POLLEN SPECTRUM OF HONEY PRODUCED IN CERRADO AREAS OF MINAS GERAIS STATE ( BRAZIL )

The pollen spectra of honey samples collected in five apiaries situated near cerrado areas in Minas Gerais State, Brazil, were studied from April 1996 to April 1998 in order to establish the contribution of different plant species in pollen or nectar production The honey samples were characterized by the following native species: Astronium sp., Alternanthera sp., Schinus sp., and Serjanea sp. The pollinic participation percentage of those species was related to the degree of preservation in the areas.


INTRODUCTION
Located in central Brazil, cerrado vegetation constitutes an important ecosystem, for both economic and ecological reasons (Carneiro, 1982).It includes about 120 million hectares, of which about 90% is in the states of São Paulo, Minas Gerais, Mato Grosso, Goiás, and Bahia.
The State of Minas Gerais presents great diversity in its vegetation covering, a great part of which consists of a complex of cerrado.This complex is physiognomically homogeneous, even though the floristic surveys show a great wealth in number of species and great variety in the floristic composition (Brandão, 1991).
The areas covered by cerrado are characterized in accordance with their diversified vegetation, richness of nectar-polliniferous elements, and low density of arboreal elements, which facilitates the rational handling of beehives and as well as a great number of beekeepers.
Bees depend on flowers for food, and plants benefit by pollination in a quite profitable relationship (Pirani & Cortopassi, 1993).Pollen and nectar from flowers constitute practically the only food source for bees, from larval through adult phases (Freitas, 1991).
Pollen supplies bees with proteins, lipids, vitamins, and minerals, being the only nitrogenated source of food available for feeding the larvae.Lacking pollen, the beehive neither grows nor develops and in the absence of protein may die.
Nectar is the basic energy source of bees and the into lipids and glycogen they transform into honey (Freitas, 1991).When extracted from honey storage cells it contains nectar and pollen from different plant species (Santos, 1960;Barth & Melhem, 1988).The pollen grains in honey serve as indicators of its geographic origin and main botanical sources.
The present work aims to study the pollen spectra of honeys produced during the dry season in areas covered by cerrado, correlating them with their botanical and geographic origins.

MATERIAL AND METHODS
The studied areas were chosen for being representative of the typical cerrado vegetation, partly preserved and partly anthropically disturbed.Monthly systematic collections were made from April 1996 to April 1998 of both mature honey and blooming species.Plants were identified and stored in the herbarium of the Empresa de Pesquisa Agropecuária do Estado de Minas Gerais (EPAMIG).
Reference slides of pollen from plants were made according to the direct method (Louveaux et al., 1970).Anthers were removed from flower buds of fresh and herbarium plants and pollen grains concentrated with the aid of a drop of alcohol in the center of a glass slide.The grains obtained by this procedure were put in glycerin jelly on glass slides and sealed with paraffin.These slides were included in the reference slide collection of the Serviço de Microscopia of the Fundação Ezequiel Dias (FUNED) for later comparison with the pollinic types found in the honey samples.

Obtainment of honey sediment for microscopic analysis
The preparation of honey samples followed the standardized method of Louveaux et al. (1970): 10 g of well-homogenized honey were dissolved in 20 ml of distilled water and centrifuged during 3 to 5 minutes at 2500 rpm.The decanted sediment was washed with 5 to 10 ml of distilled water.After another centrifugation, the sediment was resuspended in 5 ml of 1:1 glycerin:distilled water and then centrifuged again, decanted, and mounted with glycerin jelly on microscopic slides which were sealed with paraffin.
The pollen types found in the honey samples were identified, counted, and classified, according to their percentages, as dominant pollen (more than 45% of the total pollen grains counted), accessory pollen (from 15% to 45%), important-isolated pollen (from 3% to 15%), and occasional-isolated pollen (less than 3%).Between 300 and 500 pollen grains were counted (Barth, 1970a, b, c).
Sub-factors and super-representation were considered in interpreting the data (Barth, 1989).

Municipality of Cachoeira da Prata
During the experiment (April 1996 to April 1998), 11 samples of mature honey produced in the municipality of Cachoeira da Prata were analyzed.These samples showed (Table 1) 38 pollen types in the qualitative analysis.Dry-season honeys were the richest, with 36 pollen types, and rainy-season ones the poorest, with 13 types.
During the dry season, the pollen of Astronium sp.(aroeirão) (Fig. 1.1) was classified as accessory pollen (34%).This is a nectariferous species and the main source of maintenance honey for the beehives in preserved cerrado areas (Bastos et al., 1998).Pollen grains of Eucalyptus sp. (Fig. 1.2) were classified as dominant pollen (43.15%).This confirms the nectariferous and polliniferous potential of this abundantly-blooming, exotic genus cultivated in reforestation areas around the apiary.Similar data had already been obtained in previous studies in the Zona da Mata area (Bastos, 1995a, b).During the rainy season, the pollen of Mimosa sp. (Fig. 1.3) was dominant (65.41%) and that of Eucalyptus (Fig. 1.2), which was not at blooming peak during this season, was classified as occasionalisolated pollen.The honey produced in this season was characterized as wild and heterofloral, with dominance of Mimosa sp. (Fig. 1.3) and also presenting the following pollen types: Eucalyptus Characteristic plants of anthropic areas were present as occasional-isolated and isolated pollen in the two studied seasons, being represented by the genera: Baccharis (Fig. 1.4), Elephantopus (Fig. 1.7), Eupatorium (Fig. 1.5), Vernonia (Fig. 1.9), Hyptis (Fig. 1.8), Mimosa (Fig. 1.3), and Sida, confirming once again the great apicultural potential of these ruderal species (Bastos, 1995).
Exotic species like Antigonum leptopus (Fig. 1.10), a typical garden plant, and Eucalyptus sp. (Fig. 1.2), present in reforestation areas, were visited by the bees.In the crops of 1996/1998 in the Municipality of Cachoeira da Prata, the nectar and pollen sources for the beehives were the components of the cerrado flora, the local ruderal flora, and Eucalyptus sp.

Municipality of Jaboticatubas
Eleven samples of mature honey were obtained in the Municipality of Jaboticatubas from April 1996 to April 1998.In the qualitative analysis of the samples (Table 2), 33 pollen types were observed, for which the dry season was the richest, with 33 types, and the rainy season the poorest, with 20 types.
The quantitative analysis (Table 2) demonstrated the participation of typical cerrado species and anthropic flora in the honey composition.In the dry season, Eucalyptus sp. (Fig. 1.2) was dominant pollen (49.61%).Due to the presence around the apiary of some plants of Astronium sp.(aroeirão -Fig.1.1), typical of cerrado areas, its pollen was represented as accessory (41.28%).
The area around the apiary is highly degraded and the great influence of the few specimens of Eucalyptus sp. in the surroundings can be observed in the honey.The genera Astronium and Schinus appeared as accessory pollen, indicating a smaller number of representatives of these genera in the degraded cerrado areas of the Municipality of Jaboticatubas.
In the crops of 1996-1998 in the Municipality of Jaboticatubas, the nectar and pollen sources for the beehives were the components of the cerrado flora, the local ruderal flora, and the Eucalyptus sp.

Municipality of Matozinhos
Thirteen samples of mature honey were obtained in the Municipality of Matozinhos, in the period from May 1996 to October 1998.In the qualitative analysis of the samples (Table 3), 32 pollinic types were observed, the dry season being the richest, with 29 types, and the rainy season the poorest, with 20 types.
The quantitative analysis (Table 3) demonstrated the participation of some typical cerrado species, anthropic flora, and exotic species of Eucalyptus.
During the dry season, the main accessory pollen in honey composition honey was represented by the genera Astronium -24.85% (Fig. 1.1) and Eucalyptus -35.44% (Fig. 1.2).In the rainy season, there were no representatives at this level.
In the rainy season, the principle dominant pollen in honey composition was represented by the genus Mimosa -76.41% (Fig. 1.3).
The main isolated pollen in honey composition was represented by the genera: Alternanthera, Mimosa (Fig. 1.3), Antigonum (Fig. 1.10), during the dry season and by Euphorbia, Anadenanthera (Fig. 2.13), and Eucalyptus (Fig. 1.2) in the rainy season.The other pollen types were represented as occasional-isolated pollen and characterize the geographical origin of the honey: Ruelia sp. (Fig.  1.15).Among these, some are characteristic of cerrado and others of anthropic areas.

Municipality of Prudente de Morais
Eleven samples of mature honey were obtained in the Municipality of Prudente de Morais from May 1996 to October 1998.In the qualitative analysis of the samples (Table 4), 36 pollen types were observed.The dry season was the richest, with 31 types, and the rainy season the poorest, with 24 types.
During the rainy season, the dominant pollen was represented by the genus Mimosa (47.87%) and the accessory pollen represented by Eucalyptus sp.(21.96%).The important isolated pollens in honey composition were represented by: Astronium sp. (Fig. (Fig. 2.17).The pollen percentage of these species is related to the representativity of Eucalyptus.Those species have been mentioned as being typical of cerrado, and their pollen types were described by Laboriau (1973).Around the apiary is a large Eucalyptus reforestation area frequently visited by honeyproducing bees.A similar fact was observed in previous studies (Bastos, 1995a, Bastos et al., 1995b).
The genus Astronium was responsible for the honey production in all the studied municipalities and is the most important indicator of the geographical origin of honey produced in this ecosystem.
In the crop of 1996-1998 in the municipality of Prudente de Morais, the components of the cerrado flora, the local ruderal flora, and the Eucalyptus sp., were observed to be the nectar and pollen sources for beehive maintenance.

Municipality of Santana do Riacho
Eleven samples of mature honey were obtained in the municipality of Santana do Riacho from April 1996 to October 1998.In the qualitative analysis of the samples (Table 5), 50 pollinic types were observed, the dry season being the richest, with 46 types, and the rainy season the poorest, with 28 types.
The quantitative analysis (Table 5) demonstrated the contribution of typical cerrado species to the honey composition.There was no dominant pollen, which characterizes the honey produced in this area as wild and of heterofloral origin.
The isolated pollen, present in the dry-season samples, that constitutes good nectar and/or pollen sources was represented by the genera: Tagetes sp. and Vernonia sp. (Fig. 1.9), both representatives of anthropic flora, and the genera Aeschymone sp. (Fig. Pollen of Eucalyptus sp. was absent from the analyzed samples because the apiary was far from reforestation areas and the bees collected a large number of pollen types (50).This demonstrates that, where Eucalyptus sp. is absent, there is widespread foraging by the bees, guaranteeing enough pollen for brood feeding and nectar for the production of wild and organic honey, so popular in foreign markets.The honey produced in this cerrado area can be differentiated from the honeys produced in anthropic and mountainous areas of the State of Minas Gerais, where the genus Eucalyptus sp. is dominant in the pollen spectrum (Bastos, 1995a, Bastos et al., 1995b).

CONCLUSIONS
Some of the cerrado areas studied have species represented in the food collected by the bees throughout the year and others in certain periods, due to colony preferences and blooming peaks of the botanical components.
The several plant species bloomed at different times of the year, characterizing two different seasons in the apicultural year, each one with its most important species for the colonies: The pollen spectra of the honeys from the cerrado areas studied in Minas Gerais under similar climatic conditions is characterized by the dominance of pollen of the genus Astronium, with the contribution of Eucalyptus during the dry season and dominance of the genus Mimosa and contribution of Eucalyptus during the rainy season.In the cerrado areas where there is no influence of Eucalyptus, the dominant pollen in the two seasons is that of the genus Astronium, with the contribution of the genus Serjanea ("cipó-uva" or "timbó").