Pollen Quality Research Articles

Production and Quality Characteristics of Royal Jelly in Relation to Available Natural Food Resources

Royal jelly is a secretion produced from the hypopharyngeal glands of worker bees, which requires significant pollen reserves to stimulate gland secretion. The natural sources of food available to the hive during beekeeping season can greatly affect the quantity and quality of produced royal jelly. In this study, samples of royal jelly were collected throughout the beekeeping season, and their physical and chemical characteristics were analyzed to understand how natural variations in bee diet affect royal jelly production. Before each sample collection, the bees’ food reserves were removed from the experimental colonies so that the royal jelly was produced solely from natural sources. The results showed that the production was significantly lower during the summer months compared with spring and autumn. Additionally, the moisture, protein, fructose, and glucose content of fresh royal jelly also showed significant changes in the summer, and all physical and chemical characteristics decreased when the fresh samples were converted into dry matter. It seems that the quality of pollen entering the hives has a direct impact on the physical and chemical properties of the final product, highlighting the crucial role of available resources in stimulating bees to produce royal jelly.

Optimized Protocol for in vitro Pollen Germination in Brinjal (Solanum melongena L.)

Background: Understanding floral and pollen biology is essential for efficient artificial hybridization in hybrid seed production. This knowledge helps ensure proper fertilization of the ovary and optimal fruit and seed set. Selecting suitable pollen parents and preserving pollen for future use allows for better control and optimization of hybridization practices in brinjal breeding programs. To achieve this, a robust protocol for pollen collection and viability testing is necessary to monitor pollen quality in the field and during storage. This information is crucial for maintaining desired characteristics and genetic traits in the resulting hybrid seeds. Methods: This study; aimed at optimizing the pollen germination assessment protocol for brinjal. The step wise modification standard medium composition was done, the optimal growth condition was tested and in vivo predictions were made. So, the study aimed to standardization of media for in vitro pollen germination evaluate and viability in brinjal in ambient as well as cold storage conditions. The pollen germination was tested in vitro as well in vivo, by incubating the pollen grains for 3 hours at 25°C in different concentrations of sucrose, boron and agar media and distilled water at interval of 12 hours. Result: The most favorable germination of fresh pollen was achieved with a treatment consisting of 1% Agar, 12% Sucrose and 300 ppm Boron. Comparing the two storage conditions, pollen stored in the refrigerator exhibited higher in vitro germination percentages compared to ambient storage conditions. The highest in vitro pollen germination and viability percentages were observed in fresh pollen collected within 12 hours (95.00%). As the duration of pollen storage increased in both storage conditions, the in vitro pollen germination decreased. This decline in in vitro pollen germination was reflected in the in vivo fertilization fruit set percentage. The highest fruit set percentage was observed when pollen was stored in the refrigerator (64.52%) and when female flowers were pollinated with pollen stored for less than 12 hours (84.66%).

Modelling foraging strategies of honey bees as agents in a dynamic landscape representation

Introduction: Both intrinsic colony mechanisms and external environmental variables affect the honey bee colony development rates and response and a key aspect of this is the use of resources within the landscape by honey bees. Although several models have been developed to explore the foraging behaviour of bees, none fully considered the spatial and temporal dynamics of landscape resources and the role of the colony in the process. Methodology: Here, we introduce a new honey bee foraging model being developed as a part of the ApisRAM honey bee colony model. Based on agent-based modelling, we used a dynamic ALMaSS landscape model enhanced with floral resource modelling to assess the impacts of weather conditions and resource availability on the possible foraging behaviour of honey bees. Several possible mechanisms (defined, based on honey bee traits) for scouting and foraging were investigated, separately for nectar and pollen collection, including prioritising foraging polygons for nectar foraging according to their distance to the colony, the quality or the energetic efficiency and, for pollen foraging, according to their distance to the colony and pollen quantity. Results: If model foraging bees prioritised the polygons, based on their distance from the colony, the number of unsuccessful flights increased compared to other tested strategies and the total amount of sugar collected showed a high variability. Contrary to expectations, the energetic efficiency strategy did not provide the colony with the highest amount of sugar. Overall, the tested strategies provide different outcomes on the collection of resources, the number of performed flights and their success rate, evidencing that the model's outcome at the colony level arises from the individual types of behaviour. Conclusions and Relevance: Variability in the mass of collected nectar and pollen was found mostly when scout bees applied the distance strategy. This higher variability in sugar collection means that model bees were not able to find the most profitable foraging sites at the landscape level, but only at the local level. Other strategies showed less dependence on the surrounding landscape (i.e. quality or random), but it comes at a cost (i.e. lower production for both nectar and pollen collection). These outputs help us evaluate which strategies could be used for future model development and confirm the models' ability to create dynamic responses. These responses at the colony level were only possible thanks to the implementation of a dynamic landscape model and dynamic spatiotemporal resource model, as well as implementing a social communication mechanism for bees to share information about the resources. Plant nectar production and quality information is essential to predict honey bee foraging distribution. In future model development, the implementation of pollen quality should also be explored to evaluate if it influences the overall pollen collection.

Investigating the effect of postharvest conditions on the microbial quality and physicochemical characteristics of bee pollen

Considering the scarcity of information on postharvest management of bee pollen, especially its fresh form, this study aims to investigate the effect of storage conditions and duration on the microbial load of fresh and dried pollen, while also considering changes in physicochemical parameters. Specifically, microbiological analyses were applied to record the growth of Mesophilic Total Viable Counts (MTVC), Yeasts & Moulds (Y&M), Enterobacteriaceae (ENT), Lactic Acid Bacteria (LAB), and Escherichia coli. The results showed that fresh pollen can be stored in the freezer (-18 °C) for one year, without exceeding the legislative limits for the studied pathogens, as after storing for 12 months, the mean counts of MTVC, Y&M, ENT, and LAB were 3.93, 4.04, 1.71, and 2.82 log cfu/g, respectively, whereas moisture, protein and lipid content, fatty acid composition, and colour remained unchanged. When fresh pollen was stored at 4 °C, over a six-month period, the MTVC & ENT counts were out of limits, and changes were observed in colour, total lipid content (32.18% decrease), and fatty acid composition (31.68% for C18:2 and 21.56% for C18:3 reduction, 31.5% increase for C18:0). Finally, storing fresh pollen at 25 °C is deemed insufficient for maintaining quality characteristics. Dried pollen demonstrated better results, compared to fresh pollen, maintaining values of microbial load within legislative limits at all storage temperatures, thus making long-term storage easier. The data gathered during this study may form the basis for a guide including proper beekeeping practices and postharvest bee pollen treatment and management, contributing to the optimization of pollen production.

Effective population size mediates the impact of pollination services on pollen limitation.

Inadequate pollen receipt limits flowering plant reproduction worldwide. Ecological causes of pollen limitation (PL), like pollinator scarcity and low plant abundance, have been a primary research focus. The genetic diversity of plant populations could impact both quantity and quality components of PL in concert with ecological factors, yet empirical examples are lacking. We evaluated joint effects of ecological factors (flower abundance, pollinator visitation) and genetic effective population size (NE) on PL across 13 populations of the common herb Argentina anserina. We used a histological approach with 5504 styles from 1137 flowers to separate quantity and quality components of PL, and link these to reproductive output. NE and pollinator visitation interacted to shape PL, but NE had stronger direct effects. Effectively smaller populations experienced stronger quantity PL, and controlled crosses in a pollinator-free environment revealed that stigmatic pollen quantity was an intrinsic population-level attribute that increased with NE. Pollinator visitation enhanced pollen quality, but only in effectively larger populations. Quantity and quality PL negatively impacted fruit and seed set, respectively. Results highlight that PL is dictated by plant population genetic diversity in addition to commonly evaluated ecological factors. Efforts to support pollinators will more strongly enhance plant reproduction in genetically diverse populations.

Качество семян и пыльцы 7 видов сосны в условиях интродукции в Приморском крае

The purpose of the study is to study the features of generative development of introduced pine species based on the material of the arboretum of the Mountain Taiga Station. The results of studying the morphology and quality of pollen and seeds of pine species under the conditions of the introduction of Primorsky Krai are presented. Pollen and seed viability indicators are the most important characteristics of the development of male generative structures. This, in turn, determines the degree of adaptation of the species to external conditions during introduction. Morphometric indicators of pollen (length and height of the body and air sacs) were determined on micro preparations, and the number of abnormal pollen grains was counted. Pollen viability was determined by germinating it in a 15% sucrose solution in a thermostat at a temperature of 25 ºС using the “hanging drop” method. Under the conditions of introduction, a direct correlation was found between the number of germinated pollen grains and the intensity of growth of pollen tubes. Germination and seed germination energy were determined according to GOST 13056.6‑75. Germination was carried out in Petri dishes on filter paperi n a thermostat at a constant temperature of +24°C. A direct relationship was found between the number of germinated pollen grains and the rate of growth of pollen tubes. Among the studied pine species, P. banksiana, P. hamata, and especially P. sylvestris, have a sufficiently large potential for a favorable completion of the embryonic stage in the generative process. The same species have the best indicators of germination and seed germination energy. The degree of viability of pollen has a direct impact on the formation of full-grained seeds.

Assessment of pollen quality and quantity in White and Black Turkish Myrtus communis L. accessions, through In Vitro pollen germination under varied boric acid concentrations

Assessment of pollen quality and quantity in White and Black Turkish Myrtus communis L. accessions, through In Vitro pollen germination under varied boric acid concentrations

Does ash dieback affect the reproductive ecology of Fraxinus excelsior L.?

Forest tree species reproduction is a key factor in maintaining the genetic diversity of future generations and the stability of forest ecosystems. The ongoing ash dieback disease could affect the reproductive ecology of Fraxinus excelsior L. and have a major impact on the quantity and quality of pollen and seeds. In this study, we investigated pollen production and viability of pollen and seeds of ash trees with different health status from 2018 to 2022. Inflorescences were collected from 105 trees (pollen production), pollen from 125 trees (pollen viability), and seeds from 53 trees (seed quality) in two seed orchards and in one floodplain forest in southern Germany. Not all parameters were examined at every site every year. The average pollen production per tree was estimated at 471.2 ± 647.9 billion pollen grains. In addition, we found that a high number of inflorescences did not equate to high pollen production per inflorescence. Pollen production of healthy and diseased trees did not differ significantly, although only 47% of severely diseased male trees (vs. 72% for healthy trees) produced flowers. With regards to pollen viability, the TTC test showed an average viability of 73% ± 17%. Overall, there was a slight tendency for diseased trees to have less viable pollen. However, a significant difference could only be calculated for trees in the floodplain forest. The percentage of germinable seeds in 2018 was 38% in the floodplain forest and 57% in one of the seed orchards. The percentage of viable seeds (TTC test) ranged from 17 to 22% in the orchards in 2020. Non-viable seeds were usually heavily infested by insects. In general, seed quality was not significantly different between healthy and diseased trees. Our results indicate that ash dieback affects flower formation and pollen viability but not pollen production or seed quality. Nevertheless, the fact that hardly any flowering was observed, especially for trees that were seriously affected, suggests a negative effect of ash dieback on reproductive performance. Thus, severely diseased trees will transfer their genes to a smaller extent to the next generation.

Farklı Sıcaklık ve Sürelerde Bekletilen Kasımpatı Polenlerinde Polen Kalitesinin Belirlenmesi

Pollen quality is one of the most important factors in breeding programs because of its effects on seed formation. For an effective breeding program, breeders must know pollen viability, germination rate, and the duration of maintaining pollen viability. This study was carried out to determine pollen viability and germination rates of 'Chic' and 'Barolo' spray chrysanthemum varieties kept at different temperatures and times. Pollen from both varieties was obtained from plants grown in a fully automated greenhouse. Pollens were stored at +24°C and +4°C for 7 days. Pollen viability was determined by the TTC method and germination rates were determined by the hanging drop method with modified ME3-m medium, daily for 8 days, including day 0. The 'Chic' varieties had more viable pollen than the 'Barolo' variety. Viable pollen and germination rates tended to decrease continuously with time. On the 7th day, the germination rate decreased by 93.44% and 71.64% in the 'Barolo' and 'Chic' varieties, respectively. However, the capacity to maintain the viability of pollen kept at +4°C was found to be better in both varieties. In the study, it was concluded that the pollen should be applied freshly but stored at +4°C when necessary. The pollen kept at +24°C can be used for up to 2 days. This period can be extended up to 4 days at +4°C, depending on the variety.

Effects of Short Term Pollen Storage on Fruit Set, Seed Number and Seed Germination Rate in Cut Rose Hybridization

Roses are known for their low pollen quality. It remains unclear how many days of pollen should be used in order not to reduce crossbreeding success. The study was conducted to determine whether short-term pollen storage is effective on the crossing success of roses comparatively in vivo and in vitro. The study was conducted in a greenhouse and a cytology laboratory at Ankara University, Turkey. The 'Avalanche' rose variety was used as the seed parent, and 'Magnum' was the pollen parent. A total of 210 crosses were made. Pollens were used immediately (day 0) and stored at +4°C for 6 days after collection. The pollen viability by IKI and the germination rates by the petri dish method, the fruit and seed set, the fruit and seed weight, and the seed germination rate were recorded. All examined traits showed a decreasing trend as the storage time increases. The pollen germination rates were recorded at 1.63% for stored pollen at six days and 15.27% for fresh pollen. The highest fruit and seed set rates were obtained from crossing with pollen stored for one day. The fruit set decreased below 10% as of the 5th day, and the seed numbers decreased 1.8 times compared to one day of storage. No germination was observed in seeds obtained from crosses with pollen stored for 5 or 6 days. A positive correlation was found between seed number and pollen germination rate. The study concluded that successful crossing could be made with pollen stored at +4°C for up to 3 days.

Automated monitoring of pollen quality in Douglas fir using digital images: applications for handling and storage

Background: Conservation and breeding programs for forest species require efficient pollen quality monitoring strategies to maximize collection, storage and pollination efforts.
 Question: Can the ImageJ image analysis software be implemented to efficiently monitor pollen viability and germinability for quality testing?
 Studied species: Pseudotsuga menziesii (Mirb.) Franco
 Methods: Tetrazolium staining and germination on 10 % Brewback media was used to test Douglas-fir pollen quality. Two macros for automated counting were developed with ImageJ free software using digitized microscopic images, and were tested to evaluate provenances, germination in different media, dehydration/rehydration and freeze-storage treatments, and finally to compare pollen quality between mature trees and GA-induced strobili from juvenile trees.
 Results: Automated monitoring of pollen quality was feasible because the software suitably distinguishes viable from non-viable pollen grains due to differential tetrazolium staining that translates into pixel density, whereas germinability was assayed based on pollen size and circularity. This tool was used to guide the selection of appropriate pollen handling conditions and compare pollen production in adult and GA-induced juvenile trees. Pollen flash-freezing and storage at -80 °C showed recovery between 74 and 98 % of its initial germinability after rehydration; however, viability detected by tetrazolium is reduced, suggesting that handling and storage affect the reliability of the test.
 Conclusions: The flexibility of the Fiji software allowed the development of an efficient and accurate macro for monitoring P. menziesii pollen quality, reducing invested time and effort involved, which supports future research on its conservation physiology and its successful application for germplasm production.

<i>Prunus spinosa</i> L. pollen - quantity and nutritional quality

Pollen production and pollen quality in <i>Prunus spinosa</i> L. (Rosaceae), a common early-spring flowering plant from the temperate zone was evaluated. The species is an efficient pollen producer, as it can produce 0.23 mg of pollen per flower and 1.99 g of pollen per 1 m<sup>2</sup> of shrub surface, however, the values may differ considerably between seasons. Its pollen contains a high amount of proteins (22.1–34.2%). The total lipid content in the pollen ranged between 2.7 and 3.6%. The presence of omega-3, omega-6, and omega-9 fatty acids was found. Among omega-3 fatty acids, inflammation inhibitors, i.e., α-linolenic acid and arachidonic acid, were detected. The predominant mineral was potassium, followed by calcium and magnesium. <i>P. spinosa</i> pollen is an important ingredient of bee pollen loads containing 89.1–98.2% of <i>Prunus pollen</i>. <i>P. spinosa</i> should be recommended for planting in the agricultural landscape in order to support the early spring diet for pollinators.

More is not always better: Impact of nutrient-addition on floral traits important for buzz pollination

Nutrient addition can affect plant fitness by altering resource allocation to reproduction or modifying floral traits. Alterations in floral attributes, particularly in species that exhibit specialization in specific ecological niches, can disrupt or augment the dynamics of interactions between plants and their pollinators. However, very little is known about how soil enrichment affects the floral characteristics and pollen release dynamics of buzz pollinated plants. Our study analyzed the effects of nutrient enrichment on the reproductive traits of a buzz pollinated plant species. Under greenhouse conditions, we established a phosphorus-rich nutrient gradient to investigate the impact of such enrichment on tomato plants (Solanum lycopersicum). Our study focused on: i) flowering patterns, ii) flower morphology, iii) pollen release from anthers, and iv) pollen quantity and quality (protein concentration). Plants were grown in low, intermediate, and high nutrient conditions, and various functional traits that are essential for buzz pollination were examined. Adding nutrients improved the display of flowers. Morphometric traits important for pollinator attraction and interaction, such as floral diameter, anther-tube width, and petal width, showed an increase in the high nutrient condition. The pollen quality and quantity were found to be unaltered; however, flowers originating from intermediate and high nutrient conditions exhibited reduced pollen release upon buzzing despite possessing ample pollen reserves. Our findings suggest that the positive effects of nutrient addition on floral traits are limited to a narrow range of concentrations. Higher concentrations can diminish these effects and impact the accessibility of pollen, as well as the reproductive performance of plants. In conclusion, based on our results, we predict that changing land use scenarios leading to nutrient accumulation may have significant consequences for plant-pollinator interactions.

Flower Visitors, Levels of Cross-Fertilisation, and Pollen-Parent Effects on Fruit Quality in Mango Orchards

Pollination is essential for the reproductive output of crops. Anthropogenic disturbance and global pollinator decline limit pollination success, reducing the quantity or quality of pollen. Relationships between the abundance of flower visitors and fruit production are often poorly understood. We aimed to (1) identify and quantify flower visitors in a mango orchard; (2) assess how much of the crop resulted from self- versus cross-pollination at increasing distances from a cross-pollen source in large, single-cultivar blocks of the cultivar Kensington Pride or the cultivar Calypso; and (3) determine how pollen parentage affected the size, colour, flavour attributes, and nutritional quality of fruit. Mango flowers were mostly visited by rhiniid flies and coccinellid beetles. Approximately 30% of the fruit were the result of cross-pollination, with the percentage significantly decreasing with an increasing distance from a cross-pollen source in the cultivar Calypso. Self-pollinated Calypso fruit were slightly larger and heavier, with higher acid and total polyphenol concentrations than cross-pollinated fruit. Our results showed higher-than-expected levels of cross-fertilisation among fruit, although self-pollen was likely more abundant than cross-pollen in the large orchard blocks. Our results suggest the preferential cross-fertilisation of flowers or the preferential retention of cross-fertilised fruitlets, both representing strategies for circumventing inbreeding depression. Growers should establish vegetated habitats to support pollinator populations and interplant cultivars more closely to maximise cross-pollen transfer.

A Novel Method for Stimulating Cannabis sativa L. Male Flowers from Female Plants.

Female hemp plants are desired in floral hemp operations due to their higher cannabinoid contents. To produce feminized seeds, a critical step of inducing fertile male flowers on female plants is performed. In feminized seed production, freshly mixed STS (silver thiosulfate + sodium thiosulfate) is applied to female plants as an ethylene inhibitor to induce male flowers. However, the short-shelf stability of the STS buffer can cause difficulty in the application and inconsistent results. Alternative methods with improved accessibility and stable buffers will be beneficial for the hemp industry and hemp breeders. A commercially available floriculture product, Chrysal ALESCO®, contains silver nitrate, the same active ingredient as STS but with increased shelf stability. This study compares Chrysal ALESCO® to the traditional STS standard methods for male flower induction on female plants and their pollen quality. The two treatments were applied to six female hemp accessions with three replicates investigated, and the male flower counts and pollen quality were compared. No statistically significant difference was discovered in their male flower counts; the STS-treated plant produced an average of 478.18 male flowers, and the Chrysal ALESCO®-treated plant produced an average of 498.24 male flowers per plant. Fluorescein diacetate (FDA) and acetocarmine stains were used to investigate the pollen quality (non-aborted rate) of two chosen genotypes. FDA-stained pollen of Chrysal ALESCO® showed a significantly higher non-aborted rate than the pollen of traditional STS-treated plants (p < 0.001); however, only a marginally higher non-aborted rate was discovered by acetocarmine staining (p = 0.0892). In summary, Chrysal ALESCO® performed equally to traditional STS treatment at male flower counts and better or equally in pollen quality. With better shelf stability and easy application, ALESCO® can be a viable alternative option for stimulating male flowers on female hemp plants.

Development and evaluation of precision liquid pollinator for kiwifruit

Cultivation of kiwifruit heavily relies on assisted pollination, and sufficient pollination can enhance fruit quality. A precision liquid pollinator for kiwifruit robotic pollination was developed as part of the research, and it was optimized with the aim of improving pollination quality while saving pollen usage. The pollinator employs a grating ruler to measure the stroke of a pneumatic hydraulic cylinder to achieve precise control of pollen suspension dosage, and uses an internal mixing air-assisted nozzles to spray pollen suspension for pollination. Through experiments of optimizing pollen suspension volume control, constructing of pollination distance prediction model, and measuring droplet size distribution, a working range of air pressure and liquid pressure was established. Eight sets of air–liquid pressure parameters were selected to evaluate the planar pollen deposition of the pollination device, and the optimal parameters were applied to pollinate kiwifruit flowers. The results indicated that reducing droplet size enhanced the overall pollen deposition rate.. In a windless laboratory environment, the developed pollinator achieved a pollen deposition efficiency of 21.15% under an air pressure of 0.15 MPa and liquid pressure of 0.25 MPa. This precision liquid pollination device is advantageous for precise control under high pressure and low flow conditions, suitable for the end effector of autonomous pollination robots. The optimization and evaluation methods established within this study provide reference for the development of precision pollination devices.

Validation of a questionary for measuring corbicular pollen consumer preferences via structural equations models

Boyacá is one of the main bee pollen (or corbicular pollen) producers in Colombia. However, pollen consumer preferences in this region are unknown; therefore, there is no background to develop marketing strategies aiming at profiting beekeepers and consumers. This study presents the design and statistical validation of a questionary to assess the preferences of bee pollen consumers and the model that supports the relationships between the constructs characterizing them. Model development was based on the premise that pollen quality perception affects consumer satisfaction. To test this premise, a reflexive measure model was used to design the Pollen Preferences Determination Questionary (PPDQ). Data from a pilot sample were used to evaluate the measure and structural models via structural equations models fitted through partial least squares (SEM-PLS). The results showed the validity of the PPDQ since the indicators load its constructs appropriately, particularly for satisfaction and intrinsic quality.

Pollen viability, self-incompatibility, and a very singular S-allele structure between the reasons for the limited potential productivity of traditional Basque cider apple varieties

Cider regions conserve a broad diversity of traditional cultivars for which knowledge has hardly evolved. Key aspects of their reproductive biology are barely known, hindering improvement in orchard management and resulting in highly variable yields. In this study, we characterized key aspects of the reproductive biology of some traditional apple cultivars from the Basque-style cider-producing area in northern Spain (Basque Country and Navarre). We tested for pollen quality, self-compatibility, and cross-compatibility (S-genotyping). The pollen quality was good except for Urtebete, Errezila, Reineta Encarnada, and triploid varieties. Self-pollination results confirm the need for pollinators, as only Moko and Txalaka showed certain self-compatibility. Regarding S-genotyping, the population proved very singular, with an atypically high frequency of S26, a frequent allele within crabapples, and the appearance of a novel unpublished allele (S60). The knowledge generated for this variety pool will contribute to a better choice of suitable pollinators, preventing the use of popular crabapple varieties that are demonstrated to be partly incompatible with them, and will lead to an increase in potential yields in the region.

Male diversity matters: genetic structuring of insular male date palm (Phoenix dactylifera L.) revealed valuable breeding and conservation resources

ABSTRACT Most male date palms available for pollinating different female cultivars have mainly originated from seed propagation resulting in many different local males that represent a source of genetic diversity. Favourable fruit production is related to the quality of pollen and its compatibility with a certain female variety. Therefore, the genetic characterisation of the male progenitors should be the first step to establish a selection programme to produce superior males through different procedures. In this study, the genetic diversity and population structure of 72 male date palm accessions were investigated using 15 microsatellite loci. The highest mean number of alleles per locus was obtained for Tozeur group. Bayesian model-based clustering analysis indicated the presence of two differentiated endemic male date palm genetic clusters, continental and insular, with the presence of introduced accessions originating from the Middle East. The diversity analysis in the insular region of Tunisia, which had never been performed before, revealed that this germplasm enclosed valuable endemic resources supporting the hypothesis of the presence of wild material. These findings are crucial for identifying interesting genotypes that can be integrated into international coordinated actions of Phoenix dactylifera L. breeding programmes and the protection and conservation of valuable resources.

The effect of sunflower pollen age and origin on pathogen infection in the common eastern bumble bee (Apidae: Hymenoptera).

Bumble bees are globally important pollinators, contributing hundreds of millions of dollars annually in crop pollination services. Several species are in decline, making it paramount to understand how pathogens and nutrition shape bee health. Previous work has shown that consuming sunflower pollen (Helianthus annuus) dramatically reduces infection by the trypanosomatid gut pathogen, Crithidia bombi, in the common eastern bumble bee (Bombus impatiens). Sunflower pollen may therefore be useful as a dietary supplement for reducing this pathogen in managed bumble bee colonies. Here, we assessed the efficacy of freezer-stored sunflower pollen that was collected in different years and locations for reducing pathogen infection. We tested sunflower pollen that was 1, 3, 4, or 5 yr old and from sunflowers grown in the United States or China against a control of 1-yr-old buckwheat pollen from China, since buckwheat pollen results in high infection. We hypothesized that older pollen would have weaker medicinal effects due to degradation of pollen quality. We found that all sunflower pollen treatments significantly decreased Crithidia infection compared to controls. These results suggest that sunflower pollen can be freezer-stored for up to 5 yr and sourced from a wide range of geographic areas and still maintain its medicinal effects against Crithidia in the common eastern bumble bee. This is helpful information for stakeholders who might administer sunflower pollen as a dietary supplement to manage Crithidia in commercial bumble bee colonies.