The Phenotypic Effects of Royal Jelly on Wild-Type D. melanogaster Are Strain-Specific

Abstract

The role for royal jelly (RJ) in promoting caste differentiation of honeybee larvae into queens rather than workers is well characterized. A recent study demonstrated that this poorly understood complex nutrition drives strikingly similar phenotypic effects in Drosophila melanogaster, such as increased body size and reduced developmental time, making possible the use of D. melanogaster as a model system for the genetic analysis of the cellular mechanisms underlying RJ and caste differentiation. We demonstrate here that RJ increases the body size of some wild-type strains of D. melanogaster but not others, and report significant delays in developmental time in all flies reared on RJ. These findings suggest that cryptic genetic variation may be a factor in the D. melanogaster response to RJ, and should be considered when attempting to elucidate response mechanisms to environmental changes in non-honeybee species.

Phenotypic extremes or extreme phenotypes? On the use of large and small-bodied “phenocopied” Drosophila melanogaster males in studies of sexual selection and conflict

“…Rearing flies at different densities influences not only the final body size of eclosed flies, but also the size of their internal organs (Mirth and Shingleton 2012), including the primary and secondary organs of the male reproductive system (Morimoto et al 2022). Experimentally increasing larval density leads to progressively smaller males who developed larger testes and ejaculatory ducts, but smaller accessory glands and ejaculatory bulbs (Morimoto et al 2022). Morrow et al (2008) found that the production of sperm cells was affected both by a fly's genotype as well as the nature of the environment it developed in.…”

Beyond Royalactin and a master inducer explanation of phenotypic plasticity in honey bees

“…Phenotypic outcomes depend absolutely on the genetic background used in the experiments 55–57 . As just one clear example reveals, in mushroom body miniature , these important brain structures in the fly degenerate in one genetic background, but are completely normal in another 58 .…”

“…Seventh, Drosophila is indeed facile in terms of experimental manipulation, but it has major drawbacks that impinge upon data transferability (e.g., the lack of DNA methylation toolkit and reproductive division of labour 54 ). Phenotypic outcomes depend absolutely on the genetic background used in the experiments 55 – 57 . As just one clear example reveals, in mushroom body miniature , these important brain structures in the fly degenerate in one genetic background, but are completely normal in another 58 .…”

“…As just one clear example reveals, in mushroom body miniature , these important brain structures in the fly degenerate in one genetic background, but are completely normal in another 58 . Indeed, it has been shown that royal jelly/Royalactin effects in Drosophila are strain-dependent implicating genetic background and cryptic sequence variants as an important factor in phenotypic outcomes driven by the heterologous protein 57 . It is mandatory therefore that if Drosophila is to be a surrogate, than the Royalactin experiments need to be conducted in different genetic backgrounds.…”

“…It is mandatory therefore that if Drosophila is to be a surrogate, than the Royalactin experiments need to be conducted in different genetic backgrounds. Notably, royal jelly-based diet is not only atypical, but also toxic for Drosophila and even at concentrations much lower than those used for bee larvae has strong detrimental effects on life span, productivity and can negatively affect developmental processes 57 , 59 . In addition, low levels of royal jelly show similar enhancement for both males and females 59 , whereas a female-specific effect would be expected if it was acting through an analgous pathway as in honey bees.…”