Taxon-specific temporal shifts in pollinating insects in mass-flowering crops and field margins in Ireland

In intensively cropped agricultural landscapes, the vegetation in edges and hedges (henceforth “field margins”) represents an important semi-natural habitat providing fundamental resources for insect pollinators. We surveyed the pollinating insects associated with two mass-flowering crops, apple and oilseed rape, and compared the insect fauna of the main crop with that in the field margins in the grass-dominated agricultural landscapes of Ireland. Different insect groups responded differently to the presence of the flowering crop, with honey and bumble bees more abundant in crops than margins during crop flowering, but more hover flies and butterflies in margins throughout. The composition of the insect assemblage also shifted over time due to taxon-specific changes in abundance. For example, solitary bees were most abundant early in the season, whereas hover flies peaked, and butterflies declined, in mid-summer. The temporal shift in insect community structure was associated with parallel changes in the field margin flora, and, although we found no relationship between insect abundance and abundance of field margin flowers, Bombus abundance and total insect abundance were positively correlated with floral diversity. After the crop flowering period, floral abundance and diversity was maintained via margin plants, but by late summer, floral resources declined. Our results confirm the importance of field margins for insect pollinators of entomophilous crops set within grass-dominated landscapes, even during the crop flowering period, and provide additional support for agri-environment schemes that protect and/or improve field margin biodiversity. The results also demonstrate that although shifts in insect and plant communities may be linked phenologically there may not always be simple relationships between insect and floral abundance and richness.

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Physiological effects of climate warming on flowering plants and insect pollinators and potential consequences for their interactions

Current Zoology ◽

10.1093/czoolo/59.3.418 ◽

2013 ◽

Vol 59 (3) ◽

pp. 418-426 ◽

Cited By ~ 77

Author(s):

Victoria L. Scaven ◽

Nicole E. Rafferty

Keyword(s):

Climate Change ◽

Climate Warming ◽

Scale Up ◽

Flowering Plants ◽

Floral Resources ◽

Physiological Effects ◽

Pollination Success ◽

Insect Pollinators ◽

Pollinating Insects ◽

Plant Pollinator

Abstract Growing concern about the influence of climate change on flowering plants, pollinators, and the mutualistic interactions between them has led to a recent surge in research. Much of this research has addressed the consequences of warming for phenological and distributional shifts. In contrast, relatively little is known about the physiological responses of plants and insect pollinators to climate warming and, in particular, how these responses might affect plant-pollinator interactions. Here, we summarize the direct physiological effects of temperature on flowering plants and pollinating insects to highlight ways in which plant and pollinator responses could affect floral resources for pollinators, and pollination success for plants, respectively. We also consider the overall effects of these responses on plant-pollinator interaction networks. Plant responses to warming, which include altered flower, nectar, and pollen production, could modify floral resource availability and reproductive output of pollinating insects. Similarly, pollinator responses, such as altered foraging activity, body size, and life span, could affect patterns of pollen flow and pollination success of flowering plants. As a result, network structure could be altered as interactions are gained and lost, weakened and strengthened, even without the gain or loss of species or temporal overlap. Future research that addresses not only how plant and pollinator physiology are affected by warming but also how responses scale up to affect interactions and networks should allow us to better understand and predict the effects of climate change on this important ecosystem service.

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Insect pollination is important in a smallholder bean farming system

PeerJ ◽

10.7717/peerj.10102 ◽

2020 ◽

Vol 8 ◽

pp. e10102

Author(s):

Filemon Elisante ◽

Patrick Ndakidemi ◽

Sarah E.J. Arnold ◽

Steven R. Belmain ◽

Geoff M. Gurr ◽

...

Keyword(s):

Low Income ◽

Crop Production ◽

Habitat Management ◽

Smallholder Farmers ◽

Agricultural Landscapes ◽

Low Income Countries ◽

Field Margin ◽

Flower Visitors ◽

Insect Pollinators ◽

Flower Visiting

Background Many crops are dependent on pollination by insects. Habitat management in agricultural landscapes can support pollinator services and even augment crop production. Common bean (Phaseolus vulgaris L.) is an important legume for the livelihoods of smallholder farmers in many low-income countries, particularly so in East Africa. While this crop is autogamous, it is frequently visited by pollinating insects that could improve yields. However, the value of pollination services to common beans (Kariasii) yield is not known. Methods We carried out pollinator-exclusion experiments to determine the contribution of insect pollinators to bean yields. We also carried out a fluorescent-dye experiment to evaluate the role of field margins as refuge for flower-visitors. Results Significantly higher yields, based on pods per plant and seeds per pod, were recorded from open-pollinated and hand-pollinated flowers compared to plants from which pollinators had been excluded indicating that flower visitors contribute significantly to bean yields. Similarly, open and hand-pollinated plants recorded the highest mean seed weight. Extrapolation of yield data to field scale indicated a potential increase per hectare from 681 kg in self-pollinated beans to 1,478 kg in open-pollinated beans indicating that flower visitors contributed significantly to crop yield of beans. Our marking study indicated that flower-visiting insects including bees, flies and lepidopterans moved from the field margin flowers into the bean crop. Overall, these results show that insect pollinators are important for optimising bean yields and an important food security consideration on smallholder farms. Field margin vegetation also provides habitat for flower-visiting insects that pollinate beans. Hence, non-crop habitats merit further research focusing on establishing which field margin species are most important and their capacity to support other ecosystem services such as natural pest regulation or even pests.

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Linking pollinator occurrence in field margins to pollinator visitation to a mass-flowering crop

Journal of Pollination Ecology ◽

10.26786/1920-7603(2021)623 ◽

2021 ◽

Vol 28 ◽

pp. 153-166

Author(s):

Marjaana Toivonen ◽

Irina Herzon ◽

Jenni Toikkanen ◽

Mikko Kuussaari

Keyword(s):

Species Richness ◽

Landscape Heterogeneity ◽

Agricultural Landscapes ◽

Field Margins ◽

Natural Habitats ◽

Pollination Services ◽

Pollinator Visitation ◽

Mass Flowering ◽

Pollinator Abundance ◽

Management Approaches

Uncultivated field margins are important refugia for pollinating insects in agricultural landscapes. However, the spill-over of pollination services from field margins to adjacent crops is poorly understood. This study (i) examined the effects of landscape heterogeneity on pollinator occurrence in permanent field margins and pollinator visitation to adjacent mass-flowering turnip rape (Brassica rapa ssp. oleifera) in boreal agricultural landscapes, and (ii) tested whether pollinator abundance and species richness in field margins predict abundance and species richness of crop visitors. Pollinators visiting the crop were more affected by landscape heterogeneity than pollinators in adjacent margins. Species richness, total abundance, and the abundance of syrphid flies visiting the crop increased with increasing landscape heterogeneity, whereas, in field margins, landscape heterogeneity had little effect on pollinators. In field-dominated homogeneous landscapes, wild pollinators rarely visited the crop even if they occurred in adjacent margins, whereas in heterogeneous landscapes, differences between the two habitats were smaller. Total pollinator abundance and species richness in field margins were poor predictors of pollinator visitation to adjacent crop. However, high abundances of honeybees and bumblebees in margins were related to high numbers of crop visitors from these taxa. Our results suggest that, while uncultivated field margins help pollinators persist in boreal agricultural landscapes, they do not always result in enhanced pollinator visitation to the adjacent crop. More studies quantifying pollination service delivery from semi-natural habitats to crops in different landscape settings will help develop management approaches to support crop pollination.

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Urbanisation is associated with reduced Nosema sp. infection, higher colony strength and higher richness of foraged pollen in honeybees

Apidologie ◽

10.1007/s13592-020-00758-1 ◽

2020 ◽

Vol 51 (5) ◽

pp. 746-762

Author(s):

Ash E. Samuelson ◽

Richard J. Gill ◽

Ellouise Leadbeater

Keyword(s):

Land Use ◽

Rural Areas ◽

Agricultural Landscapes ◽

Urban Land Use ◽

Floral Resources ◽

Food Store ◽

Positive Effects ◽

Insect Pollinators ◽

Colony Performance ◽

Use Categories

Abstract Bees are vital pollinators, but are faced with numerous threats that include loss of floral resources and emerging parasites amongst others. Urbanisation is a rapidly expanding driver of land-use change that may interact with these two major threats to bees. Here we investigated effects of urbanisation on food store quality and colony health in honeybees (Apis mellifera) by sampling 51 hives in four different land-use categories: urban, suburban, rural open and rural wooded during two seasons (spring and autumn). We found positive effects of urban land use on colony strength and richness of stored pollen morphotypes, alongside lower late-season Nosema sp. infection in urban and suburban colonies. Our results reveal that honeybees exhibit lower colony performance in strength in rural areas, adding to the growing evidence that modern agricultural landscapes can constitute poor habitat for insect pollinators.

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Net effects of field and landscape scale habitat on insect and bird damage to sunflowers

10.1101/804328 ◽

2019 ◽

Cited By ~ 1

Author(s):

Sara M. Kross ◽

Breanna L. Martinico ◽

Ryan P. Bourbour ◽

Jason M. Townsend ◽

Chris McColl ◽

...

Keyword(s):

Habitat Type ◽

Landscape Scale ◽

Agricultural Landscapes ◽

Woody Vegetation ◽

Field Margins ◽

Field Margin ◽

Bird Abundance ◽

Avian Abundance ◽

Bird Damage ◽

Seed Crops

AbstractAgriculture-dominated landscapes harbor significantly diminished biodiversity, but are also areas in which significant gains in biodiversity can be achieved. Planting or retaining woody vegetation along field margins can provide farmers with valuable ecosystem services while simultaneously benefitting biodiversity. However, when crops are damaged by the biodiversity harbored in such vegetation, farmers are reluctant to incorporate field margin habitat onto their land and may even actively remove such habitats, at cost to both farmers and non-target wildlife. We investigated how damage by both insect pests (sunflower moth, Homoeosoma electellum) and avian pests to sunflower (Helianthus annuus) seed crops varied as a function of bird abundance and diversity, as well as by landscape-scale habitat. Surveys for insect damage, avian abundance, and bird damage were carried out over two years in 30 different fields on farms in California’s Sacramento Valley. The mean percentage of moth-damaged sunflowers sampled was nearly four times higher in fields that had bare or weedy margins (23.5%) compared to fields with woody vegetation (5.9%) and decreased in both field types as landscape-scale habitat complexity declined. Birds damaged significantly fewer sunflower seeds (2.7%) than insects, and bird damage was not affected by field margin habitat type, landscape-scale habitat variables, or avian abundance, but was significantly higher along field edges compared to ≥ 50m from the field edge. Avian species richness nearly doubled in fields with woody margin habitat compared to fields with bare/weedy margins in both the breeding season and in fall. These results indicate that the benefits of planting or retaining woody vegetation along sunflower field margins could outweigh the ecosystem disservices related to bird damage, while simultaneously increasing the biodiversity value of intensively farmed agricultural landscapes.

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How Bees Respond Differently to Field Margins of Shrubby and Herbaceous Plants in Intensive Agricultural Crops of the Mediterranean Area

Insects ◽

10.3390/insects11010026 ◽

2019 ◽

Vol 11 (1) ◽

pp. 26 ◽

Cited By ~ 3

Author(s):

Juan Sanchez ◽

Aline Carrasco ◽

Michelangelo La Spina ◽

María Pérez-Marcos ◽

F. Ortiz-Sánchez

Keyword(s):

Mediterranean Area ◽

Agricultural Landscapes ◽

Intensive Agriculture ◽

Floral Resources ◽

Conservation Strategies ◽

Wild Bees ◽

Floral Diversity ◽

Pollinating Insects ◽

Abundance And Diversity ◽

Bee Communities

(1) Intensive agriculture has a high impact on pollinating insects, and conservation strategies targeting agricultural landscapes may greatly contribute to their maintenance. The aim of this work was to quantify the effect that the vegetation of crop margins, with either herbaceous or shrubby plants, had on the abundance and diversity of bees in comparison to non-restored margins. (2) The work was carried out in an area of intensive agriculture in southern Spain. Bees were monitored visually and using pan traps, and floral resources were quantified in crop margins for two years. (3) An increase in the abundance and diversity of wild bees in restored margins was registered, compared to non-restored margins. Significant differences in the structure of bee communities were found between shrubby and herbaceous margins. Apis mellifera and mining bees were found to be more polylectic than wild Apidae and Megachilidae. The abundance of A. mellifera and mining bees was correlated to the total floral resources, in particular, to those offered by the Boraginaceae and Brassicaceae; wild Apidae and Megachilidae were associated with the Lamiaceae. (4) This work emphasises the importance of floral diversity and shrubby plants for the maintenance of rich bee communities in Mediterranean agricultural landscapes.

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Identity of mass-flowering crops moderates functional trait composition of pollinator communities

Landscape Ecology ◽

10.1007/s10980-021-01261-3 ◽

2021 ◽

Author(s):

Nicole Beyer ◽

Felix Kirsch ◽

Doreen Gabriel ◽

Catrin Westphal

Keyword(s):

Faba Bean ◽

Management Practices ◽

Functional Trait ◽

Flower Morphology ◽

Landscape Diversity ◽

Floral Resources ◽

Wild Bees ◽

Natural Habitats ◽

Mass Flowering ◽

Wild Bee

Abstract Context Pollinator declines and functional homogenization of farmland insect communities have been reported. Mass-flowering crops (MFC) can support pollinators by providing floral resources. Knowledge about how MFC with dissimilar flower morphology affect functional groups and functional trait compositions of wild bee communities is scarce. Objective We investigated how two morphologically different MFC, land cover and local flower cover of semi-natural habitats (SNH) and landscape diversity affect wild bees and their functional traits (body size, tongue length, sociality, foraging preferences). Methods We conducted landscape-level wild bee surveys in SNH of 30 paired study landscapes covering an oilseed rape (OSR) (Brassica napus L.) gradient. In 15 study landscapes faba beans (Vicia faba L.) were grown, paired with respective control landscapes without grain legumes. Results Faba bean cultivation promoted bumblebees (Bombus spp. Latreille), whereas non-Bombus densities were only driven by the local flower cover of SNH. High landscape diversity enhanced wild bee species richness. Faba bean cultivation enhanced the proportions of social wild bees, bees foraging on Fabaceae and slightly of long-tongued bumblebees. Solitary bee proportions increased with high covers of OSR. High local SNH flower covers mitigated changes of mean bee sizes caused by faba bean cultivation. Conclusions Our results show that MFC support specific functional bee groups adapted to their flower morphology and can alter pollinators` functional trait composition. We conclude that management practices need to target the cultivation of functionally diverse crops, combined with high local flower covers of diverse SNH to create heterogeneous landscapes, which sustain diverse pollinator communities.

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Tree Swallow selection for wetlands in agricultural landscapes predicted by central-place foraging theory

The Condor ◽

10.1093/condor/duaa039 ◽

2020 ◽

Author(s):

Andrew S Elgin ◽

Robert G Clark ◽

Christy A Morrissey

Keyword(s):

Habitat Selection ◽

Central Place ◽

Foraging Theory ◽

Agricultural Landscapes ◽

Tree Swallow ◽

Field Margins ◽

Central Place Foraging ◽

Prairie Pothole ◽

Prairie Wetlands ◽

Selection For

Abstract Millions of wetland basins, embedded in croplands and grasslands, are biodiversity hotspots in North America’s Prairie Pothole Region, but prairie wetlands continue to be degraded and drained, primarily for agricultural activities. Aerial insectivorous swallows are known to forage over water, but it is unclear whether swallows exhibit greater selection for wetlands relative to other habitats in croplands and grasslands. Central-place foraging theory suggests that habitat selectivity should increase with traveling distance from a central place, such that foragers compensate for traveling costs by selecting more profitable foraging habitat. Using global positioning system (GPS) tags, we evaluated habitat selection by female Tree Swallows (Tachycineta bicolor) at 4 sites containing wetlands and where terrestrial land cover was dominated by grasslands (grass, herbaceous cover) and/or cultivated cropland. We also used sweep-net transects to assess the abundance and biomass of flying insects in different habitats available to swallows (wetland pond margins, grassy field margins, and representative uplands). As expected for a central-place forager, GPS-tagged swallows selected more for wetland ponds (disproportionate to availability), and appeared to increasingly select for wetlands with increasing distance from their nests. On cropland-dominated sites, insect abundance and biomass tended to be higher in pond margins or grassy field margins compared to cropped uplands, while abundance and biomass were more uniform among sampled habitats at sites dominated by grass and herbaceous cover. Swallow habitat selection was not clearly explained by the distribution of sampled insects among habitats; however, traditional terrestrial sampling methods may not adequately reflect prey distribution and availability to aerially foraging swallows. Overall, our results underscore the importance of protecting and enhancing prairie wetlands and other non-crop habitats in agricultural landscapes, given their disproportionate use and capacity to support breeding swallow and insect populations.

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Floral Resources Sustaining African Meliponine Bee Species (Hymenoptera: Meliponini) in a Fragile Habitat of Kenya

Journal of Biology and Life Science ◽

10.5296/jbls.v8i1.10127 ◽

2016 ◽

Vol 8 (1) ◽

pp. 42 ◽

Cited By ~ 1

Author(s):

Bridget O. Bobadoye ◽

Paul N. Ndegwa ◽

Lucy Irungu ◽

Fombong Ayuka ◽

Robert Kajobe

Keyword(s):

Flowering Phenology ◽

Abundant Species ◽

Flowering Plants ◽

Flowering Plant ◽

Floral Resources ◽

Habitat Gradients ◽

Naturally Occurring ◽

Taita Hills ◽

Insect Pollinators ◽

Diverse Habitat

A vast majority of insects visit flowers for food, generally termed as floral rewards. Detailed insights on flowering phenology of plants could give a hint of habitat status and the extent to which such landscapes could support insect pollinators to render both direct and indirect ecosystem services. This study monitored flowering plants which could potentially provide both pollen and nectar sources to four African meliponine bee species (Apidae: Meliponini) naturally occurring in six diverse habitat gradients of the eastern arc mountains (Taita hills) of Kenya. Blooming sequences of identified flowering plants overlapped across seasons with approximately 80 different plant species belonging to 34 families recorded, with the highest proportions from Fabaceae and Asteraceae families dominating flowering plants that were visited (67% of the visits). A flowering calendar is presented to indicate the phenological pattern of all identified floral resources. Hypotrigona gribodoi being the most abundant species had the highest visitation rates on plants belonging to Fabaceae and Asteraceae families, followed by Meliponula ferruginea (black), Plebeina hildebrandti and Hypotrigona ruspolii. This indicates that such fragile habitat could invariably sustain nutritional requirements essential for the survival of insect pollinators such as native meliponine bee species, though bee abundance at flowers did not significantly correlate to food availability (expressed by flowering plant richness).

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