Abstract
As yet, certain aspects of the Africanization process are not well understood, for example, the reproductive behavior of African and European honeybees and how the first Africanized swarms were formed and spread. Drone congregation areas (DCAs) are the ideal place to study honeybee reproduction under natural conditions since hundreds of drones from various colonies gather together in the same geographical area for mating. In the present study, we assessed the genetic structure of seven drone congregations and four commercial European-derived and Africanized apiaries in southern Brazil, employing seven microsatellite loci for this purpose. We also estimated the number of mother-colonies that drones of a specific DCA originated from. Pairwise comparison failed to reveal any population sub-structuring among the DCAs, thus indicating low mutual genetic differentiation. We also observed high genetic similarity between colonies of commercial apiaries and DCAs, besides a slight contribution from a European-derived apiary to a DCA formed nearby. Africanized DCAs seem to have a somewhat different genetic structure when compared to the European.
Highlights
Since the introduction of the African honeybee subspecies Apis mellifera scutellata into Brazil in 1956 there has been a dramatic change in the genetic makeup of European-derived honeybee populations in South and Central America in less than 50 years (Schneider et al, 2004)
The composition of drone congregations is of great consequence for the genetic structure of honeybee colonies, as the number of colonies represented in a Drone congregation areas (DCAs) affects the genetic diversity of new colonies (Baudry et al, 1998)
Drones from the Africanized DCAs showed a higher number of alleles and gene diversity in comparison to a DCA from Germany (A. m. carnica) studied by Baudry et al (1998) (Table 5)
Summary
Since the introduction of the African honeybee subspecies Apis mellifera scutellata into Brazil in 1956 there has been a dramatic change in the genetic makeup of European-derived honeybee populations in South and Central America in less than 50 years (Schneider et al, 2004). The replacement of the European by Africanized populations, and the strong predominance of African traits in the hybrid formed with the spread of African swarms throughout the New World, have been well documented (Lobo et al, 1989; Smith et al, 1989; Quezada-Euán and Paxton, 1999; Clarke et al, 2001; Collet et al, 2006). Several reasons for the prevalence of African traits in the resultant hybrid have been proposed (Schneider et al, 2004), two important issues are, as yet, not well understood, namely, the reproductive behavior of African and European honeybees and how the first Africanized swarms were formed and spread. The reproductive behavior of A. mellifera under natural conditions can be assessed through studies on drone congregation areas (DCAs). These are where hundreds of drones from various colonies gather in the same geographical area for mating. DCAs are ideal for studying honeybee reproduction under natural conditions
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