Histomorphological study on embryogenesis of the honeybee Apis cerana

As important pollination species, honeybees play substantial impacts on the balance of global ecosystem, including two best-known honeybees Apis mellifera and Apis cerana. Embryogenesis is a fundamental stage of honeybee development and plays important roles in supporting the whole-life developmental process. However, few studies were reported on honeybee embryonic morphology using egg section, possibly due to the fragility of honeybee eggs and the difficulty of making embryonic sections. In this study, we reported a simply equipped method of frozen sectioning and PI (propidium iodide) staining to show the inner structure and cell distribution of A. cerena embryos at the different embryonic developmental stages. We found that the stages of A. cerena embryogenesis could also be typically classified into ten developmental stages, which are similar with the sister honeybee species, A. mellifera. To be noted, besides the cell distribution in the whole egg, we clearly observed the migration route of embryonic cells during the early embryonic development in A. cerena. This study provides a new insight into the whole process of honeybee embryogenesis from the perspective of egg sectioning, a histological basis for genetic manipulation using A. cerena eggs, and a reference method for egg sectioning for other insect species.     

Native Prey and Invasive Predator Patterns of Foraging Activity: The Case of the Yellow-Legged Hornet Predation at European Honeybee Hives

Contrary to native predators, which have co-evolved with their prey, alien predators often benefit from native prey naïveté. Vespa velutina, a honeybee predator originating from Eastern China, was introduced into France just before 2004. The present study, based on video recordings of two beehives at an early stage of the invasion process, intends to analyse the alien hornet hunting behaviour on the native prey, Apis mellifera, and to understand the interaction between the activity of the predator and the prey during the day and the season. Chasing hornets spent most of their time hovering facing the hive, to catch flying honeybees returning to the hive. The predation pressure increased during the season confirming previous study based on predator trapping. The number of honeybee captures showed a maximum peak for an intermediate number of V. velutina, unrelated to honeybee activity, suggesting the occurrence of competition between hornets. The number of honeybees caught increased during midday hours while the number of hornets did not vary, suggesting an increase in their efficacy. These results suggest that the impact of V. velutina on honeybees is limited by its own biology and behaviour and did not match the pattern of activity of its prey. Also, it could have been advantageous during the invasion, limiting resource depletion and thus favouring colonisation. This lack of synchronization may also be beneficial for honeybee colonies by giving them an opportunity to increase their activity when the hornets are less effective.     

Pollinator shift to managed honeybees enhances reproductive output in a bumblebee-pollinated plant

Introduced honeybees have had a large impact on native ecosystems by disrupting native plant–pollinator interactions. However, little is known of the effect of honeybees on reproduction of bumblebee-pollinated plants. Seasonal displacement of native bumblebees by introduced honeybees (Apis mellifera and A. cerana) was observed in Pedicularis densispica, endemic to Hengduan Mountains, China, providing an opportunity for honeybee presence/absence comparisons. Five-year field surveys were conducted in one frequently disturbed population at Yila Pasture (YP). We compared pollination effectiveness (combinations of visitation rate, efficiency in pollen transfer, and potential geitonogamy) between native and introduced managed bees. The total visitation rate of native bees and subsequent reproductive output decreased progressively, but honeybee introduction resulted in at least twofold increase in visitation and 70 % increase in seed set. In general, native bumblebees, which have larger bodies and longer proboscises and spent more time probing single flowers, were more efficient than honeybees in terms of pollen removal and pollen deposition during first visits to virgin flowers. Compared with bumblebees, honeybees visited markedly fewer flowers in sequence within individual plants, potentially reducing geitonogamous pollination. Our data highlight that introduced honeybees can provide pollination service in terms of both quantity and quality for P. densispica. We suggest honeybee introduction as an effective way to augment pollination of P. densispica at disturbed and isolated sites.     

Evaluation of the efficacy of mitochondrial ATP 6 and 8, Cyt b and 16S rDNA genes for differentiation of Iranian honeybees (Apis mellifera meda) from commercial subspecies of Apis mellifera L. and comparison with geometric morphometric method

Mitochondrial DNA sequence variations and the geometric morphometric method can be used to differentiate honeybee subspecies and evolutionary lineages. Molecular markers are powerful tools for discriminating honeybee subspecies. In this study, 19 beekeeping sites were selected to collect Iranian honeybee samples. The honeybee forewing images stored at Oberursel (the Bee Data Bank) were used to compare with those of Iranian honeybees using the geometric morphometric method. Furthermore, the abilities of DNA markers to differentiate Iranian honeybees (A. m. meda) from the most common commercial subspecies (A. m. carnica and A. m. ligustica) were assessed. In the present research, 16S rDNA (Mitochondrial 16S rDNA Region) showed greater ability in differentiating Iranian honeybees from other subspecies compared with ATP 6 and 8 and Cyt b. The phylogenetic tree derived from 16S rDNA differentiated A. m. carnica and A. m. ligustica from Iranian honeybees. Principle component analysis (PCA) discriminated C lineage and Z subgroup from A and M lineages using 16S rDNA. In addition, the phylogenetic tree of the 16S rDNA affirmed the findings of the cluster analysis derived from the geometric morphometric method in differentiating A. m. carnica and A. m. ligustica from Iranian honeybees. The cluster analysis grouped reference subspecies of A. m. meda with Iranian honeybees. Moreover, the Discriminant Function Analyses (DFA) differentiated Iranian honeybees from A. m. ligustica and A. m. carnica.     

Farming with native bees (<Emphasis Type="Italic">Apis mellifera</Emphasis> subsp. <Emphasis Type="Italic">capensis</Emphasis> Esch.) has varied effects on nectar-feeding bird communities in South African fynbos vegetation

Outside their natural range, honeybees (Apis mellifera) are known to have detrimental effects on indigenous pollinators through exploitative or interference competition, but little is known about the effect of honeybee farming in areas where honeybees occur naturally. In the Cape Floristic Region of South Africa, where honeybees are indigenous, managed hives potentially elevate the abundance of honeybees far above natural levels, but impacts on other floral resource-dependent species have not been studied. Here we use experimental manipulation of honeybee density to test whether honeybee farming affects nectar-feeding birds. We selected the common sugarbush (Protea repens), utilized by both birds and bees, and analysed the time (before/after) by treatment (control/experiment) interaction to explore changes in bee abundance, nectar availability and bird abundance at three sites. Hive addition increased honeybee abundance in inflorescences of P. repens above expected levels. Despite experimental increase in honeybee numbers, there is no reduction in nectar sugar availability relative to the control areas. Where honeybee density was highest, sugarbird (Promerops cafer) numbers declined relative to expected, but sunbirds (Nectarinidae) were not affected at any of the sites. We conclude that stocking rates of more than one honey bee per P. repens inflorescence have detrimental effects on bird abundance due to interference, rather than resource competition.     

Infections of Nosema ceranae in four different honeybee species

The microsporidium Nosema ceranae is detected in honeybees in Thailand for the first time. This endoparasite has recently been reported to infect most Apis mellifera honeybee colonies in Europe, the US, and parts of Asia, and is suspected to have displaced the endemic endoparasite species, Nosema apis, from the western A. mellifera. We collected and identified species of microsporidia from the European honeybee (A. mellifera), the cavity nesting Asian honeybee (Apis cerana), the dwarf Asian honeybee (Apis florea) and the giant Asian honeybee (Apis dorsata) from colonies in Northern Thailand. We used multiplex PCR technique with two pairs of primers to differentiate N. ceranae from N. apis. From 80 A. mellifera samples, 62 (77.5%) were positively identified for the presence of the N. ceranae. Amongst 46 feral colonies of Asian honeybees (A. cerana, A. florea and A. dorsata) examined for Nosema infections, only N. ceranae could be detected. No N. apis was found in our samples. N. ceranae is found to be the only microsporidium infesting honeybees in Thailand. Moreover, we found the frequencies of N. ceranae infection in native bees to be less than that of A. mellifera.     

Comparison of learning and memory of Apis cerana and Apis mellifera

The honeybee is an excellent model organism for research on learning and memory among invertebrates. Learning and memory in honeybees has intrigued neuroscientists and entomologists in the last few decades, but attention has focused almost solely on the Western honeybee, Apis mellifera. In contrast, there have been few studies on learning and memory in the Eastern honeybee, Apis cerana. Here we report comparative behavioral data of color and grating learning and memory for A. cerana and A. mellifera in China, gathered using a Y-maze apparatus. We show for the first time that the learning and memory performance of A. cerana is significantly better on both color and grating patterns than that of A. mellifera. This study provides the first evidence of a learning and memory difference between A. cerana and A. mellifera under controlled conditions, and it is an important basis for the further study of the mechanism of learning and memory in honeybees.     

Environmental factors have a strong impact on the composition and diversity of the gut bacterial community of Chinese black honeybees

The Chinese black honeybees is an ecotype of the European honeybee that is formed by the natural hybridization of Apis mellifera mellifera and A. m. carnica. It is distributed in nature reserves in North China and has been an important breeding resource for disease resistance and other desirable traits. Compared to the areas outside of reserves, the nature reserves offer significant biodiversity benefits not only to the Chinese black honey bees but also to the other valuable plants and animals. In recent years there has been growing evidence that environmental factors including food choices play an important role in shaping the composition and activity of gut microbiota, which in turn can impact host health. In the previous studies on Chinse black honeybees, little attention has been paid to the diverse population of microbes in the gut that play a vital role in host health. In order to achieve a better understanding on the role of environmental factors in diversity and composition of gut microbiota of honey bees, in the present study, we analyzed the gut bacterial communities of Chinese black honeybees using terminal restriction fragment length polymorphism (T-RFLP). The results showed that the samples from the national nature reserves that are protected and managed so as to preserve and enrich their natural condition and resources for Chinese black honeybees had higher variety and richness of gut bacteria than that collected from unreserved regions that also harbor populations of Chinese black honeybees. The four terminal restriction fragments (T-RFs), 201, 223, 247 and 320 bp, were identified to be the dominant bacteria of Chinese black honeybees. Of which 247 and 320 bp had greater differences between bee groups sampled in different regions and therefore could be used as genetic markers to separate samples collected from the national nature reserves to samples collected from unreserved regions. The results clearly indicate that national nature reserve protects biological diversity and ecological and evolutionary processes which have had a significant influence on the diversity of gut bacteria of Chinese black honeybees. The ubiquity of gut symbiotic bacteria identified in Chinese black honeybee suggests that environmental factors could play an important role in diversity and composition of gut bacteria and warrant further investigation into the functional significance of these gut bacteria for the honeybee health.     

The gene vitellogenin has multiple coordinating effects on social organization

Temporal division of labor and foraging specialization are key characteristics of honeybee social organization. Worker honeybees (Apis mellifera) initiate foraging for food around their third week of life and often specialize in collecting pollen or nectar before they die. Variation in these fundamental social traits correlates with variation in worker reproductive physiology. However, the genetic and hormonal mechanisms that mediate the control of social organization are not understood and remain a central question in social insect biology. Here we demonstrate that a yolk precursor gene, vitellogenin, affects a complex suite of social traits. Vitellogenin is a major reproductive protein in insects in general and a proposed endocrine factor in honeybees. We show by use of RNA interference (RNAi) that vitellogenin gene activity paces onset of foraging behavior, primes bees for specialized foraging tasks, and influences worker longevity. These findings support the view that the worker specializations that characterize hymenopteran sociality evolved through co-option of reproductive regulatory pathways. Further, they demonstrate for the first time how coordinated control of multiple social life-history traits can originate via the pleiotropic effects of a single gene that affects multiple physiological processes.     

Trypanosomatid parasites infecting managed honeybees and wild solitary bees

The parasite Crithidia mellificae (Kinetoplastea: Trypanosomatidae) infects honeybees, Apis mellifera. No pathogenic effects have been found in individual hosts, despite positive correlations between infections and colony mortalities. The solitary bee Osmia cornuta might constitute a host, but controlled infections are lacking to date. Here, we challenged male and female O. cornuta and honeybee workers in laboratory cages with C. mellificae. No parasite cells were found in any control. Parasite numbers increased 6.6 fold in honeybees between days 6 and 19 p.i. and significantly reduced survival. In O. cornuta, C. mellificae numbers increased 2–3.6 fold within cages and significantly reduced survival of males, but not females. The proportion of infected hosts increased in O. cornuta cages with faeces, but not in honeybee cages without faeces, suggesting faecal – oral transmission. The data show that O. cornuta is a host of C. mellificae and suggest that males are more susceptible. The higher mortality of infected honeybees proposes a mechanism for correlations between C. mellificae infections and colony mortalities.     

引入西方蜜蜂对中蜂的危害及生态影响

作者阐述自1896年中国引进西方蜜蜂Apis melliferaL.的优良品种如意大利蜂Apis mellifera ligusticaSpinola和喀尼阿兰蜂Apis mellifera Carnica Pollmann以来,使当地的东方蜜蜂Apis cerana F.受到严重危害,其分布区域缩小75%以上,种群数量减少80%以上。使山林植物授粉总量减少,导致植物多样性减少。文中提出: 建立自然保护区保存本地蜜蜂遗传特性,和采用基因转移等技术,培育具有西方蜜蜂优良生产性能的中蜂新品种,逐步恢复中蜂的种群数量。     

蜜蜂——新兴的模式生物

蜜蜂作为具有重要经济价值和生态价值的社会性昆虫, 在诸如神经生物学和社会生物学等研究领域也具有很高的模型价值。蜜蜂基因组工程为深入认识蜜蜂的生物学特点,进一步发挥其在多个研究领域的模型价值奠定了分子基础。本文基于蜜蜂的生物学特点,介绍了蜜蜂作为模式生物所具备的优势,及其在学习和记忆、劳动分工、级型分化、免疫等热点领域的研究价值。通过总结和展望国内外蜜蜂生物学研究形势,呼吁国内相关各学科开展合作研究。     

Whole-Genome Sequence of Nocardiopsis alba Strain ATCC BAA-2165, Associated with Honeybees

The actinomycete Nocardiopsis alba was reportedly associated with honeybees in separate occurrences. We report the complete genome of Nocardiopsis alba ATCC BAA-2165 isolated from honeybee guts. It will provide insights into the metabolism and genetic regulatory networks of this genus of bacteria that enable them to live in a range of environments.     

云南食用蜜蜂种类调查及鉴定

在云南,人们有食用蜜蜂幼虫和蛹的习俗。市场上销售的蜜蜂幼虫和蛹多经热水烫过或煮过,因而缺少成虫形态,俗名易混用,食用种类长期未予明确。本文在市场调查的基础上,收集其中部分样品,通过形态学和mtDNA的COI基因部分序列初步鉴定其分类地位,以明确食用种类。结果表明,云南蜜蜂的食用集中在横断山脉南部地区,接受人群广泛,食用方式多样;云南食用本地分布的全部5种野生蜜蜂,包括东方蜜蜂(Apis cerana)、小蜜蜂(A.florea)、大蜜蜂(A.dorsata)、黑大蜜蜂(A.laboriosa)和黑小蜜蜂(A.andreniformis);基于COI序列构建的邻接法(NJ)和最大简约法(MP)系统发育树支持现有的蜜蜂属系统发育关系;现有的食用蜜蜂大多采集自野外,亟待开展遗传资源保护。本研究为食用蜜蜂的鉴定提供了数据支持,也为蜜蜂自然资源的利用和保护提供参考。     

Neuromechanism Study of Insect–Machine Interface: Flight Control by Neural Electrical Stimulation

The insect–machine interface (IMI) is a novel approach developed for man-made air vehicles, which directly controls insect flight by either neuromuscular or neural stimulation. In our previous study of IMI, we induced flight initiation and cessation reproducibly in restrained honeybees (Apis mellifera L.) via electrical stimulation of the bilateral optic lobes. To explore the neuromechanism underlying IMI, we applied electrical stimulation to seven subregions of the honeybee brain with the aid of a new method for localizing brain regions. Results showed that the success rate for initiating honeybee flight decreased in the order: α-lobe (or β-lobe), ellipsoid body, lobula, medulla and antennal lobe. Based on a comparison with other neurobiological studies in honeybees, we propose that there is a cluster of descending neurons in the honeybee brain that transmits neural excitation from stimulated brain areas to the thoracic ganglia, leading to flight behavior. This neural circuit may involve the higher-order integration center, the primary visual processing center and the suboesophageal ganglion, which is also associated with a possible learning and memory pathway. By pharmacologically manipulating the electrically stimulated honeybee brain, we have shown that octopamine, rather than dopamine, serotonin and acetylcholine, plays a part in the circuit underlying electrically elicited honeybee flight. Our study presents a new brain stimulation protocol for the honeybee–machine interface and has solved one of the questions with regard to understanding which functional divisions of the insect brain participate in flight control. It will support further studies to uncover the involved neurons inside specific brain areas and to test the hypothesized involvement of a visual learning and memory pathway in IMI flight control.     

Ecdysteroid biosynthesis in workers of the European honeybee Apis mellifera L

We previously reported preferential expression of genes for ecdysteroid signaling in the mushroom bodies of honeybee workers, suggesting a role of ecdysteroid signaling in regulating honeybee behaviors. The organs that produce ecdysteroids in worker honeybees, however, remain unknown. We show here that the expression of neverland and Non-molting glossy/shroud, which are involved in early steps of ecdysteroid synthesis, was enhanced in the ovary, while the expression of CYP306A1 and CYP302A1, which are involved in later steps of ecdysone synthesis, was enhanced in the brain, and the expression of CYP314A1, which is involved in converting ecdysone into active 20-hydroxyecdysone (20E), was enhanced in the brain, fat body, and ovary. In in vitro organ culture, a significant amount of ecdysteroids was detected in the culture medium of the brain, fat body, and hypopharyngeal glands. The ecdysteroids detected in the culture medium of the fat body were identified as ecdysone and 20E. These findings suggest that, in worker honeybees, cholesterol is converted into intermediate ecdysteroids in the ovary, whereas ecdysone is synthesized and secreted mainly by the brain and converted into 20E in the brain and fat body.     

Evidence for competition between honeybees and bumblebees; effects on bumblebee worker size

Numerous studies suggest that honeybees may compete with native pollinators where introduced as non-native insects. Here we examine evidence for competition between honeybees and four bumblebee species in Scotland, a region that may be within the natural range of honeybees, but where domestication greatly increases the honeybee population. We examined mean thorax widths (a reliable measure of body size) of workers of Bombus pascuorum, B. lucorum, B. lapidarius and B. terrestris at sites with and without honeybees. Workers of all four species were significantly smaller in areas with honeybees. We suggest that reduced worker size is likely to have implications for bumblebee colony success. These results imply that, for conservation purposes, some restrictions should be considered with regard to placing honeybee hives in or near areas where populations of rare bumblebee species persist.     

Juvenile hormone III induced ultrastructural changes in the hypopharyngeal glands of honeybee Apis mellifera L. (Hymenoptera : Apidae) without and with infection by Nosema apis zander (Microsporidae : Nosematidae)

In the fully activated hypopharyngeal gland of the worker honeybee, Apis mellifera (Hymenoptera : Apidae), there were numerous electron-dense secretion granules, large secretion masses, free ribosomes, and arrays of endoplasmic reticulum. Injection of juvenile hormone into the honeybee caused crystallization of the secretion granules. After 1 and 7 days following the injection, both free and attached ribosomes were depleted from the cytoplasm. The depletion of ribosomes from the cytoplasm of the hypopharyngeal gland cells was observed only in honeybees infected by Nosema apis after injection of juvenile hormone. The appearance of an increasing number of lysosome-like bodies in the cytoplasm suggests that juvenile hormone activates the lysozymes, which leads to the degeneration of the hypopharyngeal glands.     

Genetic reincarnation of workers as queens in the Eastern honeybee Apis cerana

Thelytokous parthenogenesis, or the asexual production of female offspring, is rare in the animal kingdom, but relatively common in social Hymenoptera. However, in honeybees, it is only known to be ubiquitous in one subspecies of Apis mellifera, the Cape honeybee, A. mellifera capensis. Here we report the appearance of queen cells in two colonies of the Eastern honeybee Apis cerana that no longer contained a queen or queen-produced brood to rear queens from. A combination of microsatellite genotyping and the timing of the appearance of these individuals excluded the possibility that they had been laid by the original queen. Based on the genotypes of these individuals, thelytokous production by natal workers is the most parsimonious explanation for their existence. Thus, we present the first example of thelytoky in a honeybee outside A. mellifera. We discuss the evolutionary and ecological consequences of thelytoky in A. cerana, in particular the role thelytoky may play in the recent invasions by populations of this species.