**3. DNA barcode**

One of the biggest problems faced today by researcher is the lack of specialized personnel to identify biodiversity. In times of a rapidly changing world and fast loss of habitats and biodiversity, it is almost impossible to measure the existing species in the ecosystems. There is a lack of identification keys and genera revisions. The taxonomists are few and normally have more complexes problems to focus the simple species identification for the general public or to scientists from other science areas. The development of alternative tools to assess biodiversity other than traditional taxonomy is an urgent need.

At this point, the astonishing development of molecular biology in the last years has indicated new alternatives that can be used to identify species. Since the final of the last century, mitochondrial DNA (mtDNA) has been used as a very interesting and powerful alternative tool. This molecule has an enormous potential due to extremely peculiar and unique characteristics, like being a small circular genome, with high evolutionary rates but well conserved in animals (Arias et al., 2003). In neotropical stingless bees, it has been largely used in populational studies and in the evaluation of genetic diversity (Francisco et al., 2001; 2008; Brito & Arias, 2005; May-Itzá et al., 2010).

Although very controversial, the use of this molecule to identify species was proposed in 2003. Based on the principle that differences on the sequence of the genes are greater between species than within species, the proposition consists in sequencing approximately 650 base pair from the beginning of the Cytochrome Oxidase I (CO-I) gene and comparing it among the species (Herbert et al., 2003). According to recent revisions, the studies show the efficiency of these genic regions to discriminate species and it is working well in the vast majority of the animal cases studied until that moment (more than 95%) (Vogler and Monaghan, 2007; Waugh, 2007).

In fact, the use of a mtDNA sequence to identify cryptic species is constantly reported in literature. However, the standardization of the procedures and the establishment of some guidelines are the novelty in the DNA barcode proposition (Brown et al., 1999; Mitchell and Samways, 2005). Briefly, the following sequence is proposed in this procedure:


 an accurate organization of large data bank available to the general public at the CBOL (Consortium for the Barcode of Life) website (Mitchell, 2008).

In bees, some studies are corroborating the effectiveness of the technique in species identification. The complete bee fauna of a taxonomically well resolved region was tested and the 150 species were correctly identified. Together with these results, they also identified some cryptic species and joined individuals from different sexes in the same species. In this last case, most of these species description was based in individuals from only one gender (Sheffield et al., 2009).

Another example is the use this approach, combined with traditional morphological analysis, in a study of a taxonomically extremely difficult group of bees, the subgenus *Dialictus* (family Halictidae; genus *Lasioglossum*). In this case, DNA barcoding proved essential for the delimitation of numerous species that were morphologically almost indistinguishable. The main conclusion of these studies is that DNA barcoding is efficient at the detection of cryptic species, associating the sexes of dimorphic species, associating the castes of species with strong queen-worker dimorphism and as a generally useful tool for basic identification (Gibbs, 2009). (For a revision of successful cases see Packer et al., 2009). A global campaign to barcode the bees of the world has been initiated (see the website at:
