Genetic structure of honeybee populations from southern Brazil and Uruguay

Abstract

Apis mellifera scutellata was introduced to Brazil in 1956 and Africanized honeybee populations have now spread from Argentina to the southwestern United States. Temperate climatic restrictions seem to be a natural limit to Africanized honeybee expansion around parallels 35°to 40°SL. We used allozyme loci (Mdh-1 and Hk-1) and mtDNA haplotypes to characterize honeybee populations in southern Brazil and Uruguay and define a possible transition area between Africanized and European bees. Samples of 194 bee colonies were collected from ten localities between 30°-35°SL and 52°-59°WL. The mtDNA restriction patterns of these colonies were obtained through digestion of the mitochondrial genome by Eco RI, or by digestion by Bgl II and Xba I of the cytochrome B locus and the COI-COII intergenic region, respectively. The distribution limit of African bee colonies, i.e., those populations with only the African mtDNA haplotype and with a high proportion of African genes as shown by allozyme analysis, is located in northern Uruguay, with a hybridization zone located farther south in Uruguay. A gradual cline from north to south was observed, confirmed by mtDNA, racial admixture, and genetic distance analyses. No evidence of either gametic disequilibrium between nuclear markers or cytonuclear disequilibrium among the nuclear and mtDNA genotypes was detected, suggesting that the hybridization process has been completed.

Do agrochemicals used during soybean flowering affect the visits of Apis mellifera L.?

“…The minimum, medium and maximum values of individuals of honey bee trapped in each time, in all Suchail et al (2000). The polyhybrid origin of the Uruguayan honeybee colonies corroborated by morphometric and genetic analyses carried out by Carrasco et al (2012) has also been mentioned in earlier studies curried out in that country (Burgett et al, 1995;Diniz et al, 2003) as well as in neighbouring countries such as Argentina and Brazil (Sheppard et al, 1991a,b;Diniz et al, 2003). Moreover, Carrasco et al (2012) propose to consider Uruguay, Argentina and Brazil soybean areas as one region, as their honey bees are of similar genetic origin and the insecticides used and their suggested dosages are practically the same.…”

Temporal Pattern of Africanization in a Feral Honeybee Population From Texas Inferred From Mitochondrial Dna

“…These traits conferred high fitness to Africanized colonies allowing them to outcompete managed European colonies and, because European feral colonies were uncommon in the tropics, occupy a virtually empty feral niche (Michener 1975). Additionally, as revealed by morphometrics (Diniz-Filho and Malaspina 1995), allozymes (Del Lama et al 1988;Lobo et al 1989;Sheppard et al 1991a,b;Diniz et al 2003), restriction fragment-length polymorphisms (Hall and McMichael 2001), random amplified polymorphic DNA (Suazo et al 1998), and microsatellite markers (Clarke et al 2002), genetic mechanisms involving hybridization were implicated in the invasion event. Although nuclear markers have shown substantial introgression of European genes, mitochondrial markers have indicated a nearly fixed A. m. scutellata mitotype in feral Africanized populations of the neotropics (Hall and Muralidharan 1989;Smith et al 1989;Hall and Smith 1991;Sheppard et al 1991b;Diniz et al 2003).…”

“…Additionally, as revealed by morphometrics (Diniz-Filho and Malaspina 1995), allozymes (Del Lama et al 1988;Lobo et al 1989;Sheppard et al 1991a,b;Diniz et al 2003), restriction fragment-length polymorphisms (Hall and McMichael 2001), random amplified polymorphic DNA (Suazo et al 1998), and microsatellite markers (Clarke et al 2002), genetic mechanisms involving hybridization were implicated in the invasion event. Although nuclear markers have shown substantial introgression of European genes, mitochondrial markers have indicated a nearly fixed A. m. scutellata mitotype in feral Africanized populations of the neotropics (Hall and Muralidharan 1989;Smith et al 1989;Hall and Smith 1991;Sheppard et al 1991b;Diniz et al 2003). Hypotheses that have been proposed to explain the asymmetrical contribution of nuclear and mitochondrial markers found in Neotropical feral populations include (1) overestimation of A. m. scutellata mitotypes , (2) low fitness in F 1 hybrid colonies of European matrilines (Harrison and Hall 1993;Schneider et al 2003), (3) large differences in population sizes (Page 1989;Rinderer et al 1991), and (4) reproductive and survival advantages of colonies with queens of A. m. scutellata descent (Michener 1975;Rinderer 1988;Taylor 1988).…”

“…In spite of their astounding biological success in the neotropics, morphometrical, allozymic, and mitochondrial DNA (mtDNA) data have shown that Africanized honeybees have not expanded into temperate regions of South America, and a complex zone of hybridization has formed in temperatesubtropical boundaries (Lobo et al 1989;Sheppard 1991a;Diniz-Filho and Malaspina 1995;Diniz et al 2003;QuezadaEuán et al 2003). Extrapolating from the climatic limits of Africanized honeybees in South America, Taylor and Spivak (1984) suggested that in the United States, Africanized honeybees would saturate the southernmost regions of some southern states and that a hybrid zone would form northward.…”

“…The more favorable climatic and ecological conditions for the European honeybees and the large resident European population led to predictions that a greater contribution of European genes to the Africanized gene pool would occur as the Africanization front approached the United States, and that a hybrid zone would form as in southern regions of South America (Sheppard et al 1991a;Diniz et al 2003). However, the nearly coincidental arrival in the United States in 1987 (De Guzman et al 1997) of one of the most serious pests of honeybees worldwide, the parasitic mite Varroa destructor, might have compromised in some degree this prediction.…”