Diversity of Meliponini and anothers Apiformes (Apidae sensu lato) in a Cerrado fragment and its surrounding, Campo Grande, MS

The aim of this study was to evaluate the diversity of Meliponini and anothers Apiformes (Apidae sensu lato) from a Cerrado fragment and its surrounding. Malaise traps were installed in a pasture near a fragment of Cerrado and its surrounding, from October to December 2010. Samples were collected at seven-day intervals and preserved in Dietrich solution. The apiforms specimens from each sample were separated in morphospecies and sent to identification. The tribe Meliponini was the most abundant in open areas of pasture than in the Cerrado fragment. The Meliponini species present were Trigona gr. fulviventris, Paratrigona lineata, Trigona recursa, Partamona sp, Trigona spinipes, Trigona gr. hyalinata, Trigona gr. fulviventris, Tetragonisca fiebrigi, Tetragona clavipes, Frieseomelitta cf. flavicornis, Lestrimelitta rufipes. The dominant species was Paratrigona lineata, comprising 82.47% of all species collected.


Introduction
Bees are responsible for the pollination of plants in general, ensuring the fruit formation and the perpetuation of plant species. On the other hand, bees are rewarded with nectar supply and pollen from the plant flowers visited. According to Kerr et al. (1996), these insects are responsible for 40 to 90% of the pollination of native plants in a tropical environment. They are the best pollinator in Cerrado Biome, where they pollinate 60 to 75% of all plants species (Silberbauer-Gottsberger & Gottsberger 1988).
In Brazil there are about 3,000 bee (Apidae) species described, from a total of 17,533 bee species described in the world, with recent estimations of 20,000 (Michener 2007). Many species of native bees are in danger of extinction for several reasons. Among the main factors responsible for the extinction of bees are the fragmentation of original vegetation and the use of non-selective insecticides (Turner 1996, Kerr et al. 1996. Bees of the Tribe Meliponini, otherwise known as native stingless bees, are important pollinators for plants like strawberry, guarana, açai, coffee, and other cultivated species (Malagodi-Braga & Kleinert 2004).
The maintenance of honeybees in the field is very important for crop plants, but this practice is not very common in developing countries. In the United States the annual value of pollination by bees has been estimated at US$ 14,6 billion, thus justifying its importance for agriculture (Morse & Calderone 2000). The levels of plant pollination in Brazil are usually unsatisfactory, which cause reduction of crop yields, particularly those that depend on pollinators such as bees (Imperatriz-Fonseca 2010).
Currently, public policies are being discussed in order to assess the necessity of maintain native vegetation areas, their efficiency in maintaining beneficial organisms in adjacent areas, and how to measure this efficiency or interference in the altered environment. According to Freitas et al. (2009), the causes of pollinators' population declining in agricultural areas may be the deforestation of native vegetation, inadequate use of agricultural practices, such as the use of pesticides and monoculture. Native vegetation areas have nectar and pollen source plants for pollinators, and continuously provide flowers throughout the year for nesting and breeding (Larsen et al. 2005). However, little attention has been given to the impact of agricultural products on pollinators, especially in cultivated areas (Freitas & Pinheiro 2010). Identifying the diversity of bees present in cultivation sites close to native vegetation areas can become a tool in the evaluation of the effect of agricultural practices.
Therefore, the aim of this work was to estimate the diversity of Apidae family (sensu lato) in a Cerrado fragment and its surrounding in Campo Grande, MS, Brazil.
The samples were collected once a week, during a period of four weeks. The collected material was packed in glass vials containing 70% alcohol. In the laboratory the Apidae family (sensu lato) (apiforms) were removed from the total samples and were separated in Tribe Apini, Meliponini, Bombini and Euglossini. Dr. Gabriel Mello from Universidade Federal do Paraná, PR, carried out the Identification.
The type of soil is neossolo and the climate is humid tropical, characterized by a pronounced dry season in the winter and rainy season in summer, annual average temperature is 23.0 °C. At the time the experiments were carried out the temperature was high and there was a lot of rain. The seasonal climate date was obtained from a center installed at the University Farm (Table 1).
The area has three remaining fragments of the original vegetation of Cerrado Biome and constitute the Legal Reserve of the Property according to the current Forest Code. These three areas have 9.9 ha, 5.2 ha and 0.6 ha respectively, comprising a total of 15.6 ha of native vegetation. The most common trees in the area are Pau-terra-folhagrande (Qualea grandiflora Mart.), pau-terra-folha-pequena (Qualea multiflora Mart.), pau-pombo (Matayba ghuianensis Aubl.), Capororoca (Myrsine ferrugínea Spreng.), pimenta-de-macaco (Xylopia aromatica (Lam.) Mart.) and lixeira (Curatella americana L). These species together make up more than 50% of the wealth of the three fragments of tree presents. Some species of figueira (Moraceae) and many individuals of Alibertia sessilis Vell.
In this study, nine species from Meliponini were found:   (2008), working in a Cerrado area in São Paulo State, observed greater abundance of the subfamily Apidae, or A. mellifera (55.8%), followed by Trigona spinipes (14.4%) and Exomalopsis sp. (8.3%). The authors concluded that the low diversity of bees might be due to fragmentation and the plantation of exotic species (Pinus and Eucalyptus) in the surroundings areas of this fragment. In a survey developed at the Private Reserve of Natural Heritage Eliezer Batista, State of Mato Grosso do Sul, Aoki et al. (2012) reported bees belonging to A. mellifera as the most abundant species (50% of total). It was observed a variation according to the collection area (pasture and cerrado fragment) and sampled week (Figure 1). This could be explained by the fact that these insects are known as good flyers and live in social colonies. As a consequence, it could increase the probability of occasional catches in certain areas, with varying resource availability. The local climate, temperature, rain and wind may also help to understand the changes between different weeks of collection. The predominance of stingless bees (Meliponini) in the pasture area (Figure 1) may be due to a large capacity of flight to catch pollen from the flowers, which is more accessible in open areas.
In the pasture area it was observed an increase in the abundance of Meliponini at the three first weeks, with 129, 158, and 209 individuals captured. But in the fourth week a reduction was observed (176) (Figure 1). When fewer individuals were collected, it was observed a decrease in temperature (Table 1). The average temperature during the experiment ranged from 19 to 24°C, indicating excellent conditions for foraging. However, in the third and fourth week, heavy rains occurred with a total of 51.6 and 43.40 mm (Table 1). This cannot be the cause of a reduction in the number of collected individuals observed in all experimental areas.
Considering only Meliponini in the Cerrado fragment, it was observed a small number of stingless bees compared to the pasture area, for all traps, totalizing 258 individuals, whereas in the pasture area, 672 individuals of stingless bees were collected. However, a reduction was observed in the first and fourth week of collection (pasture and Cerrado fragment). In addition, an increase in the third week was observed (Figure 1).
The population dynamics of insects in the field is directly related to weather conditions, rain, wind and especially temperature. According to Silveira Neto et al. (1995) temperature is an important factor in the activity of the bees, which prefer a time of the day when the temperature is around 25°C for foraging. Thomazini & Thomazini (2002) reported that an increase in temperature and less rain, increased bee numbers, at Rio Branco, Acre. According to Kerr et al. (1996) around 400 species of Meliponini were described and at least 100 are in danger of extinction due to human activities, and to the loss of natural habitats. According to Imperatriz-Fonseca (2010) it is necessary the conservation of the forest for the maintenance of bee populations and pollination services on agricultural landscapes.
The colonies of stingless bees, unlike Apini, have multiple queens or bee masters, but only one queen is fertilized. In order to breed, the worker bee stay in the alveoli, which is full of honey, pollen and glandular secretions, where the larvae feed alone. The honey is deposited in pots of wax nests of hollow trees, wood and abandoned termite mounds. However, the species Trigona spinipes (Fabr.), bee Arapuá, is a citrus pest, which destroys leaves and flowers. In the case of native bees, which are social insects, pollen is used to feed the larvae, after collected from nearby plants. Therefore, the availability of flowers also influences the dynamics of the population. Social bees have no food preference, like Apis mellifera (Apinae) and T. spinipes (Meliponini), which explains the abundance of different species of plants (D'Avila & Marchini 2008).
In this study the most frequent species was Paratrigona lineata (Lepeletier 1836) with 82% (n=767) of all Meliponini captured, 72% in pasture and 28% in Cerrado area. A lower proportion was Trigona gr. fulviventris with 15% (137) of individuals captured, 41% in pasture and 59% in Cerrado area. The other species identified were only occasionally collected and in fewer numbers. Most individuals were captured in traps in the pasture area, 100 meters from the Cerrado fragment, with a total of 672 individuals. For the traps in the forest, a total of 258 individuals were captured, however, the same proportion of was maintained (Figure 2).
According to Caceres & Legendre (2009) 'indicator species" are recognized by ecologists when they are restricted to one or a few habitat types. In this study all species of Meliponini occurred in both sites. Therefore we were not able to point out an indicator species to monitor environmental changes. Lima & Silvestre (2017)