the study region might be sufficient to attain profitable yields; however, artificial pollination could be a useful tool under unpredictable pollination scenarios, but reviews of the efficiency of the methodologies used in this region are still necessary.
... Land-use change, limited foraging resources, bee pathogens, pesticides, and the interaction among these factors have been identified as the main potential causes . At the landscape scale, increases in cultivated areas are associated with natural habitat reduction and fragmentation (Petit and Firbank, 2006), leading to less floral and nesting resources for bees (Heard et al., 2007;Potts et al., 2005) and to lower bee abundance and diversity, with negative impacts on crop pollination services (Bommarco et al., 2013;Connelly et al., 2015;Kremen et al., 2002;Le Féon et al., 2010). ...
... The images per site were combined in orthophotos in which polygons of different land cover types (natural habitat, pastures, and agriculture at the 500 m radius) were manually drawn to calculate the area, and the different land covers' proportions using QGIS Development Team (2016). We choose a 500 m scale because although larger scales can impact bee responses to land-use (Ferreira et al., 2015), bees maximize their foraging and nesting activity within a few hundred meters (Zurbuchen et al., 2010;Geib et al., 2015) and scales smaller than 1km tend to have higher predictive power (Moreira et al., 2015;Connelly et al., 2015;Földesi et al., 2016). Among the land cover types, the proportion of natural habitat and the proportion of pasture were highly correlated (Pearson's r = -0.97, ...
Article
Full-text available
Land-use change and pesticides have been identified as two of the main causes behind pollinator decline. Understanding how these factors affect crop pollinator communities is crucial to inform practices that generate optimal pollination and ensure sustainable food production. In this study, we investigated the effects of landscape composition and pesticide residues on bee communities and their pollination services in Solanum quitoense Lam. “lulo” crops in Colombia. On 10 farms, located along a gradient of land use change that varied from 0.15 to 0.62 in their natural habitat proportion, we characterized the bee community visiting the crop, and carried out pollination experiments with bagged and open inflorescences to later estimate fruit set, weight, and diameter at every site. Additionally, we performed pesticide analysis on collected anthers through liquid chromatography to estimate pesticide risk coming from the crop fields using hazard quotients (HQ). Bee abundance and species richness decreased with increased HQ, but these negative pesticide effects were less detrimental in farms with higher natural habitat proportions. However, this buffer effect was lost at sites with very high HQs. Imidacloprid was frequently found in the anthers and there were extremely high concentrations in some farms (0.6 to 13063 μg/kg), representing the molecule of greatest risk for bees in this context. Pollinator’s importance to crop yield was demonstrated in the exclusion experiments, where we found a reduction in fruit set (51%), weight (39%), and diameter (25%). We found a significant effect of bee richness on fruit set, while landscape composition and HQ had no significant effect on fruit set, suggesting that the last two factors do not affect yield directly, but indirectly through a decrease in pollinator diversity. Our results provide novel evidence that natural habitat loss due to the expansion of pastures for cattle ranching and pesticide residues in anthers reduce bee diversity and abundance in this Andean cropping system, but strategies to protect and restore natural habitat can help to buffer, until certain levels, these negative effects.
... Conversely land use intensification has negative impacts on pollinating insect communities. Their abundance and richness often decline with isolation, i.e. an increasing distance from (semi-)natural habitats (Blanche et al., 2006;Carvalheiro et al., 2012Carvalheiro et al., , 2010Chacoff and Aizen, 2006;Ricketts et al., 2008), and the increase of crop area has been associated with lower pollinator abundance and richness (Connelly et al., 2015) especially wild bee abundance and diversity (Benjamin et al., 2014;Landaverde-González et al., 2017). Moreover, the consideration of landscape-scale indirect indicators requires defining relevant spatial extents. ...
... As our study sites were located in landscapes relatively rich in semi-natural habitats, the effects of landscape composition might outweigh the possible effects of landscape configuration (Kennedy et al., 2013). Regarding land covers known as detrimental to pollinators, as we expected, we observed negative impacts of crops on pollinator communities, reflecting the loss of resources and habitat due to landscape simplification (Benjamin et al., 2014;Bommarco et al., 2012;Cariveau et al., 2013;Connelly et al., 2015). Despite its potential as supplementary floral resource, orchard cover had strong negative effects on pollinators other than honeybees for whom managed beehives present in orchards would be beneficial. ...
Article
Pollination is a critical ecosystem service given its essential role in sustaining food production, while pollinating insects are declining worldwide. Pollination capacity can be estimated through direct indicators characterising pollinator communities. Pollinators need feeding and nesting resources, so their presence can also be estimated through indirect indicators characterising these resources at plot and landscape scales. In this study, we aimed to identify the subset of resource indicators accounting for pollination capacity in orchards by relating insect presence to the most relevant environmental variables for managing pollinator presence. In 31 orchards of the Grenoble region (France) we measured direct indicators of pollinator abundance and richness at plot scale. Simultaneously we quantified indirect indicators of landscape and plot scale feeding and nesting resources. We selected indicators significantly correlated with insect presence using simple linear models between resource indicators and measures of insect taxonomic richness and abundance. Multiple linear regressions including significant resource indicators at both plot and landscape scales showed that landscape composition and presence of beehives explained between 19 and 63 % of the observed variance of pollinator community indicators. Total pollinator abundance decreased with distance to the closest grassland patch and increased with abundance of beehives. Pollinator richness increased with grassland cover within a 3 km radius. Domestic honeybee abundance increased with beehives located both in the plot and the landscape, and decreased with isolation from the closest grassland patch. Wild hymenopteran abundance increased with grassland cover within 3 km and forest cover at 500 m. Dipteran abundance increased when beehives were located only in the landscape. This study highlights the prevalent role of landscape-scale resources for pollinator communities over in-field flower resources. Thus, in order to favour pollinators, management should focus mainly on the landscape scale, necessitating cooperation between farmers. However, as resource indicators explained less than half of the observed variance for most community variables, inferring pollinator community characteristics from specific environmental variables remains uncertain. Further work could explore how orchard management practices influence our conclusions.
... given the increasing importance of this crop in Flanders and Europe and its different pollination requirements compared to well studies fruit crops like apple and strawberry for example (Chagnon et al. 1993;Connelly et al. 2015;Martins et al. 2015;Mallinger and Gratton 2016). Measures to promote functional pollinators in and around crop fields and their corresponding pollination service have deliverd mixed results due to the influence of landscape structure and because the floral composition of these measures is not tailored to certain target species or target crops (Scheper et al. 2013;Wood et al. 2015). ...
... Decreasing proportions of intensive fruit cultivation from 70 % to 0 % and from 50 % to 0 % in 250 m and 1000 m respectively, lead to a 400 % increase of fruit set. Other recent studies provide evidence for negative relations between rates of fruit sets and intensive agriculture in other crops (apple, strawberry, spring oilseed rape, buckwheat, field bean and pumpkin)(Bartomeus et al. 2014; Peterson and Nault 2014;Connelly et al. 2015).WhereasHolzschuh et al. (2012) concluded a 50% reduction in fruit set of sweet cherry with decreasing amount of semi-natural habitat in 1000 m from 50% to 20%. ...
... At the landscape scale, proximity and abundance of semi-natural habitats, grasslands and forests have been positively related with diverse and abundant pollinator communities (e.g., Holzschuh et al., 2012;Morandin and Winston, 2005;Somme et al., 2014). In contrast, intensification in land-use through increased crop area and increased crop isolation, negatively impact insect pollinator communities available to crops (e.g., Connelly et al., 2015;Ricketts et al., 2008). Despite the current knowledge, further information across different crops and regions worldwide is still needed to better understand the effect of different factors in pollination ecosystem services provisioning. ...
... Consequently, increased coverage or decreased distance to natural and semi-natural areas, such as forests and grasslands, has been observed to promote diverse pollinator communities (Holzschuh et al., 2012;Kennedy et al., 2013;Morandin and Winston, 2005;Shackelford et al., 2013), as observed in our study. In contrast, more simplified pollinator communities are expected in landscapes with high agricultural coverage (Carré et al., 2009), with increased crop area being associated with lower pollinator's abundance and richness (Benjamin et al., 2014;Connelly et al., 2015;Landaverde-González et al., 2017). ...
Article
Insects are a functionally diverse group, with economically relevant roles on key ecosystem services, such as pollination. The current trend of biodiversity loss and consequent degradation of ecosystem services delivered by insects is leading to additional pressure on modern agriculture, particularly in crops that depend on insects for pollination. Understanding how insect pollinator diversity varies at local and landscape scales is very important to recognize trends in pollinator populations. The present work quantified the effect of in-field management practices and different landscape types on insect pollinator communities in kiwifruit, a pollinator-dependent crop. Twenty-two orchards were selected and characterized for in-field practices, landscape structure, plant-pollinator interactions, and productivity. We observed that orchards with practices that are less harmful to insect pollinators are related to a higher pollinator diversity and higher abundances of certain wild pollinator groups, although this was not related with increased productivity. Additionally, in the studied production region, agricultural dominated landscapes harbor lower pollinator diversity, lower wild pollinators abundance and higher managed honeybee abundance than forest and herbaceous dominated landscapes, but no differences were detected in productivity among landscape types. In turn, abundance of Bombus spp. and the use of pollination support practices were significantly and positively correlated with orchard productivity. Despite the differences in pollinator communities, comparable yields were observed across different landscape types. Additionally, simple changes towards less harmful agricultural practices and the presence of forest and herbaceous habitats can promote wild pollinators and respective pollination services.
... In agricultural landscapes, semi-natural habitats, including forest, shrubland and grassland, can provide food resources such as pollen and nectar, as well as nesting sites for wild bee species (Hevia et al., 2021). Modern homogenized agricultural landscapes commonly contain large cropland areas and only few seminatural habitat fragments, resulting in reduced nectar and pollen resources and bee nesting sites (Connelly et al., 2015). Accordingly, studies regularly report that the decrease of semi-natural habitat negatively impacts wild bee communities (Connelly et al., 2015;Cusser et al., 2019;Larkin & Stanley, 2021;Papanikolaou et al., 2017), with further potential implications for crop pollination services (Holland et al., 2017;Klein et al., 2012). ...
... Modern homogenized agricultural landscapes commonly contain large cropland areas and only few seminatural habitat fragments, resulting in reduced nectar and pollen resources and bee nesting sites (Connelly et al., 2015). Accordingly, studies regularly report that the decrease of semi-natural habitat negatively impacts wild bee communities (Connelly et al., 2015;Cusser et al., 2019;Larkin & Stanley, 2021;Papanikolaou et al., 2017), with further potential implications for crop pollination services (Holland et al., 2017;Klein et al., 2012). ...
Article
1. Traditional smallholding-dominated agricultural landscapes in Southern China are increasingly homogenized and consolidated, resulting in large mono-cropped fields and impoverished pollinator communities. The exact impact of this farmland consolidation on composition and functional traits of wild bee communities remains poorly understood. 2. We studied these communities and functional traits in oilseed rape fields embedded in 18 agricultural landscapes located in Jiangxi Province, China, with 11 sites representing traditional (pre-consolidation) and the remaining 7 sites consolidated agricultural landscapes. 3. The composition of wild bee assemblages was not differentiated into consolidated and traditional farmland communities. The mean body size of wild bee species similarly did not shows significant differences between consolidated and traditional farmland. The mean intraspecific body size for a dominant species, Lasioglossum proximatum, was larger in consolidated than traditional farmland, while individuals of co-dominant Eucera floralia showed no such differentiation. In consolidated farmland, the proportion of semi-natural habitat was positively linked to the abundance-based average interspecific body size of wild bee species. For abundance-based calculations, the proportion of aboveground nesting bee species was lower in consolidated landscapes than in traditional ones. 4. Our study suggests that farmland consolidation might affect intraspecific composition, particularly in abundant small-bodied species. Above-ground nesting bees may require specific management interventions in consolidated agricultural landscapes to promote their persistence, which could take the form of semi-natural habitat patches introduced to fields that can also benefit the pollinator community more widely.
... Strawberries provided the most feasible system for this study for three reasons: (1) pollinators enhance fertilization and strawberry fruit production (McGregor, 1976;Lopez-Medina et al., 2004;Albano et al., 2009;Connelly et al., 2015), (2) A diverse range of insects pollinate strawberry (Albano et al., 2009;Connelly et al., 2015) and pollinator diversity has been shown to enhance strawberry pollination through functional complementarity (Chagnon et al., 1993;Klatt et al., 2014), (3) strawberry crops can be found in all four qualifying farm type settings (i.e., polyculture and monoculture, each within largely agricultural vs. largely natural landscapes); no other crop types met this study requirement in this or other farming areas in California at the time of the study. ...
... Strawberries provided the most feasible system for this study for three reasons: (1) pollinators enhance fertilization and strawberry fruit production (McGregor, 1976;Lopez-Medina et al., 2004;Albano et al., 2009;Connelly et al., 2015), (2) A diverse range of insects pollinate strawberry (Albano et al., 2009;Connelly et al., 2015) and pollinator diversity has been shown to enhance strawberry pollination through functional complementarity (Chagnon et al., 1993;Klatt et al., 2014), (3) strawberry crops can be found in all four qualifying farm type settings (i.e., polyculture and monoculture, each within largely agricultural vs. largely natural landscapes); no other crop types met this study requirement in this or other farming areas in California at the time of the study. ...
Article
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Numerous studies show that semi-natural habitats within agricultural landscapes benefit native pollinating insects and increase resultant crop pollination services. More recently, evidence is emerging that agricultural diversification techniques on farms, as well as increased compositional and configurational heterogeneity within the cropped portion of landscapes, enhance pollinator communities. However, to date, only a few studies have investigated how diversifying the crops within the farm field itself (i.e., polyculture) influences wild pollinator communities and crop pollination services. In the Central Coast of California, we investigate how local crop diversification within fields, crossed with the proportion of natural habitat in the surrounding landscape, jointly affect pollinator communities and services to strawberry. On 16 organic farms varying in farm type (monoculture vs. polyculture) and proportion of natural land cover, we find that both factors enhance pollinator abundance and richness, although neither affect honey bee abundance. Further, natural cover has a stronger effect on pollinator richness on monoculture (vs. polyculture) farms. Although strawberry can self-pollinate, we document experimentally that pollinator exclusion doubles the probability of berry malformation, while excluding both pollinators and wind triples malformation, with corresponding effects on berry marketability. Finally, in post-hoc tests, we find that berry malformation is significantly higher with greater visitation by honey bees, and observed a trend that this reduction was mitigated by increased native bee richness. These results suggest that both polyculture and semi-natural habitat cover support more abundant and diverse pollinator communities, and that ambient levels of pollinator visitation to strawberry provide an important crop pollination service by improving berry marketability (i.e., by reducing berry malformation). Although further confirmation would be needed, our work suggests that honey bees alone do not provide sufficient pollination services. Prior work has shown that honey bees tend to visit only the top of the strawberry flower receptacle, while other native bees often crawl around the flower base, leading to more complete pollination of the achenes and, consequently, better formed berries. If honey bee visits reduced native bee visitation in our system, this could explain the unexpected correlation between increased honey bee visits and malformation.
... Homogenization of agricultural landscapes through the conversion of semi-natural habitat into arable land and the removal of linear perennial habitats has led to declines in farmland biodiversity, threatening the provision of key ecosystem services such as biological pest control and pollination (Connelly, Poveda, & Loeb, 2015;Dainese et al., 2019). Moreover, crop rotations have been substantially shortened following the industrialization of agriculture and due to specialization of crop growing in different landscapes (Bennett, Bending, Chandler, Hilton, & Mills, 2012). ...
Article
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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.
... Currently, the number of insect pollinators is decreasing worldwide (Potts et al., 2010;Biesmeijer et al., 2006;Rhodes, 2018;Thomann et al., 2013;Connelly et al., 2015). About 35% crops directly dependent on pollinators (Klein et al., 2007), with the cost approximately 153 billion euros per year (Gallai et al., 2009). ...
Article
Bumblebees are important for crop pollination. Currently, the number of pollinators is decreasing worldwide, which is attributed mostly to the widespread use of pesticides. The aim of this work was to develop a method for assessing the genotoxicity of pesticides for the Bombus terrestris L. bumblebee using long-range PCR of mitochondrial DNA fragments. We have developed a panel of primers and assessed the genotoxicity of the following pesticides: imidacloprid, rotenone, deltamethrin, difenocanozole, malathion, metribuzin, penconazole, esfenvalerate, and dithianon. All pesticides (except imidacloprid) inhibited mitochondrial respiration fueled by pyruvate + malate; the strongest effect was observed for rotenone and difenocanozole. Three pesticides (dithianon, rotenone, and difenocanozole) affected the rate of H2O2 production. To study the pesticide-induced DNA damage in vitro and in vivo, we used three different mtDNA. The mtDNA damage was observed for all studied pesticides. Most of the studied pesticides caused significant damage to mtDNA in vitro and in vivo when ingested. Our results indicate that all tested pesticides, including herbicides and fungicides, can have a toxic effect on pollinators. However, the extent of pesticide-induced mtDNA damage in the flight muscles was significantly less upon the contact compared to the oral administration.
... Such a bias is especially likely if wild pollinator activity varies over time in a nonrandom manner, in which case crop-or region-specific fixed effects would fail to control for its effects. If wild pollinators function as complements in production to managed honey bees, as found in some studies (e.g., Connelly et al. 2015;Garibaldi et al. 2013;Mallinger & Gratton 2015), the estimated parameters likely overstate the effectiveness of pollination provided by honey bees. ...
Preprint
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Many food crops rely on pollination by animals. Historically, wind and wild organisms provided pollination as an ecosystem service that varied across agroecological zones, cropping systems, and time. The value of these pollination services is likely substantial but has not been estimated reliably. More recently, pollination services in major crop-producing regions have been provided through organized markets, primarily the rental of honey bees. The sustainability of commercially provided pollination services is being challenged by parasites, diseases, pesticide exposures, poor nutrition, and Colony Collapse Disorder. Economic analyses indicate that honey bee rental markets have been able to adjust to those challenges, at least to date. Understanding the future sustainability of rental markets requires greater knowledge of the contributions of wild pollinators, optimal management of pollination services from wild and managed organisms, and the value of pollination services provided by wild and managed organisms. Expected final online publication date for the Annual Review of Resource Economics, Volume 13 is October 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
... During the relatively short pan-trapping time period of 48 h, we recorded on average 10 species per site (ranging from 5 to 15), in line with the results of long-term monitoring of orchard bee diversity (on average 36.5 species per site across the whole apple flowering season) in the United States of America by Russo et al. (2015). Field-based correlational and experimental research suggests that species richness is more important for high pollination provision in extremely species-poor systems, in study systems with gradients in species diversity that include very species-poor sites (Albrecht et al., 2012;Connelly et al., 2015;Blitzer et al., 2016) or at high spatial (e.g., regional) scales due to species turnover (Winfree et al., 2018). Controlled cage experiments by Fründ et al. (2013) showed the highest increase in pollination service provision when augmenting species richness from one to more than one species. ...
Article
Pollinator biodiversity may benefit crop pollination. Yet benefits in agro-ecosystems may be context-dependent and offset by agronomic or other limiting orchard-specific or tree-specific factors that obscure biodiversity-ecosystem service relationships. To test if crop pollination benefitted from pollinator biodiversity, we sampled local wild bee communities in five organic and five Integrated Pest Management (IPM) apple orchards in Ger-many and experimentally measured the pollination success of apple flowers, quantified as the number of pollen tubes reaching the base of styles. Using standard statistical modelling approaches for over-dispersed count data, we found little or no effect of wild bee biodiversity on pollination success, irrespectively of farm management (organic versus IPM). There was, however, a positive relationship between the number of pollen tubes in insect-pollinated and pollen-supplemented flowers across trees and orchards, suggesting confounding effects of local tree-or orchard-specific factors limiting pollination success. Using a statistical two-part hurdle model which allowed us to separate (i) the probability of pollination and (ii) the quantity of pollination, we were able to demonstrate that the collective effects of local tree/orchard factors acted as a primary limiting threshold for pollination success. Once the threshold was crossed, the hurdle model demonstrated that increasing wild bee abundance enhanced pollination success of apple trees. We advocate the use of statistical two-part models as a more powerful approach to identifying limiting factors of, and the role of biodiversity in, crop pollination and potentially other ecosystem services in agro-ecosystems.
... It should be considered, however, that these studies use larger landscape scales, and both the total area of semi-natural elements and type and intensity of land use vary greatly, which could explain the increase in richness associated with different covers (Tscharntke et al., 2005). The type of landscape present in this study, composed of large monoculture fields, as in most of the extended croplands in the Pampas, may be affecting most native pollinator species, in general with lower foraging ranges, which decrease their richness and abundance (Connelly et al., 2015). However, except for species foraging only in a very narrow range around their nest (less than 125 m), 200 and 500 m landscape scale might not be enough for larger pollinators, such as A. mellifera and Bombus ssp. ...
... Negative relationships have been demonstrated between wider land-use intensity, often measured in terms of inputs of nitrogen fertilizer or agrochemical use, and wild bee diversity [55] or honey bee performance [56]. Similarly, pollination services provided by wild bees, often a function of bee abundance and/or diversity, can be reduced in simplified, monoculture, landscapes compared with more complex and diverse agricultural settings [57]. Many of these patterns are not universal, however, and contrary situations exist where, for example, organic management and enhanced landscape complexity have no demonstratable beneficial effects on insect pollinators [55,58,59]. ...
Article
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To provide a complete portrayal of the multiple factors negatively impacting insects in agricultural landscapes it is necessary to assess the concurrent incidence, magnitude, and interactions among multiple stressors over substantial biogeographical scales. Trans-national ecological field investigations with wide-ranging stakeholders typically encounter numerous challenges during the design planning stages, not least that the scientific soundness of a spatially replicated study design must account for the substantial geographic and climatic variation among distant sites. ‘PoshBee’ (Pan-European assessment, monitoring, and mitigation of Stressors on the Health of Bees) is a multi-partner transdisciplinary agroecological project established to investigate the suite of stressors typically encountered by pollinating insects in European agricultural landscapes. To do this, PoshBee established a network of 128 study sites across eight European countries and collected over 50 measurements and samples relating to the nutritional, toxicological, pathogenic, and landscape components of the bees’ environment. This paper describes the development process, rationale, and end-result of each aspect of the of the PoshBee field investigation. We describe the main issues and challenges encountered during the design stages and highlight a number of actions or processes that may benefit other multi-partner research consortia planning similar large-scale studies. It was soon identified that in a multi-component study design process, the development of interaction and communication networks involving all collaborators and stakeholders requires considerable time and resources. It was also necessary at each planning stage to be mindful of the needs and objectives of all stakeholders and partners, and further challenges inevitably arose when practical limitations, such as time restrictions and labour constraints, were superimposed upon prototype study designs. To promote clarity for all stakeholders, for each sub-component of the study, there should be a clear record of the rationale and reasoning that outlines how the final design transpired, what compromises were made, and how the requirements of different stakeholders were accomplished. Ultimately, multi-national agroecological field studies such as PoshBee benefit greatly from the involvement of diverse stakeholders and partners, ranging from field ecologists, project managers, policy legislators, mathematical modelers, and farmer organisations. While the execution of the study highlighted the advantages and benefits of large-scale transdisciplinary projects, the long planning period emphasized the need to formally describe a design framework that could facilitate the design process of future multi-partner collaborations.
... Honey bees are the most prolific pollinators of pollinator dependent crops [3], however annual losses of managed honey bees can currently reach as high as 50% due to a suite of factors such as exposure to pesticides, reduced forage availability, parasites, and diseases [4,5]. As a result, researchers are investigating the role of wild bees as crop pollinators, which are declining due to human disturbances such as habitat loss/fragmentation [6], landscape simplification [7], and increased pesticide use [8]. Management practices that increase abundance and species richness of native bees can ...
Article
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Native bees provide essential pollination services in both natural and managed ecosystems. However, declines in native bee species highlight the need for increased understanding of land management methods that can promote healthy, persistent populations and diverse communities. This can be challenging and costly using traditional scientific methods, but citizen science can overcome many limitations. In this study, we examined the distribution and abundance of an agriculturally important wild bee species, the squash bee (Eucera (Peponapis) pruinosa, Hymenoptera: Apidae). They are ground nesting, specialist bees that depend on cultivated varieties of Cucurbita (squash, pumpkins, gourds). The intimate relationship between squash bees and their host plants suggests that they are likely sensitive to farm management practices, particularly those that disturb the soil. In this study, citizen scientists across Michigan used a survey to submit field management and bee observation data. Survey results indicated that squash bees occupy a wide geographic range and are more abundant in farms with reduced soil disturbance. Citizen science provided an inexpensive and effective method for examining impacts of farm management practices on squash bees and could be a valuable tool for monitoring and conserving other native pollinators.
... Either way, our results were consistent with other studies showing that landscape simplification and homogenization affect bee abundance and richness, which could result from the lack of or reduced food resources (Benton et al. 2003;Dainese et al. 2019). In a landscape with relatively low cover of native vegetation, management intensity is a strong predictor of bee diversity (Batáry et al. 2011;Kennedy et al. 2013) and thus can negatively impact bee diversity and pollination services (Connelly et al. 2015). Our results suggested that increasing the interspersion of focal crops and forest fragments could facilitate the flow of pollinators and avoid crop areas with low pollinator abundance (Mitchell et al. 2015;Holzschuh et al. 2016). ...
Article
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ContextAs agricultural demands for land continues to expand, strategies are urgently needed to balance agricultural production with biodiversity conservation and ecosystem service provision in agricultural landscapes.Objectives We used a factorial landscape design to assess the relative contributions of forest proximity and local forest cover to bee diversity and the provision of coffee pollination services.Methods We quantified bee diversity and fruit set in 24 sun-grown coffee fields in Southeast Region of Brazil that were selected following a factorial sampling design to test the independent effects of local forest cover (in a radius of 400 m) and proximity to forest fragments. To assess the impact of landscape simplification, we also evaluated local coffee cover.ResultsBee richness and abundance were higher in the proximity of forest fragments, but only bee abundance decreased when the coffee cover dominated the surrounding landscapes. Coffee fruit set was 16% higher overall with bee visitations compared with bee exclusion and increased to 20% when coffee bushes were near forest fragments, and the coffee cover was low. Surprisingly, local forest cover did not affect the bee community or coffee fruit set.Conclusion Our results provide clear evidence that the proximity of coffee crops to forest fragments can affect the abundance and richness of bees visiting the coffee flowers and thereby facilitate the provision of pollination services. The positive association between forest proximity and fruit set reinforces the importance of natural vegetation in enhancing bee diversity and, therefore, in the provision of pollination services. The negative effect of coffee cover on fruit set at the local scale suggests that the service demand can surpass the capacity of pollinators to provide it. These effects were independent of the local forest cover, although all studied landscapes had more than 20% remaining forest cover (within a 2 km radius), which is considered the extinction threshold for Atlantic Forest species. Interspersion of forest fragments and coffee plantations in regions with more than 20% of forest cover left could thus be a useful landscape management target for facilitating pollinator flows to coffee crops and thus for increasing coffee yields.
... Previous studies have concluded that, in terms of strawberry crop pollination, flies provide a unique contribution, in that they visit flowers during periods of inclement weather when other pollinators were absent (Ellis et al., 2017), and hoverflies have been found to be efficient pollinators of strawberry (Hodgkiss, Brown, & Fountain, 2018). Indeed, studies conclude that it is abundance and functional trait, more than pollinator type, which contributes most to pollination efficiency in strawberries (Connelly, Poveda, & Loeb, 2015;Ellis et al., 2017). In both the citizen science and researcher experiments, beetles were also frequent visitors to strawberry plants. ...
Article
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1. Global pollinator declines have led to concern that crop yields might fall as a result of a pollination deficit. Companion planting is a traditional practice thought to increase yield of insect pollinated crops by planting a co‐flowering species next to the crop. 2. Using a combination of conventional researcher‐led experiments and observational citizen scientist data, we tested the effectiveness of bee‐friendly borage (Borago officinalis) as a companion plant to strawberry (Fragaria x ananassa). Insect visitors to the ‘Test’ (strawberry + borage) versus ‘Control’ (strawberry only) plants were observed, and strawberry fruit collected. Strawberries collected during the researcher‐led experiment were also subject to fruit measurements and assessments of market quality. 3. Companion plants were found to significantly increase both yield and market quality of strawberries, suggesting an increase in insect pollination per plant. Test strawberries companion planted with borage produced an average of 35% more fruits, and 32% increased yield by weight. Test strawberry plants produced significantly more fruit of higher aesthetic quality when assessed by Marketing Standards for Strawberries. 4. Although there was no significant difference in the overall insect visits, when broken down by broad insect group there were significantly more flies visiting the test strawberries than controls. 5. These results could have implications for both gardeners and commercial growers. As consumers prefer a cosmetically perfect fruit, the production of fruit with increased aesthetics aids food waste reduction.
... At this time there is a global trend of pollinators decreasing [64][65][66][67][68]. Possible reason for this is the toxic pesticides effects [69,70]. ...
Article
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In recent decades an increase in the use of pesticides to protect plants from pests, diseases and weeds has been observed. There are many studies on the effects of various pesticides on non-target organisms. This review aims to analyze and summarize published scientific data on the effects of pesticides on the animal microbiome. Pesticides can affect various parameters of the animal microbiome, such as the taxonomic composition of bacteria, bacterial biodiversity, and bacterial ratios and modify the microbiome of various organisms from insects to mammals. Pesticide induced changes in the microbiome reducing the animal’s immunity. The negative effects of pesticides could pose a global problem for pollinators. Another possible negative effect of pesticides is the impact of pesticides on the intestinal microbiota of bumblebees and bees that increase the body’s sensitivity to pathogenic microflora, which leads to the death of insects. In addition, pesticides can affect vitality, mating success and characteristics of offspring. The review considers methods for correcting of bee microbiome.
... In some ways, the ultimate criterion for judging the success of agroecological management is whether or not production amount and/or quality is improved. While the general consensus seems to be that conservation biological control regularly does enhance production, counter examples are common, and it is clear that results are system-specific and cannot be safely presumed (Letourneau et al. 2011, Winqvist et al. 2011, Veres et al. 2013, Begg et al. 2017; see, positive effects from NY in Connelly et al. 2015 [looking at the effect of landscape simplification]). It's worth noting that there may be an inherent bias in these results given the probably greater excitement to publish positive rather than negative results. ...
Technical Report
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Report on several years of agroecological study of the effects of perennial wildflowers and forest edge on insects and spiders on a Mid-Hudson Valley Farm.
... Effects of landscape composition are similar across northeastern United States crop systems. Isolation from natural areas reduces bee visitation in multiple northeastern United States specialty crops (Connelly et al. 2015, Nicholson et al. 2017; however, crop systems are not always isolated from natural areas (Winfree et al. 2008, this study). ...
Article
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Homogeneous, agriculturally intense landscapes have abundant records of pollinator community research, though similar studies in the forest-dominated, heterogeneous mixed-use landscape that dominates the northeastern United States are sparse. Trends of landscape effects on wild bees are consistent across homogeneous agricultural landscapes, whereas reported studies in the northeastern United States have not found this consistency. Additionally, the role of noncrop habitat in mixed-use landscapes is understudied. We assessed wild bee communities in the mixed-use lowbush blueberry (Vaccinium angustifolium Ait.) production landscape of Maine, United States at 56 sites in eight land cover types across two regional landscapes and analyzed effects of floral resources, landscape pattern, and spatial scale on bee abundance and species richness. Within survey sites, cover types with abundant floral resources, including lowbush blueberry fields and urban areas, promoted wild bee abundance and diversity. Cover types with few floral resources such as coniferous and deciduous/mixed forest reduced bee abundance and species richness. In the surrounding landscape, lowbush blueberry promoted bee abundance and diversity, while emergent wetland and forested land cover strongly decreased these measures. Our analysis of landscape configuration revealed that patch mixing can promote wild bee abundance and diversity; however, this was influenced by strong variation across our study landscape. More surveys at intra-regional scales may lead to better understanding of the influence of mixed-use landscapes on bee communities.
... Like Connelly et al. (2015), we found that Bombus species were the most dominant group in strawberry fields (54.1 %). Together with solitary bees (19.7 %), they represent about 75 % of the bee community in strawberry fields. ...
Article
The demand for crop pollination is increasing and honey bees are frequently used, in particular as wild pollinators are in decline. Temporal and spatial variation of flower resources affects foraging decisions of wild and honey bees. To optimise crop pollination management a better understanding of potential competition for pollinators in mass- and minor-flowering crops is needed. We combined waggle dance decoding, pollen load analysis and field surveys to identify the habitat preferences and pollen use of honey bees in response to spatio-temporal changes in resource availability. Observation hives were placed on the edge of eleven fields of blooming strawberries (mean 2.24 ha) located in landscapes with different amounts of oilseed rape (OSR), semi-natural habitats (SNH) and apple trees in Germany. In addition, we surveyed honey bees and wild bees in strawberry fields. Honey bee dances more often indicated strawberry, OSR fields and SNH than expected given their landscape-wide areas. Honey bees collected on average 7.9 % strawberry, 49.0 % OSR, 30.2 % Pyrus type (e.g. apple) and 12.9 % other pollen types. The mean honey bee foraging distance was 740 m, and decreased with OSR availability. In the observation hives, dances for strawberry fields were not directly affected by OSR availability or SNH land cover. But large amounts of OSR reduced overall honey bee and bumble bee abundance in strawberry fields, while solitary bees were unaffected. Bumble bees were most abundant in strawberry fields (54.1%) and together with solitary bees (19.7%) they represented about 75.0% of the observed bees. Minor-flowering strawberry fields represent a preferred resource for honey bees, especially for small colonies as indicated by decoding of waggle dances. However, the availability of more attractive OSR and local strawberry flower cover moderates the abundance of social bees (honey bees and bumble bees) in strawberry fields while other wild bees were less affected. Hence, we conclude that wild bee conservation plays a major role for strawberry pollination. If pollination services by solitary bees are limited, small honey bee hives can be used scrupulously to supplement pollination services in strawberries.
... Our findings show that the foraging behaviour of bumble bees is more likely to facilitate cross pollination than the foraging behaviour of honey bees in sweet cherry. This foraging behaviour is a good proxy for pollination service and can also explain the positive relationship between wild pollinators and enhanced crop pollination in similar crop systems (Willmer et al., 1994;Klein et al., 2012;Holzschuh et al., 2012;Mallinger & Gratton, 2015;Connelly, Poveda, & Loeb, 2015;Alomar et al., 2018). In addition, bumble bee diversity and abundance also promote pollination service indirectly by altering honey bee foraging behaviour to promote their pollination performance. ...
Article
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Pollination service in agricultural crops increases significantly with pollinator diversity and wild pollinator abundance.Differences in the foraging behaviour of pollinating insects are one of the reasons why pollinator diversity and abundanceenhances crop pollination. Here, we focused on the foraging behaviour of honey bees and bumble bees in sweet cherry orchards.In addition, we studied the influence of bee diversity and abundance on the foraging behaviour of honey bees and bumble bees.Honey bees were found to visit fewerflowers than bumble bees. Bumble bees also showed a higher probability of changingtrees between rows than honey bees. Both visitation rate and probability of row changes of honey bees increased with bumblebee diversity and with bumble bee abundance. We also found that the probability of row changes of honey bees increased withincreasing bumble bee abundance. These effects of bumble bee richness and abundance on the pollination behaviour of honeybees can improve the pollination performance of honey bees in crops that depend on cross pollination. Our results highlight thehigher pollination performance of bumble bees and the facilitative effect of wild pollinators to crop pollination.
... Soil communities, and thereby the supporting function of soils, can be enhanced by altered management practices, active modification of the rhizosphere microbiome can enhance the crops' resistance to pests and facilitate nutrient uptake [32], new plant breeding techniques to improve immune resilience of plants may reduce susceptibility against diseases and extreme environmental conditions [33,34], and innovative fertilization techniques and promoting facilitative plant processes in multi-species cropping systems may enhance crop access to soil nutrients, resilience to pests, and productivity [35,36]. At the landscape level, more evidence is accumulating that the spatial organization (amount, diversity, and layout) of natural elements in agricultural landscapes can reduce pest pressure, and can increase natural pest control and pollination, as well as biodiversity in general [37,38]. Some of these techniques can also be applied in conventional systems to reduce their dependency on external inputs, which may contribute to changing the mindset of farmers and opening up the institutions of the current food system to accept more drastic changes towards sustainability [29,39]. ...
Article
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The future of food is one of the major world-wide challenges. In this perspective paper, we set-up a framework for a multi-disciplinary future food systems approach, building on the UN Sustainable Development Goals. We hereby combine a truly sustainable approach including social science aspects combined with the One Health approach. Scientists from a large number of backgrounds have addressed four key areas that are discussed in more detail in this paper: (i) nature inspired food production, (ii) sustainable immune resilience, (iii) social and cultural change of food behavior, and (iv) food fairness. We believe that transformations to integrated future food system approaches should move beyond single solutions and can only be solved by working in transdisciplinary settings of science, society, and industry.
... Hal yang menarik adalah, walaupun sebagian besar tanaman budidaya merupakan tanaman yang dapat melakukan penyerbukan sendiri keberadaan kunjungan serangga dapat meningkatkan produktivitas dari tanaman tersebut (Pellegrino et al., 2005). Akan tetapi, seringkali kondisi agroekosistem tidak menunjang keberadaan serangga-serangga penyerbuk liar (Connelly et al., 2015). Peran dari serangga-serangga liar ini selanjutnya dapat digantikan dengan lebah madu yang telah didomestikasi (Ige et al., 2011). ...
Article
Penyerbukan serangga merupakan salah satu upaya peningkatan efisiensi produksi tanaman berbuah pada lahan terbatas. Penelitian bertujuan mengamati aktivitas dan efisiensi penyerbukan serangga liar dan Tetragonula laeviceps pada tanaman ranti dan kacang panjang dengan sistem tanam tumpang sari di Desa Sukawangi, Kabupaten Sumedang pada bulan September hingga Januari 2020. Pengamatan dilakukan pada pukul 08:00-15:00 WIB selama periode perbungaan. Pengamatan dilakukan pada perlakuan aplikasi T. laeviceps, open-pollination, dan self-pollination, masing-masing perlakuan terdiri atas 100 bunga ranti dan 100 bunga kacang panjang dan dianalisis menggunakan one way analysis of variance (α = 0.05). Aktivitas serangga diukur berdasarkan flower handling time, foraging rate, visitation rate, dan fruit set. Kualitas buah diukur berdasarkan diameter, bobot, panjang, dan oBrix. Hasil penelitian ditemukan masing-masing tiga serangga pengunjung berpotensi polinator pada ranti dan kacang panjang dengan pola kunjungan bervariasi pada open-pollination. Efisiensi fruit set tertinggi ranti terjadi pada perlakuan aplikasi T. laeviceps dan kacang panjang pada perlakuan open-pollination. Terdapat perbedaan nyata pada oBrix buah ranti dan kacang panjang, sedangkan self-pollination hanya menghasilkan buah yang secara signifikan lebih panjang pada kacang panjang. Dengan demikian, T. laeviceps dapat dijadikan salah satu alternatif serangga penyerbuk terdomestikasi dalam upaya efisiensi fruit set dan kualitas buah tanaman ranti dan kacang panjang. Kata kunci: aktivitas serangga, fruit set, kualitas buah
... Such a bias is especially likely if wild pollinator activity varies over time in a nonrandom manner, in which case, crop-or region-specific fixed effects would fail to control for its effects. If wild pollinators function as complements in production to managed honey bees, as found in some studies (e.g., Connelly et al. 2015, Mallinger & Gratton 2015, the estimated parameters likely overstate the effectiveness of pollination provided by honey bees. ...
... Pollinator diversity has been declining globally in the last few decades due to increased habitat loss and fragmentation caused by land-use changes, such as urbanization or intensive farming (Biesmeijer et al., 2006;Potts et al., 2010). Since approximately 35% of global crop production volume relies on pollinators (Klein et al., 2007), pollinator decline is becoming a serious problem for human food security (Connelly et al., 2015;Potts et al., 2016). Thus, understanding the maintenance and enhancement mechanisms of pollinator diversity and pollination services in agricultural landscapes is essential for sustainable crop production. ...
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Pollinators have been declining in recent years due to changes in land use, and the negative impacts on food production are concern. Wildflowers play an important role in maintaining pollinators and pollination services in agricultural landscapes, but little is known about the effects of wildflowers at field margins on crop pollinators. We aimed to clarify the relationship between crop pollination and the species richness of wildflowers at field margins through sharing of flower visitors. We focused on insects that visit the flowers of buck-wheat, Fagopyrum esculentum, in fields in Japan. Field surveys were conducted to investigate flower-visiting insect communities in both the pre-blooming and blooming periods of buckwheat in summer and autumn. The community structure of flower-visiting insects differed between buckwheat and wildflowers in both seasons, but buckwheat shared beetles with co-flowering plants in autumn. The abundance of insects visiting buckwheat increased with species richness of co-flowering plants in autumn but was not related to wildflowers in summer. The morphological similarity of floral traits would not be important for these positive effects of wildflowers. Thus, co-flowering plants have positive or neutral effects on the insects visiting buck-wheat, which may contribute to the enhancement of buckwheat yields. K E Y W O R D S agricultural management, crop pollination, floral resources, indirect effects, pollinator sharing
... Similarly, it follows that, when pests are controlled, fruit production increases (Grass, Bohle, Tscharntke, & Westphal, 2018;Lundin et al., 2017). While past strawberry research emphasizes the importance of pollination services (Connelly, Poveda, & Loeb, 2015;Hodgkiss, Brown, & Fountain, 2018;Klatt et al., 2014;MacInnis & Forrest, 2019), we show that it is necessary to understand the implications of insect pollination in imperfect systems, such as organic urban farms, where pathogen and pest damage may be higher compared with conventional agricultural systems (Crowder, Northfield, Strand, & Snyder, 2010). Other studies in urban settings have shown that for certain crops, such as cucumber and tomato, bee visitation results in higher fruit productivity when wild bees are the dominant pollinators, as was the case in our study (Lowenstein, Matteson, & Minor, 2015;Potter & LeBuhn, 2015). ...
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While many cities have embraced urban agriculture, research examining crop productivity in urban environments is limited. Little is known about how abiotic and biotic factors affecting productivity on urban farms compare with those in rural environments. In this study, we investigated environmental factors influencing strawberry (Fragaria x ananassa) productivity for two cultivars at ten farms across a rural-urban gradient in Michigan, USA over a three-year period. We evaluated key drivers of production, namely temperature, pathogens, pests, and pollinators, which we hypothesized would be altered by urbanization. We found no direct effect of urbanization on strawberry production or fruit pathogen and pest damage. However, temperature, an environmental correlate of urbanization, significantly influenced crop productivity. In particular, cooler temperatures at rural farms and warmer temperatures at urban farms limited fruit number in the peak production year. We found no relationship between urbanization and overall abundances of arthropod pests, their predators, or pollinators. However, we found opposite effects of urbanization for two arthropod groups – Vespidae (paper wasps) and Araneae (spiders). Vespidae abundance was positively associated with increased urbanization. These omnivorous wasps are both predators of strawberry pests and pests of fruits themselves. Conversely, spiders, which are predators of strawberry pests, were negatively associated with urbanization. Greater pollinator visitation incrementally improved fruit weight, but only at low to moderate levels of pathogen and pest damage. At high levels of damage, the benefits of pollination were not apparent. Our study reveals that environmental drivers of variation in crop yield, such as pathogen and herbivore damage and pollinator visitation, can be comparable across rural-urban gradients. Some factors, however, such as temperature stress and the abundances of certain pest and beneficial organisms may be affected by urbanization.
... The less flexible specialist bees, for example, H. truncorum or M. versicolor (Michener, 2007), may in turn be restricted to specific landscapes and habitats providing suitable resources (Mallinger et al., 2016). This likely explains why intensively managed agricultural grasslands with severely reduced floral diversity harbor fewer bee species and impoverished F I G U R E 2 Effect of land-use intensity (LUI) on (a) plant taxonomic Shannon diversity, (b) total fatty acid (FA) concentration (c) total amino (AA) acid concentration, and (d) total essential AA concentration and (e) the ratio of total FA to total AA in Osmia bicornis larval pollen provisions sampled from nests installed at plots differing in land-use intensity (LUI) in three biogeographical regions in Germany (Exploratories: Swabian Alb, Hainich-Dün and Schorfheide-Chorin). Plant diversity is based on revealed ASVs (Amplicon sequent variants) per bee nest bee communities (Grab et al., 2015;Mallinger et al., 2016), which does not only negatively affect bee populations (Renauld et al., 2016;, but also services provided as for example pollination (Goulson et al., 2015;Jauker et al., 2016;Potts et al., 2010). ...
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Biodiversity loss, as often found in intensively managed agricultural landscapes, correlates with reduced ecosystem functioning, for example, pollination by insects, and with altered plant composition, diversity, and abundance. But how does this change in floral resource diversity and composition relate to occurrence and resource use patterns of trap-nesting solitary bees? To better understand the impact of land-use intensification on communities of trap-nesting solitary bees in managed grasslands, we investigated their pollen foraging, reproductive fitness, and the nutritional quality of larval food along a land-use intensity gradient in Germany. We found bee species diversity to decrease with increasing land-use intensity irrespective of region-specific community compositions and interaction networks. Land use also strongly affected the diversity and composition of pollen collected by bees. Lack of suitable pollen sources likely explains the absence of several bee species at sites of high land-use intensity. The only species present throughout, Osmia bicornis (red mason bee), foraged on largely different pollen sources across sites. In doing so, it maintained a relatively stable, albeit variable nutritional quality of larval diets (i.e., protein to lipid (P:L) ratio). The observed changes in bee-plant pollen interaction patterns indicate that only the flexible generalists, such as O. bicornis, may be able to compensate the strong alterations in floral resource landscapes and to obtain food of sufficient quality through readily shifting to alternative plant sources. In contrast, other, less flexible, bee species disappear.
... A intensificação agrícola também resulta na simplificação da paisagem, ameaçando o fornecimento de serviços ecossistêmicos essenciais, como a polinização (Connelly et al., 2015). Atividades como a pecuária, o extrativismo e o crescimento urbano exagerado também tem elevada relevância nesse processo, impulsionando o desmatamento e a simplificação dos habitats (Fearnside, 2005). ...
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O reconhecimento sobre os benefícios que as abelhas oferecem para a manutenção da vida não está sendo revertido em ações efetivas para conservação desses polinizadores. Nesse sentido, o objetivo deste artigo é apresentar e discutir os impactos de três importantes características do sistema agrícola industrial, que vem causando danos às abelhas no Brasil: desmatamento, uso de agrotóxicos e cultivo em larga escala de variedades transgênicas. Os danos agudos têm sido frequentemente relatados, tanto em estudos científicos quanto pela imprensa, diante de eventos de mortalidade em massa. Igualmente relevante, os danos crônicos informam sobre enfraquecimento e mortalidade de colmeias, sem apresentar uma causa única ou conclusiva. Estudos têm evidenciado que herbicidas, fungicidas e plantas transgênicas, mesmo considerados inócuos às abelhas, promovem alterações fisiológicas e comportamentais nesses insetos. Porém grande parte deles não indicam os reais prejuízos às colmeias, que só podem ser observados em estudos de longo prazo, realizados a campo. Isso também revela uma falha grave nas avaliações de riscos de agrotóxicos e transgênicos sobre organismos não alvo, que consideram válidos testes feitos em indivíduos isolados de organismos que naturalmente vivem em colônias, como é o caso das abelhas eussociais. Resultados obtidos para um grupo de indivíduos em laboratório, que não necessariamente refletem o efeito na colmeia, são muito comuns. Contudo, resultados de ensaios que consideram a complexidade de interações entre castas e diferentes gerações desses insetos, são muito escassos. Assim constata-se que o princípio da precaução foi sumariamente ignorado em detrimento aos lucros financeiros que se concentram para poucos, enquanto os prejuízos ambientais e à saúde são repartidos entre todos. Desse modo, apresentamos e discutimos os efeitos danosos de três das principais práticas utilizadas no âmbito do agronegócio brasileiro, que afetam de diferentes modos a saúde e sobrevivência das abelhas, assim como os serviços por elas prestados.
... Increasing landscape complexity is often associated with increased pollinator abundance, and diversity (Kennedy et al. 2013, Connelly et al. 2015. Our findings suggest that some of these effects may be mediated by a reduction in pathogen-associated mortality, as we found that increasing cover of open natural habitats and urban habitats around apple orchards led to a decrease in chalkbrood incidence in larval O. cornifrons and Ascosphaera prevalence in adult O. cornifrons. ...
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Both ecosystem function and agricultural productivity depend on services provided by bees; these services are at risk from bee declines which have been linked to land use change, pesticide exposure, and pathogens. Although these stressors often co-occur in agroecosystems, a majority of pollinator health studies have focused on these factors in isolation, therefore limiting our ability to make informed policy and management decisions. Here, we investigate the combined impact of altered landscape composition and fungicide exposure on the prevalence of chalkbrood disease, caused by fungi in the genus Ascosphaera Olive and Spiltoir 1955 (Ascosphaeraceae: Onygenales), in the introduced solitary bee, Osmia cornifrons (Radoszkowski 1887) (Megachilidae: Hymenoptera). We used both field studies and laboratory assays to evaluate the potential for interactions between altered landscape composition, fungicide exposure, and Ascosphaera on O. cornifrons mortality. Chalkbrood incidence in larval O. cornifrons decreased with high open natural habitat cover, whereas Ascosphaera prevalence in adults decreased with high urban habitat cover. Conversely, high fungicide concentration and high forest cover increased chalkbrood incidence in larval O. cornifrons and decreased Ascosphaera incidence in adults. Our laboratory assay revealed an additive effect of fungicides and fungal pathogen exposure on the mortality of a common solitary bee. Additionally, we utilized phylogenetic methods and identified four species of Ascosphaera with O. cornifrons, both confirming previous reports and shedding light on new associates. Our findings highlight the impact of fungicides on bee health and underscore the importance of studying interactions among factors associated with bee decline.
... A intensificação agrícola também resulta na simplificação da paisagem, ameaçando o fornecimento de serviços ecossistêmicos essenciais, como a polinização (Connelly et al., 2015). Atividades como a pecuária, o extrativismo e o crescimento urbano exagerado também tem elevada relevância nesse processo, impulsionando o desmatamento e a simplificação dos habitats (Fearnside, 2005). ...
Article
The benefits that bees offer the ecosystem are increasingly recognized, but not met by actions designed to conserve these pollinators. Therefore, the present work aims to describe the impact of three key characteristics of agroindustry that are currently damaging bees in Brazil: deforestation, use of pesticides and large-scale cultivation of genetically modified (GM) varieties. We hear of mass mortality and weakening and damage to hives, but no conclusive causes are announced. In particular, studies indicate that fungicides, herbicides and GM plants, even when considered harmless to bees, still promote physiological and behavioral changes in these insects. However, most of these studies do not indicate the real damage to the hives, which can only be observed in long-term studies carried out in the field. Even when risk assessments of fungicides and herbicides are conducted in the field on non-targeted organisms, the tests are considered valid for isolated individuals without regard to the eusocial behavior of bees in their colonies. Some studies present results from experiments performed on individuals in the lab, again not necessarily reflecting hive activity. Results of trials that consider the complexity of interactions among castes and different generations of bees are very scarce. Therefore, we herein take a comprehensive and detailed approach to three practices of Brazilian agribusiness that directly affect bee and colony health and survival, as well as their ecoservices
... Pollinator declines reported worldwide are especially high in regions characterised by intensive agriculture (Chagnon, 2008;Vanbergen and the Insect Pollinators Initiative, 2013;Connelly et al., 2015;Kovács-Hostyánszki et al., 2017). ...
... This was attributed to lack of habitat diversity, suggesting that greater targeting of AES towards orchards would be beneficial for visitation, especially in more intensive agricultural landscapes (Holzschuh et al., 2012). Landscape fragmentation and simplification around strawberry crops is also associated with lower wild bee abundance and lower crop visitation rates (Bukovinszky et al., 2017;Castle et al., 2019;Connelly et al., 2015). ...
Article
Agri-environment schemes are programmes where landholders enter into voluntary agreements (typically with governments) to manage agricultural land for environmental protection and nature conservation objectives. Previous work at local scale has shown that these features can provide additional floral and nesting resources to support wild pollinators, which may indirectly increase floral visitation to nearby crops. However, the effect of entire schemes on this important ecosystem service has never previously been studied at national scale. Focusing on four wild pollinator guilds (ground-nesting bumblebees, tree-nesting bumblebees, ground-nesting solitary bees, and cavity-nesting solitary bees), we used a state-of-the-art, process-based spatial model to examine the relationship between participation in agri-environment schemes across England during 2016 and the predicted abundances of these guilds and their visitation rates to four pollinator dependent crops (oilseed rape, field beans, orchard fruit and strawberries). Our modelling predicts that significant increases in national populations of ground-nesting bumblebees and ground-nesting solitary bees have occurred in response to the schemes. Lack of significant population increases for other guilds likely reflects specialist nesting resource requirements not well-catered for in schemes. We do not predict statistically significant increases in visitation to pollinator-dependent crops at national level as a result of scheme interventions but do predict some localised areas of significant increase in bumblebee visitation to crops flowering in late spring. Lack of any significant change in visitation to crops which flower outside this season is likely due to a combination of low provision of nesting resource relative to floral resource by scheme interventions and low overall participation in more intensively farmed landscapes. We recommend future schemes place greater importance on nesting resource provision alongside floral resource provision, better cater for the needs of specialised species and promote more contiguous patches of semi-natural habitat to better support solitary bee visitation.
... When the orchards have a good provision of pollination services (either through the wild pollinator communities alone or by its complementation with Apis mellifera colonies) and of pollen (through an adequate male to female ratio, proper distribution of males and flowering synchronization), natural pollination levels can be sufficient to produce high quality marketable fruits. Several studies have shown that pollination services are affected by the interplay between landscape composition and heterogeneity and farm management, and that landscape simplification and intensive farm management have a synergistically negative effect on pollination services [37][38][39][40][41]. In Portugal, kiwifruit orchards are of a small size, with low pesticide input and low insect non-friendly management practices, and are imbedded in a diversified landscape [27]. ...
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Inadequate quantity and quality of pollen reaching the stigmas decreases the sexual reproductive output of plants, compromising yield. Still, the current extent of pollen limitation affecting yield (i.e., pollination deficits) is poorly quantified. This study is aimed at quantifying pollination deficits in kiwifruit orchards, a dioecious plant with a fruit caliber and market value largely dependent on pollination services. For that, we set up a pollination experiment and quantified services and yield provided by current pollination vectors, and under optimal pollination, over two years in a total of twenty-three orchards covering the kiwifruit production range in Portugal. We characterized nine fruit traits and used: (1) fruit weight to calculate pollination deficits and relate them with pollinator diversity and abundance, and environmental variables; and (2) production values, fruit caliber, and market values to calculate economic impact of pollination deficits. Results showed that pollination deficits were variable in time and space and were significantly and negatively correlated with pollinator abundance, while the opposite pattern was obtained for production, supporting the notion that a higher pollinator’s abundance is related to lower pollination deficits and higher yields. Understanding the factors affecting pollination deficits is crucial to depict the need for nature-based solutions promoting pollinators and to resort to management practices assisting pollination.
... Beside landscape composition and configuration, agricultural practices can impact insect abundance and richness; effects at the local and landscape scale are often additive [22,28]. An increase in croplands in a landscape is known to negatively influence insect abundance and diversity [37,65], particularly when paired with the use of insecticides [36] and big crop size [34,35]. Surprisingly, we did not show any link between local management practices and markers of agricultural intensification on fennel insect abundance and family richness. ...
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Agricultural landscapes are increasingly characterized by intensification and habitat losses. Landscape composition and configuration are known to mediate insect abundance and richness. In the context of global insect decline, and despite 75% of crops being dependent on insects, there is still a gap of knowledge about the link between pollinators and aromatic crops. Fennel (Foeniculum vulgare) is an aromatic plant cultivated in the South of France for its essential oil, which is of great economic interest. Using pan-traps, we investigated the influence of the surrounding habitats at landscape scale (semi-natural habitat proportion and vicinity, landscape configuration) and local scale agricultural practices (insecticides and patch size) on fennel-flower-visitor abundance and richness, and their subsequent impact on fennel essential oil yield. We found that fennel may to be a generalist plant species. We did not find any effect of intense local management practices on insect abundance and richness. Landscape configuration and proximity to semi-natural habitat were the main drivers of flying insect family richness. This richness positively influenced fennel essential oil yield. Maintaining a complex configuration of patches at the landscape scale is important to sustain insect diversity and crop yield.
... Apart from the aspects strictly related to climate change, other issues dealing with bee hive and farm management and honey production have also emerged. These include intensive agriculture including continuous cropping with crops not useful for pollinating insects [62][63][64][65]; the reduction of pasture meadows with the consequent loss of blooms widely present in the past such as dandelion (Taraxacum officinale) or white clover (Trifolium repens) all providing forage for typical honey; the use of chemicals (e.g., neonicotinoids) and herbicides (e.g., glyphosate) [66][67][68][69][70][71][72][73][74] applied in pre-flowering or flowering without respecting the imposed restrictions; the cultivation of hybrids, such as sunflower (Helianthus annuus) and buckwheat, important resources during the summer, which do not provide nectar; the release of the parasitoid Neodryinus typhlocybae (Ashmead), controlling M. pruinosa populations [75], and consequently the production of honeydew and honeydew honey; and the loss of plant biodiversity. On the other hand, the abandonment of the woodlands may allow the spread of useful plants such as cherry (Prunus avium) and ivy, offering an important nectar flow for honey bees, as one beekeeper observed: "Recently, an important source of nectar is the cherry tree, which was not very common until ten years ago. ...
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(1) Background: Bees are the primary animal pollinators in most ecosystems, and honey bees (Apis mellifera L.) are important providers of pollination ecosystem services and products. Climate change is one of the major threats for honey bees. (2) Objectives and methods: Qualitative research using focus group discussions was carried out in northwestern Italy, to investigate the beekeepers’ perceptions of climate change effects, the relevant management adaptations, and the main issues affecting the sector. (3) Results: Beekeepers reported several consequences related to severe weather events (weakening or loss of colonies; scarcity of nectar, pollen, and honeydew; decrease or lack of honey and other bee products; greater infestation by varroa; decline in pollination), making it necessary to provide supplemental sugar feeding, intensive transhumance, more effective and sustainable techniques for varroa control, and increased production of nuclei. A strengths, weaknesses, opportunities, and threats (SWOT) analysis was completed, displaying the factors able to strengthen or weaken the resilience of the beekeeping sector to climate change. (4) Conclusions: Thanks to their strong motivation and collaborative attitude, beekeepers succeed in adopting farm and bee hive adaptation strategies that are able to limit the climatic adverse effects. However, these findings highlight how the institutional and financial support for the beekeeping sector should be strengthened and better targeted.
... We observed enhanced winter squash fruit count with increasing species richness and not abundance, suggesting rarer species contributed crucial pollination services in winter squash. Our results also support past work suggesting pollination efficiency in strawberries is not associated with species richness 56,57 . ...
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Pollinator refuges such as wildflower strips are planted on farms with the goals of mitigating wild pollinator declines and promoting crop pollination services. It is unclear, however, whether or how these goals are impacted by managed honey bee (Apis mellifera L.) hives on farms. We examined how wildflower strips and honey bee hives and/or their interaction influence wild bee communities and the fruit count of two pollinator-dependent crops across 21 farms in the Mid-Atlantic U.S. Although wild bee species richness increased with bloom density within wildflower strips, populations did not differ significantly between farms with and without them whereas fruit counts in both crops increased on farms with wildflower strips during one of 2 years. By contrast, wild bee abundance decreased by 48%, species richness by 20%, and strawberry fruit count by 18% across all farm with honey bee hives regardless of wildflower strip presence, and winter squash fruit count was consistently lower on farms with wildflower strips with hives as well. This work demonstrates that honey bee hives could detrimentally affect fruit count and wild bee populations on farms, and that benefits conferred by wildflower strips might not offset these negative impacts. Keeping honey bee hives on farms with wildflower strips could reduce conservation and pollination services.
... Previous studies have concluded that, in terms of strawberry crop pollination, flies provide a unique contribution, in that they visit flowers during periods of inclement weather when other pollinators were absent (Ellis et al., 2017), and hoverflies have been found to be efficient pollinators of strawberry (Hodgkiss, Brown, & Fountain, 2018). Indeed, studies conclude that it is abundance and functional trait, more than pollinator type, which contributes most to pollination efficiency in strawberries (Connelly, Poveda, & Loeb, 2015;Ellis et al., 2017). In both the citizen science and researcher experiments, beetles were also frequent visitors to strawberry plants. ...
... Paradoxically, agricultural intensification is a key driver of biodiversity loss (Kehoe et al., 2017;Lanz et al., 2018). Large-scale food production typically simplifies landscape structure and homogenizes crop diversity to promote more efficient provisioning services (Matson et al., 1997;Gámez-Virués et al., 2015), and it intensifies chemical inputs for insect and plant pest suppression (Meehan et al., 2011;Connelly et al., 2015). These actions have demonstrable negative impacts on multiple taxonomic groups (e.g., Emmerson et al., 2016;Arntzen et al., 2017;Stanton et al., 2018;Powney et al., 2019), resulting in the degradation or complete loss of many critical ecosystem services (Landis, 2017). ...
Article
Biodiversity directly influences the delivery of multiple ecosystem services, most notably within agriculture. Projected future global demands for food, fiber and bioenergy will require enhancement of agricultural productivity, but favoring biodiversity-based ecosystem services generally remains underutilized in agricultural practice. In addition, agricultural intensification is a key driver of biodiversity loss. A significant obstacle preventing the adoption of ecologically sensitive practices is a lack of knowledge of the species delivering the services. Insectivorous bats have long been suggested to regulate insect pest populations and may be a critical component of biodiversity-based ecosystem services. Bats may also serve as agents of insect pest surveillance through environmental DNA (eDNA) monitoring approaches. However, the biological and economic importance of bats to agriculture remains under-quantified. Here we catalogued the dietary niche of two North American bats, little brown bat (Myotis lucifugus) and big brown bat (Eptesicus fuscus), through DNA metabarcoding of guano collected from seven roosting sites over a 26-week period. We measured the frequency of occurrence of known pest species in guano samples, compared interspecific differences in diet, and examined seasonal patterns in prey selection. Overall, we detected 653 unique prey species, 160 of which were known agricultural pests or disease vectors. Species diversity of prey species consumed varied by bat species and across the season, with big brown bats accounting for the majority of arthropod diversity detected. However, little brown bats consumed relatively more aquatic insects than big brown bats, suggesting that increased bat species richness in a landscape can amplify their net pest regulation service. Further, we hypothesized that detection probabilities of target insect pests would be higher in guano samples than in conventional survey methods. Multi-survey occupancy modeling revealed significantly lower detectability in bat guano than in conventional monitoring traps, however, highlighting important tradeoffs in selection of survey methods. Overall, the results presented here contribute to a growing evidence base supporting the role bats play in the provisioning of biodiversity-based ecosystem services.
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Recently, the Yukon has seen a large growth in agricultural activity. Crops of commercial interest for local consumption and the export market include domestic berries, especially haskap ( Lonicera caerulea L.). However, information on the pollination of these crops in our northern climate is lacking. To begin addressing this knowledge gap, we characterized foraging habits of on-farm bees in southwest Yukon by: 1) identifying pollen collected by bees occupying solitary bee houses; and 2) identifying and counting insect visitors to haskap flowers. Results show that cavity-nesting bees collect a wide variety of pollen including pollen from haskap, and that bumble bees ( Bombus spp.) were much more common on haskap flowers than domestic honey bees ( Apis mellifera L.), other bee species, syrphid flies, and butterflies. The number of bumble bees per haskap flower was also higher than reported elsewhere in Canada. The ability of bumble bees to be active in cool temperatures and the proximity of the study farms to natural ecosystems likely explain the prevalence of bumble bees in this study. In Yukon, it is still possible to support insect pollinators by maintaining natural areas among agricultural lands. Such undeveloped lands are, at present, typical of agricultural landscapes in subarctic Canada.
Article
Biodiversity-friendly farming practices may create a win-win scenario for biodiversity and crop production by supporting ecosystem services to agriculture. On-farm wildflower plantings and conserving semi-natural habitat surrounding farms are two such practices that focus on the integration of non-crop components into production systems at the local and landscape scale, respectively. Here, we examine the impact of these practices on the regulating services of biological control and pollination, as well as the provisioning service of crop yield in four crops replicated across 22 farms in two US states. Wildflower plantings had no effect on pollination while their influence on pest control was both dependent on the landscape context and inconsistent across crops. In contrast, farms surrounded by higher amounts of semi-natural habitat had consistently higher marketable yields for all four crops. Our findings suggest a need to account for non-production values of wildflower plantings as they provide fewer direct production benefits than surrounding semi-natural habitats.
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The population of bumble bees and other pollinators has considerably declined worldwide, probably, due to the toxic effect of pesticides used in agriculture. Inexpensive and available antidotes can be one of the solutions for the problem of pesticide toxicity for pollinators. We studied the properties of the thiazine dye Methylene blue (MB) as an antidote against the toxic action of pesticides in the bumble bee mitochondria and found that MB stimulated mitochondrial respiration mediated by Complex I of the electron transport chain (ETC) and increased respiration of the mitochondria treated with mitochondria-targeted (chlorfenapyr, hydramethylnon, pyridaben, tolfenpyrad, and fenazaquin) and non-mitochondrial (deltamethrin, metribuzin, and penconazole) pesticides. MB also restored the mitochondrial membrane potential dissipated by the pesticides affecting the ETC. The mechanism of MB action is most probably related to its ability to shunt electron flow in the mitochondrial ETC.
Article
Increasing biodiversity loss due to human activities may compromise ecosystem functions and services, with serious consequences for human well-being. Pollination and biological control are among the ecosystem services most affected by landscape changes, where cavity-nesting hymenopteran species are important agents of such services. We analyzed how cavity-nesting bee and wasp communities are affected by landscape structure at different scales since a multi-scale perspective is more efficient in detecting landscape effects on species, communities, and ecological processes. The study was carried out in the Cantareira-Mantiqueira Corridor (CCM) located within the Atlantic Forest, São Paulo, Brazil. We used trap-nests distributed in 29 sampling points following a nested design of ten regional landscapes with three nested local landscapes. We recorded 25 bee species, 21 wasp species, and 25 species of brood cell parasites. The bee and wasp communities were explained by landscape heterogeneity and forest cover: at the local level, landscape heterogeneity had a positive effect on almost all response variables, while forest cover was also important at the regional level, mainly for bee diversity and wasp abundance. Our results highlight the need to conduct studies at multiple scales to understand how landscape heterogeneity and forest cover affect the diversity of pollinating and predatory insects.
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1. Threats to bee pollinators such as land use change, high pesticide risk, and reduced floral diet diversity are usually assessed independently, even though they often co‐occur to impact bees in agroecosystems. 2. We established populations of the non‐native mason bee O. cornifrons at 17 NY apple orchards varying in proportion of surrounding agriculture and measured floral diet diversity and pesticide risk levels in the pollen provisions they produced. We used path analysis to test the direct and indirect effects of different habitats, diet diversity, and pesticide risk on emergent female offspring number and weight. 3. High proportions of agricultural habitat surrounding bee nests indirectly reduced the number of female offspring produced, by reducing floral diet diversity in pollen. 4. When the proportion of agriculture surrounding bee nests was high, bees collected increased proportions of Rosaceae in their pollen provisions, which marginally (0.05<p<0.1) increased fungicide risk levels in pollen. This, in turn, marginally reduced female offspring weight. In contrast, female offspring weight increased as proportions surrounding open habitat (wildflowers, grassland, pasture) increased, but this effect was not influenced by proportion Rosaceae or fungicide risk levels in pollen. 5. Synthesis and applications. Threats to bee health such as land use change, pesticide exposure, and changes in pollen diet composition are often studied in isolation. However, our results suggest that these threats can simultaneously influence one another to impact bee populations in the agroecosystems where we rely on them for pollination. By replacing surrounding agricultural habitats with more natural habitats, such as grasslands and pastures, we can increase floral diet diversity and reduce pesticide exposure in bee‐collected pollen, resulting in healthier mason bee populations in apple orchards.
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Human land use threatens global biodiversity and compromises multiple ecosystem functions critical to food production. Whether crop yield–related ecosystem services can be maintained by a few dominant species or rely on high richness remains unclear. Using a global database from 89 studies (with 1475 locations), we partition the relative importance of species richness, abundance, and dominance for pollination; biological pest control; and final yields in the context of ongoing land-use change. Pollinator and enemy richness directly supported ecosystem services in addition to and independent of abundance and dominance. Up to 50% of the negative effects of landscape simplification on ecosystem services was due to richness losses of service-providing organisms, with negative consequences for crop yields. Maintaining the biodiversity of ecosystem service providers is therefore vital to sustain the flow of key agroecosystem benefits to society.
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Background. Up to 75% of crop species benefit at least to some degree from animal pollination for fruit or seed set and yield. However, basic information on the level of pollinator dependence and pollinator contribution to yield is lacking for many crops. Even less is known about how insect pollination affects crop quality. Given that habitat loss and agricultural intensification are known to decrease pollinator richness and abundance, there is a need to assess the consequences for different components of crop production. Methods. We used pollination exclusion on flowers or inflorescences on a whole plant basis to assess the contribution of insect pollination to crop yield and quality in four flowering crops (spring oilseed rape, field bean, strawberry, and buckwheat) located in four regions of Europe. For each crop, we recorded abundance and species richness of flower visiting insects in ten fields located along a gradient from simple to heterogeneous landscapes. Results. Insect pollination enhanced average crop yield between 18 and 71% depending on the crop. Yield quality was also enhanced in most crops. For instance, oilseed rape had higher oil and lower chlorophyll contents when adequately pollinated, the proportion of empty seeds decreased in buckwheat, and strawberries’ commercial grade improved; however, we did not find higher nitrogen content in open pollinated field beans. Complex landscapes had a higher overall species richness of wild pollinators across crops, but visitation rates were only higher in complex landscapes for some crops. On the contrary, the overall yield was consistently enhanced by higher visitation rates, but not by higher pollinator richness. Discussion. For the four crops in this study, there is clear benefit delivered by pollinators on yield quantity and/or quality, but it is not maximized under current agricultural intensification. Honeybees, the most abundant pollinator, might partially compensate the loss of wild pollinators in some areas, but our results suggest the need of landscape-scale actions to enhance wild pollinator populations.
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Insect-pollinated crops provide important nutrients for human health. Pollination, water and nutrients available to crops can influence yield, but it is not known if the nutritional value of the crop is also influenced. Almonds are an important source of critical nutrients for human health such as unsaturated fat and vitamin E. We manipulated the pollination of almond trees and the resources available to the trees, to investigate the impact on the nutritional composition of the crop. The pollination treatments were: (a) exclusion of pollinators to initiate self-pollination and (b) hand cross-pollination; the plant resource treatments were: (c) reduced water and (d) no fertilizer. In an orchard in northern California, trees were exposed to a single treatment or a combination of two (one pollination and one resource). Both the fat and vitamin E composition of the nuts were highly influenced by pollination. Lower proportions of oleic to linoleic acid, which are less desirable from both a health and commercial perspective, were produced by the self-pollinated trees. However, higher levels of vitamin E were found in the self-pollinated nuts. In some cases, combined changes in pollination and plant resources sharpened the pollination effects, even when plant resources were not influencing the nutrients as an individual treatment. This study highlights the importance of insects as providers of cross-pollination for fruit quality that can affect human health, and, for the first time, shows that other environmental factors can sharpen the effect of pollination. This contributes to an emerging field of research investigating the complexity of interactions of ecosystem services affecting the nutritional value and commercial quality of crops.
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Pollination improves the yield of most crop species and contributes to one-third of global crop production, but comprehensive benefits including crop quality are still unknown. Hence, pollination is underestimated by international policies, which is particularly alarming in times of agricultural intensification and diminishing pollination services. In this study, exclusion experiments with strawberries showed bee pollination to improve fruit quality, quantity and market value compared with wind and self-pollination. Bee-pollinated fruits were heavier, had less malformations and reached higher commercial grades. They had increased redness and reduced sugar-acid-ratios and were firmer, thus improving the commercially important shelf life. Longer shelf life reduced fruit loss by at least 11%. This is accounting for 0.32 billion US$ of the 1.44 billion US$ provided by bee pollination to the total value of 2.90 billion US$ made with strawberry selling in the European Union 2009. The fruit quality and yield effects are driven by the pollination-mediated production of hormonal growth regulators, which occur in several pollination-dependent crops. Thus, our comprehensive findings should be transferable to a wide range of crops and demonstrate bee pollination to be a hitherto underestimated but vital and economically important determinant of fruit quality.
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Most ecological processes and interactions depend on scales much larger than a single habitat, and therefore it is important to link spatial patterns and ecological processes at a landscape scale. Here, we analyzed the effects of landscape context on the distribution of bees (Hymenoptera: Apoidea) at multiple spatial scales with respect to the following hypotheses: (1) Local abundance and diversity of bees increase with increasing proportion of the surrounding seminatural habitats. (2) Solitary wild bees, bumble bees, and honey bees respond to landscape context at different spatial scales. We selected 15 landscape sectors and determined the percentage of seminatural habitats and the diversity of habitat types at eight spatial scales (radius 250-3000 m) by field inspections and analyses of vegetation maps using two Geographic Information Systems. The percentage of semi- natural habitats varied between 1.4% and 28%. In the center of each landscape sector a patch of potted flowering plants (four perennial and two annual species) was placed in the same habitat type, a grassy field margin adjacent to cereal fields. In all, 865 wild bee individuals and 467 honey bees were observed and an additional 475 individuals were caught for species identification. Species richness and abundance of solitary wild bees showed a close positive correlation with the percentage of seminatural habitats at small scales up to 750 m, whereas bumble bees and honey bees did not respond to landscape context at these scales. In contrast, honey bees were correlated with landscape context at large scales. The densities of flower-visiting honey bees even increased with decreasing proportion of seminatural habitats at a radius of 3000 m. We are not aware of any empirical studies showing contrasting foraging patterns related to landscape context at different spatial scales. We conclude (1) that local landscape destruction affects solitary wild bees more than social bees, possibly changing mutualistic plant-pollinator and competitive wild bees- honey bees interactions and (2) that only analyses of multiple spatial scales may detect the importance of the landscape context for local pollinator communities.
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To preserve populations of endangered bee species, sound knowledge of their maximum foraging distance between nest and host plants is crucial. Previous investigations predicted maximum foraging distances of 100–200m for small bee species and up to 1100m for very large species based on mainly indirect methods. The present study applied a new and direct approach to experimentally investigate maximum foraging distances in solitary bees. One endangered and two common species of different body sizes, all of which restrict pollen foraging to a single plant genus, were established in a landscape lacking their specific host plants. Females were forced to collect pollen on potted host plants that were successively placed in increasing distance from fixed nesting stands. The maximum foraging distance recorded for the small Hylaeus punctulatissimus was 1100m, for the medium sized Chelostoma rapunculi 1275m and for the large Hoplitis adunca 1400m, indicating that maximum foraging distances at species level have been underestimated. However, the capability to use resources on such a large spatial scale applied only to a small percentage of individuals as 50% of the females of H. punctulatissimus and H. adunca did not forage at distances longer than 100–225m and 300m, respectively. This finding suggests that a close neighbourhood of nesting and foraging habitat within few hundred meters is crucial to maintain populations of these species, and that threshold distances at which half of the population discontinues foraging are a more meaningful parameter for conservation practice than the species specific maximum foraging distances.
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If climate change affects pollinator-dependent crop production, this will have important implications for global food security because insect pollinators contribute to production for 75% of the leading global food crops. We investigate whether climate warming could result in indirect impacts upon crop pollination services via an overlooked mechanism, namely temperature-induced shifts in the diurnal activity patterns of pollinators. Using a large data set on bee pollination of watermelon crops, we predict how pollination services might change under various climate change scenarios. Our results show that under the most extreme IPCC scenario (A1F1), pollination services by managed honey bees are expected to decline by 14.5%, whereas pollination services provided by most native, wild taxa are predicted to increase, resulting in an estimated aggregate change in pollination services of +4.5% by 2099. We demonstrate the importance of native biodiversity in buffering the impacts of climate change, because crop pollination services would decline more steeply without the native, wild pollinators. More generally, our study provides an important example of how biodiversity can stabilize ecosystem services against environmental change. This article is protected by copyright. All rights reserved.
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This study was carried out in a strawberry (Fragaria ×× ananassa Duch.) field located in Ribatejo, Por- tugal, and aims to describe the qualitative component of the visits for three strawberry floral visitors, attaining the best results in a previous work. The main objectives were: (1) to assess the pollination rate (PR) resulting from a single visit of Apis mellifera L., Syrphidae and native bees, and (2) to characterize the foraging behaviour of each of these categories in order to select the potential pollinators of strawberry crops under open field con- ditions in the Ribatejo. All analysed categories were shown to be potentially useful pollinators, since there were no significant differences among them in the pollination rates, after a single visit. The observed distinct foraging behaviour among them did not result in significantly different pollination rates. Growers are recommended to take advantage of the several pollinators, either the honey bee or the native pollinators (Syrphidae and native bees). The importance of diversifying pollination sources, avoiding the dependence on a single specific group is stressed. This study also suggests measures which envisage the conservation, establishment and increase of native pollinators' populations in the typical agro-ecosystem of the Ribatejo region.
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Bees provide essential pollination services that are potentially affected both by local farm management and the surrounding landscape. To better understand these different factors, we modelled the relative effects of landscape composition (nesting and floral resources within foraging distances), landscape configuration (patch shape, interpatch connectivity and habitat aggregation) and farm management (organic vs. conventional and local-scale field diversity), and their interactions, on wild bee abundance and richness for 39 crop systems globally. Bee abundance and richness were higher in diversified and organic fields and in landscapes comprising more high-quality habitats; bee richness on conventional fields with low diversity benefited most from high-quality surrounding land cover. Landscape configuration effects were weak. Bee responses varied slightly by biome. Our synthesis reveals that pollinator persistence will depend on both the maintenance of high-quality habitats around farms and on local management practices that may offset impacts of intensive monoculture agriculture.
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Diversity and abundance of wild-insect pollinators have declined in many agricultural landscapes. Whether such declines reduce crop yields, or are mitigated by managed pollinators such as honey bees, is unclear. Here, we show universally positive associations of fruit set with wild-insect visits to flowers in 41 crop systems worldwide, and thus clearly demonstrate their agricultural value. In contrast, fruit set increased significantly with visitation by honey bees in only 14% of the systems surveyed. Overall, wild insects pollinated crops more effectively, because increase in their visitation enhanced fruit set by twice as much as an equivalent increase in honey bee visitation. Further, visitation by wild insects and honey bees promoted fruit set independently, so high abundance of managed honey bees supplemented, rather than substituted for, pollination by wild insects. Our results suggest that new practices for integrated management of both honey bees and diverse wild-insect assemblages will enhance global crop yields.
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The pollination effectiveness (floral visitation rate, percentage of flowers pollinated, and pollen deposition) of indigenous and introduced bees visiting lowbush blueberry (Vaccinium angustifolium Aiton) was studied in Nova Scotia from 1992 to 1994. Floral visitation rate alone was not a good indicator of pollination effectiveness, as not all floral visits resulted in successful pollination events. As a group, pollen-harvesting taxa pollinated >85% of flowers visited as compared with under 25% for nectar foragers. Equivalencies derived from floral visitation rates and pollination percentages show that the most effective pollen-harvesters, Bombus spp. queens and Andrena spp., would pollinate 6.5 and 3.6 flowers, respectively, in the time it would take a nectar-foraging honey bee, Apis mellifera L., to pollinate a single flower. Average pollen deposition for nectar-foragers (A. mellifera and Megachile rotundata F.) did not exceed 13 tetrads per visit, which was significantly less than all pollen-harvesters. Among pollen-harvesters, Bombus spp. workers, M. rotundata and Halictus spp. deposited moderate stigmatic loads (34, 28, and 26 tetrads, respectively), whereas Bombus spp. queens and Andrena spp. deposited >45 tetrads per single visit. Pollination equivalencies show A. mellifera would have to visit a flower four times to deposit the same amount of pollen as single visits by Bombus spp. queens or Andrena spp.
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We evaluate whether species interaction frequency can be used as a surrogate for the total effect of a species on another. Because interaction frequency is easier to estimate than per-interaction effect, using interaction frequency as a surrogate of total effect could facilitate the large-scale analysis of quantitative patterns of species-rich interaction networks. We show mathematically that the correlation between interaction frequency (I) and total effect (T) becomes more strongly positive the greater the variation of I relative to the variation of per-interaction effect (P) and the greater the correlation between I and P. A meta-analysis using data on I, P and T for animal pollinators and seed dispersers visiting plants shows a generally strong, positive relationship between T and I, in spite of no general relationship between P and I. Thus, frequent animal mutualists usually contribute the most to plant reproduction, regardless of their effectiveness on a per-interaction basis.
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Bee pollinators are currently recorded with many different sampling methods. However, the relative performances of these methods have not been systematically evaluated and compared. In response to the strong need to record ongoing shifts in pollinator diversity and abundance, global and regional pollinator initiatives must adopt standardized sampling protocols when developing large-scale and long-term monitoring schemes. We systematically evaluated the performance of six sampling methods (observation plots, pan traps, standardized and variable transect walks, trap nests with reed internodes or paper tubes) that are commonly used across a wide range of geographical regions in Europe and in two habitat types (agricultural and seminatural). We focused on bees since they represent the most important pollinator group worldwide. Several characteristics of the methods were considered in order to evaluate their performance in assessing bee diversity: sample coverage, observed species richness, species richness estimators, collector biases (identified by subunit-based rarefaction curves), species composition of the samples, and the indication of overall bee species richness (estimated from combined total samples). The most efficient method in all geographical regions, in both the agricultural and seminatural habitats, was the pan trap method. It had the highest sample coverage, collected the highest number of species, showed negligible collector bias, detected similar species as the transect methods, and was the best indicator of overall bee species richness. The transect methods were also relatively efficient, but they had a significant collector bias. The observation plots showed poor performance. As trap nests are restricted to cavity-nesting bee species, they had a naturally low sample coverage. However, both trap nest types detected additional species that were not recorded by any of the other methods. For large-scale and long-term monitoring schemes with surveyors with different experience levels, we recommend pan traps as the most efficient, unbiased, and cost-effective method for sampling bee diversity. Trap nests with reed internodes could be used as a complementary sampling method to maximize the numbers of collected species. Transect walks are the principal method for detailed studies focusing on plant–pollinator associations. Moreover, they can be used in monitoring schemes after training the surveyors to standardize their collection skills.
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Pan and Malaise traps have been used widely to sample insect abundance and diversity, but no studies have compared their performance for sampling pollinators in forested ecosystems. Malaise trap design and color of pan traps are important parameters that influence insect pollinator catches. We compared pan trap (blue, yellow, white, and red) and Malaise trap catches from forests in three physiographic provinces (Piedmont, Coastal Plain, and Blue Ridge) of the southeastern United States. Similarities in trap performance between sites were observed with blue pan traps being most effective overall. Our results showed that various pollinator groups preferred certain pan trap colors and that adding color to Malaise traps influenced insect pollinator catches. However, pan traps generally caught more pollinators than Malaise traps. Because of their low cost and simplicity, using several colors of pan traps is an effective way to sample relative abundance and species richness of flower-visiting insects.
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1. Concern about a global decline in wild pollinators has increased interest in how pollinators are affected by human land use, and how this, in turn, affects crop pollination. 2. We measured wild bee visitation to four summer vegetable crops, and investigated associations between flower visitation rates and land-use intensity at local and landscape scales. We studied 29 farms in New Jersey and Pennsylvania, USA. Over 2 years we recorded >7400 bee visits to crop flowers and identified 54 species of wild bees visiting crops. 3. Wild bees were the dominant flower visitors at three of the four crops studied; domesticated honeybees, Apis mellifera L., provided the remainder of visits. 4. Ordination of the two best studied crops showed that the wild bee species visiting tomato, Solanum lycopersicum L., were distinct from those visiting watermelon, Citrullus lanatus (Thunb.) Matsum. & Nakai. 5. Crop visitation by wild bees was not associated with organic farming, nor with natural habitat cover at either local or landscape scale. 6. Synthesis and applications. The extent of crop visitation by wild bees observed in this study is among the highest recorded. In contrast to previous studies of crop visitation by wild bees, we did not find negative effects of conventional farming or natural habitat loss. In our study system, organic and conventional farms differ little in field size, crop diversity and weedy flower diversity, unlike some systems where organic farms have smaller fields with greater crop and weed diversity. Such variables may be more important than organic vs. conventional farming practices. Second, small patches of natural habitat are dispersed throughout our entire study system, and this habitat heterogeneity may support high bee abundance even in landscapes with a low proportion of natural habitat overall. Our findings suggest that agri-environment schemes and similar programmes that work through local habitat restoration should target farms in intensively agricultural (homogeneous) landscapes to gain maximum conservation benefits.
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The contribution of nutrients from animal pollinated world crops has not previously been evaluated as a biophysical measure for the value of pollination services. This study evaluates the nutritional composition of animal-pollinated world crops. We calculated pollinator dependent and independent proportions of different nutrients of world crops, employing FAO data for crop production, USDA data for nutritional composition, and pollinator dependency data according to Klein et al. (2007). Crop plants that depend fully or partially on animal pollinators contain more than 90% of vitamin C, the whole quantity of Lycopene and almost the full quantity of the antioxidants β-cryptoxanthin and β-tocopherol, the majority of the lipid, vitamin A and related carotenoids, calcium and fluoride, and a large portion of folic acid. Ongoing pollinator decline may thus exacerbate current difficulties of providing a nutritionally adequate diet for the global human population.
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Pollinators may be declining globally, a matter of concern because animal pollination is required by most of the world's plant species, including many crop plants. Human land use and the loss of native habitats is thought to be an important driver of decline for wild, native pollinators, yet the findings of published studies on this topic have never been quantitatively synthesized. Here we use meta-analysis to synthesize the literature on how bees, the most important group of pollinators, are affected by human disturbances such as habitat loss, grazing, logging, and agriculture. We obtained 130 effect sizes from 54 published studies recording bee abundance and/or species richness as a function of human disturbance. Both bee abundance and species richness were significantly, negatively affected by disturbance. However, the magnitude of the effects was not large. Furthermore, the only disturbance type showing a significant negative effect, habitat loss and fragmentation, was statistically significant only in systems where very little natural habitat remains. Therefore, it would be premature to draw conclusions about habitat loss having caused global pollinator decline without first assessing the extent to which the existing studies represent the status of global ecosystems. Future pollinator declines seem likely given forecasts of increasing land-use change.
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Biological diversity could enhance ecosystem service provision by increasing the mean level of services provided, and/or by providing more consistent (stable) services over space and time. Ecological theory predicts that when an ecosystem service is provided by many species, it will be stabilized against disturbance by a variety of 'stabilizing mechanisms.' However, few studies have investigated whether stabilizing mechanisms occur in real landscapes affected by human disturbance. We used two datasets on crop pollination by wild native bees to screen for and differentiate among three stabilizing mechanisms: density compensation (negative co-variance among species' abundances); response diversity (differential response to environmental variables among species); and cross-scale resilience (response to the same environmental variable at different scales by different species). In both datasets, we found response diversity and cross-scale resilience, but not density compensation. We conclude that stabilizing mechanisms may contribute to the stability of pollination services in our study areas, emphasizing the insurance value of seemingly 'redundant' species. Furthermore, the absence of density compensation that we found at the landscape scale contrasts with findings of previous small-scale experimental and modelling work, suggesting that we should not assume that density compensation will stabilize ecosystem services in real landscapes.
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The worldwide decline of pollinators may negatively affect the fruit set of wild and cultivated plants. Here, we show that fruit set of the self-fertilizing highland coffee (Coffea arabica) is highly variable and related to bee pollination. In a comparison of 24 agroforestry systems in Indonesia, the fruit set of coffee could be predicted by the number of flower-visiting bee species, and it ranged from ca. 60% (three species) to 90% (20 species). Diversity, not abundance, explained variation in fruit set, so the collective role of a species-rich bee community was important for pollination success. Additional experiments showed that single flower visits from rare solitary species led to higher fruit set than with abundant social species. Pollinator diversity was affected by two habitat parameters indicating guild-specific nesting requirements: the diversity of social bees decreased with forest distance, whereas the diversity of solitary bees increased with light intensity of the agroforestry systems. These results give empirical evidence for a positive relationship between ecosystem functions such as pollination and biodiversity. Conservation of rainforest adjacent to adequately managed agroforestry systems could improve the yields of farmers.
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Analysis of Phylogenetics and Evolution (APE) is a package written in the R language for use in molecular evolution and phylogenetics. APE provides both utility functions for reading and writing data and manipulating phylogenetic trees, as well as several advanced methods for phylogenetic and evolutionary analysis (e.g. comparative and population genetic methods). APE takes advantage of the many R functions for statistics and graphics, and also provides a flexible framework for developing and implementing further statistical methods for the analysis of evolutionary processes. Availability: The program is free and available from the official R package archive at http://cran.r-project.org/src/contrib/PACKAGES.html#ape. APE is licensed under the GNU General Public License.
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The extent of our reliance on animal pollination for world crop production for human food has not previously been evaluated and the previous estimates for countries or continents have seldom used primary data. In this review, we expand the previous estimates using novel primary data from 200 countries and found that fruit, vegetable or seed production from 87 of the leading global food crops is dependent upon animal pollination, while 28 crops do not rely upon animal pollination. However, global production volumes give a contrasting perspective, since 60% of global production comes from crops that do not depend on animal pollination, 35% from crops that depend on pollinators, and 5% are unevaluated. Using all crops traded on the world market and setting aside crops that are solely passively self-pollinated, wind-pollinated or parthenocarpic, we then evaluated the level of dependence on animal-mediated pollination for crops that are directly consumed by humans. We found that pollinators are essential for 13 crops, production is highly pollinator dependent for 30, moderately for 27, slightly for 21, unimportant for 7, and is of unknown significance for the remaining 9. We further evaluated whether local and landscape-wide management for natural pollination services could help to sustain crop diversity and production. Case studies for nine crops on four continents revealed that agricultural intensification jeopardizes wild bee communities and their stabilizing effect on pollination services at the landscape scale.