Lian-Fei Cao

Transcriptome comparison between honey bee queen- and worker-destined larvae

Caste differentiation in the female honey bee is one of the most intriguing polyphenism phenomena. This developmental switch depends on the differential expression of entire suites of the genes involved in the larval fate between the queens and workers. In this study, we compared the transcriptome differences between full-sister queen- (QL) and worker-destined larvae (WL) using high-throughput RNA-Seq. QL and WL at fourth (L4) and fifth instar (L5) were used to prepare four libraries and to generate 50,191,699 (QL4), 57,628,541 (WL4), 56,613,619 (QL5), and 58,626,829 (WL5) usable reads, which were assembled into groups of 7,952, 7,993, 7,971, and 8,023 genes, respectively. The transcriptome changes were investigated using the DEGs Package (DEGseq), which resulted in more than 4,500 differentially expressed genes (DEGs) between the castes. Eight of the DEGs were verified by quantitative real-time RT-PCR (qRT-PCR), and the results supported our sequencing data. All of the DEGs were analysed using Web Gene Ontology Annotation Plot (WEGO) and then mapped using the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. These results suggest that over 70% of the DEGs in each instar were more highly expressed in QL than in WL, possibly suggesting that the QL genes had higher transcriptional activity than the WL genes during differentiation. The same gene set is active (but differentially expressed) in both castes, which in turn result in dimorphic females. The L4 stage is a very active gene expression period for both QL and WL before their pupal stage. The activity of the mTOR (a target of rapamycin) encoding gene in the mTOR signalling pathway is higher in QL4 than in WL4, and this difference was no longer present by the L5 feeding stage. The genes down-stream of mTOR maintained this change at the L5 stage. These results could contribute to an in-depth study of the candidate genes during honey bee caste differentiation and improve our current understanding of the polyphenism phenomenon in insects.

Geographical Influences on Content of 10-Hydroxy- trans -2-Decenoic Acid in Royal Jelly in China

ABSTRACT The content of 10-hydroxy-trans-2-decenoic acid (10-HDA), a marker compound in royal jelly (RJ), is the most important criterion in grading RJ for commercial trade and varies with its origin. To identify the effect of geographical origin on 10-HDA content in RJ, 138 samples were collected from 19 provinces of China (divided into three groups) produced by either Apis mellifera ligustica Spinola, 1806 or a hybrid of A. m. ligustica and Apis mellifera carnica Pollman, 1879 and analyzed for moisture, sugar, crude protein, ash, acid, and 10-HDA concentration. The results show that RJ from western China has a significantly higher 10-HDA level (2.01 ± 0.05%) than those from northeastern (1.87 ± 0.05%) and eastern (1.75 ± 0.03%) China. RJ secreted by hybrid bees contained more 10-HDA (1.89 ± 0.03%) than that secreted by A. m. ligustica (1.78 ± 0.03%). The 10-HDA content of RJ produced during flowering of rape (Brassica campestris L.), lime (Tilia amurensis Ruprecht), and vitex (Vitex negundo L. variety heterophylla (Franch.) Rehder) was 1.92,1.80, and 1.68%, respectively. The results would be helpful during the process of price determination of RJ by providing some basis of geographical, bee strain, and botanical information for commercial trade.

High Royal Jelly-Producing Honeybees (Apis mellifera ligustica) (Hymenoptera: Apidae) in China

Abstract China is the largest producer and exporter of royal jelly (RJ) in the world, supplying >90% of the global market. The high production of RJ in China is principally owing to the high RJ-producing lineage of honeybees (Apis mellifera ligustica Spinola, 1806) established by beekeepers in the 1980s. We describe the development of high royal jelly-producing honeybees and the management of this lineage today. Previous research and recent advances in the genetic characterization of this lineage, and the molecular markers and mechanisms associated with high RJ production are summarized. The gaps in our knowledge and prospects for future research are also highlighted.

Genetic structure of Chinese Apis dorsata population based on microsatellites

We investigated the genetic structure of Chinese Apis dorsata population based on DNA microsatellites. The results show that populations from different geographical regions are significantly differentiated. Furthermore, the A. dorsata population from Hainan Island very probably diverged from that of the China mainland and also exhibits a lower level of genetic diversity, which is probably the result of founder effects and genetic drift. The results provide useful information for effective management and conservation of A. dorsata in China, particularly with regard to the population of Hainan Island.

Multivariate morphometric analyses of the giant honey bees, Apis dorsata F. and Apis laboriosa F. in China

Summary Multivariate morphometric analyses were performed on the giant honey bees Apis dorsata F. and Apis laboriosa F. of China. The two giant honey bee species were readily separated by principal components, cluster and discriminant analyses. Apis laboriosa showed higher values for the variables of size and cubital index than A. dorsata (ranging respectively as the width of the wax mirror 2.83~2.99 mm and 2.36~2.56 mm, width of sternum 6 3.61~3.86 mm and 3.03~3.26 mm, cubital index 10.36~14.56 and 6.38~9.61). Most of the wing venation angles were also significantly different in the two giant honey bees (angle J10 were 38.2°~40.7° and 34.7°~37.7° respectively). A. dorsata is distributed widely across China, and cluster and discrimination analyses indicated that they could be subdivided into two morphometric subclusters: one from the Chinese mainland and another from Hainan Island which reflects their relative geographic isolation. Few characters differed in the two A. dorsata morphometric subclusters, however, which suggests that they possibly diverged from each other very recently.

Genomic and transcriptomic analysis of the Asian honeybee Apis cerana provides novel insights into honeybee biology.

The Asian honeybee Apis cerana is one of two bee species that have been commercially kept with immense economic value. Here we present the analysis of genomic sequence and transcriptomic exploration for A. cerana as well as the comparative genomic analysis of the Asian honeybee and the European honeybee A. mellifera. The genome and RNA-seq data yield new insights into the behavioral and physiological resistance to the parasitic mite Varroa the evolution of antimicrobial peptides, and the genetic basis for labor division in A. cerana. Comparison of genes between the two sister species revealed genes specific to A. cerana, 54.5% of which have no homology to any known proteins. The observation that A. cerana displayed significantly more vigilant grooming behaviors to the presence of Varroa than A. mellifera in conjunction with gene expression analysis suggests that parasite-defensive grooming in A. cerana is likely triggered not only by exogenous stimuli through visual and olfactory detection of the parasite, but also by genetically endogenous processes that periodically activates a bout of grooming to remove the ectoparasite. This information provides a valuable platform to facilitate the traits unique to A. cerana as well as those shared with other social bees for health improvement.

Phylogenetic relationships of honey bees (Hymenoptera: Apinae) in-ferred from mitochondrial and nuclear DNA sequences: Phylogenetic relationships of honey bees (Hymenoptera: Apinae) in-ferred from mitochondrial and nuclear DNA sequences

The sequences of mitochondrial ND2, CO2, and 16S rRNA genes and nuclear ITPR gene were obtained from 22 samples of 5 Apis species from China. The characteristics of the sequences and the pairwise distances among species were analyzed. Phylogenetic trees were reconstructed for Apis species using maximum parsimony, neighbor-joining and maximum likelihood methods together with the sequences of the other 4 Apis species downloaded from GenBank. Results supported that Apis species were divided into three major clusters: dwarf bees (A. florea and A. andreniformis), giant bees (A. dorsata and A. laboriosa), and cavity-nesting bees (A. mellifera, A. cerana, A. koschevnikovi, A. nigrocinta, and A. nuluensis). The dwarf honey bees were confirmed as basal lineage. Our study also revealed a high level of genetic divergence between A. dorsata from Hainan Island and China mainland.

Current Status of the Beekeeping Industry in China

China is a country with high honeybee diversity, long history of beekeeping and large amount of managed honeybee colonies. Based on the development of a high royal jelly-producing lineage of honeybees and related techniques and tools, China is producing nearly all of royal jelly in the world market. Over the past decade, great development has occurred in Chinese beekeeping industry, e.g., the development of honeybee pollination market, the promotion of beekeeping with Apis cerana, and the mechanization of beekeeping. However, there are also challenges facing the industry, e.g., honey adulteration and colony losses caused by biotic and/or non-biotic factors. The exploitation of native bumble bees and stingless bees is still in the very early initial stage. The role of honeybee pollination in agriculture has been recognized by government and farmers. We believe that Chinese beekeeping is entering an era full of opportunities.