Bees play an important role in agriculture and ecology, and their pollination efficiency is essential to the economic profitability of farms. The drastic decrease in bee populations witnessed over the last decade has attracted great attention to automated remote beehive monitoring research, with beehive acoustics analysis emerging as a prominent field. In this paper, we review the existing literature on bee acoustics analysis and report on the articles published between January 2012 and December 2021. Five categories are explored in further detail, including the origin of the articles, their study goal, experimental setup, audio analysis methodology, and reproducibility. Highlights and limitations in each of these categories are presented and discussed. We conclude with a set of recommendations for future studies, with suggestions ranging from bee species characterization, to recording and testing setup descriptions, to making data and codes available to help advance this new multidisciplinary field.

Microbial symbionts inhabiting the honeybee gut (i.e., gut microbiota) are essential for food digestion, immunity, and gut protection of their host. The taxonomic composition of the gut microbiota is dynamic throughout the honeybee life cycle and the foraging season. However, it remains unclear how drastic changes occurring in winter, such as food shortage and cold weather, impact gut microbiota dynamics. The objective of this study was to characterize the gut microbiota of the honeybee during the overwintering period in a northern temperate climate in Canada. The microbiota of nine honeybee colonies was characterized by metataxonomy of 16S rDNA between September 2017 and June 2018. Overall, the results showed that microbiota taxonomic composition experienced major compositional shifts in fall and spring. From September to November, Enterobacteriaceae decreased, while Neisseriaceae increased. From April to June, Orbaceae increased, whereas Rhizobiaceae nearly disappeared. Bacterial diversity of the gut microbiota decreased drastically before and after overwintering, but it remained stable during winter. We conclude that the honeybee gut microbiota is likely to be impacted by the important meteorological and dietary changes that take place before and after the overwintering period. Laboratory trials are needed to determine how the observed variations affect the honeybee health.

Hygienic behavior is a complex, genetically-based quantitative trait that serves as a key defense mechanism against parasites and diseases in Apis mellifera. Yet, the genomic basis and functional pathways involved in the initiation of this behavior are still unclear. Deciphering the genomic basis of hygienic behavior is a prerequisite to developing an extensive repertoire of genetic markers associated to the performance level of this quantitative trait. To fill this knowledge gap, we performed an RNA-seq on brain samples of 25 honeybees per hives from five hygienic and three non-hygienic hives. This analysis revealed that a limited number of functional genes are involved in honeybee hygienic behavior. The genes identified, and especially their location in the honeybee genome, are consistent with previous findings. Indeed, the genomic sequences of most differentially expressed genes were found on the majority of the QTL regions associated to the hygienic behavior described in previous studies. According to the Gene Ontology annotation, 15 genes are linked to the GO-terms DNA or nucleotide binding, indicating a possible role of these genes in transcription regulation. Furthermore, GO-category enrichment analysis revealed that electron carrier activity is over-represented, involving only genes belonging to the cytochrome P450. Cytochrome P450 enzymes’ overexpression can be explained by a disturbance in the regulation of expression induced by changes in transcription regulation or sensitivity to xenobiotics. Over-expressed cytochrome P450 enzymes could potentially degrade the odorant pheromones or chemicals that normally signal the presence of a diseased brood before activation of the removal process thereby inhibit hygienic behavior. These findings improve our understanding on the genetics basis of the hygienic behavior. Our results show that hygienic behavior relies on a limited set of genes linked to different regulation patterns (expression level and biological processes) associated with an over-expression of cytochrome P450 genes.

Honey bees (Apis mellifera) are facing multiple stressors affecting their lifespan, health and productivity. Among them, Nosema ceranae is an intracellular microsporidian parasite, which plays a major impact on honey bees colonies. However, both efficiency and innocuity of current treatment against N. ceranae are being questioned, thus raising the urgent need to develop alternative prophylactic and curative strategies. Endogenous microbial communities (i.e., host microbiota) are known to play a major role in disease prevention, and more recently both bacterial and yeast strains issued from gut microbiota were observed to improve hosts resistance against intracellular parasites both in mammals and insect models. The use of probiotics in honey bee nutrition is therefore promising to treat or prevent diseases. Therefore, further investigations are needed to properly select microorganisms with probiotic properties. In an in vivo experimental infection by N. ceranae, the probiotic effect of two honeybee gut bacterial strains (Parasaccharibacter apium (PC1 sp.) and Bacillus sp. (PC2 sp.)), and two broad spectra probiotics (Bactocell^® and Levucell SB^®) has been measured. Both curative and prophylactic administrations were tested: honey bees infected with N. ceranae and non-infected. For the four probiotic candidates, significant increases of survival probabilities (20–30%) were measured after two weeks of treatment with the administration of 10³ CFU/mL in sugar syrup, both in curative and prophylactic treatments. The present study shows that endogenous bacterial strains were at least as much efficient and safe than broad spectra probiotics in increasing survival in the context of experimental infection with N. ceranae. Therefore, taking advantage of beneficial host microbiota properties is a promising avenue to develop efficient and sustainable curative strategies against opportunistic diseases in honey bee colonies.

The objective of this study was to measure the efficacy of two organic acid treatments, formic acid (FA) and oxalic acid (OA) for the spring control of Varroa destructor (Anderson and Trueman) in honey bee (Apis mellifera L.) colonies. Forty-eight varroa-infested colonies were randomly distributed amongst six experimental groups (n = 8 colonies per group): one control group (G1); two groups tested applications of different dosages of a 40 g OA/l sugar solution 1:1 trickled on bees (G2 and G3); three groups tested different applications of FA: 35 ml of 65% FA in an absorbent Dri-Loc^® pad (G4); 35 ml of 65% FA poured directly on the hive bottom board (G5) and MiteAwayII™ (G6). The efficacy of treatments (varroa drop), colony development, honey yield and hive survival were monitored from May until September. Five honey bee queens died during this research, all of which were in the FA treated colonies (G4, G5 and G6). G6 colonies had significantly lower brood build-up during the beekeeping season. Brood populations at the end of summer were significantly higher in G2 colonies. Spring honey yield per colony was significantly lower in G6 and higher in G1. Summer honey flow was significantly lower in G6 and higher in G3 and G5. During the treatment period, there was an increase of mite drop in all the treated colonies. Varroa daily drop at the end of the beekeeping season (September) was significantly higher in G1 and significantly lower in G6. The average number of dead bees found in front of hives during treatment was significantly lower in G1, G2 and G3 versus G4, G5 and G6. Results suggest that varroa control is obtained from all spring treatment options. However, all groups treated with FA showed slower summer hive population build-up resulting in reduced honey flow and weaker hives at the end of summer. FA had an immediate toxic effect on bees that resulted in queen death in five colonies. The OA treatments that were tested have minimal toxic impacts on the honey bee colonies.

Honey bees (Apis mellifera L.) are pollinators of major importance for crop production. In recent years, colony management has become more difficult due to multiple problems such as pesticide exposure, exotic parasites, pathogens and nutritional deficiencies. The latter has incited beekeepers to provide protein supplements to their colonies to make up for the lack of pollen resources in the environment. However, their efficiency varies depending on their composition and the surrounding landscape. In this field study, we provided two different protein supplements (Global Patties^® and Ultra Bee®) to colonies with either limited or unlimited access to natural pollen to assess their impacts on various colony and individual bee parameters. We used 50 colonies distributed among three sites in the Montérégie area, in Quebec, Canada. We found that supplemented colonies limited in pollen collection were able to raise the same amount of brood than control colonies. Nurse bees in supplemented colonies also had a higher protein content compared to control bees. However, bees from supplemented colonies displayed shorter lifespan, which casts a doubt on the suitability of these products for honey bee nutrition. The supplement containing natural pollen, Global Patties®, was the most consumed and the most beneficial of the two for the colonies. Finally, colonies from the apiary surrounded by the highest proportion of cultivated land in a 5-km radius performed better toward the end of the season, which could be due to the presence of nutritionally interesting plants specific to the agricultural landscape at that time of the year.