Stingless Bee Melipona Subnitida Research Articles

Pesticide Residues in Honey from Stingless Bee Melipona Subnitida (Meliponini, Apidae)

Abstract The present study aimed to detect pesticide residues in the honey produced by the stingless bee Melipona subnitida. A total of thirty-five samples of honey from M. subnitida were collected from twelve municipalities of the semiarid region of Rio Grande do Norte state, northeastern Brazil. Of these thirty-five samples, fourteen were from colonies raised in an urban area, while the other twenty-one were from the countryside. The pesticides in the samples were extracted using a modified QuEChERS method. The simultaneous analysis of 116 analytes in the honey samples was performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Twenty-five samples (71.4% of samples) were contaminated by some amount of pesticide, and of them twenty-four had just one pesticide and one had three. The detected compounds included organophosphate pesticides (OPP) monocrotophos (24 samples), trichlorfon (6 samples) and chlorpyrifos-methyl (2 samples). In conclusion, the honey produced by the stingless bee M. subnitida may be contaminated by pesticides, which emphasizes the need for food monitoring before commercialization.

Why do stingless bees (Melipona subnitida) leave their nest with resin loads?

Stingless bees (Apidae, Meliponini) collect plant resins and deliver them to their nest for use as construction material. In some species, however, workers can be observed leaving their colonies with resin loads on their corbiculae. The present study investigated the role of these "resin bees" in the Brazilian stingless bee Melipona subnitida. In 7 nests, we observed a total of 424 workers departing the nest under undisturbed colony conditions. One tenth (11.3%) of these outgoing bees carried resin on their corbiculae. The average weight of the loads was 5.2 mg, approximately, 10% of the bees' body weight. The round-trip duration of resin bees (1.3 min) was significantly shorter than that of nectar foragers (12.3 min). When the colonies were experimentally disturbed, the majority of the agitated bees that left the colony in response carried resin loads (90.5%). Our results suggest that resin bees in M. subnitida are nest defenders. Under undisturbed colony conditions, these bees may perform surveillance flights close to the nest, watching out for potential intruders and even mummify them with resin. Additionally, the deterrent effect of plant resins on many bee predators may reduce the workers' risk during these flights.

Adjustment of fuel loads in stingless bees (Melipona subnitida).

Eusocial bee foragers leave their nest with nectar as flight fuel, therewith reducing the risk of starvation during a foraging trip. Yet, the extra mass results in an increase of energetic expenditure for flight. Thus, bees should tune their fuel loads to the respective foraging situation. In the present study, we investigated the fuel adjustment in the Brazilian stingless bee Melipona subnitida (Apidae, Meliponini). Specifically, we examined whether foragers of this species increase their fuel loads when they have low expectation for nectar collection during a foraging trip. Crop load measurements revealed that nectar foragers carried significantly less fuel on departing the nest than foragers collecting either pollen, clay, or resin. Surprisingly, 75% of nectar foragers left the nest without any detectable amount of nectar, which suggests that the majority of bees collected at nearby nectar sources and avoided an increase in foraging costs. Moreover, foragers increased their fuel loading when repeatedly experiencing empty food sources that had previously been rewarding. These results support our hypothesis and demonstrate that the capability of fuel adjustment is not restricted to honey bees.

Geopropolis gel for the adjuvant treatment of candidiasis – formulation and in vitro release assay

The geopropolis produced by the stingless bee Melipona subnitida (popularly called “jandaíra” in Brazil) is a mixture of resin, wax, and mud. This study analyzed the antifungal activity of the geopropolis extract from Candida spp., developed a gel formulation with this extract and analyzed the delivery of bioactives (kinetics release) in the formulation and their chemical profile by UHPLC-PDA-qTOF-MS/MS. Three different gels were prepared using the geopropolis extract, carbomer, propylene glycol, and water. Formulations with different amounts of propylene glycol were investigated. Physical, visual, pH, viscosity, adhesion, spreadability, leakage, and in vitro release tests were performed in the proposed formulations. Antifungal tests with the geopropolis ethanolic extract were carried out against six Candida species. The chemical profile of the geopropolis extract and compounds released from the formulations were analyzed after the release test. The formulations had a pH between 4.6 and 4.8 and viscosity between 535,600 and 920,400 cPs. The geopropolis extract presented excellent antifungal activity against the tested yeasts. The results of the release test in semipermeable cellulose membrane showed that all formulations containing 5%, 10% and 40% propylene glycol presented release of geopropolis extract. For adhesion and leakage tests, the gel formulation with 5% propylene glycol was more effective. Both geopropolis ethanolic extract and the liquid obtained in the release test showed the presence of flavonoids (flavonol/flavone, flavanone, and chalcones). Gel formulations with geopropolis extract that are rich in flavonoids are promising as an adjuvant treatment of vaginal candidiasis.

Landscape genomics to the rescue of a tropical bee threatened by habitat loss and climate change.

Habitat degradation and climate change are currently threatening wild pollinators, compromising their ability to provide pollination services to wild and cultivated plants. Landscape genomics offers powerful tools to assess the influence of landscape modifications on genetic diversity and functional connectivity, and to identify adaptations to local environmental conditions that could facilitate future bee survival. Here, we assessed range‐wide patterns of genetic structure, genetic diversity, gene flow, and local adaptation in the stingless bee Melipona subnitida, a tropical pollinator of key biological and economic importance inhabiting one of the driest and hottest regions of South America. Our results reveal four genetic clusters across the species’ full distribution range. All populations were found to be under a mutation–drift equilibrium, and genetic diversity was not influenced by the amount of reminiscent natural habitats. However, genetic relatedness was spatially autocorrelated and isolation by landscape resistance explained range‐wide relatedness patterns better than isolation by geographic distance, contradicting earlier findings for stingless bees. Specifically, gene flow was enhanced by increased thermal stability, higher forest cover, lower elevations, and less corrugated terrains. Finally, we detected genomic signatures of adaptation to temperature, precipitation, and forest cover, spatially distributed in latitudinal and altitudinal patterns. Taken together, our findings shed important light on the life history of M. subnitida and highlight the role of regions with large thermal fluctuations, deforested areas, and mountain ranges as dispersal barriers. Conservation actions such as restricting long‐distance colony transportation, preserving local adaptations, and improving the connectivity between highlands and lowlands are likely to assure future pollination services.

Occurrence of deformed wing virus variants in the stingless bee Melipona subnitida and honey bee Apis mellifera populations in Brazil.

The global spread of the parasitic Varroa mite has introduced a new bee to the bee horizontal transmission route for several RNA viruses that bypasses existing barriers in honey bees. From among these viruses, deformed wing virus (DWV) is now among the most widespread insect pathogens in the world. Brazilian stingless bees are a diverse group often managed in close proximity to honey bees. Therefore, we investigated the prevalence and load of DWV in 21 stingless bee (Melipona subnitida) and 26 honey bee (Apis mellifera) colonies from Brazil. DWV was detected in all colonies with DWV-A and DWV-C dominating in M. subnitida, while DWV-A dominated in A. mellifera. Average total viral loads per bee were 8.8E+07 and 6.3E+07 in M. subnitida and A. mellifera, respectively, which are much lower than DWV levels (>1E+10) found in honey bees in the northern hemisphere. In colonies introduced 30 years ago to the remote island of Fernando de Noronha, the DWV load was low (<1E+03) in honey bees but we detected higher loads (1.6E+08) in all M. subnitida colonies on the island. This may suggest that minimal, if any, viral transmission of DWV from stingless bees to honey bees has occurred on this island. Furthermore, the ubiquitous presence of the DWV-C variant in M. subnitida colonies, and its rarity in A. mellifera, may again suggest that limited viral exchange between these two species is occurring.

Population variation and island effect in Melipona subnitida (Hymenoptera: Apidae)

We examined the head morphology of island and mainland populations of the stingless bee Melipona subnitida. We employed geometric morphometrics to test for differences in head morphology and analyzed 122 colonies. Head measurements were performed using 25 landmarks and semi-landmarks. For head shape, landmarks were analyzed by generalized procrustes analysis, principal component analysis (PCA), Mahalanobis distance, discriminant function analysis, cross-validation and unweighted pair-group method clustering (UPGMA). For head size, data were analyzed by analysis of variance (ANOVA), followed by the Tukey test. In addition, the relations between head shape, head size, geographical distance and altitude were analyzed using Pearson’s correlation coefficients. Morphological analyses revealed significant differences (p<.01) between mainland and island populations. Moreover, island bees differed in head shape and head size. The first two principal components explained 69.72% of the total variation, and UPGMA revealed that the individuals collected on the Island of Fernando de Noronha differed from the remaining locations, with 100% bootstrap support. Cross-validation correctly classified 84% of the individuals into their respective locations. The results also indicated structuring of those populations introduced to and isolated on the Island of Fernando de Noronha for more than 30 years. The characterization of the studied M. subnitida populations, especially the island populations, alerts us to the fact that isolation may lead to a loss of diversity, or even of the whole population, in M. subnitida and the remaining meliponines, possibly negatively affecting biotic interactions, especially plant–pollinator interactions.Variación poblacional y efecto insular en Melipona subnitida (Hymenoptera: Apidae)Examinamos la morfología de la cabeza de poblaciones insulares y continentales de Melipona subnitida. Empleamos morfometría geométrica para probar las diferencias en la morfología de la cabeza y analizamos 122 colonias. Las mediciones de la cabeza se realizaron utilizando 25 puntos y semi-puntos de referencia. Para la forma de la cabeza, los puntos de referencia se analizaron mediante el análisis procrustal generalizado, el análisis de componentes principales (PCA), la distancia Mahalanobis, el análisis de funciones discriminantes, la validación cruzada y la agrupación de métodos de grupos de pares no ponderados (UPGMA). Para el tamaño de la cabeza, los datos se analizaron mediante el análisis de varianza (ANOVA), seguido de la prueba de Tukey. Además, se analizaron las relaciones entre la forma de la cabeza, el tamaño de la cabeza, la distancia geográfica y la altitud utilizando los coeficientes de correlación de Pearson. Los análisis morfológicos revelaron diferencias significativas (p < 0,01) entre las poblaciones del continente y de las islas. Además, las abejas insulares diferían en la forma y el tamaño de la cabeza. Los dos primeros componentes principales explicaron el 69,72% de la variación total, y la UPGMA reveló que los individuos recolectados en la Isla de Fernando de Noronha difirieron del resto de las localidades, con un 100% de apoyo de bootstrap. La validación cruzada clasificó correctamente al 84% de los individuos en sus respectivas ubicaciones. Los resultados también indicaron la estructuración de las poblaciones introducidas y aisladas en la isla de Fernando de Noronha durante más de 30 años. La caracterización de las poblaciones estudiadas de M. subnitida, especialmente las poblaciones insulares, nos alerta de que el aislamiento puede llevar a una pérdida de diversidad, o incluso de toda la población, en M. subnitida y los meliponinos restantes, afectando posiblemente negativamente a las interacciones bióticas, especialmente las interacciones planta-polinizador.

Temporal Variation in Honey Production by the Stingless Bee Melipona subnitida (Hymenoptera: Apidae): Long-Term Management Reveals its Potential as a Commercial Species in Northeastern Brazil.

Even though stingless beekeeping has a great potential as a sustainable development tool, the activity remains essentially informal, technical knowledge is scarce, and management practices lack the sophistication and standardization found in apiculture. Here, we contributed to the further development of stingless beekeeping by investigating the long-term impact of management and climate on honey production and colony survival in the stingless bee Melipona subnitida Ducke (1910). We analyzed a 10-yr record of 155 M. subnitida colonies kept by a commercial honey producer of northeastern Brazil. This constitutes the longest and most accurate record available for a stingless bee. We modeled honey production in relation to time (years), age, management practices (colony division and food supplementation), and climatic factors (temperature and precipitation), and used a model selection approach to identify which factors best explained honey production. We also modeled colony mortality in relation to climatic factors. Although the amount of honey produced by each colony decreased over time, we found that the probability of producing honey increased over the years. Colony divisions decreased honey production, but did not affect honey presence, while supplementary feeding positively affected honey production. In warmer years, the probability of producing honey decreased and the amount of honey produced was lower. In years with lower precipitation, fewer colonies produced honey. In contrast, colony mortality was not affected by climatic factors, and some colonies lived up to nine years, enduring extreme climatic conditions. Our findings provide useful guidelines to improve management and honey production in stingless bees.

Survival strategies of stingless bees (Melipona subnitida) in an unpredictable environment, the Brazilian tropical dry forest

Unpredictableenvironmentsareachallengetohighlyeusocialbeesbecauseunreliablefoodavailability, owing mainly to seasonally unpredictable precipitation rates, renders the maintenance of permanent colonies difficult. Here, we investigated the strategy of the stingless bee Melipona subnitida to cope with elevated temperatures and extended, irregular periods of drought in the Brazilian tropical dry forest. We found a high association between colony behaviour (pollen foraging and brood production) and environmental parameters (abiotic factors and availability of pollen sources), suggesting that colonies tightly adjust their activities to the respective environmental conditions. This minimises unnecessary costs related to foraging and brood rearing when forage availability is low. Additionally, M. subnitida selectively foraged at the most lucrative pollen-sources (mass- flowering trees, plants with poricidal flowers), which indicates that the colonies maximise their food intake as soon as resources are available.

Population Structure of Melipona subnitida Ducke (Hymenoptera: Apidae: Meliponini) at the Southern Limit of its Distribution Based on Geometric Morphometrics of Forewings

Bees provide fundamental services to humanity, and the world has been concerned about the rapid loss of genetic diversity that these organisms have been suffering. The stingless bee Melipona subnitida is endemic to northeastern Brazil and has high potential for the production of honey and wax; it is also an important pollinator in the Caatinga biome. Populations of M. subnitida have increasingly declined due to predatory extractivism and destruction of its habitat. However, knowledge about its population structure could give insights on strategies for monitoring and conservation of this species. Here we collected workers from nine sites located at the southern limit of the species distribution and employed geometric morphometric techniques on their forewings in search of covariance between sampling site and wing morphology. It was observed a very significant correlation between both variables, indicating that the divergence among the sampled populations of M. subnitida was due to geographical distance among the sampling sites and, hence, suggesting the formation of different groups of populations along the studied geographical zone, each one with specific characteristics. Since M. subnitida habitat has been increasingly fragmented thus difficulting the genetic flow among populations, our findings will contribute to the formulation of management and conservation plans for this species in order to preserve its genetic diversity and, hence, to contribute to the generation of income for beekeepers in meliponiculture programs.

Foraging distance of Melipona subnitida Ducke (Hymenoptera: Apidae)

The current study aimed at estimating the maximum foraging distance of the stingless bee Melipona subnitida by comparing the efficacy of two methods: training of workers with an artificial feeding source and the capture-recapture technique, which consisted at marking bees that were released at different distances from the nest, after which the number of bees that returned to the colony was recorded. Under the training method, the mean foraging distance of the three colonies studied was 1,120 m and maximum foraging distance of 1,160 m. Yet the number of recruits and reactivated foragers for each colony were quantified, the average maximum distance unil recruitment occurred was 886,66 m. In the capture-recapture method, the maximum flight distance of captured foragers ranged from 3,600 to 4,000 m, which was 2,700 m farther than the maximum flight distance recorded using the artificial feeding method. Therefore, we verified that M. subnitida is a species that can travel long distances in search for food. Our results also suggest that an abundance of resources near the nest can reduce its foraging area.

Isolation and characterization of 23 microsatellite loci in the stingless bee Melipona subnitida using next-generation sequencing

We described the isolation and characterization of 23 microsatellite loci from the stingless bee (Melipona subnitida). Out of 52 microsatellite primer pairs screened, 17 loci displayed polymorphism and 6 were monomorphic. The analysis of variability was performed in 56 individuals. The number of alleles per locus ranged from 2 to 22 among populations; values for expected and observed heterozygosities ranged from 0.125 to 1.000 and from 0.121 to 0.923, respectively. These are the first microsatellite markers characterized for M. subnitida and they will be useful in obtaining estimates of population-level genetic diversity studies in a near future.

Aspectos bioecológicos e genético-comportamentais envolvidos na conservação da abelha Jandaíra, Melipona subnitida Ducke (Apidae, Meliponini), e o uso de ferramentas moleculares nos estudos de diversidade

A abelha sem ferrão Melipona subnitida atualmente está presente em quase toda a região nordeste, em função da boa adaptabilidade ao semiárido nordestino e do potencial econômico-ecológico proporcionado pela produção de mel e pela polinização de cultivos em condições de confinamento. Apesar disso, é uma espécie ameaçada devido a processos de degradação ambiental, dentre os quais estão o desmatamento, o uso indiscriminado de agrotóxicos e o extrativismo. Tais interferências tendem a isolar as populações de Jandaíra, provocando uma queda na variabilidade genética e, consequentemente, uma redução na capacidade adaptativa da espécie. Porém, técnicas de biologia molecular estão sendo implementadas, possibilitando que populações desse tipo sejam avaliadas quanto ao seu grau de variabilidade genética. Marcadores moleculares do tipo microssatélites de DNA vêm sendo bastante usados, porém, em função do alto custo exigido para seu desenvolvimento, diversos estudos vêm empregando microssatélites transferidos de táxons próximos com amplo sucesso em estudos voltados à caracterização e à diversidade genética. Dessa forma, a presente revisão objetivou avaliar os mais relevantes aspectos bioecológicos e genético-comportamentais envolvidos na conservação da abelha Jandaíra, a fim de auxiliar na avaliação do grau de diversidade genética da espécie, bem como da sua distribuição entre indivíduos e populações da abelha sem ferrão M. subnitida.

Chemical composition and free radical scavenging activity of pollen loads from stingless bee Melipona subnitida Ducke

Bee-collected pollen (“bee pollen”) is promoted as a health food with a wide range of nutritional and therapeutic properties. In order to evaluate the chemical composition, botanical origin and free radical scavenging activity of this food, two sample pollen loads from stingless bee Melipona subnitida were studied. The yellow pollen loads were composed of three pollen types, with a predominance of Mimosa gemmulata pollen grains (98.95%); and the brown pollen showed five floral taxa, with the bright pollen grains of Fabaceae predominating (89.84%). The foraging variety specific to M. subnitida is impressive even in a rich environmental flora like the semi-arid region in Northeastern Brazil. The compounds naringenin, isorhamnetin, and d-mannitol were isolated from yellow pollen loads, and β-sitosterol, tricetin, selagin, and 8-methoxiherbacetin were found in brown pollen. Selagin is reported as a pollen constituent for the first time, and also d-mannitol, which was found in a substantial proportion (34.9%). The free radical-scavenging activities of different solvent extracts of pollen were determined using a 1,1-diphenyl-2-picrylhydrazine (DPPH) assay. This activity decreases in the order: ethyl acetate>ethanol>hexane extract, which suggests that the ethyl acetate extract of the pollen, rich in flavonoids, is a good scavenger of active oxygen species.

Pollination efficiency of the stingless bee Melipona subnitida on greenhouse sweet pepper

The present study was carried out in Northeastern Region of Brazil, in order to investigate the use of stingless bee Melipona subnitida Ducke in the pollination of greenhouse sweet pepper (Capsicum annuum L.). Treatments of hand cross-pollination, hand self-pollination, pollination by bees and restricted pollination were performed. Results showed that despite sweet pepper flowers are considered autogamous, this crop benefits from pollination by M. subnitida, producing fruits significantly heavier and wider, containing a greater number of seeds and of better quality (lower percentage of malformed fruits) than self-pollinated sweet pepper. Thus, M. subnitida can be considered an efficient pollinator of greenhouse sweet pepper.

How queen and workers share in male production in the stingless bee Melipona subnitida Ducke (Apidae, Meliponini)

Potential conflict between the queen and workers over the production of males is expected in stingless bees as a result of the higher relatedness of workers with their sons than with their brothers. This conflict was studied in Melipona subnitida by observing how the queen and the workers share in male production. The oviposition of individual cells was observed in two colonies with individually marked workers for a period of 51 and 40 days respectively. The gender that developed from these cells was then determined. The results revealed that most male production was concentrated in a 2–3-week period, during which laying workers were present. During these weeks, the queens produced twice as many males as all laying workers together. Outside this distinct period, the queens produced an occasional male. A reproductive worker either oviposited before the queen did, in which case she immediately proceeded to close the cell and thus prevented the queen from oviposition, or oviposited and sealed the cell after the queen had laid an egg. When cell construction and oviposition occured on several combs simultaneously, the workers preferentially laid male eggs on the newest combs. We discuss the proximate mechanism and ultimate cause of the way in which queen-worker male production occurred. In conclusion, we argue that overt behavioural conflict, occasionally displayed by reproductive workers of this species, can be of great cost to the colony.

Adaptação e comportamento de pastejo da abelha jandaíra (Melipona subnitida Ducke) em ambiente protegido

The effect of caged environment on the foraging behavior of the stingless bee Melipona subnitida Ducke was studied in the state of Ceara, NE Brazil. Species adaptation to enclosures, foraging behavioral aspects and daily foraging pattern were investigated in a greenhouse sweet pepper ( Capsicum annuum L.) crop. Data were analyzed by Anova and means were compared a posteriori using Tukey test. The results showed that M. subnitida Ducke adapts well to greenhouses and forages throughout the day. It may be concluded that this bee species can be used for crop pollination in protected environments.

Clustered male production by workers in the stingless bee Melipona subnitida Ducke (Apidae, Meliponinae)

In stingless bees brood cells are sequentially filled with liquid larval food (mass-provisioning), upon which the queen lays an egg. Thereafter the cell is closed by a worker. This study showed that during these processes workers of Melipona subnitida regularly laid eggs that served as food for the queen. Occasionally cells were oviposited in and immediately closed by a worker. These cells always rendered males. Some of these reproductive workers were seen to lay a trophic egg as well. Cells which were exclusively oviposited in by the physogastric queen gave rise to workers and queens only. In one colony it could be verified that three workers alone, which differed in age by one day, laid 15 male-producing eggs within a period of two successive weeks. Among them the number of ovipositions was positively related to the order in which workers eclosed - the oldest worker laying most eggs - and inversely related to the number of times they closed cells oviposited in exclusively by the queen. Apparently the physogastric queen was not able to stop certain workers from reproducing. We therefore conclude that some workers in M. subnitida temporarily dominated their queens in egg-laying.