RECENT HONEYBEE SCIENTIFIC PUBLICATIONS By the SNGTV* Honeybee Commission & other contributors

By the SNGTV* Honeybee Commission & other contributors
Number 7 – April, 2020
Have collaborated on this issue :
– For the selection of articles: G. Therville, S. Boucher & Ch. Roy
– For the English version : N. Vidal-Naquet
Warning : this review does not claim to be exhaustive and only includes publications of interest in
the eyes of members of the SNGTV Honeybee commission;
Thus, only 10 publications per issue are chosen.
* Société Nationale des Groupements Techniques Vétérinaires (National Society of the Veterinary Technical Groups)
Number – main topic that can motivate you to read the article
(First author et al ; Year ; Scientific Journal ; Impact Factor)
1- Ants are mechanical and biological vectors of some viruses of the Honey bee
(Schläppi et al 2020 ; Viruses ; IF 3.81)
2- Melipona species are also sensitive to European foulbrood
(Teixeira et al 2020 ; Journal of Invertebrate Pathology ; IF 2.10)
3- Fighting Varroa by total brood removal appears to have an interesting
economic impact (Mancuso et al 2020 ; Sustainability ; IF 2.07)
4- Thymol in combination with trace levels of imidacloprid reduces visual
learning performance in honey bees (Colin et al 2020 ; Apidologie ; IF 2.25)
5- An original method for evaluating Varroa destructor infestation
(Szczurek et al 2020 ; Science of the Total Environment ; IF 5.59)
6- Abdominal colour pattern is a witness of hybridization’s degree in Apis
mellifera mellifera (Henriques et al 2020 ; Apidologie ; IF 2.25)
7- How undertaker workers recognize dead honey bees (Apis cerana)?
(Wen et al 2020 ; Animal Behavior and Cognition ; Preprint )
8- The bee will sting more than what it protects is valuable
(Schmidt 2020 ; Insectes Sociaux ; IF 1.49)
9- Vaporization of oxalic acid, with or without queen caging, is not enough to
manage Varroa infestation (Jack et al 2020 ; Journal of Economic Entomology ; IF 1.86)
10- A fungus as a biological control method against Varroa infestation
(Fernandez Ferrari et al 2020 ; Journal of Apiculture Research ; IF 1.75)
International Press Review by SNGTV Honeybee commission 2
1. Ants are mechanical and biological vectors of some viruses of the Honey bee
Schläppi, D., Chejanovsky, N., Yañez, O., Neumann, P., 2020. Foodborne Transmission and Clinical Symptoms of Honey Bee Viruses in Ants Lasius
spp. Viruses 12, 321.
Abstract: Emerging infectious diseases are often the products of host shifts, where a pathogen
jumps from its original host to a novel species. Viruses in particular cross species barriers
frequently. Acute bee paralysis virus (ABPV) and deformed wing virus (DWV) are viruses
described in honey bees (Apis mellifera) with broad host ranges. Ants scavenging on dead honey
bees may get infected with these viruses via foodborne transmission. However, the role of black
garden ants, Lasius niger and Lasius platythorax, as alternative hosts of ABPV and DWV is not
known and potential impacts of these viruses have not been addressed yet. In a laboratory
feeding experiment, we show that L. niger can carry DWV and ABPV. However, negative-sense
strand RNA, a token of virus replication, was only detected for ABPV. Therefore, additional L.
niger colonies were tested for clinical symptoms of ABPV infections. Symptoms were detected at
colony (fewer emerging workers) and individual level (impaired locomotion and movement
speed). In a field survey, all L. platythorax samples carried ABPV, DWV-A and –B, as well as the
negative-sense strand RNA of ABPV. These results show that L. niger and L. platythorax are
alternative hosts of ABPV, possibly acting as a biological vector of ABPV and as a mechanical one
for DWV. This is the first study showing the impact of honey bee viruses on ants. The common
virus infections of ants in the field support possible negative consequences for ecosystem
functioning due to host shifts.
Free download
2. Melipona species are also sensitive to European foulbrood
Teixeira, É.W., Ferreira, E.A., Luz, C.F.P. da, Martins, M.F., Ramos, T.A., Lourenço, A.P., 2020. European Foulbrood in stingless bees (Apidae:
Meliponini) in Brazil: Old disease, renewed threat. Journal of Invertebrate Pathology 172, 107357.
Abstract : Stingless bees (Apidae: Meliponini) are a group of bees with vestigial stings showing a
high level of social organization. They are important pollinators in tropical and subtropical
regions, and, in the last decades, stingless beekeeping has increased rapidly in Brazil.
Beecollected pollen and honey of Apis mellifera can be an important source of disease when
used as supplements to feed stingless bee colonies, a common and increasing practice adopted
by stingless beekeepers. Here, we aimed to investigate the presence of pathogens commonly
found in honey bees in diseased colonies of Melipona species in Espírito Santos and São Paulo
States, Southeast Brazil. We detected, for the first time, the bacterium Melissococcus plutonius
and symptoms of European foulbrood in Melipona spp., associated with brood death and colony
losses in some cases. In addition, we tested for the presence of the bacterium Paenibacillus
larvae and the fungus Aschosphaera apis, as well as the six more common honey bee viruses in
Brazil (BQCV, ABPV, DWV, KBV, IAPV, CBPV) and the microsporidia Nosema apis and Nosema
ceranae. However, only one sample of brood was infected with N. ceranae and all other
pathogens, with the exception of Melissococcus plutonius, were absent in the analyzed brood.
Lastly, we looked for toxic pollen in all food fed to diseased colonies, but none was present.
Download not free
International Press Review by SNGTV Honeybee commission 3
3- Fighting Varroa by total brood removal appears to have an interesting economic impact
Mancuso, T., Croce, L., Vercelli, M., 2020. Total Brood Removal and Other Biotechniques for the Sustainable Control of Varroa Mites in Honey
Bee Colonies: Economic Impact in Beekeeping Farm Case Studies in Northwestern Italy. Sustainability 12, 2302.
Abstract: Honey bee colonies are affected by many threats, and the Varroa mite represents one
of the most important causes of honey bee disease. The control of the Varroa population is
managed by different methods, and in recent years, biotechnical practices are considered
preferable to chemical approaches in order to safeguard honey bee health and avoid residues in
bee products as well as the appearance of acaricide resistance. However, little is known about
the economic performance of beekeeping exploitations in relation to the methods used for
tackling Varroa. This study aims to investigate the economic impact of total brood removal (TBR)
as a biotechnique to keep Varroa mites under control, and compare this to other common
biotechniques and chemical Varroa control in numerous Italian beekeeping case studies. A pool
of economic and technical indexes was proposed. The proposed index pool can be included in
the development of an expert system (such as a decision support system) able to address the
optimal management of this very complex activity, which requires natural resources, land
protection, capital and high technical skills. The result showed that the adoption of the TBR
biotechnique vs. other biotechniques led to an increase in terms of total revenue (increase
values ranging from 11% to 28%) even though more labor is needed (increase values ranging
from 43 to 83 min/hive) and a loss of honey production could be recorded in some cases.
Additionally, the total expenses, represented mainly by supplemental nutrition and treatments
with oxalic acid, affected the economic results of the biotechnical practices. The use of
biotechniques vs. chemical control resulted in decreased treatment costs and increased feeding
costs. The advantages resulting from not using synthetic acaricides (which are dangerous for
honey bee and human health as well as the environment) as well as the advantages linked to the
production of new nuclei (which are involved in the maintenance of bee stock and counteract
the decline in honey bee population) and pollination ecosystem services could make beekeeping
farms more resilient over time.
Free download
4- Thymol in combination with trace levels of imidacloprid reduces visual learning
performance in honey bees
Colin, T., Plath, J.A., Klein, S., Vine, P., Devaud, J.-M., Lihoreau, M., Meikle, W.G., Barron, A.B., 2020. The miticide thymol in combination with
trace levels of the neonicotinoid imidacloprid reduces visual learning performance in honey bees (Apis mellifera). Apidologie. Abstract : Despite growing concerns over the impacts of agricultural pesticides on honey bee
health, miticides (a group of pesticides used within hives to kill bee parasites) have received little
attention. We know very little about how miticides might affect bee cognition, particularly in
interaction with other known stressors, such as crop insecticides. Visual learning is essential for
foraging bees to find their way to flowers, recognize them, and fly back to the nest. Using a
standardized aversive visual conditioning assay, we tested how field exposure to three pesticides
affects visual learning in European honey bees (Apis mellifera). Our pesticides were two common
miticides, thymol in the commercial formulation Apiguard® and tau-fluvalinate in the
formulation Apistan® and one neonicotinoid, imidacloprid. We found no effect of miticides
alone, nor of field-relevant doses of imidacloprid alone, but bees exposed to both thymol and
imidacloprid showed reduced performance in the visual learning assay.
Download not free
International Press Review by SNGTV Honeybee commission 4
5- An original method for evaluating Varroa destructor infestation
Szczurek, A., Maciejewska, M., Bąk, B., Wilk, J., Wilde, J., Siuda, M., 2020. Detecting varroosis using a gas sensor system as a way to face the
environmental threat. Science of The Total Environment 722, 137866.
Abstract: Colony Collapse Disorder (CCD) is an environmental threat on a global scale due to the
unreplaceable role of bees in crop pollination. Varroa destructor (V.d.), a parasite that attacks
honeybee colonies, is one of the primary causes of honey bee population decline and the most
serious threat to the beekeeping sector. This work demonstrates the possibility of quantitatively
determining bee colony infestation by V.d. using gas sensing. The results are based on analysing
the experimental data acquired for eighteen bee colonies in field conditions. Their infestation
rate was in the 0 to 24.76% range. The experimental data consisted of measurements of beehive
air with a semiconductor gas sensor array and the results of bee colony V.d. infestation
assessment using a flotation method. The two kinds of data were collected in parallel. Partial
least square regression was applied to identify the relationship between the highly multivariate
measurement data provided by the gas sensor array and the V.d. infestation rate. The quality of
the developed quantitative models was very high, as demonstrated by the coefficient of
determination exceeding R2
=0.99. Moreover, the prediction error was less than 0.6% for V.d.
infestation rate predictions based on the measurement data that was unknown to the model.
The presented work has considerable novelty. To our knowledge, the ability to determine the
V.d. infestation rate of bee colony quantitatively based on beehive air measurements using a
semiconductor gas sensor array has not been previously demonstrated.
Free download
6- Abdominal colour pattern is a witness of hybridization’s degree in Apis mellifera mellifera
Henriques, D., Lopes, A.R., Ferrari, R., Neves, C.J., Quaresma, A., Browne, K.A., McCormack, G.P., Pinto, M.A., 2020. Can introgression in Mlineage honey bees be detected by abdominal colour patterns? Apidologie. Abstract : Honey bee abdominal pigmentation is one of the most recognisable traits and it is
often used by beekeepers as an indicator of M-lineage subspecies purity. However, this approach
may negatively impact population diversity and is futile if there is no association between tergite
colour patterns and the genetic background. To assess whether this trait can be used as a proxy
for introgression proportions in M-lineage subspecies, we genotyped, with highly informative
SNP assays, A. m. mellifera and A. m. iberiensis individuals displaying four different colour
phenotypes. The SNP data detected highly introgressed bees exhibiting a black phenotype and,
at the same time, pure or marginally introgressed bees with yellow banding patterns, in both
subspecies. Despite these observations, contrary to A. m. iberiensis , in A. m. mellifera ,
introgression proportions revealed to be a significant predictor of abdominal pigmentation.
Therefore, abdominal pigmentation could be used by A. m. mellifera conservationists to guide
colony selection when genetic tools are unavailable.
Download not free
International Press Review by SNGTV Honeybee commission 5
7- How undertaker workers recognize dead honey bees (Apis cerana)?
Wen, P., 2020. Death recognition by undertaker bees (preprint). Animal Behavior and Cognition. Abstract: Dead conspecifics removal is important of being social to avoid pathogen transmission,
which resulted in the evolution of a specific caste of undertaking workers in all hives bee species.
However, it is mysterious that how the undertakers distinguish death and life instantly. Through
integrative studies of behavioural tests and chemical analyses, a novel mechanism for dead
conspecifics recognition is found in the Asian bee Apis cerana cerana Fabricius. The bees detect
quickly the death of conspecifics based on decreased cuticular hydrocarbon (CHC) emissions,
caused by the cooling of the dead bee. Specifically, with the decline of body temperature in
death, the CHC emission was reduced. Undertakers perceived the major CHCs. Addition of
synthetic CHCs, followed by heating, inhibited undertaking behaviour. Among these CHCs,
heptacosane and nonacosane are the major compounds in a natural bee hive, providing a
continuous signal associated with life. Via changing the vapour pressure then the ratio of emitted
compounds encoding the physiological status of signal sender, insect chemical communication
can be finely tuned by body temperature. This straightforward death recognition mechanism
requiring little cost can be universal in animal living in social groups, especially in the social
insects. Body temperature affected behaviour can response to increasing frequency of extreme
weathers in global climate change, which help explain the recent worldwide bee health problem.
Free download
8- The bee will sting more than what it protects is valuable
Schmidt, J.O., 2020. Decision making in honeybees: a time to live, a time to die? Insectes Sociaux.
Abstract : Honeybees that sting vertebrate predators embed and leave their stingers in the flesh
of the stung animal and die shortly thereafter. To determine whether bees make life-or-death
decisions based upon risk–benefit evaluations, the vigor of defenses of colonies that had a small
loss potential versus those that have large loss potential was compared. Colonies 3–4 days old
have small reserves, and thus, risk fewer reserves to lose to a potential predator. In contrast,
colonies 19–22 days old risk large quantities of vulnerable immature brood, constructed wax
comb, nectar/honey, and pollen and have limited future reproductive potential if their nest is
abandoned. As predicted by a risk–benefit hypothesis, older colonies with much at risk sent
proportionately larger percentages of stinging defenders to confront threats than younger
colonies with less to lose. The percentage of defenders that issue from the 19–22-day-old
colonies correlated with the population of workers within the colonies. The percentage of
workers that attack strongly increased as the weight of colony-fixed resources within the combs
increased. In queenless colonies having no potential to reproduce by swarming and little, or no,
reserves of nectar or pollen, only a small percentage of workers defended the colony. These
results provide support for the ability of defending honeybee workers to make life-or-death
decisions based on evaluating risks of colony loss versus the benefit derived from their personal
loss of life.
Download not free
International Press Review by SNGTV Honeybee commission 6
9- Vaporization of oxalic acid, with or without queen caging, is not enough to manage Varroa
infestation Jack, C.J., van Santen, E., Ellis, J.D., 2020. Evaluating the Efficacy of Oxalic Acid Vaporization and Brood Interruption in
Controlling the Honey Bee Pest Varroa destructor (Acari: Varroidae). Journal of Economic Entomology 113, 582–588.
Abstract: A successful Integrated Pest Management approach to Varroa destructor Anderson and
Trueman control in managed colonies of western honey bees Apis mellifera Linnaeus
(Hymenoptera: Apidae) must be an improvement over conventional control methods and include
cost-effective treatments that can be readily employed by beekeepers. Herein, we tested the
efficacy of oxalic acid (OA) vaporization and brood interruption as Varroa controls. Sixty
experimental colonies were randomly assigned to one of six treatment groups with 10 colonies
per group. The six treatments were: 1) OA applied once, 2) OA applied three times, 3) brood
interruption, 4) OA applied once + brood interruption, 5) OA applied three times + brood
interruption, and 6) no OA or brood interruption. The OA was applied via vaporization, with each
application being 1 g OA applied through the hive entrance (label rate), on the bottom board.
Brood interruption was accomplished by caging a colony’s queen in a queen cage for a period of
24 d. An additional 10 colonies were treated with amitraz (Apivar – positive control). Varroa
levels were estimated before, during, and after treatment applications using sticky boards left in
colonies for 3 d. Our data suggest that queen caging to achieve brood interruption during the fall
season can negatively impact colony strength and survival. We observed high colony mortality in
some treatments, despite diligent colony management to alleviate the side effects of the
treatments. Colonies treated with amitraz were healthier and had better survival than those
treated with OA vaporization. In conclusion, OA and/or brood interruption did not provide
sufficient Varroa control.
Download not free
10- A fungus as a biological control method against Varroa infestation
Fernandez Ferrari, M.C., Favaro, R., Mair, S., Zanotelli, L., Malagnini, V., Fontana, P., Angeli, S., 2020. Application of Metarhizium anisopliae as a potential biological control of Varroa destructor in Italy. Journal of Apicultural Research 1–11
Abstract : The ectoparasitic mite Varroa destructor is a serious threat to European honey bees.
Traditionally, Varroa mites has been controlled with synthetic pesticides, but residues in honey
bee products and recently arisen resistances to chemicals call for new control methods. One
alternative approach is the use of biological control methods, such as acaropathogenic fungi. In
this field study, we evaluated a special isolate of M. anisopliae var. anisopliae BIPESCO 5 as a
possible biological control for V. destructor. The colonies were divided in two treatments of eight
replicates. During the first month of the experiment, every colony of the ‘Metarhizium’ group
was dusted weekly with 10 g of conidia in the concentration of 1×1010 conidia per gram. After 14
days, all the colonies were split, moving the frames with broods to new nuclei and leaving the
remaining brood-less colonies with the queens. The brood-less colonies were exposed to a
follow-up oxalic acid treatment to assess the residual mite level, while the nuclei were
transferred in a new apiary and were observed for a further 24 days until all broods hatched and
were then treated with oxalic acid. The results showed significant lower mite levels in the
treatment group than in the control (<60%). In addition, M. anisopliae had no impact on colony
strength and development. An increased number of dead bees found in the under baskets of the
treated colonies did not affect any of the colony strength parameters. To conclude, these results
lead us to consider BIPESCO 5 a promising biological control agent against Varroa.