Sexing of newly hatched live larvae of the honey bee, Apis mellifera, allows the recognition of diploid drones

Abstract

-In the honey bee, it is difficult to recognise the sex in first instar larvae. As workers and haploid drones develop in differently sized brood cells, they can be discriminated without sex inspection. However, because diploid drone larvae originate from fertilised eggs like workers, they hatch in brood cells of the same type and cannot be sampled according to cell size. In search of a reliable method of sexing live first instar larvae, we found that the contour and size proportions of the epiproct can be used for discrimination. The sex diagnosis based on these characters is carried out rapidly under a stereo microscope and allows the collection of pure samples of newly hatched diploid drone larvae from brood combs of inbred colonies.Apis mellifera / sexing of live larvae / epiproct / diploid drones

Larval sex identification in the paper wasp Polistes dominulus (Vespidae, Hymenoptera)

“…A recent paper (OrtiusLechner et al, 2003) described differences in male and female reproductive organs in larvae of the ant Leptothorax acervorum and its social parasite Epimyrma ravouxi. There are a few studies which describe larval sex determination on the basis of cuticular structures in other Hymenoptera species (in Bombus terrestris, Duchateau and Van Leeuwen, 1990, in Vespa analis insularis, Yamane, 1976 in Apis mellifera, Santomauro and Engels, 2002). Although Lester and Selander (1981) found male and female larvae of Polistes to be morphologically indistinguishable, we found anatomical structures that make reliable and easy discrimination of male and female larvae possible, as is described in this paper.…”

Discrimination of haploid and diploid males of Bombus terrestris (Hymenoptera; Apidae) based on wing shape

“…Use of morphological, instead of genetic, characters could provide an alternative, but has not been developed until now. Even though morphological methods have been developed to detect A. mellifera diploid drone larvae (Santomauro and Engels 2002) or adults based on testes and genital hooks (Herrmann et al 2005), fast and effective morphometrics identifiers are still lacking for wild bees.…”

Transcriptional Profiles of Diploid Mutant Apis mellifera Embryos after Knockout of csd by CRISPR/Cas9

“…In this study, the development of the diploid mutant male embryos was delayed when compared with the mock-treated embryos (female). The haploid and diploid male first-instar larvae showed no difference in the contour of epiproct [10]. The diploid mutant larvae had different epiproct characters compared with their female sisters in this study.…”

“…In the colonies, nurse bees discover diploid male larvae through the cuticle secretions, in which alkanes are the most significant compounds [8,9]. Moreover, the sex of live firstinstar diploid males can be recognized through the contour and size proportions of the epiproct [10]. The discovery of diploid drones enabled the hypothesis of complementary sex determination [11].…”