Contribution of insect pollinators to crop yield and quality varies with agricultural intensification

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 fromsimple 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.

High night temperature induces contrasting responses for spikelet fertility, spikelet tissue temperature, flowering characteristics and grain quality in rice

Climate change is increasing night temperature (NT) more than day temperature (DT) in rice-growing areas. Effects of combinations of NT (24-35°C) from microsporogenesis to anthesis at one or more DT (30 or 35°C) at anthesis on rice spikelet fertility, temperature within spikelets, flowering pattern, grain weight per panicle, amylose content and gel consistency were investigated in contrasting rice cultivars under controlled environments. Cultivars differed in spikelet fertility response to high NT, with higher fertility associated with cooler spikelets (P < 0.01). Flowering dynamics were altered by high NT and a novel high temperature tolerance complementary mechanism, shorter flower open duration in cv. N22, was identified. High NT reduced spikelet fertility, grain weight per panicle, amylose content and gel consistency, whereas high DT reduced only gel consistency. Night temperature >27°C was estimated to reduce grain weight. Generally, high NT was more damaging to grain weight and selected grain quality traits than high DT, with little or no interaction between them. The critical tolerance and escape traits identified, i.e. spikelet cooling, relatively high spikelet fertility, earlier start and peak time of anthesis and shorter spikelet anthesis duration can aid plant breeding programs targeting resilience in warmer climates.

The inclusion of forage mixtures in the diet of growing dairy heifers: impacts on digestion, energy utilisation, and methane emissions

Intensive farming focusing on monoculture grass species to maximise forage production has led to a reduction in the extent and diversity of species-rich grasslands. However, plant communities with higher species number (richness) are a potential strategy for more sustainable production and mitigation of greenhouse gas (GHG) emissions. Research has indicated the need to understand opportunities that forage mixtures can offer sustainable ruminant production systems. The objective of the two experiments reported here were to evaluate multiple species forage mixtures in comparison to ryegrass-dominant pasture, when conserved or grazed, on digestion, energy utilisation, N excretion, and methane emissions by growing 10–15 month old heifers. Experiment 1 was a 4 × 4 Latin square design with five week periods. Four forage treatments of: (1) ryegrass (control); permanent pasture with perennial ryegrass (Lolium perenne); (2) clover; a ryegrass:red clover (Trifolium pratense) mixture; (3) trefoil; a ryegrass:birdsfoot trefoil (Lotus corniculatus) mixture; and (4) flowers; a ryegrass:wild flower mixture of predominately sorrel (Rumex acetosa), ox-eye daisy (Leucanthemum vulgare), yarrow (Achillea millefolium), knapweed (Centaurea nigra) and ribwort plantain (Plantago lanceolata), were fed as haylages to four dairy heifers. Measurements included digestibility, N excretion, and energy utilisation (including methane emissions measured in respiration chambers). Experiment 2 used 12 different dairy heifers grazing three of the same forage treatments used to make haylage in experiment 1 (ryegrass, clover and flowers) and methane emissions were estimated using the sulphur hexafluoride (SF6) tracer technique. Distribution of ryegrass to other species (dry matter (DM) basis) was approximately 70:30 (clover), 80:20 (trefoil), and 40:60 (flowers) for experiment 1. During the first and second grazing rotations (respectively) in experiment 2, perennial ryegrass accounted for 95 and 98% of DM in ryegrass, and 84 and 52% of DM in clover, with red clover accounting for almost all of the remainder. In the flowers mixture, perennial ryegrass was 52% of the DM in the first grazing rotation and only 30% in the second, with a variety of other flower species occupying the remainder. Across both experiments, compared to the forage mixtures (clover, trefoil and flowers), ryegrass had a higher crude protein (CP) content (P < 0.001, 187 vs. 115 g kg −1 DM) and DM intake (P < 0.05, 9.0 vs. 8.1 kg day −1). Heifers in experiment 1 fed ryegrass, compared to the forage mixtures, had greater total tract digestibility (g kg −1) of DM (DMD; P < 0.008, 713 vs. 641) and CP (CPD, P < 0.001, 699 vs. 475), and used more intake energy (%) for body tissue deposition (P < 0.05, 2.6 vs. −4.9). For both experiments, heifers fed flowers differed the most compared to the ryegrass control for a number of measurements. Compared to ryegrass, flowers had 40% lower CP content (P < 0.001, 113 vs. 187 g kg −1), 18% lower DMD (P < 0.01, 585 vs. 713 g kg −1), 42% lower CPD (P < 0.001, 407 vs. 699 g kg −1), and 10% lower methane yield (P < 0.05, 22.6 vs. 25.1 g kg −1 DM intake). This study has shown inclusion of flowers in forage mixtures resulted in a lower CP concentration, digestibility and intake. These differences were due in part to sward management and maturity at harvest. Further research is needed to determine how best to exploit the potential environmental benefits of forage mixtures in sustainable ruminant production systems.

The drowned and the saved: shipwrecks and the 'cursus' of Latin love elegy

Throughout the corpus of Latin love elegy, the imaginary tombs envisaged by the elegists for their own personae and for other inhabitants of their poetic world display a striking tendency to take on the characteristic attributes and personalities of those interred within. The final resting-place of Propertius, for instance, that self-proclaimed acolyte of Callimachean miniaturism and exclusivity, is to be sequestered from the degrading attentions of the passing populace (Prop. 3.16.25–30) and crowned with the poet's laurel (2.13.33–4). What remains of his meagre form will rest in a ‘tiny little urn’ (paruula testa, 2.13.32) beneath a monument declaring the lover's slavery to a single passion (2.13.35–6), and the grave is to be attended, or so he hopes, by the object of that passion herself (3.16.23–4), or occasionally (though he is not so confident of this) by his patron Maecenas (2.1.71–8). Likewise the memorial designed by Ovid for Corinna's pet parrot - an imitatrix ales endowed with the most distinctive foibles of the elegiac tradition - in Amores 2.6, comprising a burial mound pro corpore magnus (2.6.59) topped with a tombstone described as exiguus (‘tiny’, 2.6.60; cf. Prop. 2.1.72, 2.13.33), exhibits an elegiac emphasis worthy of the parrot's human counterparts among Ovid's poetic predecessors.

Interactive effect of floral abundance and semi-natural habitats on pollinators in field beans (Vicia faba)

Pollination services are economically important component of agricultural biodiversity which enhance the yield and quality of many crops. An understanding of the suitability of extant habitats for pollinating species is crucial for planning management actions to protect and manage these service providers. In a highly modified agricultural ecosystem, we tested the effect of different pollination treatments (open, autonomous self- and wind-pollination) on pod set, seed set, and seed weight in field beans (Vicia faba). We also investigated the effect of semi-natural habitats and flower abundance on pollinators of field beans. Pollinator sampling was undertaken in ten field bean fields along a gradient of habitat complexity; CORINE land cover classification was used to analyse the land use patterns between 500–3000 m around the sites. Total yield from open-pollination increased by 185% compared to autonomous self-pollination. There was positive interactive effect of local flower abundance and cover of semi-natural habitats on overall abundance of pollinators at 1500 and 2000 m, and abundance of bumblebees (Bombus spp.) at 1000–2000 m. In contrast, species richness of pollinators was only correlated with flower abundance and not with semi-natural habitats. We did not find a link between pod set from open-pollination and pollinator abundance, possibly due to variations in the growing conditions and pollinator communities between sites. We conclude that insect pollination is essential for optimal bean yields and therefore the maintenance of semi-natural habitats in agriculture-dominated landscapes should ensure stable and more efficient pollination services in field beans.

A SNP-based consensus genetic map for synteny-based trait targeting in faba bean (Vicia faba L.)

Faba bean (Vicia faba L.) is a globally important nitrogen-fixing legume, which is widely grown in a diverse range of environments. In this work, we mine and validate a set of 845 SNPs from the aligned transcriptomes of two contrasting inbred lines. Each V. faba SNP is assigned by BLAST analysis to a single Medicago orthologue. This set of syntenically anchored polymorphisms were then validated as individual KASP assays, classified according to their informativeness and performance on a panel of 37 inbred lines, and the best performing 757 markers used to genotype six mapping populations. The six resulting linkage maps were merged into a single consensus map on which 687 SNPs were placed on six linkage groups, each presumed to correspond to one of the six V. faba chromosomes. This sequence-based consensus map was used to explore synteny with the most closely-related crop species, lentil, and the most closely related fully sequenced genome, Medicago. Large tracts of uninterrupted colinearity were found between faba bean and Medicago, making it relatively straightforward to predict gene content and order in mapped genetic interval. As a demonstration of this, we mapped a flower colour gene to a 2 cM interval of Vf chromosome 2 which was highly collinear with Mt3. The obvious candidate gene from 77 gene models in the collinear Medicago chromosome segment was the previously characterized MtWD40-1 gene (Mt3g092830, Mt3g092840) controlling anthocyanin production in Medicago and re-sequencing of the Vf orthologue showed a putative causative deletion of the entire 5’ end of the gene.

Effect of high temperature and water stress on groundnuts under field conditions

Groundnuts cultivated in the semiarid tropics are often exposed to water stress (mid-season and end season) and high temperature (> 34 °C) during the critical stages of flowering and pod development. This study evaluated the effects of both water stress and high temperature under field conditions at ICRISAT, India. Treatments included two irrigations (full irrigation, 100 % of crop evapotranspiration; and water stress, 40 % of crop evapotranspiration), four temperature treatments from a combination of two sowing dates and heat tunnels with mean temperatures from sowing to maturity of 26.3° (T1), 27.3° (T2), 29.0° (T3) and 29.7 °C (T4) and two genotypes TMV2 and ICGS 11. The heat tunnels were capable of raising the day temperature by > 10 °C compared to ambient. During the 20-day high-temperature treatment at flowering, mean temperatures were 33.8° (T1), 41.6° (T2), 38.7° (T3) and 43.5°C (T4). The effects of water stress and high temperature were additive and temporary for both vegetative and pod yield, and disappeared as soon as high-temperature stress was removed. Water use efficiency was significantly affected by the main effects of temperature and cultivar and not by water stress treatments. Genotypic differences for tolerance to high temperature can be attributed to differences in flowering pattern, flower number, peg-set and harvest index. It can be inferred from this study that genotypes that are tolerant to water stress are also tolerant to high temperature under field conditions. In addition, genotypes with an ability to establish greater biomass and with a significantly greater partitioning of biomass to pod yield would be suitable for sustaining higher yields in semiarid tropics with high temperature and water stress.

The effects of diesel exhaust pollution on floral volatiles and the consequences for honey bee olfaction

There is growing evidence of a substantial decline in pollinators within Europe and North America, most likely caused by multiple factors such as diseases, poor nutrition, habitat loss, insecticides, and environmental pollution. Diesel exhaust could be a contributing factor to this decline, since we found that diesel exhaust rapidly degrades floral volatiles, which honey bees require for flower recognition. In this study, we exposed eight of the most common floral volatiles to diesel exhaust in order to investigate whether it can affect volatile mediated plant-pollinator interaction. Exposure to diesel exhaust altered the blend of common flower volatiles significantly: myrcene was considerably reduced, β-ocimene became undetectable, and β-caryophyllene was transformed into its cis-isomer isocaryophyllene. Proboscis extension response (PER) assays showed that the alterations of the blend reduced the ability of honey bees to recognize it. The chemically reactive nitrogen oxides fraction of diesel exhaust gas was identified as capable of causing degradation of floral volatiles.

Testing projected wild bee distributions in agricultural habitats: predictive power depends on species traits and habitat type

Species distribution models (SDM) are increasingly used to understand the factors that regulate variation in biodiversity patterns and to help plan conservation strategies. However, these models are rarely validated with independently collected data and it is unclear whether SDM performance is maintained across distinct habitats and for species with different functional traits. Highly mobile species, such as bees, can be particularly challenging to model. Here, we use independent sets of occurrence data collected systematically in several agricultural habitats to test how the predictive performance of SDMs for wild bee species depends on species traits, habitat type, and sampling technique. We used a species distribution modeling approach parametrized for the Netherlands, with presence records from 1990 to 2010 for 193 Dutch wild bees. For each species, we built a Maxent model based on 13 climate and landscape variables. We tested the predictive performance of the SDMs with independent datasets collected from orchards and arable fields across the Netherlands from 2010 to 2013, using transect surveys or pan traps. Model predictive performance depended on species traits and habitat type. Occurrence of bee species specialized in habitat and diet was better predicted than generalist bees. Predictions of habitat suitability were also more precise for habitats that are temporally more stable (orchards) than for habitats that suffer regular alterations (arable), particularly for small, solitary bees. As a conservation tool, SDMs are best suited to modeling rarer, specialist species than more generalist and will work best in long-term stable habitats. The variability of complex, short-term habitats is difficult to capture in such models and historical land use generally has low thematic resolution. To improve SDMs’ usefulness, models require explanatory variables and collection data that include detailed landscape characteristics, for example, variability of crops and flower availability. Additionally, testing SDMs with field surveys should involve multiple collection techniques.

Exploring broad mitigation strategies for pollinators in agroecosystems

An increasing world population has put great pressure on agricultural landscapes to continually increase in efficiency whilst avoiding negative impacts on the environment. Protected areas, mass flower crops and agri-environment schemes have been identified as three broad complimentary mitigation strategies to protect and conserve pollinators. Each strategy differs temporarily and spatially but all offer significant benefits to pollinators. It is vital we identify the value of these mitigation strategies and their complementarity if we are to tailor landscape management for optimal results and work towards safeguarding our pollination service.

Non-bee insects are important contributors to global crop pollination

Wild and managed bees are well documented as effective pollinators of global crops of economic importance. However, the contributions by pollinators other than bees have been little explored despite their potential to contribute to crop production and stability in the face of environmental change. Non-bee pollinators include flies, beetles, moths, butterflies, wasps, ants, birds, and bats, among others. Here we focus on non-bee insects and synthesize 39 field studies from five continents that directly measured the crop pollination services provided by non-bees, honey bees, and other bees to compare the relative contributions of these taxa. Non-bees performed 25–50% of the total number of flower visits. Although non-bees were less effective pollinators than bees per flower visit, they made more visits; thus these two factors compensated for each other, resulting in pollination services rendered by non-bees that were similar to those provided by bees. In the subset of studies that measured fruit set, fruit set increased with non-bee insect visits independently of bee visitation rates, indicating that non-bee insects provide a unique benefit that is not provided by bees. We also show that non-bee insects are not as reliant as bees on the presence of remnant natural or seminatural habitat in the surrounding landscape. These results strongly suggest that non-bee insect pollinators play a significant role in global crop production and respond differently than bees to landscape structure, probably making their crop pollination services more robust to changes in land use. Non-bee insects provide a valuable service and provide potential insurance against bee population declines.

Opening movements in Ophuls: Caught (and Madame de …)

This audiovisual essay was created at the wonderful NEH-funded workshop in videographic criticism at Middlebury College, ‘Scholarship in Sound and Image’. The essay provides an analysis of the orchestration of long takes and camera movement in the opening of Caught (Ophuls, 1949), and develops a comparison with the opening of Madame de… (Ophuls, 1953 – U.S. release title The Earrings of Madame de…), not least through a series of juxtapositions, which can be directly presented and compared in an audiovisual essay. The openings share a concern with the subjectivity of the female protagonists and our relationship toward it, evoking the women’s experience while balancing this with other kinds of perspective. As has been noted in the critical literature on Ophuls, and on melodramas of passion more generally, such views enable us to perceive the women concerned to be caught in material and ideological frameworks of which they are at best partially aware. Among the interests of this particular comparison, however, is the extent to which the dynamic around female subjectivity is played in relation to luxury goods, imagined, owned or admired. Tensions between on- and off-screen spaces and sounds are critical to the interest of the long takes under discussion. Camera movements subtly inflect the extent to which we are aligned (or otherwise) with the characters and the ways in which their material circumstances are revealed to us.

The circulation of romances from England in late-medieval Ireland

The fifteenth century saw a striking upturn in the number of texts from foreign vernaculars that were translated into Irish. Indeed, one might go so far as to speak in terms of a ‘translation trend’ in Ireland during the mid to late fifteenth century. A notable feature of this trend is that a particularly high number of these Irish translations are of romances; contextual and textual evidence suggests that the original exemplars for many of these translated texts appear to have come from England, though not all of them were necessarily in English. Irish translations of eight romances have survived to the present day: Guy of Warwick; Bevis of Hampton; La Queste de Saint Graal; Fierabras; Caxton’s Recuyell of the Histories of Troie; William of Palerne; the Seven Sages of Rome; and Octavian. This paper addresses two aspects of these texts of particular relevance to romance scholars who do not work within the sphere of Celtic studies. Firstly, it argues that certain aspects of the dissemination and reception of romance in Ireland are quite distinctive. Manuscript and textual evidence suggests that the religious orders, particularly the Franciscans, seem to have played a role in the importation and translation of these narratives. Secondly, examination of the Irish versions of romance tends to bear out an observation made by Flower many years ago, but not pursued by subsequent scholars: ‘texts of an unusual kind were current in Ireland, and it may be that interesting discoveries are to be made here’. Certain narrative features of several of these Irish translations diverge from all the surviving versions of the relevant romance in other languages and may witness to a variant exemplar that has since been lost from its own linguistic corpus.

Pasolini and Third World hunger: an approach to Cinema Novo through 'La ricotta'

Among the links between Pier Paolo Pasolini and Brazilian Cinema Novo, one of the most inspiring is the political approach to hunger and consumption. In this text, I analyse this topic to look at how some of the aesthetic ideas in Pasolini’s La ricotta (1963) can also be found in some of the most important films of Cinema Novo. In 'La ricotta' (1963), the irresistible need to eat of a subproletarian interacts and clashes with his responsibilities as an actor in a movie version of the Passion of Christ, so that the film creates a complex network of relations between film shooting, social differences, art, hunger, consumption, time and light, which turns the film set into a space for displaying political relations, differences, exploitation and revolution. The correspondences between these concepts and some aggression techniques of Cinema Novo are numerous and confirm the capacity of Pasolini’s film to project ideas on cinema and politics beyond its particular production context.

Apple pollination: demand depends on variety and supply depends on pollinator identity

Insect pollination underpins apple production but the extent to which different pollinator guilds supply this service, particularly across different apple varieties, is unknown. Such information is essential if appropriate orchard management practices are to be targeted and proportional to the potential benefits pollinator species may provide. Here we use a novel combination of pollinator effectiveness assays (floral visit effectiveness), orchard field surveys (flower visitation rate) and pollinator dependence manipulations (pollinator exclusion experiments) to quantify the supply of pollination services provided by four different pollinator guilds to the production of four commercial varieties of apple. We show that not all pollinators are equally effective at pollinating apples, with hoverflies being less effective than solitary bees and bumblebees, and the relative abundance of different pollinator guilds visiting apple flowers of different varieties varies significantly. Based on this, the taxa specific economic benefits to UK apple production have been established. The contribution of insect pollinators to the economic output in all varieties was estimated to be £92.1M across the UK, with contributions varying widely across taxa: solitary bees (£51.4M), honeybees (£21.4M), bumblebees (£18.6M) and hoverflies (£0.7M). This research highlights the differences in the economic benefits of four insect pollinator guilds to four major apple varieties in the UK. This information is essential to underpin appropriate investment in pollination services management and provides a model that can be used in other entomolophilous crops to improve our understanding of crop pollination ecology.