Floral Preferences Research Articles

Dual ecosystem services of syrphid flies (Diptera: Syrphidae): pollinators and biological control agents

With increasing worldwide pressure on bee pollinator populations and an increase in insecticide resistance amongst pest insects, there is a growing need for diversification of pollinator and pest control systems. Syrphid flies (Diptera: Syrphidae) contribute ecosystem services to agroecosystems through their supporting roles as crop pollinators and predators of pests. Adult syrphids are important pollinators with high floral visitation rates and pollen carrying capacity, while predatory syrphid larvae are natural biological control agents, reducing aphid populations in both field and laboratory conditions. The present challenge is to determine whether syrphid flies have the potential for application as pollinators and in integrated pest management (IPM) schemes as biological control agents. Currently, there are gaps in research that are hindering the use of syrphids as dual service providers. Such gaps include a lack of knowledge of syrphid floral preferences, the role and viability of adult syrphids as pollinators in natural and agro-ecological pollinator networks, and the predatory efficiency of larvae in field and greenhouse conditions. By reviewing relevant literature, we demonstrate syrphids flies have the potential to be used as pollinators and biological control agents. This article is protected by copyright. All rights reserved.

Diversification of floral orientation in Lonicera is associated with pollinator shift and flowering phenology

AbstractFloral orientation has been suggested to be a functional floral trait that can enhance reproductive fitness through adaptation to both biotic factors (e.g., pollination) and abiotic factors (e.g., temperature). However, whether those factors drive the diversification of floral orientation needs to be explored through multiple related species. Phylogenetic relationships in Lonicera were identified by incorporating the species’ floral orientation (upward vs. downward) and pollinator types. Furthermore, transitions in floral orientation were evaluated together with pollinator shift, and seven Lonicera species were used to detect the influence of floral orientation on pollination and reproductive success. The relationship between temperature and the angle of floral orientation was investigated. Floral orientation in Lonicera showed that most of the closely related species within the same node displayed a similar pattern of floral orientation, and pollinator shift can lead to transitions between upward and downward orientation. Additionally, the angle of floral orientation increased with flowering phenology from spring to summer, and changing floral orientation significantly decreased pollination and seed production. Moreover, the average daily temperature during flowering phenology was significantly correlated with the angle of floral orientation. Our results indicate that pollinator shift could be an important event, leading to the diversification of floral orientation. Results of field investigations inferred that floral orientation should be a functional floral trait adapted to flowering phenology. Downward‐facing flowers might help decrease heat loss to adapt to cold conditions. This study disentangled the influences of historical events and local adaptation on the evolution of floral orientation.

Diversity and floral preferences of solitary bees occurring in agroecosystems of Tamil Nadu

Solitary bees are excellent ecosystem servants for efficient pollination in angiosperms. The present study on these was carried out at the Agricultural College and Research Institute, Madurai campus through surveys carried out in various zones. Species diversity, richness, evenness and floral preference were explored for the variations in the zones. The results revealed that the variation is depending upon the nature of the locations included in these agroclimatic zones. The foraging activity of sonicating native bees was predominant on the plants belonging to the in families like Fabaceae, Pedaliaceae, Bignoniaceae, Asteraceae followed by Verbenaceae, Solanaceae, Malvaceae and Cucurbitaceae. Comparatively less preference could be observed on Apocynaceae, Punicaceae and Polygonaceae as regards cultivated and uncultivated crops. Mostly the bees preferred floral colour like purple and yellow followed by white for both nectar as well as pollen collection, whereas the least preference was for pink.

Associative learning and memory retention of nectar yeast volatiles in a generalist parasitoid

Understanding how animals learn is crucial to interpreting animal behaviour. Flower-visiting insects, such as bees and parasitoids, are excellent animal models to study visual and olfactory learning, including memory phenomena. The diversity of resources flower-visiting insects exploit predisposes them to learn and remember the colours, shapes and odours associated with rewarding experiences (e.g. flowers), allowing them to focus on the most rewarding resources. Recent research has shown that nectar-living microbes release volatile organic compounds (VOCs) that contribute to overall flower scent. Nevertheless, little is known about the extent to which nectar microbiota mediate insect learning of floral preferences. In this study, we investigated whether VOCs produced by nectar microbes serve as a learning cue to parasitoids and how long any developed preference is maintained. Experiments were performed using the generalist aphid parasitoid Aphidius ervi and three nectar yeasts, including the nectar specialist Metschnikowia reukaufii and the generalist species Hanseniaspora uvarum and Sporobolomyces roseus. Results showed that naive parasitoids had an innate preference for nectar fermented by the nectar specialist M. reukaufii, but not by the other two yeasts which had either a neutral (H. uvarum) or deterrent (S. roseus) effect. When parasitoids were conditioned with yeast-fermented nectar, they were strongly attracted to their odours 2 and 24 h after conditioning, but not after 48 h. Furthermore, when parasitoids were conditioned to one yeast-fermented nectar, they also showed increased attraction to other yeast-fermented nectars. This generalization suggests that their learning ability may have broader ecological consequences. However, this generalized response to other yeast VOCs lasted for only 2 h. We conclude that parasitoids show conditioned responses to the scent of yeast-fermented nectar, and yeasts, therefore, may play an important but understudied role in shaping their foraging behaviour.

Pollen analysis of honey samples from the Peruvian Amazon

Melissopalynological studies are useful to determine the floral contents and geographical origin of honey samples. The great botanical diversity in the Amazon allows bees to produce honey that is highly valuable in Peruvian culture. However, pollen analyses and labels that provide information on honey contents are scarce; therefore, people do not know what types of honey they are consuming and paying for, especially when many Amazonian honeys are traditionally referred to as being monofloral honey types with medicinal properties. For this reason, we conducted a melissopalynological study to evaluate the pollen content of 14 honey samples from lowland and highland regions of the Peruvian Amazon. A total of 40 pollen types from 28 families were identified and most of the samples were multifloral. Pollen from Fabaceae, Asteraceae and Citrus were very frequent in the samples while Myrciaria dubia, Trema and Paullinia were frequently found in the samples. Pollen from Bombax, Gouania and Mimosa were infrequent within the samples. Pollen concentration class values per 10 g of honey varied from very rich to very poor and a low index of similarity in pollen content was observed between the samples, but there was a higher similarity between samples that came from the same region. Most of the identified floral sources in the honey are related to taxa that are traditionally used for medicinal purposes. The bioactive compounds of the nectar of these plants may be producing the ‘healthier’ properties that people associate with Amazonian honeys in Peru. This pollen study provides important information on the floral source preferences of bees and on honey contents, which can be used by traditional beekeepers and the public in general. Melissopalynological analyses are also useful for promoting the production and consumption of high-quality local honeys from the Peruvian Amazon.

Pollen Analysis of the Post-Emergence Residue of Euglossa Bees (Apidae: Euglossini) Nesting in an Urban Fragment

Euglossini bees are considered pollinators of a wide variety of plants in the Neotropical region, but little is known about their floral preferences. In this study, we identified the botanical species used as pollen and nectar sources by three Euglossa species (Euglossa cordata, Euglossa townsendi, and Euglossa securigera) using pollen residue found in brood cells from trap nests installed in an urban fragment in São Luís, Maranhão, Brazil. In 14 analyzed Eg. cordata nests, 23 pollen types were observed, in 7 Eg. townsendi nests, 10 pollen types were observed, and in 1 nest of Eg. securigera, 6 morph types were identified. Solanum (Solanaceae), Zanthoxylum (Rutaceae), Mimosa pudica (Fabaceae), and Chamaecrista (Fabaceae) pollen types were common to all three bee species. Principal components analysis showed 83.04% variability on the first two axes, demonstrating substantial similarity among the samples. Solanum, Mimosa pudica, and Zanthoxylum were the principal components in the ranking. Larger diversity values (mean = 0.80) in some samples indicate that the species gathered resources in a heterogeneous manner; this resembles the findings of other studies of Euglossa. In general, the bees exhibited overlapping niches with regard to the most abundant pollens in the nests, but the females showed individual plasticity when gathering the floral resources.

Male and female bees show large differences in floral preference

BackgroundIntraspecific variation in foraging niche can drive food web dynamics and ecosystem processes. In particular, male and female animals can exhibit different, often cascading, impacts on their interaction partners. Despite this, studies of plant-pollinator interaction networks have focused on the partitioning of the floral community between pollinator species, with little attention paid to intraspecific variation in plant preference between male and female bees. We designed a field study to evaluate the strength and prevalence of sexually dimorphic foraging, and particularly resource preferences, in bees.Study designWe observed bees visiting flowers in semi-natural meadows in New Jersey, USA. To detect differences in flower use against a shared background of resource (flower) availability, we maximized the number of interactions observed within narrow spatio-temporal windows. To distinguish observed differences in bee use of flower species, which can reflect abundance patterns and sampling effects, from underlying differences in bee preferences, we analyzed our data with both a permutation-based null model and random effects models.FindingsWe found that the diets of male and female bees of the same species were often dissimilar as the diets of different species of bees. Furthermore, we demonstrate differences in preference between male and female bees. We show that intraspecific differences in preference can be robustly identified among hundreds of unique species-species interactions, without precisely quantifying resource availability, and despite high phenological turnover of both bees and plant bloom. Given the large differences in both flower use and preferences between male and female bees, ecological sex differences should be integrated into studies of bee demography, plant pollination, and coevolutionary relationships between flowers and insects.

Comparative floral preferences in nectar and pollen foraging by Scaptotrigona postica (Latreille 1807) in two different biomes in São Paulo (Brazil)

To describe the trophic resources used by Scaptotrigona postica, honey and bee bread samples were taken monthly from May 2015 to December 2016 at two different localities. Fontes do Ipiranga State Park (PEFI), an urban remnant of the Atlantic Forest, and the Mogi Guaçu Biological Reserve (RBMG), in the Cerrado. Two colonies were kept in each site. Samples were analysed with the melissopalynological method in order to calculate the relative frequencies. Principal component analysis was used to compare the similarity between the samples and to examine the influence of quantitative and qualitative data on the ordination of the pollen types. Similarity tests were performed to compare the pollen spectra of the bee bread and honey samples between the study sites and seasons. Hence, 69 and 61 pollen types were identified in 33 honey and 29 bee bread samples. The main families in honey were Asteraceae, Euphorbiaceae and Fabaceae; in bee bread Fabaceae, Myrtaceae and Sapindaceae were the main families for both localities, followed by Asteraceae, Euphorbiaceae and Solanaceae at the RBMG. The results showed that the species maintains its floral preferences regardless of the biome in which it occurs. Also, demonstrates that the bees make use of nectariferous and polliniferous sources available in the preserved areas as well as in its surroundings. There is a risk of pesticides exposure caused by the use of trophic resources of cultivated plants by this bee. This points to the need for further studies.

Plant Preferences of Halictus Latreille (Halictidae: Hymenoptera) in the Mediterranean Region of Southern Turkey

Objective: Lack of information regarding the floral preferences of wild bees is one of the major problems in understanding plant–bee interactions. Therefore, we investigated the plant preferences of Halictus Latreille (Halictidae: Apoidea: Hymenoptera) species that are distributed in the Mediterranean Region of southern Turkey. Materials and Methods: Bees were collected through field studies that were performed during the spring and summer seasons between 2008 and 2009. The flowers visited by bees were also recorded. In total, 516 bee specimens belonging to 19 species were collected, and 54 plant taxa were found to be related to these Halictus species. In addition to field study data, information collected from the literature was included in the study. The most commonly visited plant families, genera, and species are described using diversity indices scores in terms of the plant taxa preferences of the bees. Results: A total of 516 bee and 195 plant specimens were sampled from 76 stations located in 14 provinces. In total, 54 plant taxa were found to be related to 19 Halictus species. Among such large plant taxa preferences, the most commonly visited ones were Onopordum, Centaurea, and Carduus members. Conclusion: This study suggests that members of the genus Halictus primarily prefer to visit plants belonging to the Asteraceae family. However, they may also visit several other types of flowers such as those belonging to Rosaceae and Brassicaceae families.

Low trophic niche overlap among trap-nesting bee species (Hymenoptera: Anthophila) in a semideciduous forest fragment

Bees are important components of mutualistic interactions with plants, playing a key role as pollinators of both wild and crop plants. In this context, studies on the plants visited by bees are important to determining conservation strategies. We investigated the use of floral resources by the trap-nesting bee species sampled in a semideciduous forest fragment. Trap nests were set in the forest fragment in three different zones: forest edge, 250 m away from the edge and 500 m away from the forest edge. Pollen analysis of the residual pollen content removed from the nests of 12 bee species revealed a total of 63 pollen types from 16 botanical families. The bee community showed specialized populations with no overlap in diet. Within the community, the diet overlap was higher in closely related species, the two Tetrapedia species and the two Centris (Heterocentris) species, than in the other sampled species. Although the studied bee community is composed of widespread bee species, our data showed a low niche overlap among them, suggesting the occurrence of food niche partitioning at our study site. The asymmetry in the period of nesting activities and floral preferences among the bee species are factors that might have contributed to the low niche overlap observed.

Floral Resources Partitioning by Two Co-occurring Eusocial Bees in an Afromontane Landscape

Floral preferences of generalist foragers such as eusocial bees influence the success of pollination of many flowering plants, as well as competition with many other bee species in tropical communities. Eusocial bees are important for the pollination success of many flowering plants, as well as for food resources availability for many other species. However, their foraging preferences are still unknown in many tropical areas, especially in the Afrotropics. We studied the foraging activity of two syntopic eusocial bees with large colonies, the honeybee Apis mellifera Linnaeus and the stingless bee Meliplebeia ogouensis (Vachal), on seven plant species in the Bamenda Highlands, Cameroon, in two consecutive years. Simultaneously, we quantified intra- and inter-annual changes in the food resources. We observed resource partitioning among the two bee species. Although both species are considered as generalists, their short-term food niches overlap was very low. Their preferences to the most often visited plants differed even more strongly interannually. Our results bring the first evidence on such relatively strong resource partitioning among two dominant eusocial bee species from West/Central Africa.

Floral usage partitioning and competition between social (Apis mellifera, Bombus terrestris) and solitary bees in New Zealand: Niche partitioning via floral preferences?

AbstractWorldwide, studies of interactions between introduced and native bees have produced contradictory evidence regarding the potential for competition. Different resource requirements and the impact of tongue length on resource use are often overlooked aspects of these studies. Here, we examine floral resource use and niche overlap between introduced social bees and native solitary bees over two flowering seasons on The Remarkables mountain range, South Island, New Zealand. The native bee fauna of New Zealand is composed of short‐tongued solitary bees in the families Colletidae and Halictidae. Long‐tongued social bees were introduced 150 years ago, and Apis mellifera and Bombus species are now widespread. We analysed floral resource utilization by introduced bees (mainly Bombus terrestris) and native bees in relation to resource abundance across elevations in montane to alpine grassland communities. We modelled resource utilization and overlap between bee taxa using a novel index of floral resource availability, developed to more accurately describe floral density. Additionally, we sought to quantify the impact of honey bees by introducing hives, however, low densities in study plots prevented direct conclusions from being drawn. Native and introduced bees did, however, have distinctly different floral preferences over the flowering season with more niche overlap within, rather than between, native and introduced groups. Introduced bees showed a preference for introduced species in the family Fabaceae which native bees could not access. Native bees heavily utilized introduced Asteraceae as well as native floral resources that introduced bees did not prefer. The limited resource overlap between bee taxa indicated that bee communities in New Zealand may have reduced potential for competition, owing to the different resource requirements of solitary versus social bees and their differing abilities to access floral resources. These findings provide some potential explanations for contradictory evidence worldwide regarding the perceived detrimental impacts of introduced social bees.

Floral preferences of hoverflies (Diptera: Syrphidae) in response to the abundance and species richness of flowering plants

For understanding the relationship between floral resources and the abundance of hoverflies, five meadows were selected at different elevations in a forested region. At each site the number of flowering herbaceous plants was assessed along a transect at 10-m intervals. To measure floral density, we counted the number of open flowers per species in each plot. Hoverflies visiting flowering plants were captured in each plot during 10 minutes. Path analysis showed that there was a negative correlation between plant species richness and syrphid abundance. Flower abundance had a strong positive direct effect on syrphid abundance but had indirect effects on the number of syrphid species. Only altitude had a strong positive direct effect on the number of syrphid species and this may be explained by the different climatic conditions. Some plant species attracted more syrphids than others. There were significantly fewer species of hoverfly per plot with increasing numbers of flowers. We interpret this to mean that plant species with a high density of flowers attracted more syrphids of the same species. Analysis of pollen grains extracted from two species of hoverflies showed that flower constancy occurred in three examined sites.

Evolution of Darwin's Peloric Gloxinia (Sinningia speciosa) Is Caused by a Null Mutation in a Pleiotropic TCP Gene.

Unlike most crops, which were domesticated through long periods of selection by ancient humans, horticultural plants were primarily domesticated through intentional selection over short time periods. The molecular mechanisms underlying the origin and spread of novel traits in the domestication process have remained largely unexplored in horticultural plants. Gloxinia (Sinningia speciosa), whose attractive peloric flowers influenced the thoughts of Darwin, have been cultivated since the early 19th century, but its origin and genetic basis are currently unknown. By employing multiple experimental approaches including genetic analysis, genotype–phenotype associations, gene expression analysis, and functional interrogations, we showed that a single gene encoding a TCP protein, SsCYC, controls both floral orientation and zygomorphy in gloxinia. We revealed that a causal mutation responsible for the development of peloric gloxinia lies in a 10-bp deletion in the coding sequence of SsCYC. By combining genetic inference and literature searches, we have traced the putative ancestor and reconstructed the domestication path of the peloric gloxinia, in which a 10-bp deletion in SsCYC under selection triggered its evolution from the wild progenitor. The results presented here suggest that a simple genetic change in a pleiotropic gene can promote the elaboration of floral organs under intensive selection pressure.

The function of floral orientation in bluebells: interactions with pollinators and rain in two species ofMertensia(Boraginaceae)

Pollinators are traditionally considered to be the primary agent of selection on floral traits. However, floral traits may also be under selection from abiotic agents (e.g. rain), which makes considering the relative importance of pollinators and abiotic selective agents on floral traits essential. The functional significance of floral orientation is often ascribed to pollinator attraction, but orientation can also protect reproductive structures from rain. Therefore, a study that incorporates both factors will enhance our understanding of the ecological roles of floral orientation in plant fitness. Mertensia brevistyla and M. fusiformis are herbaceous species that differ in their floral orientations. A series of field and laboratory experiments was used to investigate the adaptive function of floral orientation in these species, particularly with respect to pollinators and rain. We measured and compared floral orientation and visitor assemblages between M. brevistyla and M. fusiformis populations in western Colorado, USA. We manipulated floral stems and conducted a choice experiment with floral visitors, and also compared orientations of pollinator-visited stems with those of unvisited stems in a natural setting. We examined pollinator- and rain-mediated selection on floral orientation by manipulating orientation, conducting supplemental pollinations, applying watering treatments and measuring subsequent seed set. We also experimentally tested the likelihood of rain contact with anthers, and the effect of rainwater on pollen germinability. Mertensia brevistyla had a significantly more upright floral orientation than M. fusiformis, and seed set was highest in upright M. brevistyla and in horizontal/pendant M. fusiformis stems, supporting an adaptive function (via female fitness) of the interspecific difference in orientation. However, floral visitor assemblages did not differ significantly between the two species; visitors did not exhibit significant preference for either orientation; and pollinator-mediated selection on orientation was undetectable. Similarly, there was little effect of water on seed set in either species, regardless of floral orientation. However, pollen germinability was reduced in both species by immersion in water; and water was more likely to contact anthers in M. fusiformis than in M. brevistyla, due to interspecific differences in floral morphology. We conclude that pollinators are likely not the primary selective agent driving differences in orientation in these Mertensia species. Instead, the negative effect of rain on pollen germinability helps explain the more pendant orientation of M. fusiformis, while short anthers in more upright M. brevistyla provide an alternative adaptation to rain. The selective agent driving effects of orientation on seed set remains unclear. This study illustrates the necessity of considering male fitness and abiotic agents in interpreting the functional significance of inflorescence traits.

A Natural History of Change in Native Bees Associated with Lowbush Blueberry in Maine

More than 120 native bee species have been documented in Maine since 1930 in association with the native plant Vaccinium angustifolium (Lowbush Blueberry). We report 3 studies in commercial Lowbush Blueberry fields: (1) a survey of diversity in Osmia (mason bees) and closely related Megachile (leaf-cutter bees) using trap nests in 93 fields from 1990 to 2012, (2) a 29-year study of a native bee community, and (3) an examination of climate-change effects on bee-foraging periods during blueberry bloom. Osmia appeared to be more stable over a 22- year period in their species richness and relative abundances in Lowbush Blueberry fields when compared to Megachile over a similar 17-year period. The native bee community in a single location in Winterport was observed to fluctuate in abundance 2 to 3 times annually. Modeling of the total bee community and taxa-specific group abundances (Bombus, Megachilids, Andrenids, and Halictids and other bees) suggest that while stochastic density-independent processes such as weather can play a role in determining their annual oscillations, density-dependent lags of 1 and 2 years appear to be the main driving forces. Estimation of fruit set over the same 29-year period, based upon native bee abundance, suggests that pollination is more buffered than community bee abundance, resulting in a lesser degree of fluctuation over time. We speculate that this finding is due to redundancy in floral preferences, multiple floral visitations, and differing pollination efficiencies by the highly diverse native bee community associated with Lowbush Blueberry. Effects of climate change in Maine Lowbush Blueberry fields during May bloom was investigated using a historic weather database. Since the early 1990s, precipitation has, to a large degree, reduced the number of optimal bee foraging days during bloom, with implications for pollination and bee species abundances. This new information reinforces the need for provision of pollinator gardens to support native pollinators of Lowbush Blueberry.

The role of Mimosa L. (Fabaceae) on pollen provision of Melipona asilvai Moure 1971 in a Caatinga area from Brazil

The pollen spectrum of Melipona asilvai pollen samples, collected over the course of two years, was analysed with the objective of inferring the flora visited by this bee in a region of Caatinga in Bahia, Brazil. This study also evaluated the role of Mimosa species as a source of resources used by Melipona asilvai. Forty-eight pollen types, distributed in 22 families, were morphologically distinguished. The family Fabaceae was notable in the pollen spectrum, with 14 identified types. Mimosa was the most representative and found in all samples analysed, sometimes with high frequency. Mimosa tenuiflora had a 91.5% frequency of occurrence in the sample set and greatly contributed to the monthly samples with percentages over 95% in four of the months analysed. The other Mimosa pollen types identified were M. arenosa, M. quadrivalvis, M. misera and M. pudica. In addition, the Angelonia (Plantaginaceae) type in three samples and the Chamaecrista racemosa (Fabaceae) type in one sample had frequencies over 50% in the pollen spectrum. Other very frequent types in the sample set, occurring in more than 50% of the samples analysed, were the following: Melastomataceae, Solanum paniculatum (Solanaceae), Borreria verticillata (Rubiaceae) and Myrcia (Myrtaceae). Despite the variety of floral sources recorded, it was possible to identify the floral preference of this bee as Mimosa, indicating the importance of Mimosa species as a source of resources used by this bee.

Disentangling the contributions of dispersal limitation, ecological drift, and ecological filtering to wild bee community assembly

AbstractThe species composition within communities is highly dependent on the rate of species immigration and whether immigrating species possess the functional traits required by the prevailing environmental conditions. Once established, random fluctuations in birth and death rates may reduce the diversity of ecologically equivalent species if local populations are not replenished by immigrating individuals. Consequently, three key processes drive community assembly: dispersal limitation, ecological filtering, and ecological drift. However, disentangling the relative contribution of these processes remains a challenge in community ecology. We used a binomial generalized linear mixed model to test whether the occurrences of solitary bees within 46 communities in southeast Norway were driven by (1) dispersal limitation, that is, the geographic distance to the nearest site where conspecifics occurred; (2) ecological filtering, that is, if forb species richness selected for non‐Ericaceae‐affiliated species; and (3) ecological drift, that is, if small, isolated communities were dominated by regionally common species. The regression slopes from the model for each potential driver of community composition were compared with those expected under a null model, in which species were treated as ecologically equivalent. Both dispersal limitation and ecological filtering influenced the probability of species occurring within communities. The occurrence of species decreased with elevation, and this relationship depended on the relative commonness of species and their floral preferences. For non‐Ericaceae‐affiliated species, the patterns of occurrence mirrored that expected under the null (neutral) model, resulting in the same patterns as would be expected under ecological drift. In contrast, the response of Ericaceae‐affiliated species differed from what would be expected from the null model. Our results also indicate that processes leading to neutral dynamics in species compositions drive a large part of the gradient in species richness in Norwegian bee communities. These processes seem related to sampling effects so that large and interconnected communities have a higher probability of including regionally rare species than small, isolated communities. Our results suggest that targeting habitats—where the influence of ecological filtering is expected to be greater than that of neutral dynamics—can increase the success of habitat management plans aimed at promoting rare species.

Assessing pollinators' use of floral resource subsidies in agri-environment schemes: An illustration using Phacelia tanacetifolia and honeybees.

BackgroundHoneybees (Apis mellifera L.) are frequently used in agriculture for pollination services because of their abundance, generalist floral preferences, ease of management and hive transport. However, their populations are declining in many countries. Agri-Environment Schemes (AES) are being implemented in agricultural systems to combat the decline in populations of pollinators and other insects. Despite AES being increasingly embedded in policy and budgets, scientific assessments of many of these schemes still are lacking, and only a few studies have examined the extent to which insect pollinators use the floral enhancements that are part of AES and on which floral components they feed (i.e., pollen and/or nectar).MethodsIn the present work, we used a combination of observations on honeybee foraging for nectar/pollen from the Californian annual plant Phacelia tanacetifolia in the field, collection of pollen pellets from hives, and pollen identification, to assess the value of adding phacelia to an agro-ecosystem to benefit honeybees.ResultsIt was found that phacelia pollen was almost never taken by honeybees. The work here demonstrates that honeybees may not use the floral enhancements added to a landscape as expected and points to the need for more careful assessments of what resources are used by honeybees in AES and understanding the role, if any, which AES play in enhancing pollinator fitness.DiscussionWe recommend using the methodology in this paper to explore the efficacy of AES before particular flowering species are adopted more widely to give a more complete illustration of the actual efficacy of AES.

An assessment of bumblebee (Bombus spp) land use and floral preference in UK gardens and allotments cultivated for food

There is increasing interest in the value of domestic gardens for supporting biodiversity. While it is well established that bumblebees exploit urban green spaces, this is the first study to explore the land use and floral preferences of the UK’s seven most common bumblebees in gardens and allotments cultivated for food. A citizen science survey was carried out at 38 sites, between 1st June and 30th September 2013. At the landscape scale, bumblebee abundance and species richness was not significantly correlated with surrounding land use characteristics (both p > 0.05). Bombus pratorum was the only species to show correlations with surrounding land use, demonstrating a positive relationship with built areas and gardens and allotments, and a negative correlation with greenspace and agriculture. At the local site-level scale, bumblebee abundance was negatively correlated with areas cultivated for vegetables and fruits, and positively correlated with areas cultivated for flowers, although neither correlation was statistically significant (p = 0.070 and p = 0.051 respectively). Bumblebee species richness was not correlated with either land use (p > 0.05). All bumblebee species were negatively correlated with areas cultivated for vegetables and fruit, bare ground and hard paving. Several flowering plants were visited by all bumblebee species, although relative preferences varied between bumblebee species. Results emphasise the importance of including floral resources within garden and allotment areas cultivated for food, and the need for a mosaic of different flowering plants to cater for varying floral preferences demonstrated by bumblebee species.