Nectar Concentration Research Articles

Effects of tongue hair flexural deformation on viscous fluid transport by bees

A bee’s tongue is coated in dynamic hairs that gradually unfold to entrain the viscid nectar, during which hairs inevitably deflect as a result of fluid drag. The hair deflection induced decline in nectar capture rate may be a coupled elastoviscous problem and remains poorly understood. Here we employed geometric beam theory coupled with the effective viscous force to derive a dynamic model for a rotary tongue hair deflection in a viscous fluid. Considering deflection of the tongue hair, we rationalized the nectar capture rate by taking Bombus terrestris as a model system. When the nectar concentration increases from 20% to 70%, the nectar capture rate declines by 87%, indicating that hair erection is more severely impeded in thicker nectar. Based on this model, we predicted an optimal hair length with which the bee can reach the maximum nectar capture rate. This work may provide a new theoretical framework for quantifying viscous liquid transport by hairy surfaces and shed light on design methodologies for fluid transport devices using hairy beds.

Honey bees save energy in honey processing by dehydrating nectar before returning to the nest

Honey bees process nectar into honey by active evaporation on the tongue and passive evaporation involving nest ventilation and fanning behaviour, as well as enzymatic action. The elimination of excess water from nectar carries considerable energetic costs. The concentration of the nectar load is assumed to remain constant during transport. However, some of this water elimination may occur before foragers return to the nest and pass their nectar loads to receiver bees. In honey bees captured while foraging in Macadamia orchards, we show that the nectar in their crops has approximately twice the sugar concentration of the fresh nectar in flowers. This was true for four Macadamia cultivars, with up to 75% of the initial water content being removed. There is a further concentration increase in the crops of returning bees captured at the hive entrance. The only possible route of water elimination from the crop is via evaporation from the mouthparts. We calculate the savings in honey processing costs to be on average 35 times more than the reduction in flight costs due to reduced body mass. Pre-concentration of nectar in foraging honey bees may be widespread, and of crucial importance for honey storage.

The FloRes Database: A floral resources trait database for pollinator habitat-assessment generated by a multistep workflow.

The decline of pollinating insects in agricultural landscapes proceeds due to intensive land use and the associated loss of habitat and food sources. The feeding of those insects depends on the spatial and temporal distribution of nectar and pollen as food resource. Hence, to protect insect biodiversity, a spatio-temporal assessment of food quantity of their habitats is necessary. Therefore, sufficient data on traits of floral resources are required. As floral resources' traits of plants are important to quantify food availability, we present two databases, the FloRes Database (Floral Resources Database) and the raw database, from where FloRes was derived. Both databases contain the plant traits: (1) flowering period, (2) floral-unit density per day, (3) nectar volume per floral unit per day, (4) sugar content per floral unit, (5) sugar concentration in nectar, (6) pollen mass or volume per floral unit and per day, (7) protein content of pollen and (8) corolla depth. All traits were sampled from literature and online databases. The raw database consists of 702 specified plant species, 138 unspecified species 37 species (spec., sp), 22 species pluralis (spp) and, for 79, only the genus was identified) and two species complexes (agg.). Those 842 taxa belong to 488 genera and 102 families. Finally, only 27 taxa have a complete set of traits, too few for a sufficient assessment of spatio-temporal availability of floral food-resources.As information on floral resources is scattered throughout many publications with different units, we also present our multistep workflow implemented in five consecutive R-scripts. The multistep workflow standardises the trait units of the raw database to comparable entities with identical units and aggregates them on a reasonable taxonomic level into the second application database, the FloRes Database. Finally, the FloRes Database contains aggregated information of traits for 42 taxa and, when corolla depth is excluded, for 72 taxa.This is the first attempt to gather these eight traits from different literature sources into one database with a multistep workflow. The publication of the multistep workflow enables the users to extend the FloRes Database on their own demands with other literature data or newly-gathered data to improve quantification of food resources. Especially, the combination of pollen, nectar and the open flowers per square metre is, as far as we know, a novelty.The FloRes Database can be used to evaluate the quantity of food-resource habitats available for pollinators, for example, to compare seed mixtures of agri-environmental measures, such as flower strips, considering flower phenology on a daily basis.

Comparative analyses of the metabolite and ion concentrations in nectar, nectaries, and leaves of 36 bromeliads with different photosynthesis and pollinator types.

Floral nectar contains mainly sugars as well as smaller amounts of amino acids and further compounds. The nectar composition varies between different plant species and it is related to the pollination type of the plant. In addition to this, other factors can influence the composition. Nectar is produced in and secreted from nectaries. A few models exist to explain the origin of nectar for dicotyl plant species, a complete elucidation of the processes, however, has not yet been achieved. This is particularly true for monocots or plant species with CAM photosynthesis. To get closer to such an elucidation, nectar, nectaries, and leaves of 36 bromeliad species were analyzed for sugars, starch, amino acids, and inorganic ions. The species studied include different photosynthesis types (CAM/C3), different pollination types (trochilophilous/chiropterophilous), or different live forms. The main sugars in nectar and nectaries were glucose, fructose, and sucrose, the total sugar concentration was about twofold higher in nectar than in nectaries, which suggests that sugars are actively transported from the nectaries into the nectar. The composition of amino acids in nectar is already determined in the nectaries, but the concentration is much lower in nectar than in nectaries, which suggests selective retention of amino acids during nectar secretion. The same applies to inorganic ions. Statistical analyses showed that the photosynthesis type and the pollination type can explain more data variation in nectar than in nectaries and leaves. Furthermore, the pollinator type has a stronger influence on the nectar or nectary composition than the photosynthesis type. Trochilophilous C3 plants showed significant correlations between the nitrate concentration in leaves and the amino acid concentration in nectaries and nectar. It can be assumed that the more nitrate is taken up, the more amino acids are synthesized in leaves and transported to the nectaries and nectar. However, chiropterophilous C3 plants show no such correlation, which means that the secretion of amino acids into the nectar is regulated by further factors. The results help understand the physiological properties that influence nectaries and nectar as well as the manner of metabolite and ion secretion from nectaries to nectar.

Pollination syndrome accurately predicts pollination by tangle-veined flies (Nemestrinidae: Prosoeca s.s.) across multiple plant families.

The idea that a syndrome of floral traits predicts pollination by a particular functional group of pollinators remains simultaneously controversial and widely used because it allows plants to be rapidly assigned to pollinators. To test the idea requires demonstrating that there is an association between floral traits and pollinator type. I conducted such a test in the Cape Floristic Region of South Africa, by studying the pollination of eight plant species from six families that flower in spring and have scentless, actinomorphic, upwards-facing flowers, with orbicular petals all held in the same plane. The petals are brilliant-white with red-purple nectar guides. The tubes are short and hold small volumes of concentrated nectar, except in the rewardless Disa fasciata (Orchidaceae). Pollinators were photographed and captured, pollen loads were analysed and pollination networks were constructed. Consistent with the pollination syndrome hypothesis, the species with the defined syndrome shared a small group of pollinators. The most frequent pollinators belonged to a clade of four tangle-veined fly species with relatively short proboscises (Nemestrinidae: Prosoeca s.s.), while functionally similar Bombyliidae and Tabanidae played minor roles. Among the four Prosoeca species, only Prosoeca westermanni has been described, a result that highlights our ignorance about pollinators. The demonstration of an association between the syndrome of traits and pollination by this group of flies explains the repeated evolution of the syndrome across multiple plant families, and allows prediction of pollinators in additional species. More generally, the result validates the idea that the traits of organisms determine their ecology.

Potential use of floral nectar sugar characteristics in plant selection for pollinator habitats

The use of urban green spaces, including gardens, in pollinator conservation initiatives, excites significant public interest but advice on effective plants frequently relies on qualitative data. This study considered pollinator responses to specific nectar sugar characteristics to determine if they offer the potential for the selection of candidate plants. Pollinator feeding on 60 plant species at the National Botanic Garden of Wales was related to their nectar characteristics to investigate response consistency at different taxonomic levels. The feeding frequency of Hymenoptera, particularly the social Hymenoptera, was significantly correlated with the volume of nectar offered by flowers, but greater differentiation between plant species occurred when specific nectar sugar characteristics were considered. Feeding was significantly correlated with the volume of the hexose monosaccharides glucose or fructose for the Hymenoptera, particularly the social Hymenoptera (and for the two social genera analysed individually, Apis spp. Bombus spp.), but not for non-social species. Similarly, feeding visits were correlated with the percentage of glucose or fructose in nectar in the Hymenoptera, social Hymenoptera and non-social groups (including three individual genera tested (Apis spp., primitively eusocial Lasioglossum, and non-social Andrena spp.). Fewer and less consistent outcomes were recorded when the (disaccharide) sucrose content of nectar was investigated. In comparative analyses conducted for other pollinator groups (Diptera and Lepidoptera), feeding was only found to be correlated with glucose content. The social Hymenoptera are a particular focus of gardeners and the use of percentage glucose or fructose in nectar is discussed as a potential component of a screening approach to identify keystone plant species.

Warming temperatures affect meadow‐wide nectar resources, with implications for plant–pollinator communities

AbstractNectar production may be a point of sensitivity that can help link primary and secondary trophic responses to climate shifts, and is therefore important to our understanding of ecosystem responses. We evaluated the nectar response of two widespread native forbs, Balsamorhiza sagittata and Eriogonum umbellatum, to experimental warming in a high‐elevation sagebrush meadow in the Teton Range, WY, USA, over two years, 2015 and 2016. Warming treatments reduced the occurrence of nighttime freezing and nectar volume but increased sugar concentration in nectar in both species in both years. Warming effects were also evident in a consistent increase in the number of flowers produced by B. sagittata. Our research suggests that warming associated with climate change has the potential to induce shifts in the nectar‐feeding community by changing nectar characteristics such as volume and sugar concentration to which nectar feeders are adapted.

Evaluating The Effect of Time and Temperature on The Ph, Titratable Acidity &Brix of Pasteurized LowTo-No Nectar Orange Drinks Packed in Paper Based Aseptic Packages

Orang drink is the most common flavoured drink consumed in Iraq and it can be found in markets of all sizes and in all provinces making them subjected to a wide range of storage temperature and storage time. In this work, the effect of storage time and temperature was studied on three different local brands of Orange drink with Low-to-No nectar content; all were packed in Laminated Aseptic Cartons (LAC). Samples were stored in a fixed and controlled temperature environment ranging between 10 ?C-50 ?C for a period of 5 weeks and the samples were tested for the values of Brix, Titratable Acidity (TA), and pH at the beginning and at the end of each week. The results showed that no significant difference (p > 0.05) was found, which showed that there is low-to-no evidence that the selected range of storage temperature and time in this study significantly affected the values of Brix, TA, and pH.

Can floral nectars reduce transmission of Leishmania?

Insect-vectored Leishmania are responsible for loss of more disability-adjusted life years than any parasite besides malaria. Elucidation of the environmental factors that affect parasite transmission by vectors is essential to develop sustainable methods of parasite control that do not have off-target effects on beneficial insects or environmental health. Many phytochemicals that inhibit growth of sand fly-vectored Leishmania-which have been exhaustively studied in the search for phytochemical-based drugs-are abundant in nectars, which provide sugar-based meals to infected sand flies. In a quantitative meta-analysis, we compare inhibitory phytochemical concentrations for Leishmania to concentrations present in floral nectar and pollen. We show that nectar concentrations of several flowering plant species exceed those that inhibit growth of Leishmania cell cultures, suggesting an unexplored, landscape ecology-based approach to reduce Leishmania transmission. If nectar compounds are as effective against parasites in the sand fly gut as predicted from experiments in vitro, strategic planting of antiparasitic phytochemical-rich floral resources or phytochemically enriched baits could reduce Leishmania loads in vectors. Such interventions could provide an environmentally friendly complement to existing means of disease control.

Sodium-enriched floral nectar increases pollinator visitation rate and diversity.

Plants have evolved a variety of approaches to attract pollinators, including enriching their nectar with essential nutrients. Because sodium is an essential nutrient for pollinators, and sodium concentration in nectar can vary both within and among species, we explored whether experimentally enriching floral nectar with sodium in five plant species would influence pollinator visitation and diversity. We found that the number of visits by pollinators increased on plants with sodium-enriched nectar, regardless of plant species, relative to plants receiving control nectar. Similarly, the number of species visiting plants with sodium-enriched nectar was twice that of controls. Our findings suggest that sodium in floral nectar may play an important but unappreciated role in the ecology and evolution of plant-pollinator mutualisms.

Pollen tube growth in Calotropis procera is controlled by environmental changes: does it have an impact on delayed fertilization?

Calotropis procera (Apocynaceae) is a Sudanian plant that grows throughout the eastern Saharo-Arabian region. In Israel, it grows along the Rift Valley under extremely hot and dry climatic conditions. In C. procera, as in many other Apocynaceae, the nectar is secreted in the flowers from the nectaries located inside the stigmatic chamber, with the excess flowing via the capillary system into special reservoirs (cucculi). The nectar has two functions: it is used as a reward to attract pollinating insects and it serves as the germination medium for pollen grains. Under natural conditions the nectar concentration is subjected to a large variability, ranging from 22-68% sucrose. The aim of this study was to elucidate the effects of the natural fluctuations of nectar concentration on pollen germination and pollen tube growth, and their possible role in delaying fertilization in Calotropis procera. We followed the process of pollen germination under various experimental sucrose concentrations simulating the nectar. We found that the optimal concentration of a sucrose medium for pollen germination is 20%. However, if the already-germinated pollen grains are subjected to high sucrose concentration for different periods of time (between one and three hours), elongation of the pollen tubes is inhibited. In all the experimental groups, the pollen tubes renewed their elongation following a reduction of the sucrose. In conclusion, we found that C. procera pollen grains’ germination is able to adjust to the large fluctuations in sucrose concentration, caused by the changes in temperature and relative humidity conditions of the plant’s habitat during the day. This phenomenon probably enables postponing the fertilization towards a time of better conditions and enables the plant to retain the pollen tubes alive, albeit inactive, and thus allow the plant to overcome temporary harsh conditions and develop seeds.

Preventing inbreeding depression in Anacamptis coriophora (Orchidaceae) as a model of food-rewarding orchid

Pollination of deceptive orchids has enabled scientists to understand how these species avoid inbreeding depression by reducing the number of pollinator visits per inflorescence. In rewarding species, which receive a higher rate of visits per plant, geitonogamy is usually higher and therefore the risk of inbreeding increases. In this study, we assess the breeding system of the rewarding orchid A. coriophora, and the spatio-temporal changes in its fitness as well as variation in nectar content after pollination. We found that the species partially selects allogamous pollen if pollinia from the same stalk and other plants arrive to the stigma. Furthermore, when self-pollination occurs, despite successful fructification, seed viability is significantly lower than that of cross-pollinated plants. A. coriophora exhibits spatio-temporal variation in fitness that does not correlate with any plant feature. Moreover, nectar volume is reduced after pollination, but the sugar concentration is maintained. This study emphasizes how essential the pre-zygotic and post-zygotic reproductive barriers are for rewarding orchids to avoid inbreeding depression.

Addition of Medicinal Plants Increases Antioxidant Activity, Color, and Anthocyanin Stability of Black Chokeberry (Aronia melanocarpa) Functional Beverages.

The present study investigates the effect of the addition of medicinal plants, such as lady’s mantle, lavender, rosehip, and meadowsweet, on the chemical composition, antioxidant activity, and color intensity of ready-to-drink aronia nectar during pasteurization and long-term storage. Pasteurization caused a significant decrease in anthocyanin content of aronia nectar, which reduced to 20% of the initial value after four months of storage. Herbs provided different protection to aronia anthocyanins that degraded more slowly during the four-month storage compared to pasteurized control without herbs. The addition of medicinal plants enriched aronia nectar with phenolic compounds and increased its antioxidant activity by up to 52% in meadowsweet-aronia nectar. Moreover, it was accompanied by a color intensity magnification due to co-pigmentation of aronia anthocyanins and herbal phenolics. In contrast to anthocyanins, which constantly degraded during the whole period, color intensity began to stabilize after 30 days, demonstrating that co-pigmentation was progressively established during the time and rosehip provided the best stabilization of aronia nectar color. Current research demonstrates for the first time that medicinal plants such as lady’s mantle, rosehip, and especially meadowsweet can be used to increase antioxidant activity, color, and anthocyanin stability of black chokeberry functional beverages.

ATLANTIC POLLINATION: a data set of flowers and interaction with nectar-feeding vertebrates from the Atlantic Forest.

Flowering plant species and their nectar-feeding vertebrates exemplify some of the most remarkable biotic interactions in the Neotropics. In the Brazilian Atlantic Forest, several species of birds (especially hummingbirds), bats, and non-flying mammals, as well as one lizard feed on nectar, often act as pollinators and contribute to seed output of flowering plants. We present a dataset containing information on flowering plants visited by nectar-feeding vertebrates and sampled at 166 localities in the Brazilian Atlantic Forest. This dataset provides information on 1902 unique interactions among 515 species of flowering plants and 129 species of potential vertebrate pollinators and the patterns of species diversity across latitudes. All plant-vertebrate interactions compiled were recorded through direct observations of visits, and no inferences of pollinators based on floral syndromes were included. We also provide information on the most common plant traits used to understand the interactions between flowers and nectar-feeding vertebrates: plant growth form, corolla length, rate of nectar production per hour in bagged flowers, nectar concentration, flower color and shape, time of anthesis, presence or absence of perceptible fragrance by human, and flowering phenology as well as the plant's threat status by International Union for Conservation of Nature (IUCN) classification. For the vertebrates, status of threat by IUCN classification, body mass, bill or rostrum size are provided. Information on the frequency of visits and pollen deposition on the vertebrate's body is provided from the original source when available. The highest number of unique interactions is recorded for birds (1771) followed by bats (110). For plants, Bromeliaceae contains the highest number of unique interactions (606), followed by Fabaceae (242) and Gesneriaceae (104). It is evident that there was geographical bias of the studies throughout the southeast of the Brazilian Atlantic Forest and that most effort was directed to flower-hummingbird interactions. However, it reflects a worldwide tendency of more plants interacting with birds compared with other vertebrate species. The lack of similar protocols among studies to collect basic data limits the comparisons among areas and generalizations. Nevertheless, this dataset represents a notable effort to organize and highlight the importance of vertebrate pollinators in this hotspot of biodiversity on Earth and represents the data currently available. No copyright or proprietary restrictions are associated with the use of this data set. Please cite this data paper when the data are used in publications or scientific events.

Honey bee (Apis mellifera ligustica) acetylcholinesterase enzyme activity and aversive conditioning following aluminum trichloride exposure

BackgroundAluminum is the third most prevalent element in the earth’s crust. In most conditions, it is tightly bound to form inaccessible compounds, however in low soil pH, the ionized form of aluminum can be taken up by plant roots and distributed throughout the plant tissue. Following this uptake, nectar and pollen concentrations in low soil pH regions can reach nearly 300 mg/kg. Inhibition of acetylcholinesterase (AChE) has been demonstrated following aluminum exposure in mammal and aquatic invertebrate species. In honey bees, behaviors consistent with AChE inhibition have been previously recorded; however, the physiological mechanism has not been tested, nor has aversive conditioning.ResultsThis article presents results of ingested aqueous aluminum chloride exposure on AChE as well as acute exposure effects on aversive conditioning in an Apis mellifera ligustica hive. Contrary to previous findings, AChE activity significantly increased as compared to controls following exposure to 300 mg/L Al3+. In aversive conditioning studies, using an automated shuttlebox, there were time and dose-dependent effects on learning and reduced movement following 75 and 300 mg/L exposures.ConclusionsThese findings, in comparison to previous studies, suggest that aluminum toxicity in honey bees may depend on exposure period, subspecies, and study metrics. Further studies are encouraged at the moderate-high exposure concentrations as there may be multiple variables that affect toxicity which should be teased apart further.

IVAN OLEKSIYOVYCH LEVCHENKO. MAN AND HER AFFAIRS

Introduction. One of the ways in which bee colonies interact is through stereotypical dances. Many authors have studied the relationship between dance. However, there was no consensus on their functional significance. Finding out the question of the signal significance of bee dances became the main direction of Ivan Levchenko’s scientific research. In addition to theoretical significance, such studies are needed to develop new methods for controlling the flight-collecting activity of bees. The goal of the work. To trace the main stages of IO Levchenko's life and creative path. To give the main achievements of his research, to characterize their theoretical and practical significance for beekeeping. Materials and methods of research. The basis of this study is the scientific literature on the topic of work, scientific works of domestic and foreign scientists. In the process of research, historical-comparative, analytical-synthetic, as well as the method of source analysis are used. Results of research and discussion. Ivan Levchenko was born on August 31, 1930 in the village of Samara, Azov district, Rostov region, in a large family of workers. The formation of Ivan Lavchenko as a researcher took place at the Kyiv State University named after T.G. Shevchenko (1951‒1956). After graduating from university he worked in the laboratory of arachnoentomology, in the Kaniv Biological Reserve. This was the period of further development of the researcher. During this time, techniques have been developed that make it possible to record the reaction of bees to various processes occurring in the central nervous system of insects. A fruitful period in the scientific activity of Ivan Levchenko were the years of work at the Institute of Zoology named after I. Schmalhausen National Academy of Sciences (1962-1994). Here, in 1966, he defended his dissertation on "The main forms of relationship in bees - collectors." Considering bees' dances as a special form of reflecting the excitation of the bee's nervous system, Ivan Levchenko naturally raised and successfully solved the question of the impact on bee signaling of such factors as air temperature, features of the terrain, bee strength, sugar concentration in nectar, carbohydrate characteristics feed composition. Ivan Levchenko considered the discovery of individual smell in worker bees to be an important factor in his scientific work. Since 1994, I. Levchenko worked at the NSC "Institute of Beekeeping named after P.I. Prokopovich "in the established laboratory of bee ethology. The direction of research has changed, but has always been associated with practical beekeeping. І. Levchenko conducted active training of junior specialists in the field of beekeeping. Under his supervision, six PhD theses were defended. Published 300 scientific papers. Conclusions and prospects for further research. Ivan Levchenko proved by his research that the transmission of information about the coordinates of the source of the bribe in the family of the honey bee is carried out by many factors - smell, acoustic and tactile stimuli, including dancing. An attempt to explain the process of mobilizing bees to collect food with just one stimulus is invalid. We can talk about the relative importance of a factor in a particular situation, but the effect of mobilization in general must be considered as an adequate response of the family to a set of stimuli. Honey bees have undergone a long process of evolution from a solitary form to a highly organized and family with a social - collective way of life. Ways of relations in them include both ancient forms (sight and smell) and new, highly specialized moving reactions - dances of scouts. Accordingly, the search for honey flow by bees can be carried out both at the level of individuals and the family as a whole. But there is no doubt that all forms of search are of great biological importance to the family and together provide rapid mobilization for food collection.

Trade-off mechanism of honey bee sucking and lapping.

Animals have developed various drinking strategies in capturing liquid to feed or to stay hydrated. In contrast with most animals, honey bees Apis mellifera that capture nectar with their tongue, can deliberately switch between sucking and lapping methods. They preferentially suck diluted nectar whereas they are prone to lap concentrated nectar. In vivo observations have shown that bees select the feeding method yielding the highest efficiency at a given sugar concentration. In this combined experimental and theoretical investigation, we propose two physical models for suction and lapping mode of capture that explain the transition between these two feeding strategy. The critical viscosity, μ*, at which the transition occurs, is derived from these models, and agrees well with in vivo measurements. The trade-off mechanism of honey bee sucking and lapping may further inspire microfluidics devices with higher capability of transporting liquids across a large range of viscosities.

Honey Bees (Apis mellifera Hymenoptera: Apidae) Preferentially Avoid Sugar Solutions Supplemented with Field-Relevant Concentrations of Hydrogen Peroxide Despite High Tolerance Limits.

Honey bees (Apis mellifera L. Hymeoptera: Apidae) use hydrogen peroxide (synthesized by excreted glucose oxidase) as an important component of social immunity. However, both tolerance of hydrogen peroxide and the production of glucose oxidase in honey is costly. Hydrogen peroxide may also be encountered by honey bees at high concentrations in nectar while foraging, however despite its presence both in their foraged and stored foods, it is unclear if and how bees monitor concentrations of, and their behavioral responses to, hydrogen peroxide. The costs of glucose oxidase production and the presence of hydrogen peroxide in both nectar and honey suggest hypotheses that honey bees preferentially forage on hydrogen peroxide supplemented feed syrups at certain concentrations, and avoid feed syrups supplemented with hydrogen peroxide at concentrations above some tolerance threshold. We test these hypotheses and find that, counter to expectation, honey bees avoid glucose solutions supplemented with field-relevant hydrogen peroxide concentrations and either avoid or don’t differentiate supplemented sucrose solutions when given choice assays. This is despite honey bees showing high tolerance for hydrogen peroxide in feed solutions, with no elevated mortality until concentrations of hydrogen peroxide exceed 1% (v/v) in solution, with survival apparent even at concentrations up to 10%. The behavioral interaction of honey bees with hydrogen peroxide during both within-colony synthesis in honey and when foraging on nectar therefore likely relies on interactions with other indicator molecules, and maybe constrained evolutionarily in its plasticity, representing a constitutive immune mechanism.

Extrafloral nectar secretion does not mediate ant predatory activity on Pityrocarpa moniliformis plants in a seasonally dry forest

Plants bearing extrafloral nectaries (EFNs) and their attendant ants are part of a mutualistic, facultative and generalized interaction. The final balance of this interaction can vary greatly over time and space, making the outcome context-dependent. In this study, we investigated how nectar volume and concentration mediate ant attraction and ant predatory activity on a legume species, as well as evaluate their daily variation in a seasonally dry tropical forest in northeastern Brazil. Our study model was the tree species Pityrocarpa moniliformis (Benth.) Luckow & R. W. Jobson (Fabaceae), and we used simulated herbivores (termites) to assess the predatory activity of ants. We found that ants interacted more on the EFNs of plants that produce higher nectar volumes, but not to those producing higher nectar concentrations. Ant predatory activity was not influenced by the volume or concentration of extrafloral nectar. Regarding the daily variation in nectar secretion, we found higher volumes secreted at nighttime, but no difference in nectar concentrations between day and night. Ant predatory activity was similar throughout the day and night. Our results indicate that ants are more sensitive to variations in nectar volume than concentration and that the volume secreted is higher at night; both probably due to the water restriction of the Caatinga. However, ant predatory activity is not related to nectar secretion volume or concentration, highlighting the complexity of mechanisms mediating the interaction between EFN-bearing plants and ants.

MEDICINAL PROPERTIES, RESOURCES AND PROTECTION OF CAPPARIS SPINOSA L. (CAPPARACEAE) IN THE NORTHWESTERN ADYRS OF THE FERGANA VALLEY

This work is devoted to the study of the medicinal properties of Capparis spinosa L. on the basis of the literatures and the assessment of natural resources in the Chust adyrs of the Namangan region of the Republic of Uzbekistan, as well as the protection measures. The medicinal properties of this plant are high, and it is widely used in folk and modern medicine, and the plant also contains a high concentration of nectar and is of great importance for beekeeping. In Europe it is used in the food industry and in cooking as a dietary product.
 Plants are one of the most demanded medicinal raw materials, the demand is growing, but the available natural resources cannot meet this demand. Expansion of the plantation of Capparis spinosa and with rational use we will be able to conserve the natural resources of the plant.