Bjørn Dahle

Bjørn Dahle
Norwegian Beekeepers Assocation

PhD

About

85
Publications
41,717
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
3,407
Citations
Citations since 2017
46 Research Items
1946 Citations
20172018201920202021202220230100200300400
20172018201920202021202220230100200300400
20172018201920202021202220230100200300400
20172018201920202021202220230100200300400
Additional affiliations
January 2019 - April 2019
Norwegian University of Life Sciences (NMBU)
Position
  • Professor (Associate)
August 2004 - June 2007
University of Oslo
Position
  • PostDoc Position
August 2003 - January 2004
Norwegian University of Life Sciences (NMBU)
Position
  • Researcher

Publications

Publications (85)
Article
Full-text available
Monitoring virus infections can be an important selection tool in honey bee breeding. A recent study pointed towards an association between the virus-free status of eggs and an increased virus resistance to deformed wing virus (DWV) at the colony level. In this study, eggs from both naturally surviving and traditionally managed colonies from across...
Article
Full-text available
Proteins are under selection to maintain central functions and to accommodate needs that arise in ever‐changing environments. The positive selection and neutral drift that preserve functions result in a diversity of protein variants. The amount of diversity differs between proteins: multifunctional or disease‐related proteins tend to have fewer var...
Preprint
Full-text available
The ‘suppressed in-ovo virus infection’ trait (SOV) was the first trait applied in honey bee breeding programs aimed to increase resilience to virus infections, a major threat for colony survival. By screening drone eggs for viruses, the SOV trait scores the antiviral resistance of queens and its implications for vertical transmission. In this stud...
Article
Full-text available
Citation: Guiné, R.P.F.; Mesquita, S.; Oliveira, J.; Coelho, C.; Costa, D.T.; Correia, P.; Correia, H.E.; Dahle, B.; Oddie, M.; Raimets, R.; et al. Abstract: Beekeeping is an ancient activity that is gaining interest among practitioners and society in general. It is as an activity with positive impacts in the environmental, social and economic sphe...
Article
Full-text available
A diverse supply of pollen is an important factor for honey bee health, but information about the pollen diversity available to colonies at the landscape scale is largely missing. In this COLOSS study, beekeeper citizen scientists sampled and analyzed the diversity of pollen collected by honey bee colonies. As a simple measure of diversity, beekeep...
Article
Full-text available
The ectoparasitic mite, Varroa destructor, is unarguably the leading cause of honeybee (Apis mellifera) mortality worldwide through its role as a vector for lethal viruses, in particular, strains of the Deformed wing virus (DWV) and Acute bee paralysis virus (ABPV) complexes. Several honeybee populations across Europe have well-documented adaptatio...
Article
Full-text available
Citizen Science contributes significantly to the conservation of biodiversity, but its application to honey bee research has remained minimal. Even though certain European honey bee (Apis mellifera) populations are known to naturally survive Varroa destructor infestations, it is unclear how widespread or common such populations are. Such colonies a...
Article
Full-text available
Cell recapping is a behavioural trait of honeybees (Apis mellifera) where cells with developing pupae are uncapped, inspected, and then recapped, without removing the pupae. The ectoparasitic mite Varroa destructor, unarguably the most destructive pest in apiculture world-wide, invades the cells of developing pupae to feed and reproduce. Honeybees...
Article
Full-text available
Comparative studies of genetic diversity and population structure can shed light on the ecological and evolutionary factors governing host-parasite interactions. Even though invasive parasites are considered of major biological importance, little is known about their adaptative potential when infesting the new hosts. Here, the genetic diversificati...
Preprint
Full-text available
Populations of European honeybee subspecies, Apis mellifera , have the ability to adapt naturally to the ectoparasitic mite, Varroa destructor . It is possible that a tolerance to mite-vectored viruses may contribute to colony survival. If this is the case, surviving populations should show lower virus titers and prevalence compared to susceptible...
Article
Full-text available
In the fight against the Varroa destructor mite, selective breeding of honey bee (Apis mellifera L.) populations that are resistant to the parasitic mite stands as a sustainable solution. Selection initiatives indicate that using the suppressed mite reproduction (SMR) trait as a selection criterion is a suitable tool to breed such resistant bee pop...
Article
Full-text available
This article presents managed honey bee colony loss rates over winter 2018/19 resulting from using the standardised COLOSS questionnaire in 35 countries (31 in Europe). In total, 28,629 beekeepers supplying valid loss data wintered 738,233 colonies, and reported 29,912 (4.1%, 95% confidence interval (CI) 4.0–4.1%) colonies with unsolvable queen pro...
Article
Full-text available
Displacement and admixture are threatening the survival and genetic integrity of the European dark bee, Apis mellifera mellifera. Studies on the phenotype-genotype map and genotype by environment interactions in honey bees are demonstrating that variation at subspecies level exists and is worth conserving. SNP-based tools for monitoring genetic int...
Article
Meiotic recombination is an essential component of eukaryotic sexual reproduction, but its frequency varies within and between genomes. Although it is well established that honey bees have a high recombination rate with about 20 cM/Mbp, the proximate and ultimate causes of this exceptional rate are poorly understood. Here, we describe six linkage m...
Preprint
Full-text available
It was brought to our attention that a preprint version of a refutation to our paper titled “Rapid parallel evolution overcomes global honey bee parasite” was posted through PeerJ recently. This is our formal response to the refutation, which can be found through this link: https://peerj.com/preprints/27938/ Here we have broken down the arguments o...
Conference Paper
Nowadays the Western honey bee (Apis mellifera) is present worldwide, wherever beekeeping is possible, though its native habitat spreads out across Europe, Africa and parts of Western Asia. About 26 different subspecies evolved through time, each adapted by natural selection to cope with the local environmental conditions. During the past 2 centuri...
Article
Full-text available
This short article presents loss rates of honey bee colonies over winter 2017/18 from 36 countries, including 33 in Europe, from data collected using the standardized COLOSS questionnaire. The 25,363 beekeepers supplying data passing consistency checks in total wintered 544,879 colonies, and reported 26,379 (4.8%, 95% CI 4.7–5.0%) colonies with uns...
Article
Full-text available
Host-parasite co-evolution history is lacking when parasites switch to novel hosts. This was the case for Western honey bees (Apis mellifera) when the ectoparasitic mite, Varroa destructor, switched hosts from Eastern honey bees (Apis cerana). This mite has since become the most severe biological threat to A. mellifera worldwide. However, some A. m...
Article
Full-text available
The ectoparasitic mite Varroa destructor is a key threat for European honeybee subspecies (Apis mellifera) globally. However, some A. mellifera populations are known to survive mite infestations by means of natural selection (naturally surviving), likely due to reduced mite reproductive success. The effect of small brood cell size on mite reproduct...
Article
Full-text available
The ectoparasitic mite Varroa destructor is a key factor for colony losses in European honey bee subspecies (Apis mellifera), but it is also known that some host populations have adapted to the mite by means of natural selection. The role of a shorter host brood postcapping period in reducing mite reproductive success has been investigated in other...
Article
Full-text available
In eusocial insect colonies nestmates cooperate to combat parasites, a trait called social immunity. However, social immunity failed for Western honey bees (Apis mellifera) when the ectoparasitic mite Varroa destructor switched hosts from Eastern honey bees (Apis cerana). This mite has since become the most severe threat to A. mellifera world-wide....
Article
Full-text available
In this short note we present comparable loss rates of honey bee colonies during winter 2016/2017 from 27 European countries plus Algeria, Israel and Mexico, obtained with the COLOSS questionnaire. The 14,813 beekeepers providing valid loss data collectively wintered 425,762 colonies, and reported 21,887 (5.1%, 95% confidence interval 5.0–5.3%) colo...
Article
Full-text available
In this short note we present comparable loss rates of honey bee colonies during winter 2016/2017 from 27 European countries plus Algeria, Israel and Mexico, obtained with the COLOSS questionnaire. The 14,813 beekeepers providing valid loss data collectively wintered 425,762 colonies, and reported 21,887 (5.1%, 95% confidence interval 5.0–5.3%) col...
Article
The tracheal mite, Acarapis woodi, may be one of many factors contributing to the decline in honey bee (Apis mellifera) populations. Databases on the widespread distribution of A. woodi exist, but the data seem patchy. Norway is not listed as being infested, although there have been at least two separate introductions of the parasite. Investigation...
Article
Full-text available
Background. Managed, feral and wild populations of European honey bee subspecies, Apis mellifera, are currently facing severe colony losses globally. There is consensus that the ectoparasitic mite Varroa destructor, that switched hosts from the Eastern honey bee Apis cerana to the Western honey bee A. mellifera, is a key factor driving these losse...
Data
Mite bottom board counts A dataset containing varroa mite population estimates via bottom board counts.
Data
Distribution of multiple foundress infestation events A dataset containing the distribution of the varying number of foundresses infesting single cells.
Data
Metadata describing column names and command scripts created for statistics in R Listed first are the descriptions for each column name in each dataset. Listed second are all scripts used and outputs drawn from the statistical program R.
Data
Average fecundity, varroa-sensitive hygiene and infestation rates A dataset containing the fecundity measures for varroa mites, the level of brood removal (VSH) and the proportion of infested cells determined on all test frames.
Data
Mite grooming proportions Dataset containing the proportion of damaged mites (grooming measure) found within all test colonies.
Preprint
Full-text available
Background: Managed, feral and wild populations of European honey bee subspecies, Apis mellifera , are currently facing severe colony losses globally. There is consensus that the ectoparasite mite Varroa destructor , that switched hosts from the Eastern honey bee Apis cerana to the Western honey bee A. mellifera , is a key factor driving these loss...
Preprint
Full-text available
Background: Managed, feral and wild populations of European honey bee subspecies, Apis mellifera , are currently facing severe colony losses globally. There is consensus that the ectoparasite mite Varroa destructor , that switched hosts from the Eastern honey bee Apis cerana to the Western honey bee A. mellifera , is a key factor driving these loss...
Research
Full-text available
En guide for birøktere i Europa
Article
Full-text available
In this short note we present comparable loss rates of honey bee colonies during winter 2015/16 from 29 countries, obtained with the COLOSS questionnaire. Altogether, we received valid answers from 19,952 beekeepers. These beekeepers collectively wintered 421,238 colonies, and reported 18,587 colonies with unsolvable queen problems and 32,048 dead...
Article
Full-text available
Insects hold enormous potential to address food and nutritional security issues. The honey bee is a key insect, given its importance for pollination, as well as its products which can be directly consumed, like honey, pollen and brood. Research on edible insects is an emerging field that draws upon methods and techniques from related fields of rese...
Article
Full-text available
Honeybee (Apis mellifera) brood is enjoyed as food in many regions of the world. The Nordic region of Europe is not currently one of them, but it could be. The drone brood in particular constitute an untapped source of delicious, nutritious and potentially sustainable food. Currently, it is removed by many beekeepers as part of a strategy to lower...
Article
Full-text available
Understanding a species' feeding ecology is essential for successful management and conservation, because food abundance can influence body mass, survival, reproductive success, movements, and habitat use. We describe annual and seasonal variations in the diet of brown bears Ursus arctos in southcentral Sweden, based on analysis of 527 fecal sample...
Conference Paper
Full-text available
Since its establishment in 2008, the COLOSS (Prevention of honey bee COlony LOSSes) association has been successful in bringing together bee research scientists, bee health specialists and extension advisors to study the causes of global honey bee losses, and now has a substantial output of papers published in refereed scientific journals. The newl...
Conference Paper
There are two significant bacterial diseases of honeybees; European foulbrood (EFB) caused by Melissococcus plutonius and American foulbrood (AFB) caused by the spore forming bacterium Paenibacillus larvae. In both diseases the bacteria multiply in developing honeybee larvae and, dependant on the dose and virulence of bacterial strain, infection ma...
Article
Full-text available
The honeybee Apis mellifera has major ecological and economic importance. We analyze patterns of genetic variation at 8.3 million SNPs, identified by sequencing 140 honeybee genomes from a worldwide sample of 14 populations at a combined total depth of 634×. These data provide insight into the evolutionary history and genetic basis of local adaptat...
Data
Losses of honey bee colonies over the 2013/14 winter Preliminary results from an international study The honey bee protection network COLOSS1 has today announced the preliminary results of an international study to investigate honey bee winter colony losses. Data were collected from Israel and Algeria and 19 European countries. In total 17,135 resp...
Article
Full-text available
The recognition that the Dark European honey bee, Apis mellifera mellifera, is increasingly threatened in its native range has led to the establishment of conservation programmes and protected areas throughout western Europe. Previous molecular surveys showed that, despite management strategies to preserve the genetic integrity of A. m. mellifera,...
Article
Full-text available
This article presents results of an analysis of winter losses of honey bee colonies from 19 mainly European countries, most of which implemented the standardised 2013 COLOSS questionnaire. Generalised linear mixed effects models (GLMMs) were used to investigate the effects of several factors on the risk of colony loss, including different treatment...
Article
Full-text available
Several North American studies have reported significant predation rates on moose Alces alces by brown bears Ursus arctos. We documented predation on moose by brown bears in south-central Sweden, where brown bears and moose occurred at estimated densities of 10-30 and 400-1,340/1,000 km2, respectively. Bears killed 0.8% of radio-collared adult fema...
Article
Full-text available
In 2008 the COLOSS network was formed by honey bee experts from Europe and the USA. The primary objectives set by this scientific network were to explain and to prevent large scale losses of honey bee (Apis mellifera) colonies. In June 2008 COLOSS obtained four years support from the European Union from COST and was designated as COST Action FA0803...
Article
Full-text available
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...
Article
ABSTRACT Because wild reindeer (Rangifer tarandus) are hunted in southern Norway, reindeer may perceive all recreationists as threats. Potential adverse effects of hunting on reindeer behavior may be exacerbated by other forms of recreation because the number of skiers and hikers in areas inhabited by reindeer has also increased. The Norefjell-Rein...
Article
In North America, brown bears (Ursus arctos) can be a significant predator on moose (Alces alces) calves. Our study in Sweden is the first in which brown bears are the only predator on moose calves. Bears and moose occurred at densities of about 30/1,000 km2 and 920/1,000 km2, respectively, and bears killed about 26% of the calves. Ninety-two perce...
Article
Full-text available
We studied the effects of primiparity on litter size, offspring size, and cub loss in brown bears (Ursus arctos) in two study areas (north, south) in Sweden from 1987 to 2006. Sexually selected infanticide (SSI) has been suggested previously as a mortality factor in our study populations. Females in the south became primiparous earlier than females...
Article
Reindeer and caribou Rangifer tarandus are reported to avoid human infrastructure such as roads, high-voltage power lines, pipelines, and tourist resorts. Lichens are important forage for reindeer during winter, and their relatively slow growth rates make them vulnerable to overgrazing. Height and volume of lichens are often used as an indicator of...
Article
Linear infrastructures such as roads, pipelines and power lines can hinder Rangifer migration and reduce the total amount of area available for foraging. We studied the barrier and aversion effect of a 66kV power line transecting the range of wild reindeer in North Ottadalen, south central Norway using aerial surveys of reindeer distribution (direc...
Article
Full-text available
Increasing outdoor activities by humans could negatively influence reindeer and caribou Rangifer tarandus populations. We recorded the behaviour of feral reindeer R. t. tarandus when a person directly approached them on foot or on skis in Forolhogna, Norway, during March, July and September–October 1996. The farther away the person was when first s...
Article
Most studies of animals' home-range sizes have focused on adults, and the home ranges of subadults are usually, at best, only mentioned anecdotally. In this paper we report home-range sizes of 56 philopatric sexually immature (1.5- and 2.5-year-old) brown bears (Ursus arctos) in 2 Swedish study areas and how size is influenced by sex, age, body siz...
Article
Full-text available
Body size and mass have a strong effect on an individual's fitness, and conditions experienced early in life may affect survival to adulthood, age and size at maturation, and reproductive success. For this reason, body size and mass of 226 yearling brown bears Ursus arctos were analysed in relation to maternal size, litter size, sex, multilocus het...
Article
Full-text available
We investigated growth and determinants of adult female body size in brown bears (Ursus arctos) in 2 study areas in Sweden. Scandinavian female brown bears reached 90% of their asymptotic size at 4.1-4.7 years. Four factors were considered in our analysis of the determinants of adult female size: annual food conditions, population density, multiloc...
Technical Report
Full-text available
This report summarizes results of the Scandinavian Brown Bear Research Project obtained during 2000-04. The specific results relevant for the Large Carnivore and Society Project (RoSa) funded by the Research Council of Norway are the following. 1) We have documented the dispersal behavior of young male and female bears. We found, for the first time...
Article
Full-text available
Length of maternal care, i.e. the interval between successfully raised litters, is the most important factor explaining the variation in reproductive rate among brown-bear (Ursus arctos) populations. In this paper, we examine the variation in length of maternal care in radio-marked brown bears and its effect on their offspring in northern Sweden. Y...