Eucalyptus Pollen Research Articles

Survivorship and food consumption of immatures and adults of Apis mellifera and Scaptotrigona bipunctata exposed to genetically modified eucalyptus pollen

Eucalyptus comprises the largest planted area of cultivated production forest in Brazil. Genetic modification (GM) of eucalyptus can provide additional characteristics for increasing productivity and protecting wood yield, as well as potentially altering fiber for a diversity of industrial uses. However, prior to releasing a new GM plant, risk assessments studies with non-target organisms must be undertaken. Bees are prominent biological models since they play an important role in varied ecosystems, including for Eucalyptus pollination. The main goal of this study was to evaluate whether a novel event (Eucalyptus 751K032), which carries the cp4-epsps gene that encodes the protein CP4-EPSPS and nptII gene that encodes the protein NPTII, might adversely affect honey bees (Apis mellifera) and stingless bees (Scaptotrigona bipunctata). The experiments were performed in southern Brazil, as follows: (i) larvae and adults were separately investigated, (ii) three or four different pollen diets were offered to bees, depending on larval or adult status, and (iii) two biological attributes, i.e., survivorship of larvae and adults and food intake by adults were evaluated. The diets were prepared with pollen from GM Eucalyptus 751K032; pollen from conventional Eucalyptus clone FGN-K, multifloral pollen or pure larval food. The insecticide dimethoate was used to evaluate the sensitivity of bees to toxic substances. Datasets were analyzed with Chi-square test, survival curves and repeated measures ANOVA. Results indicated no evidence of adverse effects of Eucalyptus pollen 751K032 on either honey bees or stingless bees assessed here. Therefore, the main findings suggest that the novel event may be considered harmless to these organisms since neither survivorship nor food consumption by bees were affected by it.

Temporal Changes in Gut Microbiota Composition and Pollen Diet Associated with Colony Weakness of a Stingless Bee.

Compared to honeybees and bumblebees, the effect of diet on the gut microbiome of Neotropical corbiculate bees such as Melipona spp. is largely unknown. These bees have been managed for centuries, but recently an annual disease is affecting M. quadrifasciata, an endangered species kept exclusively by management in Southern Brazil. Here we report the results of a longitudinal metabarcoding study involving the period of M. quadrifasciata colony weakness, designed to monitor the gut microbiota and diet changes preceding an outbreak. We found increasing amounts of bacteria associated to the gut of forager bees 2months before the first symptoms have been recorded. Simultaneously, forager bees showed decreasing body weight. The accelerated growth of gut-associated bacteria was uneven among taxa, with Bifidobacteriaceae dominating, and Lactobacillaceae decreasing in relative abundance within the bacterial community. Dominant fungi such as Candida and Starmerella also decreased in numbers, and the stingless bee obligate symbiont Zygosaccharomyces showed the lowest relative abundance during the outbreak period. Such changes were associated with pronounced diet shifts, i.e., the rise of Eucalyptus spp. pollen amount in forager bees' guts. Furthermore, there was a negative correlation between the amount of Eucalyptus pollen in diets and the abundance of some bacterial taxa in the gut-associated microbiota. We conclude that diet and subsequent interactions with the gut microbiome are key environmental components of the annual disease and propose the use of diet supplementation as means to sustain the activity of stingless bee keeping as well as native bee pollination services.

The pollen record from marine core MD03-2607 from offshore Kangaroo Island spanning the last 125 ka; implications for vegetation changes across the Murray-Darling Basin

A palynological record spanning the last glacial–interglacial period was derived from high-resolution, deep-sea core MD03-2607, located near Kangaroo Island in South Australia. The core site lies opposite the mouth of the River Murray that, together with the Darling River, drains the extensive (∼1.6 × 106 km2) Murray-Darling Basin (MDB). The record comprises 120 samples and is compared with detailed records of sea-surface temperature (SST), the C3/C4 plant ratio obtained from the δ13C of n-alkanes from leaf waxes, the fluvial clay fraction and its neodymium isotopic composition, airborne dust and the biomass-burning component levuglosan. The chronology of the core is robust; it is built on 24 radiocarbon dates derived from planktic foraminifera, 16 optically stimulated luminescence dates, plus 12 tie points linked to the astronomically tuned marine isotopic record. Algal remains are found in nearly all samples supporting our postulation that the palynoflora is predominantly waterborne. Major findings are that the gymnosperm Callitris, together with high percentages of herb pollen (mostly C3 plants), is predominant during cold, arid phases, whereas Eucalyptus, is predominant during warmer and wetter periods. High charcoal concentration coincides with high percentages of Eucalyptus, mostly during wet and warm periods. Using the geochemistry of the core’s fluvial sediments, it has been possible to identify when water-transported palynoflora and charcoal originated from the Murray sub-basin (consisting of the River Murray and its main tributaries but not from central or western South Australia). During those periods, rainfall principally originated from the southeastern Indian Ocean. When the Darling sub-basin was the main source of the palynoflora, rainfall must have instead originated from northern Australia. The eolian dust record from the core shows that the dust signal generally coincides with the increased values in herb pollen, in particular during the Last Glacial Maximum (LGM) when, in addition to high herb percentages, Callitris representation also increased. This dry landscape taxon likely colonised the then-exposed Lacepede Shelf during this period of extreme low sea-level. There is a good correspondence between SST and mean annual precipitation reconstructed from the pollen counts. During warm phases in the ocean, Eucalyptus was the dominant tree taxon, especially for the entirety of Marine Isotope Stages (MIS) 5, plus MIS 3 and MIS 1. Charcoal levels were particularly low during the dry phases MIS 4 and 2, and even more so during the LGM. KEY POINTS We provide a very detailed pollen diagram from a deep-sea core taken offshore from the mouth of the River Murray. This record details vegetation changes in the Murray-Darling Basin spanning the last glacial/interglacial cycle. The pollen record is compared with other proxies obtained from the marine core, such as sea-surface temperature, changes in C3/C4 plants percentages, geochemical analyses of terrigenous sediments that inform on the origin of the sediments reaching the ocean and by implication the origin of the pollen. Charcoal counts obtained from the core are compared with the pollen spectra and clearly indicate the large incidence of fires during wet and warm periods when Eucalyptus pollen was abundant. Low charcoal counts occur during dry and cold phases when Callitris pollen were predominant over Eucalyptus.

Diversity of pollen sources used by managed honey bees in variegated landscapes

Honey bees are the most economically important crop pollinator worldwide. They depend on a diversity of pollen for reproduction and colony growth. However, the influence of landscape composition on diversity and quantity of pollen collection by honey bees remains largely unexplored, particularly in variegated landscapes. Pollen on honey bees was trapped from 41 hives across ten sites in the Western Cape, South Africa during summer. Sampled hives were near eucalyptus trees surrounded by a high percentage of natural vegetation. Hives could therefore potentially be presented with a diverse range of flowers. To obtain a measure of relative abundance and representation of plant taxa pollen samples were collected at hives, sorted by color, weighed and DNA barcoded. Landscape analysis was performed to estimate the relative availability of the main floral resource-types and how this influenced the composition of pollen collected. Overall, eucalyptus made up the largest portion (∼49%) of pollen loads, the remainder was composed of 31 other taxa (12% native and 39% alien plants). An increase in the area of eucalyptus resulted in an increased as well as the relative amount of eucalyptus and natural pollen collected. Conversely, an increase in the area of eucalyptus resulted in a decrease in alien plant pollen and vice versa. Our results provide important quantitative evidence that shows the amount and diversity of pollen used by honey bees in summer appears to be disproportionately met by human-modified landscapes; whereas, natural vegetation, despite its large extent and diversity, performs a lower-level role during this season.

Effects of essential amino acid supplementation to promote honey bee gland and muscle development in cages and colonies

There is growing concern about the impact of poor nutrition on honey bee health. With caged bee experiments and whole-colony field experiments, we examined the effects of supplementing bees with essential amino acids (EAA), or a control treatment of nonessential amino acids (NAA). Caged bees fed EAA developed significantly greater head weights than controls, weights that were similar to nurse bees. Caged bees fed EAA developed significantly greater thorax weights than controls, weights that were similar to foragers. Higher head and thorax weights may respectively reflect increased glandular development in nurse bees and higher flight muscle mass in forager bees. In our field study, 29% of the pollen collected by our honey bee colonies came from eucalyptus trees. Amino acid analyses revealed no EAA deficiencies for the bee-collected polyfloral pollen or for monofloral eucalyptus pollen. Colonies fed 29 g EAA supplement may have slightly increased individual bee growth and brood rearing, but this effect was not significant. A clear colony result was a correlation between nurse bee physiology and brood development: 17% increase in nurse bee weight corresponded to 100% more capped brood cells (R2 = 0.38). We suggest that colony supplementation should target nurse bee nutrition. Nurse bees eventually become forager bees. Hence, increased glandular development may support colony brood development and greater flight muscle mass may assist colony foraging.

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

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

Water activity of fresh bee pollen and mixtures of bee pollen-honey of different botanical origin

A mixture of bee pollen and honey could represent a complete food supplement for human diet. In this study, for three bee pollen-honey mixtures ratios at two storage times (0 and 90 days) at room temperature, water activity (aw) were investigated. For the mixtures were employed Castanea and Eucalyptus pollen species, and acacia, chestnut and “beach” honeys. In the mixtures, Castanea and Eucalyptus pollen showed a different aw trend in relation to pollen concentration and to storage time. In Castanea-honeys mixtures and in Eucalyptus-honey mixtures (only at time 0) aw values were higher than each component of the corresponding mixtures. In Eucalyptus-honeys mixtures (only at time 90) aw values were lower than each component. This investigation highlights that honey, bee-pollen and their mixtures, stored at room temperature, could have a little change in their aw content, in time. Results shows that aw values of bee pollen mixed with honey were all lower than 0.7, although bee pollen-honey mixtures were stored at room temperature instead at freezing temperature (−15 °C) for 90 days.

Realized pollen flow and wildling establishment from a genetically modified eucalypt field trial in Southeastern Brazil

Confined field trials of genetically modified (GM) trees are the essential step toward the identification of the most productive cultivars and the assessment of the likely environmental impacts of the GM trees including the potential for gene flow by pollen and distance dispersal by seeds. Our study investigated the potential for wildling establishment and realized pollen flow from a clonal GM eucalypt field trial in Southeastern Brazil. The GM eucalypt stand was established in 2009, surrounded by a 3m wide forest road and signal grass (Bracharia sp.) fields. No seedling regeneration was found between 2010 and 2014 in and around the stand, confirming the expectations of the unlikelihood of eucalypt seedling establishment based on its limited invasive potential in competitive tropical environments. In 2014, open-pollinated seeds were collected from 28 non-GM eucalypts located between three and 650m distance from the GM trial. A total of 420 seedlings were grown in a greenhouse and screened for the presence of the transgenic construct by a multiplexed PCR assay targeting two transgenes and an internal control. The highest average transgene pollen flow (16%) was seen at short distances (3–15m), rapidly diminishing to 3% by a 240m distance and continued at this low rate up to the furthest distance assessed (650m) from the GM trial. The negative exponential distribution of GM pollination success was similar to that observed in non-GM eucalypt pollen flow studies, indicating that low levels of effective pollination are expected over long distances. To the best of our knowledge, this is the first experimental assessments of realized pollen flow measured by the effective production of seedlings from a genetically modified tree in field conditions.

Environmental Impacts of Industrial Pollution on Pollen Morphology of Eucalyptus globulus Labill. (Myrtaceae)

Study was aimed to investigate the effect of industrial air pollution on pollen morphology of Eucalyptus globulus Labill. , belonging to family Myrtaceae. Data revealed that there are differences in pollen morphological characteristics of E. globulus that grows in polluted industrial area in comparing with the pollen of that plant grows in healthy conditions (control area). Eucalyptus pollen grains are flattened triangular- obtuse- convex shape in polar view (the only view that is usually present). Aperture ( trizonocolpate- syncolpate), colpi fusing in each apocolpium to cut off an island of exine shaped like a triangle. Sculpture, psilate. The LM and SEM studies revealed that pollen grains of the control area showed normal size, shape and sculpture. While in case of polluted industrial one there is a shrinkage in size, thinning of exine, protrusion elements on the pollen surface, some attached particulate materials on the pollen surface ; that may be affected due to air pollution.

Omega-3 deficiency impairs honey bee learning

Deficiency in essential omega-3 polyunsaturated fatty acids (PUFAs), particularly the long-chain form of docosahexaenoic acid (DHA), has been linked to health problems in mammals, including many mental disorders and reduced cognitive performance. Insects have very low long-chain PUFA concentrations, and the effect of omega-3 deficiency on cognition in insects has not been studied. We show a low omega-6:3 ratio of pollen collected by honey bee colonies in heterogenous landscapes and in many hand-collected pollens that we analyzed. We identified Eucalyptus as an important bee-forage plant particularly poor in omega-3 and high in the omega-6:3 ratio. We tested the effect of dietary omega-3 deficiency on olfactory and tactile associative learning of the economically highly valued honey bee. Bees fed either of two omega-3-poor diets, or Eucalyptus pollen, showed greatly reduced learning abilities in conditioned proboscis-extension assays compared with those fed omega-3-rich diets, or omega-3-rich pollen mixture. The effect on performance was not due to reduced sucrose sensitivity. Omega-3 deficiency also led to smaller hypopharyngeal glands. Bee brains contained high omega-3 concentrations, which were only slightly affected by diet, suggesting additional peripheral effects on learning. The shift from a low to high omega-6:3 ratio in the Western human diet is deemed a primary cause of many diseases and reduced mental health. A similar shift seems to be occurring in bee forage, possibly an important factor in colony declines. Our study shows the detrimental effect on cognitive performance of omega-3 deficiency in a nonmammal.

Pollen loads of eucalypt and other pollen types in birds in NW Spain.

Here we present the amount of pollen of eucalypt and pollen of other types for birds captured in two bird ringing stations for 14 months (March 2014 to April 2015) in NW Spain. Common and latin names of all birds species captured, together with the number of captured individuals (N), prevalence of eucalypt pollen (percentage of individuals with eucalypt pollen) and of pollen of other types and average pollen loads per individual for eucalypt and other pollen types is presented. See [1] for further information and discussion.

Ecological integration of eucalypts in Europe: Interactions with flower-visiting birds

The degree of ecological integration of an exotic species depends on the emergence of new interactions with the host community, either antagonistic or mutualistic, such as pollination. This will determine the impact of the new species on the host community (positive or negative, direct or indirect) as well as the capacity of the new species to sustain biodiversity.Eucalypts are the most widely planted trees in the world and depend on pollination by animals for seed production. Blue gum (Eucalyptus globulus), one of the most commonly used and a dominant tree in NW of Spain, where this study has been conducted, is pollinated mainly by birds in its native range. In Europe pollination is mainly insect mediated, there are no specialized nectar-feeding birds and ornithophily (plant adaptation for bird pollination) is extremely rare (only recognized for one species, a Tertiary relict). Nevertheless, opportunistic nectar-feeding has been occasionally observed for some European songbirds.In this study, we determine the prevalence and strength of the interaction between eucalypts and birds by analyzing the occurrence and abundance of pollen in birds captured in mist nets in mixed landscapes with eucalypt plantations.Eucalypts represented the most important flower resource for the flower-visiting bird community. Eucalypt pollen was present in 171 individuals belonging to 19 bird species (out of the 485 birds captured in 33 species) and represented 98.2% of all pollen recorded. The large pollen loads found are indicative of frequent eucalypt flower use by the bird community.This study provides a good example of the ecological integration of a widely planted forestry species. The frequency of eucalypt pollen in birds points to the widespread use of this novel resource by birds and to the high ecological relevance of this interaction. The establishment of this novel interaction may favor seed production and, with it, population regeneration and spread of this exotic tree.

Registro Palinológico do Holoceno Tardio em Sedimentos Estuarinos do Rio Piraquê-Açu, Espírito Santo, Brasil

The Piraque-Acu river is located at the municipality of Aracruz, 83 km north of Vitoria city, Espirito Santo State, Brazil. Palynological analysis was performed based on one core (PA20) collected at coordinates 19°56'13.63S and 40°10'29.50W and approximately 110 cm long. The main purpose of this study was to recognise and interpret the vegetation dynamics in the region around the collection site during last 1700 cal. yrs BP for future investigations. The core was sampled at each 10 cm and the samples were submitted to standard palynological processes. One tablet of exotic spore Lycopodium clavatum was added to calculate palynomorph concentration. The material of four levels has been dated obtaining the oldest age of 1758 A 68 cal. yrs BP at an approximately 105 cm depth. The core analysis indicates a strong presence of mangrove vegetation, mainly characterized by the Rhizophora pollen type. The Alluvial Community and the Ombrophilous Forest vegetation were well represented also experiencing minor fluctuations. The increase of this elements in 10 cm depth may be associated with the human activity caused by the arrival of immigrants into the estuary area. The core top presented Eucalyptus pollen type, being related to the started expansion of large scale planting species of this genus in the Espirito Santo State.

Eucalyptus pollen allergy and asthma in children: a cross-sectional study in South-East Queensland, Australia.

ObjectivesTo investigate Eucalyptus (gum tree) pollen allergy in children in relation to geography, particularly vegetation, and its relationship to asthma.MethodsMales (n = 180) and females (n = 200) aged 9 to 14 participated. Some were healthy (asymptomatic), some had asthma, and some had other symptoms associated with atopy. School students were from three urban coastal schools and one school from a nearby semi-rural elevated area (range) near Brisbane, Australia. Coastal and range locations featured different distributions of Myrtaceae family vegetation (including Eucalyptus, Melaleuca, Leptospermum species). Skin prick test (SPT) responses to 15 commercial allergens were compared. As well, responses from coast versus range groups, and ‘asthma’ (n = 97) versus ‘healthy’ status (n = 107) groups, were compared.ResultsSPT responses (≥3mm wheal diameter) indicate that children with asthma are 31.1 times more likely to be allergic to Eucalyptus pollen extract (OR: 31.1; 95%CI 4.1- 235.7) compared to healthy children. Dust mite (p = .018), Eucalyptus (p = .046) and cockroach (p = .047) allergen SPT responses (wheals ≥3mm) were significantly greater in participants located on the coast versus range as determined by Fisher’s Exact Test (α .05). For each location, percentage of positive responses (wheals ≥3mm) was greatest for ‘dust mite’ (30.9%-46%), ‘cockroach’ (18.1% -35%) and ‘Bermuda grass’ (10.6%-19.4%).ConclusionsThe results support the hypothesis that proximity to Myrtaceae vegetation is related to positive SPT response and that Eucalyptus is an important allergen for children with asthma. Substantial response to olive allergen, in the absence of olive trees, suggests that the response may be driven by substances in other plants, perhaps Melaleuca quinquenervia, which abounds in coastal areas.ImplicationsResponse to Eucalyptus allergen indicates that changes in gardening practice in schools and public areas may be appropriate. The findings pose validity questions regarding the use of some commercial allergens due to cross-reactive responses and the sources of those responses.

Palynology as a Tool to Distinguish between Propolis and Geopropolis: Southern Brazilian Samples

Propolis is a product elaborated by honey bees (Apis) and comprises plant resins, bee wax, glandular secretions of the worker bees and pollen grains. Geopropolis is a product elaborated by stingless bees and comprises similar compounds of honey bees and soil, mud, clay, earth or sand. The present study intends to distinguish between propolis and geopropolis using pollen analysis. A total of 12 samples were obtained in the Southern Brazilian macro-region and processed by standard melissopalynological methodology. All structural components recovered after alcoholic extraction and before acetolysis treatment were evaluated. Four of the eight samples collected in the State of Parana were prepared by Apis and showed a strong contribution of Asteraceae and Eucalyptus pollen grains. On the other hand, the two geopropolis samples of Tetragonisca angustula contained mainly Cecropia pollen grains, while the samples of Melipona quadrifasciata and Melipona mondury showed a predominance of Melastomataceae pollen grains. The four propolis samples obtained in the Santa Catarina and Rio Grande do Sul States were characterized by a predominant pollen contribution of Asteraceae and Eucalyptus. Additional structured elements in propolis samples comprised frequently plant trichomes and tissue fragments. On the contrary, the geopropolis samples showed high values of spores of fungi, amorphous organic matter, sand or clay and sometimes remainder of resin. In conclusion, the pollen grain spectra do not distinguish between propolis of Apis and geopropolis of stingless bees, but the accessory elements are conclusive.

A late Quaternary record of vegetation and climate change from Hazards Lagoon, eastern Tasmania

A late Quaternary pollen and charcoal record from Hazards Lagoon on the east coast of Tasmania provides a continuous record of vegetation and climate change. The pollen record shows an Epacridaceae and Poaceae dominated grassland community replaced dry sclerophyll forest during the Last Glacial Maximum (LGM ∼22–18 cal ka BP). Eucalyptus and Casuarinaceae increased from the beginning of the deglacial period (∼18–12 cal ka BP) indicating early warming on the east coast of Tasmania. Abundant Myriophyllum and sedimentary characteristics indicate Hazards Lagoon was a permanent source of water throughout the LGM and until 16 cal ka BP suggesting either increased precipitation and/or decreased evaporation rates. A positive moisture balance throughout the LGM contrasts with records from the west coast of Tasmania and parts of mainland Australia. Fire was suppressed at the site until 14 cal ka BP, corresponding with reduced woody vegetation and a positive moisture balance. Dry sclerophyll forest established during the deglacial period, remaining stable throughout the Holocene. A coastal vegetation community developed in response to sea-level rise, characterised by abundant Eucalyptus pollen and increasing values of Casuarinaceae. By the mid-Holocene, the Hazards Lagoon pollen record is typical of a Tasmanian coastal site dominated by Casuarinaceae. This research highlights the need for spatially diverse studies throughout the Southern Hemisphere to identify drivers of environmental change during the late Quaternary.

Near infrared spectroscopy applied to the rapid prediction of the floral origin and mineral content of honeys

Consumers demand to know the floral origins of honeys. Therefore, the use of simple and reliable techniques for differentiating among honeys by their origins is necessary. Multivariate statistical techniques and near infrared spectroscopy applied to palynological and mineral characteristics make it possible to differentiate among the types of honey collected from Northwestern Spain. Prediction models using a modified partial least squares regression for the main pollen types (Castanea, Eucalyptus, Rubus and Erica) in honeys and their mineral composition (potassium, calcium, magnesium and phosphorus) were established. Good multiple correlation coefficients (higher than 0.700) and acceptable standard errors of cross-validation were obtained. The ratio performance deviation exhibited a good prediction capacity for Rubus pollen and for Castanea pollen, whereas for minerals, for Eucalyptus pollen and for Erica pollen the ratio performance deviation was excellent. Near infrared spectroscopy was established as a rapid and effective tool to obtain equations of prediction that contribute to the honey typification.

Exploring the prevalence and diversity of pollen carried by four species of migratory Old World warbler (Sylvioidea) on arrival in the UK

Capsule Pollen encrusted around the bill of migrating warblers can reveal marked differences in foraging ecology between bird species.Aims To examine patterns of the prevalence and diversity of pollen in four species of warbler, and explore the potential of pollen to act as an indicator of recent foraging behaviour.Methods By isolating pollen from bill encrustations using laboratory palynological techniques and identification by light microscopy, we examined variation in the prevalence of the five most common pollen taxa, and variation in pollen assemblages in four species of warbler arriving on the south coast of England.Results All samples contained abundant pollen, with 19 floral taxa identified. Sylvia warblers tended to carry Prunus and Citrus pollen, while Phylloscopus warblers mainly carried Eucalyptus pollen. Pollen assemblages varied markedly between bird species.Conclusion Commercial and garden flowering trees are an important resource for migrating warblers. Pollen may be such a valuable resource that flowering plants might be included in the conservation management of stopover sites. The use of pollen to resolve migratory routes may be problematic however, requiring detailed knowledge of both the distribution and flowering phenology of plants en route.

Do different landscapes influence the response of native and non-native bee species in the Eucalyptus pollen foraging, in southern Brazil?

Eucalyptus is an exotic genus in Brazil with massive flowerings that are visited by bees in search of food. To verify the use of Eucalyptus spp. in the pollinic diet of Apis mellifera L. and Melipona obscurior Moure, we evaluated the proportion of pollen that both bee species collected from Eucalyptus spp. in relation to the relative abundance of Eucalyptus spp. in the study areas. The study occurred in the localities of Riozinho and Rolante, RS, Brazil, whose land cover was characterized by remote sensing. Every two weeks from April/2009 to March/2010, pollen was collected from foragers of three hives of each bee species for posterior palynological analysis. The median percentage of Eucalyptus spp. pollen collected in Riozinho was 16.3% (0–55.3%; n=18) for A. mellifera and 2.6% (0–72.3%; n=15) for M. obscurior. In Rolante, the median was 21.9% (0–66.7%; n=19) for A. mellifera and 17.6% (0–82.9%; n=17) for M. obscurior. The difference between these values was significant only when considered the collection period. The index of use was similar for both species and both areas. The attractiveness and availability of flowering Eucalyptus spp. throughout the year allowed both species of bees to use pollen from this genus in both areas, regardless of the landscape characteristics. In southern Brazil, sustainable practices for the management of eucalypts can contribute to the survival of social bees during the periods of lower pollen production by other sources.

Contribution of botanical origin and sugar composition of honeys on the crystallization phenomenon

The present work provides information regarding the statistical relationships among the palynological characteristics, sugars (fructose, glucose, sucrose, melezitose and maltose), moisture content and sugar ratios (F+G, F/G and G/W) of 136 different honey types (including bramble, chestnut, eucalyptus, heather, acacia, lime, rape, sunflower and honeydew). Results of the statistical analyses (multiple comparison Bonferroni test, Spearman rank correlations and principal components) revealed the valuable significance of the botanical origin on the sugar ratios (F+G, F/G and G/W). Brassica napus and Helianthus annuus pollen were the variables situated near F+G and G/W ratio, while Castanea sativa, Rubus and Eucalyptus pollen were located further away, as shown in the principal component analysis. The F/G ratio of sunflower, rape and lime honeys were lower than those found for the chestnut, eucalyptus, heather, acacia and honeydew honeys (>1.4). A lower value F/G ratio and lower water content were related with a faster crystallization in the honey.