Bee Diet Research Articles

Quantification of larval food and its pollen content in the diet of stingless bees - subsidies for toxicity bioassays studies.

Laboratorio de Ecologia e Biosseguranca, Embrapa Recursos Geneticos e Biotecnologia, Empresa Brasileira de Pesquisa Agropecuaria – Embrapa, Parque Estacao Biologica PqEB, Avenida W3 Norte, CEP 70849-970, Brasilia, DF, Brazil*e-mail: annesouzar@gmail.comReceived: October 28, 2014 – Accepted: February 3, 2015 – Distributed: August 31, 2015

Floral Resources Used by Honey Bees in Agricultural Landscapes

Honey bees are polylectic insects able to forage on many flower species in order to provide enough abundant and diverse food for the colony. However, land use changes and agricultural intensification have disrupted the floral availability in agricultural landscapes. Here, we investigated empirically the floral resources used by honey bees in an intensive cereal farming system. We found that honey bees foraged on a wide diversity of flowers throughout the season, mainly derived from trees and weeds. When mass-flowering crops are available, honey bees use them. However, mass-flowering crops are highly seasonal and induce a supply depletion between two peak periods, which precisely matches the peak of demographic growth of bee colonies. Our empirical results support the Agri-Environmental Schemes intended to promote honey bees and beekeeping sustainability. The Long-Term Ecological Research “Zone Atelier Plaine et Val de Sèvre” in central western France (46°23' N, 0°41' W) hosts a study about bee ecology since 2008 through the ECOBEE platform. Local agricultural intensification has led to an intensive cereal farming system, with mass-flowering crops such as rapeseed (Brassica napus) and sunflower (Helianthus annuus). In this environmental context, we studied the foraging behavior of honey bees throughout the beekeeping season with 250 monitored colonies. Photo by Christophe Maitre/INRA. We fitted beehives with pollen grid traps at their entrance in order to sample the pollen loads harvested by foragers. This photo shows the variability of colors in collected pollen loads, witnessing the diversity of flowers visited by honey bees. In our intensive agricultural landscape, honey bees forage on a wide diversity of flowers for their pollen intakes (about 230 species). Photo by Thierry Tamic. We identified the botanical origin of pollen loads by palynological analyses. We present here the pollen grains of the three dominant floral resources used by honey bees in intensive cereal farming system, i.e. two crops, maize (Zea mays, the big pollen grain at center), and sunflower (the smaller echinate pollen grains), and a weed species, poppy (Papaver rhoeas, bottom right). The changing dynamic of crop flower availability disturbs the seasonal pattern of pollen intake with pollen supply depletion in spring. Surprisingly, poppy is a dominant species foraged for pollen in similar proportion than maize and sunflower. Poppy is especially collected during the period of pollen supply depletion, indicating a major role of weeds for honey bee diet in intensive cereal farming systems. Photos by Thierry Tamic. Honey bees forage on a wide diversity of flowers in intensive agricultural landscapes. For example, we present here four plant species foraged by honey bees for pollen and/or nectar intakes, i.e. Prunus spinosa (top left) a woody plant species foraged in April; Bellis perennis (top right) a herbaceous plant species foraged throughout the whole season; Malva sylvestris (bottom left) a herbaceous plant species foraged in July; and Phacelia tanacetifolia (bottom right) a crop foraged in May. Semi-natural habitats (i.e. grasslands, forest, and hedgerows) and weeds need to be considered for bee conservation in agricultural landscapes because they provide highly diverse and continuous floral resources throughout the season. Photos top left and bottom left by Thierry Tamic, and photos top right and bottom right by Fabrice Requier. These photographs illustrate the article “Honey bee diet in intensive farmland habitats reveals an unexpectedly high flower richness and a major role of weeds” by Fabrice Requier, Jean-François Odoux, Thierry Tamic, Nathalie Moreau, Mickaël Henry, Axel Decourtye and Vincent Bretagnolle, published in Ecological Applications 25(4):881–890, June 2015. http://dx.doi.org/10.1890/14-1011.1

Honey bee diet in intensive farmland habitats reveals an unexpectedly high flower richness and a major role of weeds

In intensive farmland habitats, pollination of wild flowers and crops may be threatened by the widespread decline of pollinators. The honey bee decline, in particular, appears to result from the combination of multiple stresses, including diseases, pathogens, and pesticides. The reduction of semi-natural habitats is also suspected to entail floral resource scarcity for bees. Yet, the seasonal dynamics and composition of the honey bee diet remains poorly documented to date. In this study, we studied the seasonal contribution of mass-flowering crops (rapeseed and sunflower) vs. other floral resources, as well as the influence of nutritional quality and landscape composition on pollen diet composition over five consecutive years. From April to October, the mass of pollen and nectar collected by honey bees followed a bimodal seasonal trend, marked by a two-month period of low food supply between the two oilseed crop mass-flowerings (ending in May for rapeseed and July for sunflower). Bees collected nectar mainly from crops while pollen came from a wide diversity of herbaceous and woody plant species in semi-natural habitats or from weeds in crops. Weed species constituted the bulk of the honey bee diet between the mass flowering crop periods (up to 40%) and are therefore suspected to play a critical role at this time period. The pollen diet composition was related to the nutritional value of the collected pollen and by the local landscape composition. Our study highlights (1) a food supply depletion period of both pollen and nectar resources during late spring, contemporaneously with the demographic peak of honey bee populations, (2) a high botanical richness of pollen diet, mostly proceeding from trees and weeds, and (3) a pollen diet composition influenced by the local landscape composition. Our results therefore support the Agri-Environmental Schemes intended to promote honey bees and beekeeping sustainability through the enhancement of flower availability in agricultural landscapes.

Anthocyanin‐rich Black Elderberry Extract Improves Markers of HDL Function and Reduces Aortic Cholesterol in Hyperlipidemic Mice

Atherosclerosis is a chronic inflammatory disease and is associated with impairments in high‐density lipoprotein (HDL) function, including reductions in HDL‐cholesterol, antioxidant and anti‐inflammatory activities. Anthocyanins are polyphenols with anti‐inflammatory properties. We investigated whether an anthocyanin‐rich black elderberry extract (Sambucus nigra) (BEE) (13% anthocyanins) would protect against inflammation‐related impairments in HDL function and atherosclerosis in apoE‐/‐ mice. We fed an AIN‐93M diet supplemented with 1.25% (wt/wt) BEE or control diet to 10 week old male apoE‐/‐ mice for 6 weeks. The BEE fed to mice was rich in cyanidin 3‐sambubioside (~9.8% wt/wt) and cyanidin 3‐glucoside (~3.8% wt/wt). After 6 weeks, serum lipids did not differ significantly between groups, while aspartate transaminase (AST) and fasting glucose were reduced in BEE‐fed mice. Hepatic and intestinal mRNA changes with BEE‐feeding were consistent with an improvement in HDL function (Apoa1, Pon1, Saa1, Lcat, Clu) and a reduction in hepatic cholesterol levels (increased Ldlr and Hmgcr, reduced Cyp7a1). In BEE‐fed mice, serum paraoxonase‐1 activity was significantly higher. In addition, mice fed BEE had significantly lower serum chemokine (C‐C motif) ligand 2 (CCL2) and tended to have lower serum thiobarbituric acid reactive substances compared to control‐fed mice. Notably, we observed significant reductions in total cholesterol content of the aorta of BEE‐fed mice, indicating less atherosclerosis progression. These findings suggest that black elderberry may be useful to prevent HDL dysfunction associated with chronic inflammation. [Supported by the USDA Hatch Project #1003343].

Nephroprotective effect of bee honey and royal jelly against subchronic cisplatin toxicity in rats.

Cisplatin is one of the most potent and effective chemotherapeutic agents. However, its antineoplastic use is limited due to its cumulative nephrotoxic side effects. Therefore, the present study was undertaken to examine the nephroprotective potential of dietary bee honey and royal jelly against subchronic cisplatin toxicity in rats. Male Wistar rats were randomly divided into controls, cisplatin-treated, bee honey-pretreated cisplatin-treated and royal jelly-pretreated cisplatin-treated groups. Bee honey and royal jelly were given orally at doses of 20 and 100mg/kg, respectively. Subchronic toxicity was induced by cisplatin (1mg/kgbw, ip), twice weekly for 10weeks. Cisplatin treated animals revealed a significant increase in serum level of renal injury products (urea, creatinine and uric acid). Histopathologically, cisplatin produced pronounced tubulointerstitial injuries, upregulated the fibrogenic factors, α-smooth muscle actin (α-SMA) and transforming growth factor β1(TGF-β1), and downregulated the cell proliferation marker, bromodeoxyuridine (Brdu). Dietary bee honey and royal jelly normalized the elevated serum renal injury product biomarkers, improved the histopathologic changes, reduced the expression of α-SMA and TGF-β1 and increased the expression of Brdu. Therefore, it could be concluded that bee honey, and royal jelly could be used as dietary preventive natural products against subchronic cisplatin-induced renal injury.

The Appropriate Supplementary Level of Tryptophan in the Diet ofApis mellifera(Hymenoptera: Apidae) Worker Bees

This study was designed to determine the appropriate levels of tryptophan (trp) in the diet of Apis mellifera worker bees. Newly emerged worker bees were enclosed in wooden cages in an incubator at 32°C with 55–60% humidity and fed a diet including 9, 10, 11, 12, 13, and 14 mg/g trp for 12 days. When the trp level was 11 mg/g, worker bees demonstrated better performance in terms of food intake, body weight, and total protein accumulation. However, 12 mg/g dietary trp promoted trp deposition in the worker bees, stimulated hypopharyngeal gland development, enhanced the survival rate and expedited the formation of 5-HT (5-hydroxytryptamine). The worker bees fed with 13 and 14 mg/g trp had higher malondialdehyde (MDA) levels, which suggested that a higher level of trp may be disadvantageous in maintaining worker-bee antioxidant ability, because MDA was the end product of lipid peroxidation. We also found that dietary trp regulated the mRNA expression of 5-HTRs and tryptophan hydroxylase (TPH) in a dose-dependent manner, which was related to phototaxis, aggression, and other factors. In conclusion, dietary trp exerts regulatory roles in the growth, development and some physiological and biochemical properties of worker bees. Therefore, 11–12 mg/g tryptophan is optimal for A. mellifera adult worker bees.

Shifts in the Midgut/Pyloric Microbiota Composition within a Honey Bee Apiary throughout a Season.

Honey bees (Apis mellifera) are prominent crop pollinators and are, thus, important for effective food production. The honey bee gut microbiota is mainly host specific, with only a few species being shared with other insects. It currently remains unclear how environmental/dietary conditions affect the microbiota within a honey bee population over time. Therefore, the aim of the present study was to characterize the composition of the midgut/pyloric microbiota of a honey bee apiary throughout a season. The rationale for investigating the midgut/pyloric microbiota is its dynamic nature. Monthly sampling of a demographic homogenous population of bees was performed between May and October, with concordant recording of the honey bee diet. Mixed Sanger-and Illumina 16S rRNA gene sequencing in combination with a quantitative PCR analysis were used to determine the bacterial composition. A marked increase in α-diversity was detected between May and June. Furthermore, we found that four distinct phylotypes belonging to the Proteobacteria dominated the microbiota, and these displayed major shifts throughout the season. Gilliamella apicola dominated the composition early on, and Snodgrassella alvi began to dominate when the other bacteria declined to an absolute low in October. In vitro co-culturing revealed that G. apicola suppressed S. alvi. No shift was detected in the composition of the microbiota under stable environment/dietary conditions between November and February. Therefore, environmental/dietary changes may trigger the shifts observed in the honey bee midgut/pyloric microbiota throughout a season.

Assessment of the pollen diet in a wood-dwelling augochlorine bee (Halictidae) using different approaches

Most studies on bee pollen diet are based on the abundance of each pollen type composing honey or pollen stores of whole nests (pollen counts). In an effort to characterize the diet of the augochlorine bee Augochlora amphitrite, we employed nest and intra-nest pollen analyses and bee flower visitation. In addition, we tested a novel approach, the index of relative importance (IRI), a method that combines pollen counts, pollen volume, and frequency of pollen occurrence. Using nest pollen analysis, we found that the Ludwigia type dominated pollen counts, comprising 56 % of whole nests, and thus would have concluded that this is the only most important pollen source in the diet. Instead, we found seven other important sources including Ipomoea alba, Ipomoea cairica, Gymnocoronis spilanthoides, and Pavonia types as well as 26 new floral hosts using all four methods in combination. Thus, we recommend that other studies of bee diet include these other approaches when possible and, especially, the novel approach of IRI.

Effects of supplementary bee pollen and its polysaccharides on nutrient digestibility and serum biochemical parameters in Holstein calves

This study investigated the effects of supplementing the diets of 14–70-day calves with dietary bee pollen (BP) or its polysaccharides (PS) on growth performance, serum biochemical parameters, and apparent nutrient digestibility. Twenty-five newborn Holstein female calves were randomly offered one of the five diets (five calves per diet): a milk replacer supplemented with 0 (Control), 10 (10BP), 25 (25BP), or 50 g/day (50BP) bee pollen, or 5 g/day (5PS) bee pollen polysaccharides. The trial lasted 56 days, during which growth performance, apparent nutrient digestibility, and serum biochemical parameters were measured. Calves fed diets with BP had a greater bodyweight gain. Supplementation with BP or PS had significant effects on the apparent digestibility of DM, Ca and P in calves (P = 0.025, 0.012, and 0.076, respectively). The apparent DM digestibility of calves from group 25BP or 5PS was increased by 9.7% or 8.2% (P = 0.007 or 0.019), respectively, compared with that in the Control group. No significant differences were observed in serum concentrations of alkaline phosphatase, urea nitrogen, glucose, total protein, albumin, total cholesterol and triglycerides. These results demonstrated that dietary supplementation of BP at 25 g/day·calf or PS at 5 g/day·calf improved nutrient digestibility in pre-ruminant calves.

Honey constituents up-regulate detoxification and immunity genes in the western honey bee Apis mellifera

As a managed pollinator, the honey bee Apis mellifera is critical to the American agricultural enterprise. Recent colony losses have thus raised concerns; possible explanations for bee decline include nutritional deficiencies and exposures to pesticides and pathogens. We determined that constituents found in honey, including p-coumaric acid, pinocembrin, and pinobanksin 5-methyl ether, specifically induce detoxification genes. These inducers are primarily found not in nectar but in pollen in the case of p-coumaric acid (a monomer of sporopollenin, the principal constituent of pollen cell walls) and propolis, a resinous material gathered and processed by bees to line wax cells. RNA-seq analysis (massively parallel RNA sequencing) revealed that p-coumaric acid specifically up-regulates all classes of detoxification genes as well as select antimicrobial peptide genes. This up-regulation has functional significance in that that adding p-coumaric acid to a diet of sucrose increases midgut metabolism of coumaphos, a widely used in-hive acaricide, by ∼60%. As a major component of pollen grains, p-coumaric acid is ubiquitous in the natural diet of honey bees and may function as a nutraceutical regulating immune and detoxification processes. The widespread apicultural use of honey substitutes, including high-fructose corn syrup, may thus compromise the ability of honey bees to cope with pesticides and pathogens and contribute to colony losses.

Supplementation of the honey bee diet with vitamin C: The effect on the antioxidative system of Apis mellifera carnica brood at different stages

SummaryDiet in the winter has a vital effect on the survival and condition of a honey bee (Apis mellifera) colony in the spring. The effect of supplementation of the diet with vitamin C (ascorbic acid) on the total antioxidant status (TAS), glutathione content, and activity of 4 antioxidative enzymes: superoxide dismutase (SOD), peroxidase (POX), catalase (CAT), and glutathione transferase (GST) of honey bee brood developing in the spring was studied. Twelve stages, from newly hatched larvae to emerging adult worker bees were studied, allowing changes in the antioxidant profile during brood development to be determined for the first time. It was shown that bees are more exposed to oxidative stress after emergence. In workers emerging in colonies after supplementation with vitamin C, higher contents of protein and glutathione, and higher activities of peroxidase, catalase, and glutathione transferase were observed. Vitamin C did not alter brood weight increase, and the level of protein in emerged workers was higher than in the control group. The mean of bee losses over winter were about 33% lower in colonies receiving vitamin C.

Bees in disturbed habitats use, but do not prefer, alien plants

Alien plants form important interactions with flower visitors across many systems and are especially likely to dominate these interactions in disturbed habitats where native plants are rare. Most studies of alien plant–pollinator interactions have focused on the effects of alien plants on native plant reproduction; however, these alien plants may also be important food resources for native bees especially if they dominate the “floral market”. Dominance of alien species in the diet of bees could occur due to high relative density and abundance of alien plants and flowers, and/or to bee preference for alien plants when they are present. We investigated bees’ use of and preference for alien plants using two data sets from distinct regions of North America, central California and southern New Jersey. In each system, we sampled bees and flowering plants in multiple habitat types that differ in level of disturbance and in the relative abundance of alien plant species. Alien plants as a group dominated interactions with bee communities in more disturbed habitats. Importance, however, varied among plant species such that a subset of highly used plant species drove the overall pattern of use within the community. Despite higher use of alien plants in more disturbed sites, alien plants as a group were not more preferred. Rather, bees’ use of individual alien plants correlated with plant abundance in the community. Consistent with the interpretation that bees use, but do not prefer, alien plants, we found no effect of alien plant abundance or richness on bee abundance or richness.

The importance of plantain (Plantago spp.) as a supplementary pollen source in the diet of honey bees.

The importance of plantain (Plantago spp.) as a supplementary pollen source in the diet of honey bees.

The importance of plantain (Plantago spp.) as a supplementary pollen source in the diet of honey bees

SummaryPlantain (Plantago spp.) is generally considered to be an anemophilous plant that produces pollen of low nutritional value to bees. Between April and September during 2002 and 2003, in two regions in northwestern Portugal, we studied both the pollen collected by honey bee colonies and airborne pollen. Plantain pollen collection by honey bees was observed only in three different periods, despite its continuous presence in the air. This behaviour was related to the beginning and ending of flowering of the honey bee's main nutritional pollen sources, with no other factor seemingly influencing the temporal collecting patterns. The collection of Plantago spp. pollen was observed in the gaps between the flowering of Eucalyptus spp., chestnut (Castanea sativa), wild blackberry (Rubus spp.) and heaths (Ericaceae family). The results suggest that pollen of Plantago species seems to be used by honey bees as a substitute for other more nutritious pollen types and is collected only as a supplementary source. The temporal patterns of Plantago pollen collection by honey bees could therefore be used as a valuable ecological indicator of periods with low availability of highly nutritious pollen sources.

Biologia reprodutiva de Psychotria suterella Muell. Arg. (Rubiaceae) e a abordagem de escalas ecológicas para a fenologia de floração e frutificação

O comportamento de forrageio de polinizadores e dispersores de sementes e influenciado pela heterogeneidade de recursos no ambiente, sendo importante conhecer a variacao espaco-temporal dos recursos a fim de compreender as relacoes mutualistas estabelecidas entre plantas e animais. Na paisagem estudada, a floracao de Psychotria suterella ocorreu de janeiro a abril, meses de maior pluviosidade no ano, e apresentou alta sincronia entre as populacoes. O padrao fenologico de floracao encontrado na categoria de individuo se assemelhou ao registrado para as categorias de populacao e paisagem. A frutificacao ocorreu durante todo o ano, com maior disponibilidade de frutos maduros em maio e dezembro, havendo menor sincronia entre as populacoes e entre os individuos nesta fenofase do que na de floracao. Apenas cruzamentos inter-morfos produziram frutos e sementes, indicando que esta especie vegetal depende de vetores de polen para reproducao sexuada. Uma vez que nao ha indicios de limitacao polinica nas populacoes estudadas, consideramos que as diferencas na frutificacao entre as populacoes poderiam estar associadas a fatores abioticos. A sobreposicao entre o padrao de floracao anual de Psychotria suterella e a atividade de forrageio de Bombus brasiliensis, o fato de B. brasiliensis ser o polinizador mais importante desta especie vegetal, bem como a importância de P. suterella na dieta desta abelha, sugerem que pressoes seletivas entre as duas especies podem condicionar o resultado desta interacao mutualista.

Effects of Selected Fungicides on Growth and Development of Larval Honey Bees,Apis melliferaL. (Hymenoptera: Apidae)

Laboratory studies were conducted to determine the effects of incorporating selected almond fungicides into the diet of larval honey bees, Apis mellifera Linnaeus. One-day-old larvae, from mixed Italian stocks, were grafted to basic larval diet or basic diet containing various fungicides. Experimental concentrations were calculated from field dose application rates of formulated product per hectare. Larvae were transferred to fresh diet daily and incubated in the dark at 35°C and 95% RH. After defecation, prepupae were moved into a dark incubator at 35°C and 75% RH. Mortalities of larvae, prepupae, and pupae were recorded daily. No larvae fed Captan, Rovral, or Ziram completed development to adults. In the case of Rovral, a novel amorphogenic effect was observed. There were no significant differences in total mortality between the controls and larvae fed Abound, Elevate, Flint, Rally, and Vangard.

Effect of an amino acid on feeding preferences and learning behavior in the honey bee, Apis mellifera

Amino acids are common constituents of floral nectars and can be critical components in the diets of insect pollinators. Yet the means through which insects detect amino acids can be complex and arise from pre- and post-ingestive mechanisms. Furthermore, the response to an amino acid can change depending on an insect's nutritional status. Here we use a sensitive feeding assay and Proboscis Extension Response (PER) conditioning in the honey bee to assay the effect of glycine, which is a common constituent of nectars and pollens. Subjects preferred to feed on a sucrose stimulus that contained glycine, and the highest relative preference was recorded for the highest concentration of glycine. However, the highest response rate occurred at lower than maximal concentrations and differed depending on the physiological status of the subjects. These results are consistent with a model in which subjects attempt to maintain a physiological target amount of glycine/amino acid relative to other nutrients. All concentrations of glycine enhanced the rate and magnitude of a conditioned response to an odor in the PER assay, which demonstrates that animals can learn to modify their responses to an odor conditioned stimulus based on the presence of amino acid. This capability would enhance a honey bee's ability to evaluate the quality of floral nectars, which are associated with, among other things, odor cues given off by flowers. In future studies these techniques will allow us to evaluate the physiological roles that amino acids play in honey bee diet and choice behavior.

Black gram as a pollen substitute for honey bees

The flour of black gram ( Phaseolus mungo) was used instead of soybean meal as a substitute for pollen in the diet of honey bees ( Apis mellifera). The colonies which were fed with pollen substitute containing black gram produced a higher number of frames, resulting in higher production of honey compared with those fed on meal containing soybean.

Standardized Analytical Techniques for Bee-Collected Pollen

Existing quantitative palynological techniques (i.e., chemical processing, counting, and numerical analysis of pollen) were adapted for use by entomologists. Particularly important were calculation of pollen concentrations and assessment of pollen volume. Corbicular pellets, honey, larval pollen provision masses, and feces contained pollen exines representative of plants visited by bees. Dietary importance of a plant was assessed from a number of pollen grains and volume. Counts of small pollen grains represented dietary importance adequately (i.e., Larrea and Ambrosia ), whereas counts of large grains (i.e., Cereus and Acacia ) underrepresented dietary importance. Data were presented in graph form and reliability was demonstrated from samples repeatedly drawn from a thoroughly mixed honey bee pollen diet. Corbicular pellets were collected from Apis mellifera (L.) colonies fitted with Ontario Agricultural College pollen traps during 1985 in Pima Canyon, near Tucson, Ariz.; 25 species were present. Results from a bee diet include pollen grains of diverse morphologies and volumes, stressing the importance of adequate sample preparation, chemical processing, and numerical analysis. Use of these methods by apiculturists and melittologists will facilitate direct, justifiable comparison of pollen diets for bees.

Definitive evidence for lack of phytosterol dealkylation in honey bees

Neither developing honey bee larvae nor queens were able to convert dietary14C-desmosterol to cholesterol, nor was larval development of sterol metabolism affected when the inhibitor, 25-azacoprostane, was included in the worker bee diet. These results provide strong evidence that this phytophagous insect is unable to dealkylate phytosterols at the C-24 position in order to produce cholesterol.