title: Workers make the queens in melipona bees: identification of geraniol as a caste determining compound from labial glands of nurse bees.
abstract: Reproductive division of labor in advanced eusocial honey bees and stingless bees is based on the ability of totipotent female larvae to develop into either workers or queens. In nearly all species, caste is determined by larval nutrition. However, the mechanism that triggers queen development in Melipona bees is still unresolved. Several hypotheses have been proposed, ranging from the proximate (a genetic determination of caste development) to the ultimate (a model in which larvae have complete control over their own caste fate). Here, we showed that the addition of geraniol, the main compound in labial gland secretions of nurse workers, to the larval food significantly increases the number of larvae that develop into queens. Interestingly, the proportion of queens in treated brood exactly matched the value (25%) predicted by the two-locus, two-allele model of genetic queen determination, in which only females that are heterozygous at both loci are capable of developing into queens. We conclude that labial gland secretions, added to the food of some cells by nurse bees, trigger queen development, provided that the larvae are genetically predisposed towards this developmental pathway. In Melipona beecheii, geraniol acts as a primer pheromone representing the first caste determination substance identified to date.
authors.affiliation: Institute for Experimental Ecology, Ulm University, Albert-Einstein-Allee 11, 89069 Ulm, Germany. stefan.jarau@uni-ulm.de
authors.forename: Stefan
authors.initials: S
authors.lastname: Jarau
authors.forename: Johan W
authors.initials: JW
authors.lastname: van Veen
authors.forename: Robert
authors.initials: R
authors.lastname: Twele
authors.forename: Christian
authors.initials: C
authors.lastname: Reichle
authors.forename: Eduardo Herrera
authors.initials: EH
authors.lastname: Gonzales
authors.forename: Ingrid
authors.initials: I
authors.lastname: Aguilar
authors.forename: Wittko
authors.initials: W
authors.lastname: Francke
authors.forename: Manfred
authors.initials: M
authors.lastname: Ayasse
mesh_terms: D000080462:Acyclic Monoterpenes; D000818:Animals; D001516:Bees / Q000254:growth & development*; D002849:Chromatography, Gas; D005260:Female; D007814:Larva / Q000254:growth & development; D012469:Salivary Glands / Q000737:chemistry; D012930:Social Dominance; D013729:Terpenes / Q000737:chemistry* / Q000494:pharmacology
chemical_list: D000080462:Acyclic Monoterpenes; D013729:Terpenes; C007836:geraniol