Search Results (111)

Crop fidelity is a desirable trait for managed pollinators and is influenced by factors like competing forage sources and colony knowledge of the surrounding environment. In European honey bees (Apis mellifera L.), colonies deployed when the crop is flowering display the highest fidelity. We tested for a similar outcome using a stingless bee species that is being increasingly used as a managed pollinator in Australian macadamia orchards. We observed Tetragonula carbonaria (Smith) colonies deployed in macadamia orchards at three time points: (1) before crop flowering (“permanent”), (2) early flowering (“early”), and (3) later in the flowering period (“later”). We captured returning pollen foragers weekly and estimated crop fidelity from the proportion of macadamia pollen they collected, using light microscopy. Pollen foraging activity was also assessed via weekly hive entrance filming. The early and later introduced colonies initially exhibited high fidelity, collecting more macadamia pollen than the permanent colonies. In most cases, the permanent colonies were already collecting diverse pollen species from the local environment and took longer to shift over to macadamia. Pollen diversity increased over time in all colonies, which was associated with an increase in the proportion of pollen foragers. Our results indicate that stingless bees can initially prioritize a mass-flowering crop, even when flowering levels are low, but that they subsequently reduce fidelity over time. Our findings will inform pollinator management strategies to help growers maximize returns from pollinator-dependent crops like macadamia. Full article

Plastic pollution has become a critical environmental issue, with vast amounts of plastic waste accumulating in aquatic and terrestrial ecosystems. Plastic pollution poses significant risks to biodiversity by introducing toxic chemicals and disrupting biological functions. The drone fly, Eristalis tenax, is perhaps the most globally widespread hoverfly. This success is aided by its development as a rat-tailed maggot in a wide array of aquatic environments where it feeds on decaying organic matter. As an adult, E. tenax is a vital pollinator, visiting a wide range of crops and wild plants, and has been shown to vector pollen over hundreds of kilometres during seasonal migrations. Exposure to microplastics during larval stages has the potential to alter the provision of these ecosystem services and to provide a route for the long-distance vectoring of microplastics. To investigate this, we rear E. tenax in water contaminated with different concentrations of microplastic particles. We show that these plastics are retained in the gut from larval through to pupal to adult developmental stages. This contamination resulted in reductions of 33% and 60% in pupal and adult weight when exposed to the highest concentrations of microplastic particles but resulted in no detectable effects on mortality or developmental length. Our results demonstrate the potential for the vectoring of microplastics by this highly mobile species. However, the associated reductions in body size likely have profound consequences for movement capability in terms of foraging and migration and should be further investigated for their impact on ecosystem service provision. Full article

Bee products, such as honey, bee pollen/bread, bee propolis and royal jelly foraged or secreted by honeybee workers, have been consumed by humans for many years and are important due to their complexity, the large number of them and the endemicity of their constituents. The health-promoting activities of bee products are widely documented all around the world. However, we have noticed a distinct but poorly described feature of bee products: groups of functionally opposite components (FOCs) related to blood sugar level, oxidative stress, cell membrane cholesterol distribution, cell membrane stability, cell membrane curvature, allergic reaction, cellular sodium influx and cardiac apoptosis that exist within these products. We then propose the Equivalence Index in order to overcome the challenges associated with FOCs; this is a concise mathematical model that can be used to optimize the evaluation of quality, determine any underlying mechanisms and provide processing guidance regarding bee products. Full article

Many rapidly expanding food crops, including avocado (Persea americana Mill.), are dependent on animal pollination but there is a growing shortfall in global pollinator supply. Avocado flowers are insect-pollinated and yields of the main cultivar, ‘Hass’, are often pollen-limited, especially in the middle of single-cultivar orchard blocks, where there is limited deposition of cross-pollen from another cultivar. We analysed two avocado cultivars of alternate flowering types, ‘Maluma’ (Type A) and ‘Shepard’ (Type B), using SNP-based DNA markers to identify the pollen parent of fruit at different distances from the other cultivar. We aimed to determine whether the numbers of cross-fertilised fruit and tree yields decline at increasing distances from a cross-pollen source, and whether cross-fertilised fruit are larger than self-fertilised fruit. We found that the number of cross-fertilised fruit produced by each tree declined in the middle of the blocks of each cultivar. Trees in the middle of the ‘Maluma’ block compensated for low levels of cross-pollination by producing more self-fertilised fruit, and their yields did not appear to be pollen-limited. However, yields in the middle of the ‘Shepard’ block declined by 25% as a direct result of a 43% reduction in the number of cross-fertilised fruit produced by each tree. ‘Shepard’ trees did not compensate for poor cross-pollination by producing more self-fertilised fruit. Cross-fertilisation of ‘Maluma’ by ‘Shepard’ increased fruit mass by 8% and cross-fertilisation of ‘Shepard’ by ‘Hass’ increased fruit mass by 5%, compared with self-fertilisation. Our results confirm that yields of avocado trees are sometimes, but not always, pollen-limited. Low levels of both self-pollination and cross-pollination resulted in pollen limitation of yield in the middle of the ‘Shepard’ block, but high levels of self-pollination were sufficient to generate high yields in the middle of the ‘Maluma’ block. Closer interplanting of Type A and Type B avocado cultivars increases the opportunities for cross-pollination, which can often increase tree yield and fruit size, and improve the financial returns for growers. Improving the pollination efficiency of foraging insects by providing them with the optimal pollen genotypes is increasingly important as we experience a growing demand for managed pollinators and a declining abundance of wild pollinators. Full article

Honeybees are of economic importance not only for honey production, but also for crop pollination, which amounts to USD 20 billion per year in the United States. However, the number of honeybee colonies has declined more than 40% during the last few decades. Although this decline is attributed to a combination of factors (parasites, diseases, pesticides, and nutrition), unlike other factors, the effect of nutrition on honeybee health is not well documented. In this study, we assessed the differential expression of seven genes linked to honeybee health under three different diets. These included immune function genes [Cactus, immune deficiency (IMD), Spaetzle)], genes involved in nutrition, cellular defense, longevity, and behavior (Vitellogenin, Malvolio), a gene involved in energy metabolism (Maltase), and a gene associated with locomotory behavior (Single-minded). The diets included (a) commercial pollen patties and sugar syrup, (b) monofloral (anise hyssop), and (c) polyfloral (marigold, anise hyssop, sweet alyssum, and basil). Over the 2.7-month experimental periods, adult bees in controls fed pollen patties and sugar syrup showed upregulated Cactus (involved in Toll pathway) and IMD (signaling pathway controls antibacterial defense) expression, while their counterparts fed monofloral and polyfloral diets downregulated the expression of these genes. Unlike Cactus and IMD, the gene expression profile of Spaetzle (involved in Toll pathway) did not differ across treatments during the experimental period except that it was significantly downregulated on day 63 and day 84 in bees fed polyfloral diets. The Vitellogenin gene indicated that monofloral and polyfloral diets significantly upregulated this gene and enhanced lifespan, foraging behavior, and immunity in adult bees fed with monofloral diets. The expression of Malvolio (involved in sucrose responsiveness and foraging behavior) was upregulated when food reserves (pollen and nectar) were limited in adult bees fed polyfloral diets. Adult bees fed with monofloral diets significantly upregulated the expression of Maltase (involved in energy metabolisms) compared to their counterparts in control diets to the end of the experimental period. Single-Minded Homolog 2 (involved in locomotory behavior) was also upregulated in adult bees fed pollen patties and sugar syrup compared to their counterparts fed monofloral and polyfloral diets. Thus, the food source significantly affected honeybee health and triggered an up- and downregulation of these genes, which correlated with the health and activities of the honeybee colonies. Overall, we found that the companion crops (monofloral and polyfloral) provided higher nutritional benefits to enhance honeybee health than the pollen patty and sugar syrup used currently by beekeepers. Furthermore, while it has been reported that bees require pollen from diverse sources to maintain a healthy physiology and hive, our data on nuclear colonies indicated that a single-species diet (such as anise hyssop) is nutritionally adequate and better or comparable to polyfloral diets. To the best of our knowledge, this is the first report indicating better nutritional benefits from monofloral diets (anise hyssop) over polyfloral diets for honeybee colonies (nucs) in semi-large-scale experimental runs. Thus, we recommend that the landscape of any apiary include highly nutritious food sources, such as anise hyssop, throughout the season to enhance honeybee health. Full article

One of the eight shortfalls in European wild bee data is the knowledge of the flowering plants they favor. This knowledge is of particular importance for bee gardens and wildflower strips initiatives aiming to provide forage for the wild bees. The aim of this study is to provide a list of plants that are used for food by certain taxa of wild bees in Bulgaria and to evaluate their potential for cultivation in bee gardens and wildflower strips. In relation to this, we discuss the food plant specialization of the wild bees. We summarize our observations on the pollination of certain plants and faunistic records considering the food plants in several grassland habitats on the territory of Bulgaria at altitudes between 0 and 1500 m above sea level, during the last 30 years. More than 54 taxa of wild bees are listed. They belong to the families Apidae, Andrenidae, Colletidae, Halictidae, and Megachilidae. Some of these bees are identified to the species level, and others to the genus or family level. Among the recorded wild bees are observed eight oligolectic species (22.2%). The listed bees are flower visitors of 60 plant taxa belonging to 20 families, which offer nectar and/or pollen. The wild bees’ food plants are predominantly from the families Fabaceae (15 species), Lamiaceae (14 species), Asteraceae (9 species), etc. The perennials are 67%, while annuals are 9%, annual or biennial 6%, biennials 5%, etc. We discuss the seed germination specifics of these plants. More studies are needed in this field. The conservation of wild bees may be supported by wildflower restoration activities, but the process depends on many factors, including seed germination difficulties. Therefore, the natural grassland habitats must be preserved and protected. Full article

Cadmium (Cd) is a heavy metal present in pollen and nectar that affects pollinator attributes. Honey bees possess the ability to eliminate Cd from honey. Consequently, the concentration of Cd in pollen, rather than nectar, is the critical factor influencing the growth and foraging behavior of honey bees. However, there is a dearth of studies regarding the specific association by which the impact on bee growth and foraging behavior fluctuates in relation to the Cd dosage of pollen or nectar. We hypothesized that at low exposure levels, the amount of Cd in pollen would affect honey bee growth, and the amount of nectar influences honey bee foraging behavior. At high exposure levels, the amount of Cd in pollen and nectar would affect both honey bee growth and foraging behavior. A field experiment was performed in Sichuan (the average background value of Cd in soil is 5.6 times higher than other regions in China) to examine the impact of different soil Cd concentrations (low: 0.60 ± 0.05 mg·kg⁻¹ (average ± SD); middle: 1.32 ± 0.08 mg·kg⁻¹; high: 1.76 ± 0.10 mg·kg⁻¹) on the Cd levels in plant organs (Brassica campestris), alongside the body mass and visitation rates of honey bees (Apis mellifera). Our results indicated in honey bees in the habitats with low concentrations of soil Cd that the Cd content in pollen was inversely correlated with the body mass of larvae, pupae, and worker bees. The quantity of nectar governed the foraging activity of honey bees in the habitats with low levels of soil Cd. At middle to high exposure levels, Cd concentrations in pollen and honey exerted a negative influence on honey bee development and foraging behavior. These findings offer novel insights into the impact of Cd on pollinator attributes, and the global decline of pollinators. Full article

Imported, non-native honey bees and bumble bees threaten native pollinators by spreading pathogens (disease and parasites) and outcompeting native pollinators for nectar and pollen. We reviewed Canadian federal, provincial/territorial, and municipal legislation to find governance requirements that potentially reduce these threats. We classified the requirements as follows: tracking the number and location of honey bee hives (registry); controlling the spread of pathogens (registry with inspections, quarantines, and cleaning regimes); controlling the competition with native pollinators (limiting shared use of space); and making regulations applicable to all domesticated bees in addition to honey bees. Policies and regulations to control the competition from honey bees are generally lacking. So, we propose the concept of “foraging leases” to manage the location and duration of honey bee apiaries on public lands. Based on the identified requirements, we recommend amendments to the legislation in Yukon Territory, a jurisdiction that still has healthy native pollinator communities that pollinate various human food and medicine crops. Recommendations include tracking hives and their pathogen status with beekeeping regulations enabled by the Animal Health Act, controlling the use of imported bumble bees with changes to the Animal Protection and Control Act and/or the Wildlife Act, and restricting use of public lands for apiaries with the Public Lands Act. Full article

Common eastern bumble bees (Bombus impatiens Cresson) play an essential role in pollinating lowbush blueberries (LB) in northern Quebec, but their costs and the suboptimal weather conditions during pollination highlight the need to find appropriate hive management strategies. A study was conducted in a LB field in Saguenay (Québec, Canada) focusing on the effects of hive insulation (I+ and I−), heating (H+ and H−), and placement in a single-row tree line windbreak. High-definition time-lapse cameras monitored hive activities and bumble bee foraging behaviors. We found that the conventional management of placing hives in full sun without insulation (I−) resulted in the lowest levels of bumble bee foraging activity and overall hive traffic. Placing bumble bee hives against a windbreak resulted in the highest numbers of bees entering hives with pollen (+156%), leaving hives (+69%), and overall hive traffic (+76%). Insulating hives with extruded polystyrene foam gave intermediate results, with a 105% increase in foraging activity compared to the conventional management method (I−H−). Interestingly, placing hives on seedling mats to maintain colony temperatures above 15 °C (H+) tended to decrease foraging activity and overall hive traffic. Our results show that strategic placement of bumble bee hives against windbreaks can significantly increase the activity of Bombus workers from those hives and can be used as a simple, low-cost, and efficient bumble bee hive management method by LB growers. Full article

The Western Flower Thrips (Frankliniella occidentalis) constitutes a significant threat to rose greenhouses in Colombia. An eco-friendly approach to managing this pest involves using the predatory bug Orius insidiosus. The pest and its predator’s food search and selection mechanisms are influenced by ecological interactions mediated by volatile organic compounds (VOCs) emitted during plant–pest interactions. To investigate the role of VOCs in the foraging and host-selection behaviors of O. insidiosus, we conducted functional response assays in greenhouses and olfactometry experiments in laboratory settings. These experiments used flowers from two rose cultivars, with and without female adult thrips, over 24, 48, and 72 h. Functional response analysis revealed a shift in O. insidiosus foraging behavior based on the duration of thrips interaction with rose flowers, transitioning from a Type II to a Type III functional response between 24 and 48 h in the ‘Freedom’ cultivar. The maximum consumption rates increased significantly, from 7.98 individuals at 24 h to 16.18 individuals at 48 h, before slightly decreasing to 14.37 individuals at 72 h. This shift coincided with an increase in O. insidiosus preference for thrips-infested ‘Freedom’ flowers over time, with selection proportions rising from 0.37 at 24 h to 0.46 at 72 h, suggesting a learning effect on prey-searching behavior mediated by VOCs. Olfactometry analyses revealed that O. insidiosus did not respond to the same VOCs that attracted F. occidentalis during flower infestation. However, O. insidiosus responded to certain VOCs likely associated with floral resources such as nectar and pollen, which also attract pollinators and zoophytophagous predators. This observation suggests a potential overlap in the chemical cues used by O. insidiosus for distinct ecological purposes. These findings highlight the complex chemical ecology underlying predator–prey interactions in agroecosystems and underscore the importance of considering VOCs in shaping the foraging behavior of natural enemies and their interactions with insect pests. Full article

Exploring the genetic diversity and reproductive strategies of Paspalum species is essential for advancing forage grass improvement. We compared morpho-phenological, molecular, and genotypic variation in five tetraploid Paspalum species with contrasting mating systems and reproductive modes. Contrary to previous findings, selfing (Paspalum regnellii and P. urvillei) and outcrossing (P. durifolium and P. ionanthum) species exhibited similar phenotypic diversity patterns, with low intrapopulation variability and no morphological differentiation among populations. The apomictic species (P. intermedium) exhibited low intrapopulation phenotypic variation but high population differentiation, indicative of genetic drift and local adaptation. Outcrossing species showed greater intrapopulation genotypic variation than selfing species, which displayed a high population structure due to restricted pollen migration. The apomictic species exhibited the lowest intrapopulation molecular diversity, forming uniclonal populations with high interpopulation differentiation, highlighting the fixation of distinct gene pools via apomixis. This is the first report about genetic diversity in populations of sexual allopolyploid species of Paspalum. Population structure in these allotetraploid Paspalum species is primarily shaped by how reproductive modes, mating systems, and geographic distribution influence gene flow via pollen and seeds. Our findings contribute significantly to the conservation and genetic improvement of forage grasses, particularly for developing cultivars with enhanced adaptability and productivity. Full article

The division of labor among honeybee workers contributes to efficient pollination activities. Lipids play a crucial role in behavioral regulation, with pollen serving as a primary source of these lipids. However, the regulatory effect of pollen lipids on the division of labor of honeybee workers remains to be studied. In this study, an in-depth lipidomic analysis based on HPLC-QTOF-MS and UPLC-IM-QTOF-MS was applied. We conducted the first comprehensive lipidomic profiling of the abdomen, brain, and intestine of emerging, nursing, and foraging bees, as well as pollen, thereby establishing a lipid library comprising 646 lipid species. The lipid composition of pollen was found to exhibit characteristics similar to those of honeybee workers, with alpha linolenic acid (ALA) validated as a key labor characteristic lipid. Moderate dietary ALA supplementation reshaped lipid levels and facilitated metabolism related to the labor of division. These findings advance the field of lipidomic analysis in honeybee workers, revealing a novel behavioral regulator and extending the understanding of the nutritional regulation of ALA in the division of labor among honeybee workers. Full article

The size of comb cells is a key factor influencing the body size of honey bee workers. Comb cells and the body size of Chinese honey bee workers are smaller than those of Italian honey bee workers. To increase the size of Chinese honey bee workers, this study used newly built combs from Chinese honey bee colonies (control group) and Italian honey bee colonies (treatment group). These combs were provided to Chinese honey bee colonies for queens to lay fertilized eggs with the aim of rearing larger workers. Workers emerging from the control and treatment combs were designated as control and treatment workers, respectively. We compared 13 external morphological traits, including right forewing length and width; linear length of veins a, b, c, and d; proboscis length; right hind femur length; tibia length; metatarsal length and width; and the longitudinal diameters of the third and fourth tergites between the two groups. The results identified six types of cell contents in the combs, excluding empty cells: capped honey (most abundant), followed by capped brood, uncapped honey, and smaller amounts of pollen, larvae, and eggs. Additionally, the average body weights of 6-day-old worker bee larvae, white-eyed pupae, adult worker bees, and honey stomachs containing sucrose solution were significantly higher in the treatment group than in the control group. Except for proboscis length, the average size of 12 out of 13 traits in the treatment group was significantly larger than in the control group, indicating that increasing cell size can produce larger Chinese honey bee workers. In the control group, only the left forewing was significantly shorter than the right, with no significant side-to-side differences in the other morphological traits. In the treatment group, the left forewing width, hind leg femur length, tibia length, and hind leg metatarsus width were significantly smaller than their right-side counterparts, while the other six traits showed no significant side-to-side differences. These findings provide a basis for using Italian honey bee combs to rear larger workers in Chinese honey bee colonies, offering beekeepers a strategy to enhance foraging capacity and improve honey production. Full article

Honey, a natural food with a rich history, is produced by honeybees and other species of bees from nectar, other plant fluids, and honeydew of sap-sucking insects. During foraging, these bees may be exposed to plant protection products (PPPs), metals, and metalloids, potentially leading to residues in honey and hive products that could have a negative impact on human safety. Recognizing the lack of an appropriate methodology for pesticide contamination of honey and other hive products, this research aims to support the need for studies on residues in pollen and bee products for human consumption to establish safe maximum residue levels (MRLs) for consumers. A UHPLC-MS/MS residues method and a modified QuEChERS extraction were applied to simultaneously determine 237 pesticide residues in honey and pollen. The study in North Sardinia analyzed honey and pollen samples from six areas for pesticide residues and verified 27 heavy metals and metalloid residues using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). The data obtained showed residues at levels close to the LOQ of the method, cycloate in a few samples of pollen, and dichlorvos, zoxamide, cycloate, and chlorantraniliprole in honey samples. All samples showed the absence of heavy metal contamination. Overall, no risk to human health was identified. The results of this study confirm that honey and pollen may be a good bioindicator of environmental contamination of a wide area surrounding honeybee hives. Full article

The appetite of honeybees for food is crucial to their survival and reproduction, as they sustain their entire colony by collecting pollen and nectar for nutrients. Dopamine, an important neurotransmitter, regulates appetite and satiety. However, how dopamine regulates honeybee foraging behavior remains unexplored. In this study, we investigated dopamine expression in 23-day-old Apis mellifera under different food-wanting conditions and identified differentially expressed genes (DEGs) in the brains of honeybees using RNA sequencing technology. We showed that dopamine levels in honeybees starved for 2 h were higher than those sated after 2 h of starvation. RNA-seq results revealed there were differences in the expression of cytochrome P450-dependent monooxygenase (CYP9Q1) in honeybees, which regulated the sucrose sensitivity of honeybees under different intake states. Furthermore, CYP9Q1 targeted the expression of the insulin receptor substrate (IRS) to promote dopamine synthesis. Our findings emphasize the relationship between dopamine and honeybees’ desire for food at the molecular level, providing a reference for further exploring the mechanism of food wanting. Full article