Melipona Seminigra Research Articles

Stingless bees as collectors of resin from Bertholletia excelsa Bonpland (Lecythidaceae)

Stingless bees build their nests using, in general, clay, wax and resins; in addition, these bees also use resins for defense against natural enemies and as an antimicrobial agent. Our goal was to register the stingless bees that collect resin from Bertholletia excelsa, and the observations were made in the Reserva Particular do Patrimônio Natural Dr. Daisaku Ikeda, Manaus, Amazonas, with five species recorded: Melipona (Michmelia) seminigra, Trigona albipennis, Trigona hypogea, Trigona williana, and Ptilotrigona lurida. Bees invest substantial amounts of energy and labor to collect resin from a wide spectrum of different plant species, and the resin must be considered as a necessary resource for the conservation of Amazonian stingless bees.

Efficiency of trap nests in attracting stingless bees in the central Brazilian Amazon

ABSTRACT Obtaining colonies of stingless bees in the wild for the formation or expansion of meliponaries and other purposes is permitted by law in Brazil using bait containers or trap nests, and other non-destructive methods. We tested the efficiency of trap nests made from plastic bottles for attraction and nesting of stingless bees in the central Brazilian Amazon. We used 2-L and 5-L bottles and three types of attractants (cerumen and geopropolis from Melipona seminigra, M. interrupta and a mix of the two). We used 216 trap nests distributed in three experimental areas during 13 months. Visitation by six species of stingless bees in 58 (26.9%) trap nests, and nesting by three species in 12 (5.6%) trap nests in two areas near meliponaries was recorded. There was no significant difference between trap-nest size, nor among attractants for visitation or nesting, suggesting that the availability of cavities or hollows is more important than odor for nesting. Monthly pooled visitation and nesting events were not correlated with monthly rainfall. Based on our results, we can conclude that, despite the low capture rate, the acquisition of swarms through nest traps is a viable alternative to obtain new colonies of stingless bees for meliponaries.

DNA barcoding reveals long-term speciation processes in subspecies of the Melipona (Michmelia) seminigra complex (Hymenoptera: Apidae)

The stingless bee Melipona (Michmelia) seminigra Friese is a polytypic species widely distributed in Brazilian Amazon and Bolivia. Seven subspecies are recognized, four are described, which inhabit mutually exclusive areas in the Amazon basin, although zones of hybridization are recorded. The three other subspecies, despite being recognized by taxonomists are undescribed. Melipona seminigra is a good honey-producer and an important pollinator of native flora and crops. Partial DNA sequence of cytochrome c oxidase subunit 1 (COI) mitochondrial gene (526 bp) was used to identify the four described subspecies of M. seminigra (M. s. abunensis, M. s. merrillae, M. s. pernigra, M. s. seminigra) and two other possible subspecies (M. s. ssp1 and M. s. ssp2). We added public data (sequences of ten other Melipona species) of the same subgenera and carried out phylogenetic analyses. The aim was to evaluate if subspecies in the M. seminigra complex could be delimited using COI and measure the genetic distances between them. Our results revealed that the genetic distances between subspecies of M. seminigra ranged from 0.4 to 2.7% (average 1.80 ± 0.47) and among Melipona species from 0.2 to 2.9% (average 2.13 ± 0.5). The average haplotype diversity was 0.8770 ± 0.0140 and average nucleotide diversity 0.0166 ± 0.0004. Phylogenetic and clustering analysis revealed well delimited clusters for subspecies of M. seminigra and that the inter subspecies divergences are similar to inter species divergence. Our findings indicate that the COI gene can be used for delimiting subspecies of M. seminigra.

EVALUACIÓN FÍSICO QUÍMICA Y PROTEICA DEL POLEN ALMACENADO EN COLMENAS DE Melipona seminigra, AMAZONAS, BRASIL.

Bee’s pollen comes from the flowers of several species of plants. The grains are transported by worker bees to their nests (honeycombs) to be used as a source of nutrients. The objective of this study was to evaluate the microbiological control, the physical chemical composition and to analyze macro and micro minerals, as well as amino acids in dehydrated pollen hives of Melipona seminigra, in rainy periods (PLL) and dry periods (PS) in Amazonas, Brazil.The physical-chemical composition (proteins, lipids, carbohydrates, fibers and ashes) was performed by the AOAC methodology. In meliponícola pollen it was detected the presence of proteins (35,97 - 36,37 g/100g), lipids (22,37 - 29,66 g/100g), ashes (4,46 - 2,83 g/100g) and ratio carbon/nitrogen (8,94 - 8,28 g/100), also minerals like copper, iron, manganese, calcium, potassium, magnesium and phosphorus were present. In the pollen of the indigenous bees, both non-essential and essential amino acids were found. The results showedthat the meliponícola pollen did not present any contamination for bacteria and fungi that comply with the Brazilian legislation. The physical-chemical analysis confirmed that pollen has nutritional amounts that can be added to other ingredients, providing enrichment of fibers, minerals and proteins to foods at different ages of the population

First report of collagenase production by Trichosporon sp. strain isolated from pollen of Amazonian bee (Melipona seminigra seminigra)

Trichosporon yeasts are widely employed to produce lipids, lipases, and aspartic peptidases, but there are no previous studies on collagenase production. This work aimed to select the best collagenase producing Amazonian Trichosporon strains. Moreover, a 23-full factorial design (FFD) and a 22-central composite design combined with Response Surface Methodology were applied to optimize production and find the best conditions for hydrolysis of type I bovine collagen. Most of the studied strains had some collagenolytic activity, but the selected one achieved the highest value (44.02 U) and a biomass concentration of 2.31 g/L. The best collagenase production conditions were 160 rpm of agitation, pH 5.5 and a substrate concentration of 4.0 g/L. The former experimental design showed that substrate concentration was the only statistically significant factor on both biomass concentration and collagenase activity, while the latter showed simultaneous effects of substrate concentration and pH on collagenolytic activity, which peaked at pH 5.5–6.4 and substrate concentration of 3.0–3.4 g/L. An additional 2³-FFD was finally used to optimize the conditions collagen hydrolysis, and pH 6, 25 °C and a substrate concentration of 7.5 (g/L) ensured the highest hydrolysis degree. This study is the first that describes optimized conditions of collagenase production by Trichosporon strains.

Nutritional composition and bioactive compounds of Melipona seminigra pot-pollen from Amazonas, Brazil.

Pot-pollen is a fermented product stored by stingless bees in cerumen pots and traditionally used as food or medicine by natives in tropical regions. Knowledge of pot-pollen composition from the Amazon region is important to strengthen the breeding of native bees and consequently contribute to sustainable development in this region. The aim of the present study was to determine the chemical composition of Melipona seminigra pot-pollen from Amazonas, Brazil. We report the identification of 21 phenolic compounds using ultra-performance liquid chromatography- electrospray ionization-quadrupole time-of-flight-mass spectrometry. Overall, the predominant constituents of pot-pollen were protein (333.8-470.7 g kg-1 ) and dietary fibers (247.6-353.3 g kg-1 ). The predominant fatty acids were polyunsaturated (44.95-59.57% of total fatty acid content) and the samples contained all essential amino acids. Total carotenoid content ranged from 3.2 to 48.0 μg g-1 , total flavonoid content (as catechin equivalents) from 1.9 to 4.5 mg g-1 , total reducing capacity (as gallic acid equivalents) from 7.0 to 15.0 mg g-1 , ferric-reducing antioxidant power from 2.8 to 8.9 μmol g-1 and oxygen radical absorbance capacity (as Trolox equivalents) from 224.9 to 1117.0 μmol g-1 . This study reports for the first time a comprehensive chemical characterization of M. seminigra pot-pollen. The samples presented antioxidant activity, high values of nutrients and bioactive compounds such as polyphenols, carotenoids, insoluble dietary fibers, polyunsaturated fatty acids, and essential amino acids, comparable to other health foods. © 2021 Society of Chemical Industry.

Foraging preferences of the native stingless bee Melipona seminigra pernigra (Apidae: Meliponini) in campo rupestre on canga of Serra dos Carajás, southeastern Amazonia

Abstract: Honey pollen samples of Melipona seminigra pernigraMoure & Kerr 1950 sampled between 2017 and 2019 from experimental apiaries installed in campo rupestre on canga (CRC) vegetation of the Serra dos Carajás aimed to evaluated seasonal floral availability of undisturbed and mining-influenced areas. Around one hundred pollen types were identified mainly belonging to Fabaceae, Myrtaceae and Euphorbiaceae (31, 6 and 5 species, respectively). Mining area presented the highest pollen richness, almost twice those identified in the undisturbed areas. 80% of the pollen types are rare with concentrations ≤ 2,000 pollen grains/10 g, while the remaining were the most abundant, frequent and the primary bee sources. These latter correspond mostly to native plants species such as Tapirira guianensis Aubl., Protium spp., Aparisthmium cordatum (A.Juss.) Baill., Mimosa acutistipula var. ferrea Barneby, Periandra mediterranea (Vell.) Taub., Miconia spp., Pleroma carajasense K.Rocha, Myrcia splendens (Sw.) DC., Serjania spp. and Solanum crinitum Lam. All pollen types were identified during both seasons, but higher concentration values are related to the dry period (June-September). The statistical analysis of the pollen data indicated that there was no significant difference between undisturbed and mining-influenced areas, since primary bee sources of this study are widespread used in revegetation of mined areas.

Pollen niche of Melipona dubia, Melipona seminigra and Scaptotrigona sp. (Apidae: Meliponini) kept in indigenous communities of the Sateré Mawé Tribe, Amazonas, Brazil

Stingless social bees have been used in the Meliponiculture as a sustainable activity by several indigenous communities in Central Amazon. Pollen samples collected by Melipona dubia, Melipona seminigra and Scaptotrigona sp. bees from communities of the Sateré Mawé tribe were analyzed and 61 pollen types were identified. The most representative botanical families in the samples were: Anacardiaceae, Arecaceae, Burseraceae, Euphorbiaceae, Dilleniaceae, Fabaceae, Melastomataceae, and Myrtaceae. Among these families, the most representative was pollen of Miconia type (Melastomataceae) collected by bees Melipona dubia and Melipona seminigra. Also, pollen of Croton cajucara (Euphorbiaceae) and Eugenia type (Myrtaceae) collected by bee Scaptotrigona sp., these species of bees presented temporary specialization (>90%) in some samples. On the other hand, Scaptotrigona sp.showed higher richness in their collections (H' =1.66 and J’= 0.45), followed by Melipona seminigra (H' = 1.43 and J’= 0.39) and Melipona dubia with (H' = 0.45 and J’= 0.14). The connectance of interactions between bees and plants in the study locations was 19.37%, which is considered high for palynological data. The other network metrics, both for presence and absence (NODF= 54.07) and for quantitative matrix (WNODF = 34.03) were found to be significant (p < 0.001) and highly nested. Cluster analysis from the collected resources presented two distinct groups, a group formed by the genus Melipona and another by Scaptotrigona.The results show that even though they have their peculiarities in the collections, these groups of bees share many resources, presenting themselves as both generalists and temporary specialists, according to the colony’s needs.

Antibacterial activity of honeys from Amazonian stingless bees of Melipona spp. and its effects on bacterial cell morphology.

Stingless bee honey has great therapeutic potential, especially as an antimicrobial agent. In the present study, we evaluated the in vitro antibacterial potential of honey from Melipona spp. with occurrence in Rio Branco-AC and Xapuri-AC from the Amazonian region. Samples were collected from the species Melipona eburnea, Melipona grandis, Melipona flavolineata and Melipona seminigra. The antibacterial activity of the honey samples was tested against standard Gram-positive and Gram-negative bacteria and two strains isolated from bovine mastitis. In the agar diffusion assay, we observed antibacterial activity for the four honeys against the tested strains. The honey from M. flavolineata showed a minimmum inhibitory concentration (MIC) lower than 3.12% (v/v). The minimum bactericidal concentration values were larger than the MIC for most of the microorganisms tested. Scanning electron microscopy (SEM) showed the damaging effect of the honey of M. flavolineata on Staphylococcus aureus cells, as well as its inhibitory effect on cell division. The results of the present study demonstrate that the honey from stingless bees possesses in vitro antimicrobial activity against pathogenic bacteria. The effects observed by SEM show that honey from the Amazonian stingless bee M. flavolineata has promising therapeutic potential as a future antimicrobial agent. © 2020 Society of Chemical Industry.

Resources Collected by two Melipona Illiger, 1806 (Apidae: Meliponini) Species Based on Pollen Spectrum of Honeys from the Amazon Basin

This study aimed to identify the pollen grains found in honeys of Melipona (Michmelia) seminigra pernigra Moure &amp; Kerr and Melipona (Melikerria) interrupta Latreille in two communities of the Tapajós-Arapiuns Extractive Reserve, Lower Amazon (Pará, Brazil) between December 2016 and November 2017. Twenty-four samples of honey were processed, 12 samples from M. seminigra pernigra collected in the Suruacá community and 12 samples from M. interrupta in the Vila Franca community. After acetolysis, 103 pollen types were identified, distributed across 22 families, plus eight indeterminate types. Fifty-nine types were exclusive to M. seminigra pernigra, 29 types were exclusive to M. interrupta and 15 pollen types were shared between both species. Anacardiaceae, Burseraceae, Melastomataceae, and Myrtaceae were the most attractive pollen families, providing key resources for maintenance of these bee populations. The sharing of pollen types between both bee species revealed a high similarity in preference for certain resources. M. seminigra showed greater diversity (H’ = 1.928) than M. interrupta (H’ = 1.292). Furthermore, the diversity (H’) and equitability (J’) indexes showed a more homogeneous pattern in the pollen spectrum of honeys from M. seminigra in most months studied. These data suggest that meliponiculturists should consider the diversity of plant species found in the two communities and keep them close to the meliponary, which will favor honey management and production, as well as the local biodiversity.

Honey botanical origin of stingless bees (Apidae Meliponini) in the Nova América community of the Sateré Mawé indigenous tribe, Amazon, Brazil

This study analysed the pollen present in honey samples collected from colonies of stingless bees (Meliponini) from the meliponary of the Nova América community of the Sateré Mawé tribe, located on the Maruá River, Maués municipality, Amazonas state, Brazil (03° 39ʹ 45.00″ S, 57° 20ʹ 17.99″ W). Collections were made directly from honey storage pots. A total of 47 pollen types were identified, belonging to 22 plant families. Bees with the largest number of pollen types were Melipona seminigra (31 collected pollen types), followed by Melipona sp. (27 pollen types), Scaptotrigona sp. (25 pollen types), and Melipona dubia (19 pollen types). Plant families most commonly collected were: Anacardiaceae, Arecaceae, Burseraceae, Chrysobalanaceae, Dichapetalaceae, Dilleniaceae, Euphorbiaceae, Fabaceae, Lecythidaceae, Melastomataceae, Myrtaceae, Rhamnaceae and Salicaceae. Scaptotrigona sp. had the highest pollen types diversity (H′ = 2.32) and, consequently, greatest between-collection uniformity. Trophic niche overlap was significant between the following pairs of bees: M. seminigra and M. dubia (O i = 0.93); M. seminigra and Scaptotrigona sp. (O i = 0.79) and M. dubia and Scaptotrigona sp. (O i = 0.69). These data demonstrate the importance of these shared groups of plants for the maintenance of these bees and, consequently, for the development of meliponiculture in Brazilian Amazonia.

Southern-Brazilian geopropolis: A potential source of polyphenolic compounds and assessment of mineral composition.

Geopropolis is a stingless bee product compose mainly by soil, presenting complex composition geopropolis has bioactive compounds that will depend on geographical characteristics as well bee species, changing their chemical and biological properties. Thus the study aims to evaluate the solubility and chemical stability of geopropolis extracts, through radical capture capacity and reducing capacity. Besides, analysis of free and bonded phenolic compounds, and mineral composition. Geopropolis samples of Melipona mondury, Melipona quadrifasciata, Melipona scutellaris, Melipona seminigra and Tetragonisca angustula were analyzed. Both reducing compounds with a maximum of 2.96% GAE and free radical scavenging potential with a maximum of 5.84% AAE and 8.58% TE increases over 30 days of storage time. Also, methanolic extracts released at least 51% more reducing compounds and exhibited at least 27% more free radical scavenging potential in comparison to ethanolic extracts. The polyphenolic profile shows 31 compounds after acid and alkaline hydrolysis as cinnamic acid, ferulic acid, p-coumaric acid, aromadendrin, vanillin. For the mineral composition, sixteen minerals were found among essential and non-essential, differentiating each sample by chemometric PCA and HCA analysis according to geographic region. Geopropolis is a potential source of natural compounds that could enhance food quality, increasing the bioactive content and preventing oxygen damages in foods, likewise for pharmacological application for healthcare.

Pollen of honey from Melipona seminigra merrillae Cockerell, 1919, Scaptotrigona nigrohirta Moure, 1968 and Scaptotrigona sp. Moure, 1942 (Apidae: Meliponini) reared in Sataré Mawé indigenous communities, Amazon, Brazil

ABSTRACTHoney samples from stingless bees (tribe Meliponini) were analyzed in three Sataré Mawé indigenous communities located along the edges of the Maruá River in the state of Amazonas, Brazil. Twenty-nine pollen types were identified for the Scaptotrigona nigrohirta colonies from the Ilha Michilis community, 43 for the Scaptotrigona sp. colonies and 39 for the Melipona seminigra colonies from the Nova Esperança community, and 34 for the M. seminigra colonies from the Monte Horeb community. Regarding the presence or absence of different pollen types in the samples, from the 65 pollen types identified, five were exclusive for the Scaptotrigona sp. from Nova Esperança, five for M. seminigra from Monte Horeb, six for S. nigrohirta from Ilha Michilis, and 13 for M. seminigra from Nova Esperança. Of the main pollen types identified (n = 22), the Miconia type had the highest proportion and was the only type shared by the bees from the three communities. The present study provides a list of important plants to be included in bee pastures for the studied bees in the Amazon, with the aim of developing stingless beekeeping as a subsistence activity in indigenous communities.

DIAGNÓSTICO DA RELAÇÃO ENTRE A ARBORIZAÇÃO E A DIVERSIDADE DE ABELHAS SEM FERRÃO (APIDAE: MELIPONINI) NO CAMPUS TAPAJÓS E NO BOSQUE MEKDECE LOCALIZADOS EM SANTARÉM, PA

RESUMO: O estudo objetivou caracterizar a significância da arborização como instrumento de conservação da biodiversidade de abelhas sem ferrão no Campus Tapajós e no Bosque Mekdece, localizados na cidade de Santarém, PA. Cada ninho encontrado foi georreferenciado, fotografado, mediu-se sua altura em relação ao solo, para substratos arbóreos mediu-se também a Circunferência do tronco a 1,30 m. As abelhas coletadas foram identificadas a partir da arquitetura de entrada do ninho e de chave de identificação. Verificou-se a riqueza, abundância e diversidade. Foram encontrados ao todo 12 ninhos, pertencentes a 6 espécies diferentes: Trigona guianae (N=2), Melipona (Melikerria) interrupta (N=3), Melipona seminigra aff pernigra (N=1), Trigona pallens (N=3), Tetragona clavipes (N=2), Scapitotrigona sp. (N=1). Os índices de diversidade Shannon-Wiener (H’) foram 1,56 no Campus Tapajós e 1,04 no Bosque Mekdece, já os índices de equitabilidade de Pielou (J) foram 0,97 no Campus Tapajós e 0,95 no Bosque Mekdece, a densidade dos ninhos foi de 1 ninho por hectare (Campus) e 3 ninhos por hectare (Bosque). Com relação à nidificação em árvores, no Campus Tapajós foram identificados 5 ninhos em Dalbergia spruceana e 1 ninho em Copaifera martii, já no Bosque Mekdece identificou-se 3 ninhos em uma mesma espécie arbórea (Inga heterophylla). Quanto à nidificação de abelhas no solo foram encontrados 2 ninhos da espécie Trigona guianae no Campus e 1 ninho de Trigona pallens no Bosque. Constatou-se nos dois locais de estudo que a maioria dos ninhos (75%) estava associada a substratos arbóreos e 25% dos ninhos encontrados estavam localizados no solo.PALAVRAS-CHAVE: Abelhas sem ferrão, Conservação, Nidificação.

Comparative cytogenetics in three Melipona species (Hymenoptera: Apidae) with two divergent heterochromatic patterns.

The genus Melipona is subdivided into four subgenera based on morphological characteristics, and two groups based on cytogenetic patterns. The cytogenetic information on this genus is still scarce, therefore, the goal of this study was to characterize Melipona paraensis, Melipona puncticollis, and Melipona seminigra pernigra using the following techniques: C-banding, DAPI/CMA3 fluorochromes, and FISH with an 18S rDNA probe. Melipona paraensis (2n=18) and M. seminigra pernigra (2n=22) were classified as high heterochromatin content species (Group II). Their euchromatin is restricted to the ends of the chromosomes and is CMA3 +; the 18S rDNA probe marked chromosome pair number 4. Melipona puncticollis (2n=18) is a low heterochromatin content species (Group I) with chromosome pair number 1 marked with CMA3 and 18S rDNA. Low heterochromatin content is a putative ancestral karyotype in this genus and high content is not a monophyletic trait (Melikerria presents species with both patterns). Differences concerning the karyotypic characteristics can be observed among Melipona species, revealing cytogenetic rearrangements that occurred during the evolution of this genus. Studies in other species will allow us to better understand the processes that shaped the chromatin evolution in Melipona.

Pollen niche and trophic interactions between colonies of Melipona (Michmelia) seminigra merrillae and Melipona (Melikerria) interrupta (Apidae: Meliponini) reared in floodplains in the Central Amazon

The growth of the Meliponiculture in floodplains in Central Amazon has aroused interest in the knowledge of trophic resources obtained by stingless bees. In this study, the pollen niche and trophic interactions were determined between colonies of Melipona (Michmelia) seminigra merrillae and Melipona (Melikerria) interrupta (Apidae: Meliponini) reared in Varzea area in the Central Amazon. The study was conducted between November 2011 and October 2012 in the Sucupira meliponary, located in Manaus, Amazonas state, Brazil. In identifying the corbicular loads of pollen, a total of 67 pollen types collected by M. seminigra merrillae and M. interrupta were recorded, distributed among 27 families, with three pollen types remaining undetermined. Of this total, 22 pollen types were exclusively collected by M. seminigra merrillae, 14 were only collected by M. interrupta, and 31 pollen types were shared between the two species studied. These results indicate that the families Fabaceae, Melastomataceae, Myrtaceae, and Anacardiaceae, in addition to exhibiting high attractiveness, are key resources in maintaining these bees in the same meliponary. Considering the Pianka overlap index, except for December (O ik = 0.116), May (O ik = 0.07), and June (O ik = 0.004), which exhibited values below the adopted significance level, the other months exhibited high interspecific competition for the aforementioned resources. From the palynological data obtained in this study, there was a high degree of connectance (C = 28 %) compared to studies conducted without the addition of palynological data, reinforcing the importance of including pollen data in studies of interaction networks.

Antimicrobial activity of honeys from two stingless honeybee species and Apis mellifera (Hymenoptera: Apidae) against pathogenic microorganisms

Honeys are described possessing different properties including antimicrobial. Many studies have presented this activity of honeys produced by Apis mellifera bees, however studies including activities of stingless bees honeys are scarce. The aim of this study was to compare the antimicrobial activity of honeys collected in the Amazonas State from Melipona compressipes, Melipona seminigra and Apis mellifera against Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Chromobacterium violaceum, and Candida albicans. Minimum inhibitory concentrations were determined using the agar dilution method with Müller-Hinton agar (for bacteria) or Saboraud agar (for yeast). Staphylococcus aureus and E. faecalis were inhibited by all honeys at concentrations below 12%, while E. coli and C. violaceum were inhibited by stingless bee honeys at concentrations between 10 and 20%. A. mellifera honey inhibited E. coli at a concentration of 7% and Candida violaceum at 0.7%. C. albicans were inhibited only with honey concentrations between 30 and 40%. All examined honey had antimicrobial activity against the tested pathogens, thus serving as potential antimicrobial agents for several therapeutic approaches.

Phenolic profile, antioxidant activity and palynological analysis of stingless bee honey from Amazonas, Northern Brazil

In this study honey samples produced by Melipona (Michmelia) seminigra merrillae, collected in seven counties distributed in the central and southern region of Amazonas state in Brazil, were analysed for their botanical origin, content and profile of phenolic compounds, and antioxidant and antimicrobial activities. Twenty-two pollen types were identified. The total phenolic content ranged from 17 to 66mgGAE/g of extract; the highest contents were found in honeys produced from pollen types such as Clidemia and Myrcia. The antioxidant activity was higher in the samples that contained higher quantities of phenolic compounds. In relation to the antibacterial activity, samples CAD3, CAD4 and SAD3 presented the best results. Fourteen phenolic compounds were determined. Among them, we identified the flavonoid taxifolin, which has not previously been described in honeys from stingless bees, and we report the identification of catechol in Brazilian honey samples for the first time.

Differential environmental effects on caste allocation in two Amazonian Melipona bees

In Melipona bees, gyne proportion is exceptionally high in relation to other genera of eusocial bees. However, hypotheses on caste determination in this genus predict gyne proportions above those usually observed. This may be because gyne production is limited by environmental conditions. Our aim was to investigate the influence of environmental factors on caste allocation in two species in the genus Melipona. Monthly caste production was monitored for almost 2 years. In Melipona interrupta, gyne proportion was negatively correlated to cumulative rainfall. However, in Melipona seminigra, caste allocation did not depend on environmental factors. Comparison among these and other congeneric species suggests that this variation reflects the diversity of food sources. Thus, although the mechanism of caste determination may be common to Melipona spp., caste allocation across species responds differently to environmental constraints.

Constituintes fenólicos e atividade antioxidante da geoprópolis de duas espécies de abelhas sem ferrão amazônicas

We investigated the phenolic constituents and antioxidant activity of geopropolis from two species of stingless Amazonian bees, Melipona interrupta and Melipona seminigra. The chemical investigation of geopropolis from Melipona interrupta led to the isolation of 5,7,4'-trihydroxyflavonone, 3,5,6,7,4'-pentahydroxyflavonol, naringenine-4'-O-b-D-glucopyranoside and myricetin-3-O-b-D-glucopyranoside. Their structures were assigned based on spectroscopic analyses, including two-dimensional NMR techniques. Antioxidant activity of methanol and ethanol extracts of M. interrupta and M. seminigra were measured using the 1,2-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging assay. This is also the first work reporting the chemical investigation of stingless bee species from the Amazonian region.