Europe harbours several endemic honeybee (Apis mellifera) subspecies. Yet the distribution of these subspecies is nowadays also much influenced by beekeeping activities. Large scale migratory beekeeping and trade in queens, coupled with the promiscuous mating system of honeybees, have exposed native European honeybees to increasing introgressive hybridization with managed non-native subspecies, which may lead to the loss of valuable combinations of traits shaped by natural selection. Other threats to European honeybees are factors that have caused a progressive decline in A. mellifera throughout the world in recent years, leading to large economic losses and jeopardizing ecosystem functioning. We review the biodiversity of European honeybees and summarize the management and conservation strategies employed by different countries. A comprehensive picture of the beekeeping industry in Europe is also provided. Finally we evaluate the potential threats affecting the biodiversity of European honeybee populations and provide some perspectives for future research.

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Biodiversity, conservation and current threats to European honeybees*

Apis mellifera is composed of three evolutionary branches including mainly African (branch A), western and northern European (branch M), and southeastern European (branch C) populations. The existence of morphological clines extending from the equator to the Polar Circle through Morocco and Spain raised the hypothesis that the branch M originated in Africa. Mitochondrial DNA analysis revealed that branches A and M were characterized by highly diverged lineages implying very remote links between both branches. It also revealed that mtDNA haplotypes from lineages A coexisted with haplotypes M in the Iberian Peninsula and formed a south-north frequency cline, suggesting that this area could be a secondary contact zone between the two branches. By analyzing 11 populations sampled along a France-Spain/Portugal-Morocco-Guinea transect at 8 microsatellite loci and the DraI RFLP of the COI-COII mtDNA marker, we show that Iberian populations do not present any trace of "africanization" and are very similar to French populations when considering microsatellite markers. Therefore, the Iberian Peninsula is not a transition area. The higher haplotype A variability observed in Spanish and Portuguese samples compared to that found in Africa is explained by a higher mutation rate and multiple and recent introductions. Selection appears to be the best explanation to the morphological and allozymic clines and to the diffusion and maintenance of African haplotypes in Spain and Portugal.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1558-5646.1998.tb01839.x

The origin of west european subspecies of honeybees (apis mellifera): new insights from microsatellite and mitochondrial data.

Variability of mitochondrial deoxyribonucleic acid (mtDNA) has been studied in 973 colonies from 23 populations of the west European honey bees (lineage M) using restriction profiles of a polymerase chain reaction (PCR) amplified DNA fragment of the COI-COII intergenic region. Although populations are almost always introgressed by two other mtDNA lineages (A and C), results confirmed that the original haplotypes in western Europe are those of mtDNA lineage M. Iberian populations (Apis mellifera iberica) are characterised by a extended cline between haplotypes A and M, the former being almost fixed in south Spain and Portugal, and the latter almost pure in northeastern populations. This introgression is most likely attributable to humans and is probably ancient. French populations (A. m. mellifera) exhibit various levels of introgression by the C mtDNA lineage. Introgression is rather low in regions with a dominance of amateur bee-keeping while it reaches very high values in regions where professional bee-keepers regularly import foreign queens (mainly A. m. ligustica and A. m. caucasica). When discarding introgressed haplotypes, French populations group in two clusters, one for the northeastern part of France, and the other one for all other populations, including Swedish and northeastern Spanish populations.

Genetic diversity of the west European honey bee (Apis mellifera mellifera and A. m. iberia). I. Mitochondrial DNA

SummaryHere, scientists from 19 European countries, most of them collaborating in Working Group 4: “Diversity and Vitality” of COST Action FA 0803 “Prevention of honey bee COlony LOSSes” (COLOSS), review the methodology applied in each country for discriminating between honey bee populations. Morphometric analyses (classical and geometric) and different molecular markers have been applied. Even if the approach has been similar, however, different methodologies regarding measurements, landmarks or molecular markers may have been used, as well as different statistical procedures. There is therefore the necessity to establish common methods in all countries in order to have results that can be directly compared. This is one of the goals of WG4 of the COLOSS project.

/pdf/a-review-of-methods-for-discrimination-of-honey-bee-4v3crtem89.pdf

A review of methods for discrimination of honey bee populations as applied to European beekeeping

The genetic variation of honeybee colonies collected in 22 localities on the Balearic Islands (Spain) was analysed using eight polymorphic microsatellite loci. Previous studies have demonstrated that these colonies belong either to the African or west European evolutionary lineages. These populations display low variability estimated from both the number of alleles and heterozygosity values, as expected for the honeybee island populations. Although genetic differentiation within the islands is low, significant heterozygote deficiency is present, indicating a subpopulation genetic structure. According to the genetic differentiation test, the honeybee populations of the Balearic Islands cluster into two groups: Gimnesias (Mallorca and Menorca) and Pitiusas (Ibiza and Formentera), which agrees with the biogeography postulated for this archipelago. The phylogenetic analysis suggests an Iberian origin of the Balearic honeybees, thus confirming the postulated evolutionary scenario for Apis mellifera in the Mediterranean basin. The microsatellite data from Formentera, Ibiza and Menorca show that ancestral populations are threatened by queen importations, indicating that adequate conservation measures should be developed for protecting Balearic bees.

/pdf/genetic-structure-of-balearic-honeybee-populations-based-on-8exfo798kj.pdf

Genetic structure of Balearic honeybee populations based on microsatellite polymorphism

SUMMARYSeven morphometric characters were measured in bees (Apis mellifera iberica) sampled from 12 locations in the south of the Iberian peninsula. A discriminant analysis showed that there were three distinct biometric groups which corresponded to the following geographical areas. Group 1: area of influence of the Guadalquivir valley (localities of Dos Hermanas, Hornachuelos, Lepe, Trassierra and Castellar de la Frontera), along with the localities of Caceres, Murcia and Vadillo; Group 2: area of Sierra Nevada and bordering areas (localities of Lanjaron, Pinos del Valle and Berja); Group 3: Mediterranean seaboard, along with the locality of Maro; 92.15% of the bees sampled were correctly assigned to their geographical locations. Groups 1 and 2 were very similar to each other, while the third differed considerably from both, displaying a very low cubital index. The variable with greatest discriminatory potential was the length of hairs on the fifth abdominal tergite. The origin of these populations and p...

F J Orantes-Bermejo

Papers

Morphological variability of Apis mellifera iberica in different apiaries of southern Spain