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The species of genus Varroa mites parasitize on the honey bees of genus Apis. Unlike the well-studied V. destructor and V. jacobsoni mites, V. underwoodi remain less known. According to English language publications, the proven V. underwoodi distribution area of A. cerana colonies covers Nepal, South Korea, Indonesia, Papua New Guinea, Vietnam and China, but not Russia even though it had been described morphometrically in Russian language publications in Russia's Primorsky Territory. According to Vavilov's law (1920) of a homologous series, all the species of V. underwoodi, V. destructor and V. jacobsoni have the ability to spill over onto new hosts. Thus, V. underwoodi is a potential parasite of A. mellifera that should be carefully studied. In this study, V. underwoodi mites in colonies of honey bee subspecies A. c. ussuriensis native to Russia's Primorsky Territory are first proven using both morphometry and mitochondrial COX1 gene sequencing. The genetic divergence and p-distances between V. underwoodi and other Varroa species ranged from 7 to 10% and from 0.072 to 0.099, respectively, which matched the intraspecific level of differences. Two identical northernmost V. underwoodi samples from Russia's Primorsky Territory and China's Jilin province with GenBank accession number MH205176 were assigned as COX1 haplotype China 1 MH205176. The first discovery of V. underwoodi in the Primorsky Territory in northern Asia outlined the northern border of its range.

Apis cerana ussuriensis Ilyasov et al., 2019 is the northernmost subspecies of the Asian honey bee A. cerana Fabricius, 1793, common in the forests of Primorsky krai and Khabarovsk krai as far as 47°54′ N. Genetic studies of this subspecies are of great interest for science and apiculture, since all its adaptive traits were formed under the influence of the natural environment without human interference. We sequenced and annotated the complete mitochondrial DNA (mtDNA) sequences of bees of subspecies Apis cerana ussuriensis Ilyasov et al., 2019 (GenBank accession number AP018450) from Primorsky krai and Apis cerana koreana Ilyasov et al., 2019 (AP018431) from South Korea, as well as six exons of the nuclear DNA (nDNA) vitellogenin VG E2–E7 gene of bee subspecies A. c. ussuriensis, A. c. koreana, A. c. japonica Radoszkowski, 1887, A. c. cerana, and A. c. indica Fabricius, 1798. Cluster analysis of the mtDNA and the nDNA VG gene sequences showed the division of bees into two groups, the southern subspecies A. c. indica and the northern subspecies A. c. ussuriensis, A. c. koreana, A. c. japonica, and A. c. cerana. On the basis of the genetic divergence, we showed that subspecies A. c. ussuriensis was genetically closer to subspecies A. c. japonica, A. c. koreana, and A. c. cerana than to subspecies A. c. indica. Values of genetic divergence (0.80–8.00%) and Jukes–Cantor genetic distance (0.005–0.100) for mtDNA and nDNA VG gene between subspecies A. c. ussuriensis, A. c. koreana, A. c. japonica, A. c. cerana, and A. c. indica are within the range of intraspecific differences between insect subspecies. The estimated time of the emergence of the A. cerana subspecies is from two to one million years ago.

Apis cerana Fabricius, 1793 is the eastern honeybee species distributed throughout Asia from the tropical climate in the southern part to the temperate climate in the northern part. We sequenced and annotated the complete mitochondrial DNA (mtDNA) of A. cerana from Vladivostok, Primorsky Krai of the Russian Far East and uploaded it to the database GenBank (AP018450). MtDNA sequence has 15,919 bp length, AT-content 84% and GC-content 16% and contains 22 tRNA genes, 13 protein-coding genes, two ribosomal RNA genes, one AT-rich region and four non-coding intergenic regions (NC1-4). All proteincoding genes start with ATT and ATG codons, except for ATC, the start codon of the ATP8 gene, which and stop with the common stop codons TAA and TAG. A comparative analysis of complete mtDNA of A. cerana from China, Indonesia, Korea, Malaysia, Russia, Taiwan, Thailand, Vietnam, and Japan found that the Russian Far East Apis cerana differed from others on the subspecies level. Based on the comparative analysis of complete mtDNA (~16,000 bp), nuclear DNA (nDNA) gene Vitellogenin (VG) (~4,100 bp) and morphological measurements (six parameters), we assumed that the Russian Far-East A. cerana can be a distinct northern Asia population and can be described as a separate unique subspecies of A. c. ussuriensis subsp. nov. A. c. koreana subsp. nov. is also validated and described as a new subspecies.

Apis cerana is an Eastern honeybee species distributed throughout Asia and closely related to the Western honeybee species Apis mellifera distributed across all of Africa, Europe and Western Asia, and subdivided into thirty confirmed subspecies. Currently, A. cerana is an endangered bee species in contrast to A. mellifera. We sequenced and annotated the complete mitochondrial genome of A. cerana from the Jeollanam-do province of South Korea and uploaded to the DDBJ/Genbank database(AP018431). MtDNA sequence is 15.925 bp long, has 84% AT-content and 16% GC-content and contains 22 tRNA genes, 13 protein-coding genes, two ribosomal RNA genes, one AT-rich region and four non-coding intergenic regions (NC1-4). All protein-coding genes are started by ATT and ATG codons, except the genes ATP8 and ND4, which started by ATC and ATA, respectively, and are stopped by the common codons TAA and TAG. A comparative analysis of the whole mtDNA sequences of A. cerana from Korea and Taiwan, A. c. cerana from China and A. c. japonica from Japan showed that the genetic divergence of the Korean A. cerana sample from subspecies A. c. cerana (2.57%) and A. c. japonica (2.58%) matched to the level of genetic divergence of mtDNA between animal subspecies (0.8-8%). Based on the comparative analysis of complete mtDNA (~16,000 bp), two nuclear gene VG and EF1- α sequences (~8,000 bp) and morphological measurements (six parameters), we assumed that Korean A. cerana, Chinese A. c. cerana and Japanese A. c. japonica are different subspecies at an early stage of sub-speciation and could be called further as subspecies of Apis cerana koreana.

International audience; The geographic relationships and biogeography of Apis cerana have been studied extensively, but Korean populations have not been investigated thoroughly. We sequenced the non-coding region between the tRNALeu and COII mitochondrial (mt) genes (herein named NC2) of Korean samples, along with the samples from seven Asian localities (China, Vietnam, and Thailand). Four undiscovered haplotypes were found in Korea and China, respectively. A phylogenetic analysis confirmed that Korean A. cerana belonged to the Mainland Asian group. Dominance of Japan1 haplotype in Mainland Asia including Korea suggests extensive gene flow and a common genetic origin. A newly developed non-coding region between the tRNAMet and tRNAGln mt genes (named NC1) provided nine haplotypes with twice the number of variable positions compared to those in NC2. A NC1-based phylogenetic analysis revealed the presence of two phylogenetic groups in Apis cerana from Korea suggesting two different sources.

Olfactory cues are important sensory modalities on individual discrimination, perception, and efficient orientation to food sources in most insects. In honey bees, which are well known as eusocial insects, olfactory cues are mainly used to maintain a colony. Although much research has been reported on olfactory systems in honey bee olfaction, little is known about the differences between two major honey bee species, the European honey bee Apis mellifera and the Asian honey bee Apis cerana. In order to understand the differences of olfactory characteristics in the two species, we compared the distribution of sensory hairs on the antennae and antennal olfactory responses, using electron microscopy, electrophysiological recording and molecular expression level of odorant receptors. Our present study demonstrated that the antennae of A. cerana have more olfactory sensilla than A. mellifera, responding more strongly to various floral volatile compounds. At the molecular level, olfactory co-receptor (Orco), which makes heterodimers with other conventional olfactory receptors, is more abundantly expressed in the antenna of A. cerana than of A. mellifera. These findings extend our understanding of the olfactory systems and behavioral responses to various ecological and biological signals in two closely related honey bee species.

Background Long non-coding RNAs (lncRNAs) are a class of RNAs that do not encode proteins. Recently, lncRNAs have gained special attention for their roles in various biological process and diseases. Results In an attempt to identify long intergenic non-coding RNAs (lincRNAs) and their possible involvement in honey bee development and diseases, we analyzed RNA-seq datasets generated from Asian honey bee (Apis cerana) and western honey bee (Apis mellifera). We identified 2470 lincRNAs with an average length of 1011 bp from A. cerana and 1514 lincRNAs with an average length of 790 bp in A. mellifera. Comparative analysis revealed that 5 % of the total lincRNAs derived from both species are unique in each species. Our comparative digital gene expression analysis revealed a high degree of tissue-specific expression among the seven major tissues of honey bee, different from mRNA expression patterns. A total of 863 (57 %) and 464 (18 %) lincRNAs showed tissue-dependent expression in A. mellifera and A. cerana, respectively, most preferentially in ovary and fat body tissues. Importantly, we identified 11 lincRNAs that are specifically regulated upon viral infection in honey bees, and 10 of them appear to play roles during infection with various viruses. Conclusions This study provides the first comprehensive set of lincRNAs for honey bees and opens the door to discover lincRNAs associated with biological and hormone signaling pathways as well as various diseases of honey bee. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1868-7) contains supplementary material, which is available to authorized users.

Background The honey bee is an important model system for increasing understanding of molecular and neural mechanisms underlying social behaviors relevant to the agricultural industry and basic science. The western honey bee, Apis mellifera, has served as a model species, and its genome sequence has been published. In contrast, the genome of the Asian honey bee, Apis cerana, has not yet been sequenced. A. cerana has been raised in Asian countries for thousands of years and has brought considerable economic benefits to the apicultural industry. A cerana has divergent biological traits compared to A. mellifera and it has played a key role in maintaining biodiversity in eastern and southern Asia. Here we report the first whole genome sequence of A. cerana. Results Using de novo assembly methods, we produced a 238 Mbp draft of the A. cerana genome and generated 10,651 genes. A.cerana-specific genes were analyzed to better understand the novel characteristics of this honey bee species. Seventy-two percent of the A. cerana-specific genes had more than one GO term, and 1,696 enzymes were categorized into 125 pathways. Genes involved in chemoreception and immunity were carefully identified and compared to those from other sequenced insect models. These included 10 gustatory receptors, 119 odorant receptors, 10 ionotropic receptors, and 160 immune-related genes. Conclusions This first report of the whole genome sequence of A. cerana provides resources for comparative sociogenomics, especially in the field of social insect communication. These important tools will contribute to a better understanding of the complex behaviors and natural biology of the Asian honey bee and to anticipate its future evolutionary trajectory. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-16-1) contains supplementary material, which is available to authorized users.

Inhibitor cysteine knot (ICK) peptides exhibit ion channel blocking, insecticidal, and antimicrobial activities, but currently, no functional roles for bee-derived ICK peptides have been identified. In this study, a bee (Apis cerana) ICK peptide (AcICK) that acts as an antifungal peptide and as an insecticidal venom toxin was identified. AcICK contains an ICK fold that is expressed in the epidermis, fat body, or venom gland and is present as a 6.6-kDa peptide in bee venom. Recombinant AcICK peptide (expressed in baculovirus-infected insect cells) bound directly to Beauveria bassiana and Fusarium graminearum, but not to Escherichia coli or Bacillus thuringiensis. Consistent with these findings, AcICK showed antifungal activity, indicating that AcICK acts as an antifungal peptide. Furthermore, AcICK expression is induced in the fat body and epidermis after injection with B. bassiana. These results provide insight into the role of AcICK during the innate immune response following fungal infection. Additionally, we show that AcICK has insecticidal activity. Our results demonstrate a functional role for AcICK in bees: AcICK acts as an antifungal peptide in innate immune reactions in the body and as an insecticidal toxin in venom. The finding that the AcICK peptide functions with different mechanisms of action in the body and in venom highlights the two-pronged strategy that is possible with the bee ICK peptide.

Insect-derived antimicrobial peptides (AMPs) have diverse effects on antimicrobial properties and pharmacological activities such as anti-inflammation and anticancer properties. Naturally occurring genetic polymorphism have a direct and/or indirect influence on pharmacological effect of AMPs, therefore information on single nucleotide polymorphism (SNP) occurring in natural AMPs provides an important clue to therapeutic applications. Here we identified nucleotide polymorphisms in melittin gene of honey bee populations, which is one of the potent AMP in bee venoms. We found that the novel SNP of melittin gene exists in these two honey bee species, Apis mellifera and Apis cerana. Nine polymorphisms were identified within the coding region of the melittin gene, of which one polymorphism that resulted in serine (Ser) to asparagine (Asp) substitution that can potentially effect on biological activities of melittin peptide. Serine-substituted melittin (Mel-S) showed more cytotoxic effect than asparagine-substituted melittin (Mel-N) against E. coli. Also, Mel-N and Mel-S had different inhibitory effects on the production of inflammatory factors such as IL-6 and TNF-α in BV-2 cells. Moreover, Mel-S showed stronger cytotoxic activities than Mel-N peptide against two human ovarian cancer cell lines. Using carbon nanotube-based transistor, we here characterized that Mel-S interacted with small unilamellar liposomes more strongly than Mel-N. Taken together, our present study demonstrates that there exist different characteristics of the gene frequency and the biological activities of the melittin peptide in two honey bee species, Apis mellifera and A. cerana.

The Asian cavity-nesting honey bee, Apis cerana, the workers ovaries is very active in queenless colonies. We investigated the duration of egg laying by laying workers, egg-laying behavior, determine egg load in ovaries, estimate oviposition rate nad number of eggs per cell in three queenless colonies of Korean A. cerana. The number of eggs laid by laying workers at different times on the manipulated comb was checked and counted. We observed that the laying workers spent, on average, 109.2 seconds per cell. During oviposition, the laying workers showed two types of behaviors, viz; a still phase, and a recovery phase. On average, 4.0 of worker eggs per cell per week was recorded. The workers laid three different shapes of eggs in a cell. The laying workers ovaries retained 1 to 4 mature eggs. This suggests that a laying worker may lay from one to four eggs per oviposition. We did not observe false-queen in Korean A. cerana in three queenless colonies. In this study, we reported for the first time that one worker cell of A. cerana retains up to 33 eggs in queenless condition. The queenless colonies build the comb and lay eggs in new comb, and also reared the new queen without successful development of the queen larva from laying worker eggs.