Study On Behavioural Observations On Two Types Of Nurses (Apis Mellifera) And The Underlying Molecular Mechanisms

In a honeybee colony queen larvae and worker larvae of1-3days of age are bothattended by nurse bees. Numerous studies have shown that nutritional components of royaljelly and worker jelly are different. Here we examined whether nurse bees collectedbreeding queen (NBQL) and worker larvae (NBWL) are separate specialized sub-castes ofnurse bees (Apis mellifera).We compared gene expression profiles of three groups (one group of head and twogroups of hypopharyngeal gland tissues) of NBQL and NBWL using Solexa/IlluminaDigital Gene Expression tag profiling (DGE). Resuts demonstrated that5950226,5910901,5911105(NBWL) and5837851,5921630,5920307(NBQL) clean tags were sequenced inhead sample, and gland A and B respectively. For these three comparisions,673,1132and768genes were found significantly differentially expressed between NBQL and NBWL.When comparing gene expression level in NBQL with that in NBWL, more genes wereup-regulated than down-regulated (387vs286) in head samples, but for the gland samplesfewer genes were up-regulated than down-regulated (79vs1053and165vs603).Of thesesignificantly differentially regulated genes, only9up-regulated genes and68down-regulated genes were found common to all three sample groups. More genes werealso identified common to both the gland samples, with41up-regulated and434down-regulated genes identified in both comparisons. Significant differences in geneexpression were found in both NBQL and NBWL of three groups of samples that includeda disproportionate number of major royal jelly protein genes.Bees’ nursing activities were recorded and analyzed in a glass observation hive.Behavioural observations showed that very few workers were observed attending queenlarvae only, and bees observed attending queen larvae at least once were observed in morelarval attendance events overall than bees that were never observed attending queens.Results of behavioural experiments did not support the idea that NBQL is a specializedsub-caste of nurse bees. Obviously division of labour among workers in honeybee do notdepend on significant differences in gene expression, but this provides a new explanationfor molecular mechanisms underlying honeybee social division.In order to explore whether there is a genetic background difference between NBWLand NBQL, we collected95of NBQL and NBWL from two honeybee colonies andanalyzed their genotypes using4microsatellite primers. Our results indicated that therewas no significant difference between two types of nurses in terms of subfamilydistribution. We concluded that there was no evidence showing honeybee’s subfamily canaffect behavioral differences between two types of nurses.