Mass‐flowering crops dilute pollinator abundance in agricultural landscapes across Europe

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.

Download Full-text

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

Journal of Pollination Ecology ◽

10.26786/1920-7603(2021)628 ◽

2021 ◽

Vol 28 ◽

pp. 90-107

Author(s):

Irene Bottero ◽

Simon Hodge ◽

Jane Stout

Keyword(s):

Agricultural Landscapes ◽

Floral Resources ◽

Field Margins ◽

Flowering Period ◽

Field Margin ◽

Mass Flowering ◽

Insect Abundance ◽

Insect Pollinators ◽

Pollinating Insects ◽

Hover Flies

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.

Download Full-text

Flower Strips in Wheat Intercropping System: Effect on Pollinator Abundance and Diversity in Belgium

Insects ◽

10.3390/insects9030114 ◽

2018 ◽

Vol 9 (3) ◽

pp. 114 ◽

Cited By ~ 4

Author(s):

Clara Amy ◽

Grégoire Noël ◽

Séverin Hatt ◽

Roel Uyttenbroeck ◽

Frank Van de Meutter ◽

...

Keyword(s):

Insect Pests ◽

Triticum Aestivum L ◽

Agricultural Landscapes ◽

Agricultural Systems ◽

System Effect ◽

Pollinator Abundance ◽

Pollinator Species ◽

Pollinator Community ◽

Abundance And Diversity ◽

Agricultural Areas

The decline of pollinators in agricultural areas has been observed for some decades, this being partly due to landscape simplification in intensive agrosystems. Diversifying agricultural landscapes by sowing flower strips within fields could reduce these adverse effects on biodiversity. In this context, the study presented here aimed at assessing and comparing the abundance and diversity of bees (Hymenoptera: Anthophila) and hoverflies (Diptera: Syrphidae) found and visiting flowers in three types of flower strips in Belgium: (i) a mixture of 11 wild flowers, (ii) a monofloral strip of Dimorphoteca pluvialis (Asteraceae) and (iii) a monofloral strip of Camelina sativa (Brassicaceae), where the last two are considered to be intercrops since they are valuable on the market, all sown within a field of winter wheat (Triticum aestivum L.). Pollinators were captured with pan traps and by netting in standardised transects from May to July 2017. One-thousand one-hundred and eighty-four individuals belonging to 43 bee species and 18 hoverfly species were collected. Significant differences in hoverfly diversity were found between the different flower strips. The multifloral treatment supported a greater diversity of syrphid species. Various pollinator species visited the different flowers composing the mixture and also D. pluvialis. The pollinator community proved to be predominantly generalist, with the exception of an oligolectic species in Belgium, Andrena nitidiuscula. Moreover, the three tested flower strips were effective in attracting hoverflies, among them natural enemies of insect pests. This study opens new perspectives in the design of intercropping systems with flower strips towards the design of sustainable agro-ecosystems. Improving economic profitability of sowing flower strips could encourage farmers to diversify their agricultural systems and foster conservation biology strategies.

Download Full-text

Fruit quantity and quality of strawberries benefit from enhanced pollinator abundance at hedgerows in agricultural landscapes

Agriculture Ecosystems & Environment ◽

10.1016/j.agee.2019.01.003 ◽

2019 ◽

Vol 275 ◽

pp. 14-22 ◽

Cited By ~ 11

Author(s):

Denise Castle ◽

Ingo Grass ◽

Catrin Westphal

Keyword(s):

Agricultural Landscapes ◽

Pollinator Abundance

Download Full-text

The Attractiveness of Five Common Mediterranean Weeds to Pollinators

Agronomy ◽

10.3390/agronomy11071314 ◽

2021 ◽

Vol 11 (7) ◽

pp. 1314

Author(s):

Jane Morrison ◽

Jordi Izquierdo ◽

Eva Hernández Plaza ◽

José L. González-Andújar

Keyword(s):

Cost Effective ◽

Agricultural Landscapes ◽

Wild Plants ◽

Weed Species ◽

Convolvulus Arvensis ◽

Daucus Carota L ◽

Pollinator Abundance ◽

Pollinator Conservation ◽

Abundance And Diversity ◽

Flower Visiting

Concerns about a global decline in pollinators have called for more knowledge about the factors influencing wild pollinator abundance and diversity in agroecosystems. Agricultural intensification has been identified as the main cause of this “global pollinator crisis”, particularly due to reductions in natural areas holding critical floral and nesting resources. Maintaining native wild plants in agricultural landscapes (e.g., in field margins) is often recommended as a cost-effective and efficient method for pollinator conservation. In this study, the role of common wild flowers, often considered weeds, in supporting pollinators in a Mediterranean agroecosystem was investigated. This work involved a two-year field trial to compare five native weed species common in Mediterranean cereal agroecosystems: Convolvulus arvensis L., Daucus carota L., Malva sylvestris L., Papaver rhoeas L., and Sonchus oleraceus L. The goal was to compare the attractiveness of these species, and a mixture of all five, to different flower-visiting insect groups in order to assess their value in supporting wild pollinators. Overall, D. carota had the highest number of insect visits, followed by P. rhoeas. C. arvensis, M. sylvestris, and S. oleraceus, which had lower numbers of visits. On the basis of their overall attractiveness to pollinators and low risk for invasiveness, D. carota, P. rhoeas, and M. sylvestris are the most likely to contribute positively to the conservation of pollinators in agroecosystems. Our results also suggest that it is advantageous for wild flowers sown for the purpose of pollinator conservation to be grown in clumps, rather than highly intermingled, for improved visitation rates.

Download Full-text

Effects of landscape complexity on pollinators are moderated by pollinators' association with mass-flowering crops

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2019.0387 ◽

2019 ◽

Vol 286 (1900) ◽

pp. 20190387 ◽

Cited By ~ 4

Author(s):

Thijs P. M. Fijen ◽

Jeroen A. Scheper ◽

Bastiaen Boekelo ◽

Ivo Raemakers ◽

David Kleijn

Keyword(s):

Natural Habitat ◽

Agricultural Landscapes ◽

Community Size ◽

Natural Habitats ◽

Pollinator Decline ◽

Mass Flowering ◽

Landscape Complexity ◽

Positive Effects ◽

Pollinator Community ◽

Core Components

Conserving and restoring semi-natural habitat, i.e. enhancing landscape complexity, is one of the main strategies to mitigate pollinator decline in agricultural landscapes. However, we still have limited understanding of how landscape complexity shapes pollinator communities in both crop and non-crop habitat, and whether pollinator responses to landscape complexity vary with their association with mass-flowering crops. Here, we surveyed pollinator communities on mass-flowering leek crops and in nearby semi-natural habitat in landscapes of varying complexity. Surveys were done before and during crop bloom and distinguished between pollinators that visit the crop frequently (dominant), occasionally (opportunistic), or not at all (non-crop). Forty-seven per cent of the species in the wider landscape were also observed on leek flowers. Crop pollinator richness increased with local pollinator community size and increasing landscape complexity, but relationships were stronger for opportunistic than for dominant crop pollinators. Relationships between pollinator richness in semi-natural habitats and landscape complexity differed between groups with the most pronounced positive effects on non-crop pollinators. Our results indicate that while dominant crop pollinators are core components of crop pollinator communities in all agricultural landscapes, opportunistic crop pollinators largely determine species-richness responses and complex landscapes are local hotspots for both biodiversity conservation and potential ecosystem service provision.

Download Full-text

Flowers in Conservation Reserve Program (CRP) Pollinator Plantings and the Upper Midwest Agricultural Landscape Supporting Honey Bees

Insects ◽

10.3390/insects11070405 ◽

2020 ◽

Vol 11 (7) ◽

pp. 405

Author(s):

Harper McMinn-Sauder ◽

Rodney Richardson ◽

Tyler Eaton ◽

Mike Smith ◽

Reed Johnson

Keyword(s):

Honey Bee ◽

Honey Bees ◽

Agricultural Landscape ◽

Conservation Reserve Program ◽

Agricultural Landscapes ◽

Primary Sources ◽

Floral Resources ◽

Pollinator Abundance ◽

Abundance And Diversity ◽

Honey Bee Nutrition

A present goal of the Conservation Reserve Program (CRP) is to manage land in agricultural landscapes to increase pollinator abundance and diversity. CP42, or the pollinator seed mix, is planted and managed to support foraging pollinators with blooming flowers present at all points in the foraging season. This high-quality habitat provides an excellent opportunity to study honey bee nutrition and determine whether honey bees located near CRP sites use known resources included in planting seed mixes. This study aims to highlight the primary sources of honey bee forage in the northern Midwest as well as to assess honey bee utilization of the floral resources provided by the pollinator seed mix used for CRP plantings. We received pollen samples collected using pollen traps by beekeepers in Ohio, South Dakota, Indiana, Illinois, and Michigan. Metabarcoding methods were used to identify and quantify pollen collected at different points in the season. The results indicate that honey bees frequently used major mass flowering resources such as Glycine, Trifolium, and Symphiotrichum throughout the season. In addition, flowers included in the CRP pollinator seed mix were used modestly. These results have implications for pollinator seed mix design.

Download Full-text