Study of plants visited by honeybees (Apis mellifera L.) in the Central Rif Region (N. Morocco) using pollen analysis

Quantitative pollen analyses of Moroccan honey samples provided by amateur beekeepers from the Central Rif region demonstrates that nectar is generally the main honey source, and that most honeys have a medium‐low presence of botanical elements. However, two samples reached values as high as 1.08–1.83 qualifying as honeydew honeys. Qualitative results yielded 60 pollen types belonging to 33 families. Ammi visnaga L., Mentha pulegium L., M. rotundifolia (L.) Hudson, Eucalyptus camaldulensis Dehnh. and Rubus ulmifolius Schott. were the main nectar sources, and Cistaceae, Poaceae, Cannabis sativa L. and grasses were exploited as a pollen source. When compared to the parent vegetation honeydew and mint sources are widely exploited, but other sources such as eucalyptus and heather are underutilised.     

Honey bees and wild pollinators differ in their preference for and use of introduced floral resources

Introduced plants may be important foraging resources for honey bees and wild pollinators, but how often and why pollinators visit introduced plants across an entire plant community is not well understood. Understanding the importance of introduced plants for pollinators could help guide management of these plants and conservation of pollinator habitat. We assessed how floral abundance and pollinator preference influence pollinator visitation rate and diversity on 30 introduced versus 24 native plants in central New York. Honey bees visited introduced and native plants at similar rates regardless of floral abundance. In contrast, as floral abundance increased, wild pollinator visitation rate decreased more strongly for introduced plants than native plants. Introduced plants as a group and native plants as a group did not differ in bee diversity or preference, but honey bees and wild pollinators preferred different plant species. As a case study, we then focused on knapweed (Centaurea spp.), an introduced plant that was the most preferred plant by honey bees, and that beekeepers value as a late‐summer foraging resource. We compared the extent to which honey bees versus wild pollinators visited knapweed relative to coflowering plants, and we quantified knapweed pollen and nectar collection by honey bees across 22 New York apiaries. Honey bees visited knapweed more frequently than coflowering plants and at a similar rate as all wild pollinators combined. All apiaries contained knapweed pollen in nectar, 86% of apiaries contained knapweed pollen in bee bread, and knapweed was sometimes a main pollen or nectar source for honey bees in late summer. Our results suggest that because of diverging responses to floral abundance and preferences for different plants, honey bees and wild pollinators differ in their use of introduced plants. Depending on the plant and its abundance, removing an introduced plant may impact honey bees more than wild pollinators.     

Mapping of key bee flora of upper Gangetic region of India – a palynological assessment through regional honeys

Fifty‐one regional honey samples, collected mainly from Uttarakhand and Uttar Pradesh districts, were studied to determine the pollen composition. Pollen spectra of the local honeys varied according to the vegetation type utilized by the bees within this floristically diverse region. Eight pollen types from Uttarakhand and seven from Uttar Pradesh were the predominant pollen types in honey and included both local naturalized flora as well as cultivated crops. The investigation revealed that in addition to already known bee forage (e.g. Brassica, Coriandrum, and Litchi) some other species including Eucalyptus, Callistemon that are planted for social forestry programs, are also heavily utilized as pollen and nectar sources by honey bees in urban and semi urban areas. Naturalized flora including Myrica, Rumex, Erigeron are also utilized and therefore are important for apiculture in these regions.     

Pollen analysis of honeys from the Mamora forest region (NW Morocco)

The present work refers to the pollen analysis of 35 Moroccan honey samples from the Mamora forest region. The samples were directly provided by the beekeepers, all professionals. The quantitative analysis showed that nectar is the main honey source in the samples studied, and that most honeys have a medium-low presence of botanical elements (BEN). The qualitative analysis of the samples showed the presence of 54 taxa belonging to 29 families, and 31 of the samples were unifloral: 24 of eucalyptus, 3 of orange, 2 of Loeflingia, 1 of mint and 1 of Ridolfia segetum. The eucalyptus honeys of the studied region are characterized by their high content in pollen grains (NGP; x¯=180000) and their low honeydew indicator elements content (HDE; x¯=4000); Plantago f. (present in 70% of the samples), Quercus f. and Brassicaceae (50%) and Ceratonia siliqua (30%) could be mentioned among the characteristic accompanying species of this honey type.     

Plant Resources Foraged by Polybia Scutellaris (Hym. Vespidae) in the Argentine Pampas

The plants foraged by Polybia scutellaris were studied by analysing the pollen of honey collected from six nests. 34 morphological types were identified. These honeys showed a predominance of Poaceae and Cyperaceae pollen. The main access to anemophilous pollen is through the honeydew produced by Claviceps in Paspalum dilatatum. The principal sources of nectar were the native “Astereae” (Aster squamatus, Baccharis sp. and Solidago chilensis) and Eucalyptus sp. When collecting honeydew and nectar, wasps foraged plants close to their nest. Most of the plants visited belonged to a dense population. The successive flowering reflected in these honeys, shows that wasps also consume honey in summer and that it is not all stored for the winter season.     

Bee diversity on nectarful and nectarless honey mesquites

Nectar production has been proposed as an adaptation to attract pollinators that benefit from this resource. Energetic investments may be expensive, so some species such as Prosopis glandulosa have developed a dimorphic system of nectar production, which is expected to affect floral visitor behaviour and then plant fitness. We quantified bee diversity during a 2 year period in a population of the honey mesquite in order to determine changes in bee diversity due to the presence of nectar, bee preferences to collect either nectar of pollen, and to determine between year variations of bee faunas. Floral visitors were captured at three different times of the day during the flowering seasons of 1994 and 1995, in a population of Prosopis glandulosa which has a 1:1 proportion of nectar: nectarless individuals. Pollinators were clearly distinct between nectar morphs, bee species diversity and relative abundance of visits were significantly greater on nectarful than on nectarless plants, with species on nectarless individuals being a subset of those in the nectarful morph. Our results suggest differences in the function of floral rewards (i.e., nectar and pollen) to attract floral visitors. For the Chihuahuan arid environment, mesquite provides floral rewards with ease, quantity and quality for close to 10% of all bee fauna making them important components of these communities.     

Palynological and geographical characterization of avocado honeys in Spain

The present work refers to the pollen analysis of 12 avocado honey samples from Spain. The samples were directly provided by the beekeepers, all professionals. The quantitative analysis showed that nectar is the main honey source in the samples studied, and that most honeys have a medium presence of botanical elements (BE); one sample belong to Class I of Maurizio, seven to Class II and four belong to Class III. The qualitative analysis of the samples showed the presence of 56 taxa belonging to 36 families. The Spanish avocado honeys are characterised by their medium content in pollen grains (NPG; x¯=117000) and their low honeydew indicator elements content (HDE; x¯=6340). Echium plantagineum gr. and Genista f. (present in 90% of the samples), and Eucalyptus f., Olea europaea L., Mentha aquatica gr. and Reseda luteola gr. (present in 80% of the samples), could be mentioned among the characteristic accompanying species of this honey type. The avocado honeys from the Iberian Peninsula and from the Canary Islands can be differentiated by the presence of Asphalthium bituminosum Medic., Cardiospermum grandiflorum Sw., Phoenix canariensis Hort. ex Chabaud and Tropaeolum majus L. in the latter.     

Pollen analysis of honeys from the Gharb region (NW Morocco)

The pollen spectra in 18 honey samples from the Gharb region (Northwest of Morocco) have been studied. The samples were collected directly from the beekeepers, both professional and amateurs. The results show that nectar was the main honey source in this region, although one forest or mixed honey was detected. Seven samples belonging to the Class I, five to the Class II and six to the Class III were found. In all the samples some honeydew indicator elements were detected, with HDEN/NPGN= 0.005-1.38. By the qualitative results 58 pollen types belonging to 28 families were identified. Some species of Lythrum , Eucalyptus , Trifolium , Citrus , Mentha , Apiaceae and Scrophulariaceae are the main nectar sources,and some of Asteraceae, Quercus sp., Olea europaea , Plantago sp. and Fragaria 2 ananassa are the most important pollen sources. At least 14 unifloral honeys (c. 77%) from Citrus , Eucalyptus , Lythrum , Mentha and Teucrium were detected.     

Invasive Africanized honey bee impact on native solitary bees: a pollen resource and trap nest analysis

Little is known of the potential coevolution of flowers and bees in changing, biodiverse environments. Female solitary bees, megachilids and Centris , and their nest pollen provisions were monitored with trap nests over a 17-year period in a tropical Mexican biosphere reserve. Invasion by feral Apis (i.e. Africanized honey bees) occurred after the study began, and major droughts and hurricanes occurred throughout. Honey bee competition, and ostensibly pollination of native plants, caused changes in local pollination ecology. Shifts in floral hosts by native bees were common and driven by plant phylogenetics, whereby plants of the same families or higher taxa were substituted for those dominated by honey bees or lost as a result of natural processes. Two important plant families, Anacardiaceae and Euphorbiaceae, were lost to competing honey bees, but compensated for by greater use of Fabaceae, Rubiaceae, and Sapotaceae among native bees. Natural disasters made a large negative impact on native bee populations, but the sustained presence of Africanized honey bees did not. Over 171 plant species comprised the pollen diets of the honey bees, including those most important to Centris and megachilids (72 and 28 species, respectively). Honey bee pollination of Pouteria (Sapotaceae) plausibly augmented the native bees' primary pollen resource and prevented their decline. Invasive generalist pollinators may, however, cause specialized competitors to fail, especially in less biodiverse environments.  No claim to original US government works. Journal compilation © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 98 , 152–160.     

Pollinator genetics and pollination: do honey bee colonies selected for pollen‐hoarding field better pollinators of cranberry Vaccinium macrocarpon?

1. Genetic polymorphisms of flowering plants can influence pollinator foraging but it is not known whether heritable foraging polymorphisms of pollinators influence their pollination efficacies. Honey bees Apis mellifera L. visit cranberry flowers for nectar but rarely for pollen when alternative preferred flowers grow nearby. 2. Cranberry flowers visited once by pollen‐foraging honey bees received four‐fold more stigmatic pollen than flowers visited by mere nectar‐foragers (excluding nectar thieves). Manual greenhouse pollinations with fixed numbers of pollen tetrads (0, 2, 4, 8, 16, 32) achieved maximal fruit set with just eight pollen tetrads. Pollen‐foraging honey bees yielded a calculated 63% more berries than equal numbers of non‐thieving nectar‐foragers, even though both classes of forager made stigmatic contact. 3. Colonies headed by queens of a pollen‐hoarding genotype fielded significantly more pollen‐foraging trips than standard commercial genotypes, as did hives fitted with permanently engaged pollen traps or colonies containing more larvae. Pollen‐hoarding colonies together brought back twice as many cranberry pollen loads as control colonies, which was marginally significant despite marked daily variation in the proportion of collected pollen that was cranberry. 4. Caloric supplementation of matched, paired colonies failed to enhance pollen foraging despite the meagre nectar yields of individual cranberry flowers. 5. Heritable behavioural polymorphisms of the honey bee, such as pollen‐hoarding, can enhance fruit and seed set by a floral host (e.g. cranberry), but only if more preferred pollen hosts are absent or rare. Otherwise, honey bees' broad polylecty, flight range, and daily idiosyncrasies in floral fidelity will obscure specific pollen‐foraging differences at a given floral host, even among paired colonies in a seemingly uniform agricultural setting.     

Nectar and Pollen Sources for Honeybee （Apis cerana cerana Fabr.） in Qinglan Mangrove Area, Hainan Island, China

In the present study, nectar and pollen sources for honeybee （Apls cerana cerana Fabr.） were studied in Qlnglan mangrove area, Hainan Island, China, based on microscopic analysis of honey and pollen load （corblcular and gut contents） from honeybees collected In October and November 2004. Qualitative and quantitative melittopalynologlcal analysis of the natural honey sample showed that the honey is of unlfloral type with Mimosa pudlca L. （Mlmosaceae） as the predominant （89.14%） source of nectar and pollen for A. cerana cerana In October. Members of Araceae are an Important minor （3%-15%） pollen type, whereas those of Arecaceae are a minor （〈3%） pollen type. Pollen grains of Nypa fruticans Wurmb., Rhlzophora spp., Excoecarla agallocha L., Lumnitzera spp., Brugulera spp., Kandella candel Druce, and Ceriops tagal （Perr.） C. B. Rob. are among the notable mangrove texa growing In Qinglan mangrove area recorded as minor taxa In the honey. The absolute pollen count （I.e. the number of pollen grains/10 g honey sample） suggests that the honey belongs to Group V （〉1 000 000）. Pollen analysis from the corblcular and gut contents of A. cerana cerana revealed the highest representation （95.60%） of members of Sonneratia spp. （Sonneratlaceae）, followed by Bruguiera spp. （Rhizophoraceae）, Euphorblaceae, Poaceae, Fabaceae, Arecaceae, Araceae, Anacardlaceae, and Rublaceae. Of these plants, those belonging to Sonneratla plants are the most Important nectar and pollen sources for A. cerana cerana and are frequently foraged and pollinated by these bees in November.     

1. Fláje–Kiefern (Krušné Hory Mountains): Late Glacial and Holocene vegetation development

This work characterises monofloral honeys of the Yucatán Peninsula based on their pollen content. The sampling was carried out from January to July 2000. We examined 78 different honey samples from various parts of the Yucatán Peninsula including the states of Yucatán, Campeche and Quintana Roo. Pollen separated from honey was acetolysed, identified and counted. Through pollen analysis, 250 pollen taxa were identified, 180 of which had not been reported previously in Mexican honeys. Thirteen different types of monofloral honeys were found (with a percentage of ≥ 45%) within the honey produced in the Yucatán, Peninsula. These were: Viguiera dentata, Bursera simaruba, Piscidia piscipula, Eugenia sp. 2, Pimenta dioica, Melothria pendula, Gymnanthes lucida, Phoradendron quadrangulare, Gymnopodium floribundum, Rubiaceae 1, Thouinia paucidentata, Thouinia sp. 1, and Pouteria mammosa. This is the first study of monofloral honeys in Mexico and Central America. The characterisation of the honey may give an added market value as it permits us to separate the honeys of monofloral or multifloral origin. The results of this study indicate that it is possible to produce several monofloral honeys in a region with great plant diversity as the Yucatán Peninsula. We recommend installing apiaries in disturbed vegetation zones of the Yucatán Peninsula where an advanced succession of a tree layer exists. This supplies the nectar and pollen during the critical period in March and April which is the driest season.     

Bee visitation rates to cultivated sunflowers increase with the amount and accessibility of nectar sugars

Pollinators make foraging decisions based on numerous floral traits, including nectar and pollen rewards, and associated visual and olfactory cues. For insect‐pollinated crops, identifying and breeding for attractive floral traits may increase yields. In this study, we examined floral trait variation within cultivated sunflowers and its effects on bee foraging behaviours. Over 2 years, we planted different sunflower inbred lines, including male‐fertile and male‐sterile lines, and measured nectar volume, nectar sugar concentration and composition, and corolla length. During bloom, we recorded visits by both managed honey bees and wild bees. We then examined consistency in relative nectar production by comparing field results to those from a greenhouse experiment. Sunflower inbred lines varied significantly in all floral traits, including the amount and composition of nectar sugars, and in corolla length. Both wild bee and honey bee visits significantly increased with nectar sugar amount and decreased with corolla length, but appeared unaffected by nectar sugar composition. While wild bees made more visits to sunflowers providing pollen (male‐fertile), honey bees preferred plants without pollen (male‐sterile). Differences in nectar quantity among greenhouse‐grown sunflower lines were similar to those measured in the field, and bumble bees preferentially visited lines with more nectar in greenhouse observations. Our results show that sunflowers with greater quantities of nectar sugar and shorter corollas receive greater pollination services from both managed and wild bees. Selecting for these traits could thus increase sunflower crop yields and provide greater floral resources for bees.     

Diversity of honey stores and their impact on pathogenic bacteria of the honeybee,Apis mellifera

Honeybee colonies offer an excellent environment for microbial pathogen development. The highest virulent, colony killing, bacterial agents are Paenibacillus larvae causing American foulbrood (AFB), and European foulbrood (EFB) associated bacteria. Besides the innate immune defense, honeybees evolved behavioral defenses to combat infections. Foraging of antimicrobial plant compounds plays a key role for this “social immunity” behavior. Secondary plant metabolites in floral nectar are known for their antimicrobial effects. Yet, these compounds are highly plant specific, and the effects on bee health will depend on the floral origin of the honey produced. As worker bees not only feed themselves, but also the larvae and other colony members, honey is a prime candidate acting as self‐medication agent in honeybee colonies to prevent or decrease infections. Here, we test eight AFB and EFB bacterial strains and the growth inhibitory activity of three honey types. Using a high‐throughput cell growth assay, we show that all honeys have high growth inhibitory activity and the two monofloral honeys appeared to be strain specific. The specificity of the monofloral honeys and the strong antimicrobial potential of the polyfloral honey suggest that the diversity of honeys in the honey stores of a colony may be highly adaptive for its “social immunity” against the highly diverse suite of pathogens encountered in nature. This ecological diversity may therefore operate similar to the well‐known effects of host genetic variance in the arms race between host and parasite.     

Flowers morphology and nectar concentration determine the preferred food source of stingless bee,Heterotrigona itama

Heterotrigona itama is a stingless bee species from Meliponini tribe. The bee collects nectar, pollen and resin to produce honey, bee bread, and propolis. The bee is also known to visit and collect nectar from various types of flowers but there are limited studies on why this species of bee prefers to visit certain types of flowers. This study was conducted to identify the nectar concentration in selected flowers favoured by H. itama and the relationship between the bee and the morphology of the flowers. Nectar was obtained from different species of flowers and the concentrations were measured using a digital refractometer. The tube length of each flower species and the tongue length of the bees were also measured. The results revealed that flowers preferred by H. itama have high nectar concentrations. The tube lengths of the preferred flowers were between 2.0 and 4.0 mm, which is compatible with the tongue length of the bee. This study revealed that both nectar concentration and flower morphology are important factors for the bees in choosing their food sources. The results from this study will benefit the beekeepers in the identification of flowers that should be planted in their farms to improve stingless bee beekeeping activities. Understanding the relationship between the bees and their flower preferences could also help us to understand the importance of conserving both the bee colonies and the various species of flowering plants to ensure the sustainability of flora and fauna in the ecosystem.     

Detection of deformed wing virus in the greenhouse for possible horizontal transmission of virus in honey bee colony

The honey bee Apis mellifera L. is a crucial insect in the agricultural industry and natural ecosystem by being a major pollinator. Nevertheless, honey bee population has been recently facing a decline. Among the several factors responsible for this decline, deformed wing virus (DWV) is considered a primary cause that negatively affects honey bee health. DWV is a cosmopolitan honey bee pathogen and causes morphological disadvantages in individual honey bees and colony collapse. Regarding the horizontal transmission of DWV, in addition to Varroa destructor, a well-known major vector of DWV, flowers have recently been implied as a transmission route. Therefore, in this study, we detected DWV from various substances, including flowers, honey bee feces, pupa, larva, nurse bee, surface of nurse bee, pollen collected by forager bee, and forager bee samples in four strawberry greenhouses, which could suggest the potential for the horizontal transmission of DWV in the semi-field condition. We also detected DWV in pollen collected by DWV-negative forager bees, implying that flowers can serve as a potential source of virus infection. These findings suggest that the surrounding environment such as shared floral sources affects the spread of DWV.     

Melissopalynology in an area of Atlantic Forest (northeast region,Brazil)

Apis mellifera is a bee that was introduced to Brazil and has adapted very well to the climate conditions and vast diversity of plants that exist in the country. In the northeast region of Brazil, beekeepers make use of the association between bees and plants by selling various bee products, notably honey. One way to identify species visited by bees in an area is by the pollen in its products. Based on this, 16 samples of honey were analysed, which were collected over a period of two years and obtained from an apiary in the Atlantic Forest biome in the municipality of Entre Rios (Bahia). In addition, climatic data (precipitation and temperature) of the region were obtained for the months sampled. The average temperature of the region during the collection months varied from 22 to 28 °C. The highest precipitation recorded in the region was 133.7 mm³ and the lowest was 0.3 mm³. Seventy pollen types were found. The family Fabaceae was notable, with ten pollen types, of which Mimosa pudica was the most important with a high frequency of occurrence and distribution. The Eucalyptus (Myrtaceae) pollen type also had a high frequency of occurrence and distribution. In addition, pollen types corresponding to species that supply nectar to bees were identified, which contributes to the large diversity of bee plants for Apis mellifera in the study area.     

Western honey bee (Apis mellifera L.) attraction to commercial pollen substitutes and wildflower pollen in vitro

Many beekeepers feed their western honey bee (Apis mellifera) colonies artificial pollen substitutes to provide colonies with adequate nutrition during times of limited pollen quantity or quality. We provided caged worker bees commercially available pollen substitutes (AP23, MegaBee, UltraBee) and wildflower pollen in a choice-test to determine their relative attraction to/preference for the diets. We measured diet consumption by honey bees and observed honey bee behaviour to evaluate bee preferences for certain diets. The bees interacted with and consumed more wildflower pollen than they did any of the commercially available pollen substitutes. Our data suggest that bees have a strong preference for wildflower pollen over commercially available pollen substitutes.     

Palynological characteristics of different unifloral honeys from Greece

Three hundred and twenty-nine Greek honey samples of different botanical and geographical origin were collected and examined by organoleptic evaluation, melissopalynological analysis, measurement of electrical conductivity and colour. The results showed that 208 samples were unifloral with 178 of them representing the main types of unifloral honey produced in Greece; that is fir, pine, chestnut, cotton, orange and thyme honey. All honeys had the sensory characteristics typical of their origin and complied with the electrical conductivity standards set by Council Directive 2001/110/EC.

Fir and pine honeydew honey had a low honeydew element/pollen (HDE/P) ratio and belonged to Maurizio's Classes II or III. The pollen types identified in these honeys ranged from 11 to 45%. Chestnut nectar honey contained >90% chestnut pollen, had a total number of plant elements of >245,000/10?g, and low pollen diversity. Cotton honey contained 1.2 to 16.5% cotton pollen, belonged to Maurizio's Class II, and had 22 pollen types, with Castanea sativa L. present in all samples. Orange honey contained 2.9 to 26.5% Citrus spp. pollen, belonged to Maurizio's Class II, and was characterized by the presence of Brassicaceae, Fabaceae, Olea europea L., Quercus coccifera L. and Rosaceae. In thyme honeys Thymus capitatus Hoffm. &; Link. pollen was secondary or predominant ranging from 18.3 to 69.3%. These honeys belonged to Maurizio's Classes I or II and contained greater than 30 pollen types. Other Lamiaceae, Hypericum spp., Brassicaceae, Fabaceae, Rosaceae, and Cistus spp. pollen types appeared in the greatest number of thyme samples.     

Specialised protagonists in a plant–pollinator interaction: the pollination of Blumenbachia insignis (Loasaceae)

• Analyses of resource presentation, floral morphology and pollinator behaviour are essential for understanding specialised plant‐pollinator systems. We investigated whether foraging by individual bee pollinators fits the floral morphology and functioning of Blumenbachia insignis, whose flowers are characterised by a nectar scale‐staminode complex and pollen release by thigmonastic stamen movements.
• We described pollen and nectar presentation, analysed the breeding system and the foraging strategy of bee pollinators. We determined the nectar production pattern and documented variations in the longevity of floral phases and stigmatic pollen loads of pollinator‐visited and unvisited flowers.
• Bicolletes indigoticus (Colletidae) was the sole pollinator with females revisiting flowers in staminate and pistillate phases at short intervals, guaranteeing cross‐pollen flow. Nectar stored in the nectar scale‐staminode complex had a high sugar concentration and was produced continuously in minute amounts (~0.09 μl·h^?1). Pushing the scales outward, bees took up nectar, triggering stamen movements and accelerating pollen presentation. Experimental simulation of this nectar uptake increased the number of moved stamens per hour by a factor of four. Flowers visited by pollinators received six‐fold more pollen on the stigma than unvisited flowers, had shortened staminate and pistillate phases and increased fruit and seed set.
• Flower handling and foraging by Bicolletes indigoticus were consonant with the complex flower morphology and functioning of Blumenbachia insignis. Continuous nectar production in minute quantities but at high sugar concentration influences the pollen foraging of the bees. Partitioning of resources lead to absolute flower fidelity and stereotyped foraging behaviour by the sole effective oligolectic bee pollinator.