Honeybees(Apismellifera)havehaplodiploidsexdetermination:malesdevelopfromunfertilizedeggsandfemalesdevelopfromfertilizedones.Thedifferencesinlarvalfoodalsodeterminethedevelopmentoffemales.Herewecomparedthetotalsomaticgeneexpressionprofilesof2-dayand4-day-olddrone,queenandworkerlarvaebyRNASeq.Theresultsfromaco-expressionnetworkanalysisonallexpressedgenesshowedthat2-day-olddroneandworkerlarvaewerecloseringeneexpressionprofilesthan2-day-oldqueenlarvae.Thisindicatedthatforyounglarvae(2-day-old)environmentalfactorssuchaslarvaldiethaveagreatereffectongeneexpressionprofilesthanploidyorsexdetermination.Droneshadthemostdistinctgeneexpressionprofilesatthe4-daylarvalstage,suggestingthathaploidy,orsexdramaticallyaffectsthegeneexpressionofhoneybeelarvae.Dronelarvaeshowedfewerdifferencesingeneexpressionprofilesatthe2-dayand4-daytimepointsthantheworkerandqueenlarvalcomparisons(598against1190and1181),suggestingadifferentpatternofgeneexpressionregulationduringthelarvaldevelopmentofhaploidmalescomparedtodiploidfemales.Thisstudyindicatesthatearlyindevelopmentthequeencastehasthemostdistinctgeneexpressionprofile,perhapsreflectingtheveryrapidgrowthandmorphologicalspecializationofthiscastecomparedtoworkersanddrones.Laterindevelopmentthehaploidmaledroneshavethemostdistinctgeneexpressionprofile,perhapsreflectingtheinfluenceofploidyorsexdeterminationongeneexpression.
