In the honey bee, Apis mellifera, colonies are composed of one queen, thousands of female workers, and a few thousand seasonal males (drones) that are reared only during the reproductive season when colony resources are plentiful. Despite their transient presence in the hive, drones have the important function of mating with virgin queens, transferring their colony’s genes to their mates for the production of fertilized, worker-destined eggs. Therefore, factors affecting drone health and reproductive competency may directly affect queen fitness and longevity, having great implications at the colony level. Several environmental and in-hive conditions can affect the quality and viability of drones in general and their sperm in particular. Here we review the extant studies that describe how environmental factors including nutrition, temperature, season, and age may influence drone reproductive health. We also review studies that describe other factors, such as pesticide exposure during and after development, that may also influence drone reproductive quality. Given that sperm development in drones is completed during pupation prior to adult emergence, particular attention needs to be paid to these factors during drone development, not just during adulthood. The present review showcases a growing body of evidence indicating that drones are very sensitive to environmental fluctuations and that these factors cause drones to underperform, potentially compromising the reproductive health of their queen mates, as well as the overall fitness of their colony.

Aerobic methane-oxidizing bacteria (methanotrophs) have the unique ability to grow on methane as their sole source of carbon and energy. They are ubiquitous in the environment and play a major role in the removal of the greenhouse gas methane from the biosphere before it is released into the atmosphere. The ability to drive oxygen-dependent methane oxidation was once assumed to be an exceptional property of a very restricted set of microbes belonging to two classes of Proteobacteria: Alphaproteobacteria and Gammaproteobacteria. While Proteobacteria still form the foundation of the methanotrophic landscape in many ecosystems, the ability to oxidize methane has also been demonstrated in the microbial phyla Verrucomicrobia and Candidatus Methylomirabilis oxyfera (phylum NC10). Over the years various methanotrophs have also been isolated, including facultative methanotrophs, extremophile species, and anaerobes, thus expanding both the taxonomic diversity and physiological range of methanotrophy. In addition, a number of cross-species interactions that enable efficient methane utilization have been identified, changing the way we view mechanisms of methane utilization. Finally, a thorough revision of core metabolic pathways has been made, and whole-genome metabolic models have been constructed, which facilitate the metabolic engineering of methanotrophic bacteria and expand the potential for their biotechnological applications.

Aerobic methane-oxidizing bacteria (methanotrophs) have the unique ability to grow on methane as their sole source of carbon and energy. They are ubiquitous in the environment and play a major role in the removal of the greenhouse gas methane from the biosphere before it is released into the atmosphere. The ability to drive oxygen-dependent methane oxidation was once assumed to be an exceptional property of a very restricted set of microbes belonging to two classes of Proteobacteria: Alphaproteobacteria and Gammaproteobacteria. While Proteobacteria still form the foundation of the methanotrophic landscape in many ecosystems, the ability to oxidize methane has also been demonstrated in the microbial phyla Verrucomicrobia and Candidatus Methylomirabilis oxyfera (phylum NC10). Over the years various methanotrophs have also been isolated, including facultative methanotrophs, extremophile species, and anaerobes, thus expanding both the taxonomic diversity and physiological range of methanotrophy. In addition, a number of cross-species interactions that enable efficient methane utilization have been identified, changing the way we view mechanisms of methane utilization. Finally, a thorough revision of core metabolic pathways has been made, and whole-genome metabolic models have been constructed, which facilitate the metabolic engineering of methanotrophic bacteria and expand the potential for their biotechnological applications.

The high altitude bee, Apis laboriosa Smith significantly differs from the close phylogenetic relative A. dorsata Fabricius in colour and shape of the abdomen, the endophalli of male genitalia, nucleotide sequence of the mitochondrial protein coding genes, chemical constituents of the cephalic and abdominal endocrine glands, nesting pattern, foraging and mating behaviour to distinguish them as separate species. They are found to construct single combed exposed nests under rock ledges in altitude ranging from 1200 to 3500 m above mean sea level from northern India to northern Vietnam. Current research trend shows the need of special attention for maximum possible and better quality agricultural and horticultural yield using A. laboriosa as it is known to pollinate a number of crops and fruits. General aspects of A. laboriosa to create sensitivity towards conservation of this species native to high altitude Himalayan foothills before being stressed by honey hunting, changing agricultural practices and crowding of natural enemies have also been focussed here.

Previous experimental studies demonstrated that small drones (SD) had lower paternity share since they were not successful in mating with queens as large drones (LD) in the mating arena. However, it remains unclear whether spermatozoa of SD can compete in vivo with those of LD if SD have mating opportunity. We, therefore, tested the spermatozoal competitiveness of SD against LD by instrumentally inseminating the queens with varying proportions of semen from LD and SD. Sister queens from a Buckfast colony and LD and SD from 15 Caucasian colonies were reared synchronously as experimental test individuals. The virgin sister queens were randomly allocated into three semen composition groups. The queens in groups A, B and C were inseminated with an equal volume of semen (7.2 μl) collected successively from 6 LD and 6 SD (50%:50% treatment), 3 LD and 9 SD (25%:75% treatment), and 9 LD and 3 SD (75%:25% treatment), respectively. Once oviposition starts in mating nucs, the queens were introduced into field colonies to proceed to lay eggs. After 3 months, about 100 newly emerged worker daughters from each queen were individually collected from the colonies for paternity assignment. Five polymorphic microsatellite loci (A024, A079, A43, A113, and Ap226) were analysed in 144 drones that were used to inseminate 12 experimental queens and 908 offspring workers. The observed patriline frequencies of LD and SD were 67.0% and 33.0% in group A, 34.6% and 65.4% in group B, and 79.8% and 20.2% in group C, respectively. The patriline frequencies within each colony were noticeably skewed. LD that were reared in QRC sired more offspring, whereas SD that were reared in LWC had lower paternity shares. When all three semen composition groups were pooled, the overall observed patriline frequency of SD (40%) was found to be 10% less than the overall expected patriline frequency (50%). The results demonstrated that SD remained a little behind LD in sperm competition.

In sexual reproduction, ejaculate components that males transfer into the females vary because of various factors. For male honey bees, the entirety of their sperm is stored in the seminal vesicles until the first copulation with a female and subsequent ejaculation, after which the male will die. Therefore, we can evaluate age-related ejaculate alterations by investigating internal sexual organ changes with age. This study found that seminal vesicle wet weight decreased following sperm transfer from testes to seminal vesicles, while mucus gland weight was unchanged, thus resulting in increased sperm density in the seminal vesicles. This suggests that the decrease of seminal fluid in the seminal vesicles may be the underlying cause for age-related ejaculate component alterations.

Assigning a functional role to a microorganism has historically relied on cultivation of isolates or detection of environmental genome-based biomarkers using a posteriori knowledge of function. However, the emerging field of function-driven single-cell genomics aims to expand this paradigm by identifying and capturing individual microbes based on their in situ functions or traits. To identify and characterize yet uncultivated microbial taxa involved in cellulose degradation, we developed and benchmarked a function-driven single-cell screen, which we applied to a microbial community inhabiting the Great Boiling Spring (GBS) Geothermal Field, northwest Nevada. Our approach involved recruiting microbes to fluorescently labeled cellulose particles, and then isolating single microbe-bound particles via fluorescence-activated cell sorting. The microbial community profiles prior to sorting were determined via bulk sample 16S rRNA gene amplicon sequencing. The flow-sorted cellulose-bound microbes were subjected to whole genome amplification and shotgun sequencing, followed by phylogenetic placement. Next, putative cellulase genes were identified, expressed and tested for activity against derivatives of cellulose and xylose. Alongside typical cellulose degraders, including members of the Actinobacteria, Bacteroidetes, and Chloroflexi, we found divergent cellulases encoded in the genome of a recently described candidate phylum from the rare biosphere, Goldbacteria, and validated their cellulase activity. As this genome represents a species-level organism with novel and phylogenetically distinct cellulolytic activity, we propose the name Candidatus ‘Cellulosimonas argentiregionis’. We expect that this function-driven single-cell approach can be extended to a broad range of substrates, linking microbial taxonomy directly to in situ function.

The early history of life harbours many unresolved evolutionary questions, none more important than the genomic origin and cellular evolution of eukaryotes. An issue central to eukaryote origin concerns the position of eukaryotes in the tree of life and the relationship of the host lineage that acquired the mitochondrion some two billion years ago to lineages of modern-day archaea. Recent analyses indicate that the host lineage branches within the Archaea, prompting the search for novel archaeal lineages that can improve our understanding of the cellular evolution of eukaryotes. Here we give a brief review of the studies on Archaea, the tree of life and the cellular evolution of eukaryotes, which is followed by an overview of recent progress fueled by new genomic technologies and recent status of archaeal research in China. Future directions for the study of early evolution are considered.

Queen reproductive potential (=quality) impacts the health and productivity of honey bee colonies. To determine the factors that affect reproductive quality during development, we tested queens produced under larval treatments by supplementing the diet with juvenile hormone (JH), additional sugars, or both, compared to untreated control. Furthermore, we varied the age of the larvae that were grafted (1 and 3 days old). We analyzed newly emerged virgin queens for their morphological characters as proxies for their reproductive potential. We found that the application of a sugar-enriched diet in combination with JH application onto 1st instar queen larvae produced higher-quality queens, while for 3rd instar larvae only the JH treatment resulted in increasing queen quality. For mated queens, those treated with JH plus supplemented sugars showed a significantly higher sperm count and sperm viability. Our findings demonstrate that honey bee queen reproductive potential can be increased through diet supplementation.

Exceptional natural phenomena, such as those that occur during a total solar eclipse, provide unique opportunities to study animal behavior outside the naturally evolved context, which can be informative in more general terms. Circumstantial descriptions of abnormal animal behavior during solar eclipses abound, although scientific studies conducted during an eclipse are relatively rare due to inherent logistical difficulties. Here, honey bee foraging and homing behavior were studied during the total solar eclipse of August 21, 2017. In the first experiment, we studied foraging behavior of honey bees during the progression of the solar eclipse and found that the foraging activity drastically decreased but did not completely cease during the totality of the eclipse, in contrast to previous reports of complete cessation. The data indicate that the level of ambient light can largely overrule the internal circadian rhythm of foraging honey bees. Furthermore, colonies with a higher need for foraging decreased their foraging activity less than satiated colonies, consistent with the hypothesis that individual foraging decisions may be influenced by colony state, which affects cost-benefit analyses. In a second experiment, the temporal dynamics of homing of released workers and drones was compared in periods before, during, and after the solar eclipse. During the totality of the eclipse, very few bees arrived back at their hive, while homing before the total eclipse was accelerated, particularly in drones. The results suggest that, while the homing abilities of honey bees are not compromised until the sun is completely eclipsed, they may still interpret the diminishing light as an indicator of deteriorating flight conditions. Our unique study provides some insight into the control of honey bee foraging behavior when external cues and internal circadian rhythms are at odds, lent support to the notion that food deprivation can lead to riskier foraging, and indicated that homing in honey bees is possible even with very small amounts of sunlight.