The honeybee (Apis mellifera) is a social insect with strong sensory capacity and diverse behavioral repertoire and is recognized as a good model organism for studying the neurobiological basis of learning and memory. In this study, we analyzed the changes in microRNA (miRNA) and messenger RNA (mRNA) following maze-based visual learning using next-generation small RNA sequencing and Solexa/lllumina Digital Gene Expression tag profiling (DGE). For small RNA sequencing, we obtained 13 367 770 and 13 132 655 clean tags from the maze and control groups, respectively. A total of 40 differentially expressed known miRNAs were detected between these two samples, and all of them were up-regulated in the maze group compared to the control group. For DGE, 5 681 320 and 5 939 855 clean tags were detected from the maze and control groups, respectively. There were a total of 388 differentially expressed genes between these two samples, with 45 genes up-regulated and 343 genes down-regulated in the maze group, compared to the control group. Additionally, the expression levels of 10 differentially expressed genes were confirmed by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and the expression trends of eight of them were consistent with the DGE result, although the degree of change was lower in amplitude. The integrative analysis of miRNA and mRNA expression showed that, among the 40 differentially expressed known miRNAs and 388 differentially expressed genes, 60 pairs of miRNA/mRNA were identified as co-expressed in our present study. These results suggest that both miRNA and mRNA may play a pivotal role in the process of learning and memory in honeybees. Our sequencing data provide comprehensive miRNA and gene expression information for maze-based visual learning, which will facilitate understanding of the molecular mechanisms of honeybee learning and memory.

The honeybee has a strong learning and memory ability, and is recognized as the best model organism for studying the neurobiological basis of learning and memory. In this study, we analyzed the gene expression difference following proboscis extension response-based olfactory learning in the A. mellifera using a tag-based digital gene expression (DGE) method. We obtained about 5.71 and 5.65 million clean tags from the trained group and untrained group, respectively. A total of 259 differentially expressed genes were detected between these two samples, with 30 genes up-regulated and 229 genes down-regulated in trained group compared to the untrained group. These results suggest that bees tend to actively suppress some genes instead of activating previously silent genes after olfactory learning. Our DGE data provide comprehensive gene expression information for olfactory learning, which will facilitate our understanding of the molecular mechanism of honey bee learning and memory.

BackgroundApis mellifera and Apis cerana are two sibling species of Apidae. Apis cerana is adept at collecting sporadic nectar in mountain and forest region and exhibits stiffer hardiness and acarid resistance as a result of natural selection, whereas Apis mellifera has the advantage of producing royal jelly. To identify differentially expressed genes (DEGs) that affect the development of hypopharyngeal gland (HG) and/or the secretion of royal jelly between these two honeybee species, we performed a digital gene expression (DGE) analysis of the HGs of these two species at three developmental stages (newly emerged worker, nurse and forager).ResultsTwelve DGE-tag libraries were constructed and sequenced using the total RNA extracted from the HGs of newly emerged workers, nurses, and foragers of Apis mellifera and Apis cerana. Finally, a total of 1482 genes in Apis mellifera and 1313 in Apis cerana were found to exhibit an expression difference among the three developmental stages. A total of 1417 DEGs were identified between these two species. Of these, 623, 1072, and 462 genes showed an expression difference at the newly emerged worker, nurse, and forager stages, respectively. The nurse stage exhibited the highest number of DEGs between these two species and most of these were found to be up-regulated in Apis mellifera. These results suggest that the higher yield of royal jelly in Apis mellifera may be due to the higher expression level of these DEGs.ConclusionsIn this study, we investigated the DEGs between the HGs of two sibling honeybee species (Apis mellifera and Apis cerana). Our results indicated that the gene expression difference was associated with the difference in the royal jelly yield between these two species. These results provide an important clue for clarifying the mechanisms underlying hypopharyngeal gland development and the production of royal jelly.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-744) contains supplementary material, which is available to authorized users.

International audienceThe Asian honey bee Apis cerana and the European honey bee Apis mellifera are closely related and morphologically very similar. Where these species coexist, they appear to compete, but the outcomes of competition vary enormously between locations. Here, we report comparative behavioural data for A. cerana and A. mellifera in China gathered by tracking bees using radio frequency identification. Both species organise their division of labour by temporal polyethism and have remarkably similar demographic structure. Analyses of the homing capacities of both species following large-scale displacement suggest that A. mellifera colonies have a larger range than A. cerana. We observed that relocation of A. mellifera to a new environment disrupted colony function for 3 weeks. Our data show that A. mellifera and. A cerana occupy extremely similar behavioural niches, and therefore, the potential for competition between these species is very high

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.