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Floral Sources and Pollen Morphology of Tetragonisca Angustula (Apidae: Meliponina) in Fragments of Atlantic Rain Forest Vegetation, in Southeastern Brazil

Juliana Braga 1, Rodrigo Nunes 1, João S. Neto 1, Marilena M.Conde 2, Érika O. Sales 3, Ortrud.M. Barth 4, Maria C. Lorenzon 5

1- Post graduating –IZ/UFRRJ, Km 7, Rod 465, Seropédica, 23871-000, Brazil, 2- MSc, Botanic Department-IB/UFRRJ, Km 7, Rod 465, Seropédica, 23871-000, Brazil, 3- Biologist, Lab de Palinologia, Brazil, 4- DSc., Lab de Palinologia, UFRJ, Rio de Janeiro, Brasil., 5- DSc, Animal Science Department-IZ/UFRRJ, Brazil [email protected]

Abstract Regarding the development of strategies for rational exploitation of stingless bee species and such relations on their forager behavior it becomes necessary to know what species are used as resources by bees in a specific area. The aim of this survey was to identify the plant species most visited by Tetragonisca angustula (jatai bee) and their pollen types. The study was carried out in the ocean-side Atlantic coast, southeastern Brazil. The vegetation of the study sites lies in the Atlantic Rain Forest and largely supports a closed-canopy forest. Over eight months bee sampling was haphazard monthly whenever flowering in the undestory were encountered, considering as far as possible the overall abundance. In the study of pollen grains for the reference material the acetolysis method was used. There were 25 plants visited by jatai bee. Among them stand out Allophilus species, Schinus molle , Tradescantia zebrin, Reisseckia smilacina , Myrsine coriaceae , Psidium guajava , aculeatissimum , Wedelia paludosa , Tapirira guianensis , Baccharis dracunculifolia , Schilozobium parahyba , Inga edulis and Solanum asperolanatum . There were no marked differences between pollinic types, the particular differences are only present on the surface of pollen grains. This survey suggests a high value of the trophic niche width of Jataí bee in the undestory of Atlantic Rain Forest.

Key Words- floral biology, pollen types, trophic niche, Meliponina, forest vegetation

Introduction In tropical ecosystems, wild bees play an important role for the maintenance of animal and plant communities. Accoding to Kerr et al . (2001) 30 to 80% of the plants are pollinated by one or more species of stingless bees (Meliponina) in their biomes. The survival of these bee species is related to one of the largest biomes in danger, the Atlantic Rainforest, which has one of the highest rate of biodiversity on the planet. This ecosystem suffers strong fragmentation and degradation due to human occupation, crops and livestock production, maintaining 7.6% only from its original area (SOS Mata Atlântica Fundation 2009). Among Meliponina, Tetragonisca angustula (jatai bee) is a species of wide geographical distribution in Brazil and nests in different substrates. Jatai bee is a gentle species, easily adjustable to the management required for its beekeeping by collecting honey or to pollininate crops (Kleinert & Fonseca 2009). To protect this species it is essential to know the attractive plants in their natural habitats. The identification of plants by forager bees by direct observation in the field can highlight the sources that stand out in their diet. This information allows the spread of certain floral species and also helps the beekeepers to organize a floral calendar and field tasks to better manage the beehives. The collecting of pollen from bee hives can also provides important information about trophic niche of bees (Louveaux et al ., 1978); this method is adequate for pratical purpose of verifying the botanical origin of pollen loads. 2

The purposes of this study were: (1) to identify the plant species mostly visited by Tetragonisca angustula in the Atlantic rainforest vegetation, using two different methodologies; (2) to describe their pollen morphology.

Methodology

The study was carried out in four regions of the state of Rio de Janeiro (Brazil) (22- 23º’S, 43-44ºW), two of them were in islands and the other was in mainland; the vegetation of these regions lies in the Atlantic Rain Forest, and largely supports a closed-canopy forest (Dense Ombrophilous Forest), a secondary growth forest, greenlands, mangrove, salt marsh and beach vegetation. In this forest, there are also some patches of human disturbance. The canopy is high, ranging from 30 to 40m in height. Firstly, the sampling of bees and plants visited were made using direct observation. Periodical sampling was made at two sites in each region, using trials and dirt road, about 8- 10m from the forest edges and 400 m of length, on the interface of the forest, which included some human influence and areas of well developed forest. Restricted areas were delimited at each site and the same route was taken on each sampled day. Most observed vegetation was confined to the understory, or subcanopy, composed by climbers, liana, herbaceous and shrubs plants, i.e., most trees were difficult to access. Jatai bees were caughted while visiting using insect nets. Sampling started in March 2008 and finished in October 2008, with two sampling per region at monthly intervals, the sites were chosen at random, and sampled 6h per day (6:00 to 12:00 AM). To reach the subcanopy, nets were attached to long poles (about 7m) Bee sampling was haphazard whenever flowering plants were encountered, considering as far as possible the overall abundance. Prolonged stay at a patch, more than 10 min, was avoided. Plant species were considered as actratives by bees when visited by more than five bees during 5 to 10 minutes. The plants were prepared as vouchers and identified with the help of specialized literature, consulting other collections and scientists belong to Universidade Federal Rural do Rio de Janeiro. The other method to know the plants visisted by jatai bee was done by collecting the pollen loads. During four months, the pollen loads were collected in 20 jatai hives, which belongs to a beekeeper located in one of the studied regions (Figure 1). For each time we captured five bees entering the hives, to take off the loads of its baskets; a total of 50 samples was obtained. Pollen analysis was carried out using the direct methodology (Louveaux et al. 1970) and acetolysis (Ertman 1960). Photomicrographs of pollen grains were also obtained and cataloged. Pollen identification used literature data (Barth 1989) and the reference pollen slide collection of the Laboratory of Palynology, Institute of Biology, Universidade Federal do Rio de Janeiro .

A B

Fernanda - UFRJ Fernanda - UFRJ

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C D

Fernanda - UFRJ

Figure 1 - Jatai bee foraging and its beekeeping. (a) in flowers, (b) meliponary, (c) the entrance and the nest (d) of the hive.

Results and Discussion

Through the direct observation, it was observed that Tetragonisca angustula visited 25 plant species, of these 11 species with low visitation by bees. The other species collected, 72% occur in Ilha Grande, 14% in Itacuruçá, 14% in Tinguá and Ariró no plant showed a considerable number of bees. The region more preserved has more bee plant species. Asteraceae and Leguminosae were the plant families best represented in the collection (three species each; and Anacardiaceae showed each one two plant species and Sapindaceae, Commelinaceae, Myrtaceae and Rhamnaceae showd only one species each. Asteraceae and Leguminosae have been related by other authors as plant families most preferred plant families by jatai bee. Studies conducted in Riparian Forest (South Brazil) (Garcia et al. 2008) identified 10 plant species visited by T. angustula , belonging to six families: Asteraceae (3), Leguminosae (2), Myrtaceae (2) e Rutaceae (2) e Euphorbiaceae (1). Of related species, Albertina brasiliensis Spreng. (Asteraceae) is the most visited plant, with the highest flower density and easy access to T. angustula , which highlights as an important source of food resources. In our study, we point out some plant species with high density and presenting great facility to be gathered by jatai bees. Important resources for bees were: Schinus molle L., Allophylus petiolulatus Radlk., Tradescantia zebrina , Reisseckia smilacina (Sm.) Steud., Schilozobium parahyba (Vell.) Blake, Inga edulis Mart., Tapirira guianensis Aubl. and Baccharis dracunculifolia DC., presenting about ten bees per plant. Myrsine coriaceae (Sw.) R. Br, Psidium guajava L., Solanum aculeatissimum Jacq., Wedelia paludosa DC. and Solanum asperolanatum Ruiz & Pav. have been occasionally visited. The lack of visits to plants of the same species in the localities shows that they are under anthropogenic pressure, making the T. angustula use the resources according to the availability and abundance of these. Anthropogenic pressure is reducing the number of these important bee plants in the studied regions. The pollen loads collected in Ilha Grande showed the presence of 22 pollen types, belonging to 17 plant families. Ulmaceae ( Trema micrantha ) and Meliaceae were the most frequent pollen types detected in this study. Asteraceae, Malpighiaceae, Leguminosae, Myrtaceae (Eucalyptus) and Ulmaceae ( Trema micrantha ) were the plant families comprising several pollen types (two types of each). Other plant families identified in pollen loads can be important throphic resources. They show a strong diversity in pollen types: Asteraceae (Piptocarpha type), Bignoniaceae, Brassicaceae, Caesalpiniaceae, Cecropiaceae ( Cecropia type), Euphorbiaceae ( Sapium type), Loranthaceae ( Struthanthus type), Piperaceae ( Piper type), Poaceae, Polygonaceae, Symplocaceae and Ulmaceae ( Celtis type). 4

Using pollen analysis of bee loads, Simioni et al. (2007) observed foraging of 43 plants by T. angustula , being Leguminosae highlighted as the main provider of pollen, followed by Asteraceae. This variation in floral preference by T. angustula is probably due to variations in the physiognomy of its habitat, composition and abiotic conditions. There were no marked differences between pollen types, the particular differences are only present on the surface of pollen grains. Bellow we present the description of pollen morphology according to figure 2: Albertina brasiliensis Spreng. - Pollen grains monads, apolar, medium size, radiosymmetry, spheroidal form, amb rounded, 3-colporate, surface with spines 4.2µm high and exine 2.6µm thick. Allophylus petiolulatus Radlk - Pollen grains of monads, isopolar, small size, amb triangular with rounded corners, 3-porate, surface microreticulate and exine 1.6µm thick. Baccharis dracunculifolia DC. - Pollen grains of monads, isopolar, radiosymmetry, small size, amb subcircular to circular, 3-colporate, surface with conical spines 2.0µm high and exine 1.4µm thick. Inga edulis Mart. –Pollen grains assembled in polyads of very large size. Each pollen grain of small size, psilate surface and exine 1.7µm thick. Myrsine coriaceae (Sw.) R. Br. - Pollen grains of monads, isopolar, small size, radiosymmetry, prolate spheroidal form, 3-colpate, surface psilate and exine 2.2µm thick. Reisseckia smilacina (Sm.) Steud. -. Pollen grains of monads, isopolar, radiosymmetry, medium size, subprolate, amb subrounded, 3-colporate, endoapertures lolongadas, surface microreticulate and exine 1.7µm thick. Schilozobium parahyba (Vell.) Blake. - Pollen grains monads, isopolar, radiosymmetry, small to medium size, amb circular, 3-colporate, surface microreticulate and exine 1.0µm thick. Schinus molle L. - Pollen grains of monads, isopolar, radiosymmetry, small to medium size, amb subcircular, 3-colporate, longicolpate, surface striate-reticulate and exine 1.4µm thick. Solanum aculeatissimum Jacq. - Pollen grains of monads, isopolar, small size, radiosymmetry, prolate spheroidal, amb rounded, 3-colporate, endoapertures lalongates, surface psilate and exine 1.6µm thick. Solanum asperolanatum Ruiz & Pav. - Pollen grains of monads, isopolar, radiosymmetry, small size, prolate spheroidal, amb subtringulate to rounded, 3-colporate, surface psilate and exine 1.3µm thick. Tapirira guianensis Aubl. - Pollen grains of monads, isopolar, radiosymmetry, small size, prolate spheroidal, amb subcircular to circular, 3-colporate, longicolpate, endoapertures lalongates, surface striate and exine 1.5µm thick. Wedelia paludosa DC. - Pollen grains of monads, isopolar, radiosymmetry, small size, amb rounded, 3-colporate, surface with spines, 3.9µm high and exine 1.0µm thick.

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These are some of these plant species:

Schinus molle , Baccharis dracunculifolia, Inga edulis, Solanum aculeatissimum, Albertina brasiliensis, Wedelia paludosa, Tapirira guianensis , Myrsine coriaceae

Acknowledgements

This study was supported by FAPERJ. We are grateful to Fundação Instituto Estadual do Meio Ambiente (INEA) for allowing part of this work. Special thanks to local beekeepers and to Dra. Leila Morgado for valuable contributing in the field.

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Figure 2 - Description of pollen morphology. 1-Inga edulis (40x), 2- Albertina brasiliensis (100x) , 3- Schinus molle (100x) , 4- Solanum asperolanatum (100x) , 5- Myrsine coriaceae (100x) , 6- Wedelia paludosa (100x) , 7- Tapirira guianensis (100x) , 8- Reisseckia smilacina (100x) , 9- Schilozobium parahyba (100x) , 10- Allophylus petiolulatus (100x) , 11- Solanum aculeatissimum (100x) , 12- Baccharis dracunculifolia (100x) .

References

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