Maria Bouga

Standard methods for characterising subspecies and ecotypes of Apis mellifera

Summary The natural diversity of honey bees in Europe is eroding fast. A multitude of reasons lead to a loss of both genetic diversity and specific adaptations to local conditions. To preserve locally adapted bees through breeding efforts and to maintain regional strains in conservation areas, these valuable populations need to be identified. In this paper, we give an overview of methods that are currently available and used for recognition of honey bee subspecies and ecotypes, or that can be utilised to verify the genetic origin of colonies for breeding purposes. Beyond summarising details of morphometric, allozyme and DNA methods currently in use, we report recommendations with regard to strategies for sampling, and suggest methods for statistical data analysis. In particular, we emphasise the importance of reference data and consistency of methods between laboratories to yield comparable results.

Conserving diversity and vitality for honey bee breeding.

Summary Beekeepers in Europe, North America and other parts of the world have repeatedly been afflicted by elevated and sometimes unexplained colony losses. Multiple factors have been considered in connection with increased winter losses. In addition to national programmes investigating possible causes for increased honey bee mortality, scientists collaborate at an international level on different aspects of bee health within the COLOSS network. Within this network, Working Group 4 explores aspects of genetic diversity in relation to the vitality and health of honey bee populations. In this paper, we briefly review the genetic diversity of honey bees in Europe, discuss the effects of beekeeping and selective breeding on honey bee populations under the aspect of genetic diversity and bee health, and review the current status of EU legislation with respect to protection of native bee populations. We introduce and discuss recent approaches in honey bee selective breeding to improve disease resistance by introducing traits related to colony vitality. Finally, we present the aims of WG4 within the COLOSS network and briefly introduce our experimental approach.

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

Summary Here, 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.

The influence of genetic origin and its interaction with environmental effects on the survival of Apis mellifera L. colonies in Europe

Summary The survival and performance of 597 honey bee colonies, representing five subspecies and 16 different genotypes, were comparatively studied in 20 apiaries across Europe. Started in October 2009, 15.7% of the colonies survived without any therapeutic treatment against diseases until spring 2012. The survival duration was strongly affected by environmental factors (apiary effects) and, to a lesser degree, by the genotypes and origin of queens. Varroa was identified as a main cause of losses (38.4%), followed by queen problems (16.9%) and Nosema infection (7.3%). On average, colonies with queens from local origin survived 83 days longer compared to non-local origins (p < 0.001). This result demonstrates strong genotype by environment interactions. Consequently, the conservation of bee diversity and the support of local breeding activities must be prioritised in order to prevent colony losses, to optimize a sustainable productivity and to enable a continuous adaptation to environmental changes.

Occurrence of parasites and pathogens in honey bee colonies used in a European genotype-environment interactions experiment

Summary Diseases are known to be one of the major contributors to colony losses. Within a Europe-wide experiment on genotype—environment interactions, an initial 621 colonies were set up and maintained from 2009 to 2012. The colonies were monitored to investigate the occurrence and levels of key pathogens. These included the mite Varroa destructor (mites per 10 g bees), Nosema spp. (spore loads and species determination), and viruses (presence/absence of acute bee paralysis virus (ABPV) and deformed wing virus (DWV)). Data from 2010 to the spring of 2011 are analysed in relation to the parameters: genotype, environment, and origin (local vs. non-local) of the colonies in the experiment. The relative importance of different pathogens as indicators of colony death within the experiment is compared. In addition, pathogen occurrence rates across the geographic locations are described.

Population dynamics of European honey bee genotypes under different environmental conditions

Summary Adaptation of honey bees to their environment is expressed by the annual development pattern of the colony, the balance with food sources and the host—parasite balance, all of which interact among each other with changes in the environment. In the present study, we analyse the development patterns over a period of two years in colonies belonging to 16 different genotypes and placed in areas grouped within six environmental clusters across Europe. The colonies were maintained with no chemical treatment against varroa mites. The aim of the study was to investigate the presence of genotype—environment interactions and their effects on colony development, which we use in this study as a measure of their vitality. We found that colonies placed in Southern Europe tend to have lower adult bee populations compared to colonies placed in colder conditions, while the brood population tends to be smaller in the North, thus reflecting the shorter longevity of bees in warmer climates and the shorter brood rearing period in the North. We found that both genotype and environment significantly affect colony development, and that specific adaptations exist, especially in terms of adult bee population and overwintering ability.

Polar tube protein gene diversity among Nosema ceranae strains derived from a Greek honey bee health study.

Honey bee samples from 54 apiaries originating from 37 geographic locations of Greece were screened for Nosema apis and Nosema ceranae. Furthermore 15 samples coming from 12 geographic locations were screened also for Paenibacilluslarvae and Melissococcus plutonius and seven honey bee virus species, for the first time on a nation-wide level. There was a tendency in finding proportionally higher spore counts in samples from apiaries that suffered important colony losses. P. larvae bacteria were identified in two samples and each of the tested bee viruses could be detected in at least one of the examined samples, with IAPV, CBPV and SBV being the least abundant and BQCV and DWV being the most abundant. In the study we focused on polymorphism of a N. ceranae gene encoding a polar tube protein (PTP) as similar genes were proven to be highly polymorphic in the microsporidian parasites Encephalitozoon cuniculi and Encephalitozoon hellem. The polymorphism observed in the PTP gene sequences from a single sample (bee hive) was unexpected and can thus be considered to be a major obstacle for genotyping.

Allozyme variability in honey bee populations from some mountainous regions in the southwest of Bulgaria

Summary Honey bee populations from different mountainous regions in southwest Bulgaria have been studied on four enzymatic systems (MDH, EST, PGM and HK) corresponding to 4 genetic loci. All loci were found to be polymorphic in almost all populations. The observed heterozygosity ranged from 0.172 to 0.262. Allele frequencies of all loci were used to estimate Neis (1972) genetic distance, which was found to range between 0.009 and to 0.052 among the populations studied. A Neighbour-Joining phylogenetic tree was obtained by genetic distance matrix methods. This is the first report of allozymic data from honey bee populations from these Bulgarian locations.

Data on honey bee losses in Greece: a preliminary note

Fani Hatjina, Maria Bouga, Aikaterini Karatasou, Aglaya Kontothanasi, Leonidas Charistos, Christina Emmanouil, Nikolaos Emmanouil and Anastasios-Damianos Maistros Hellenic Institute of Apiculture (N.AG.RE.F.), N. Moudania, Greece. Lab. of Agricultural Zoology & Entomology, Agricultural University of Athens, Athens. Federation of Greek Beekeepers’ Associations (OMSE), Larisa, Greece. Laboratory of Pesticides’ Toxicology, Benaki Phytophathological Institute, Athens, Greece. Electrical-Mechanical Engineer, Athens, Greece.

Swarming, defensive and hygienic behaviour in honey bee colonies of different genetic origin in a pan-European experiment

Summary Honey bee colonies exhibit a wide range of variation in their behaviour, depending on their genetic origin and environmental factors. The COLOSS Genotype-Environment Interactions Experiment gave us the opportunity to investigate the phenotypic expression of the swarming, defensive and hygienic behaviour of 16 genotypes from five different honey bee subspecies in various environmental conditions. In 2010 and 2011, a total of 621 colonies were monitored and tested according to a standard protocol for estimation of expression of these three behavioural traits. The factors: year, genotype, location, origin (local vs. non-local) and season (only for hygienic behaviour) were considered in statistical analyses to estimate their effect on expression of these behaviours. The general outcome of our study is that genotype and location have a significant effect on the analysed traits. For all characters, the variability among locations was higher than the variability among genotypes. We also detected significant variability between the genotypes from different subspecies, generally confirming their known characteristics, although great variability within subspecies was noticed. Defensive and swarming behaviour were each positively correlated across the two years, confirming genetic control of these characters. Defensive behaviour was lower in colonies of local origin, and was negatively correlated with hygienic behaviour. Hygienic behaviour was strongly influenced by the season in which the test was performed. The results from our study demonstrate that there is great behavioural variation among different subspecies and strains. Sustainable protection of local genotypes can be promoted by combining conservation efforts with selection and breeding to improve the appreciation by beekeepers of native stock.