Juvenile hormone accelerates ovarian development and does not affect age polyethism in the primitively eusocial wasp, Ropalidia marginata

Juvenile hormone modulates post-imaginal reproductive division of labor in primitively eusocial species and promotes the production of queens (e.g., Polistes) while it modulates age polyethism and promotes the production of foragers in highly eusocial species (e.g., the honey bee). Ropalidia marginata is a primitively eusocial wasp that shows both post-imaginal regulation of reproductive division of labor as well as age polyethism. Hence, R.marginata is a particularly interesting model system to study the effect of juvenile hormone. We demonstrate here that a single, topical application of 100 μg of juvenile hormone-III per female wasp accelerates ovarian development of wasps held in isolation. Similar application to wasps released back on to their natal nests has no effect on their rate of behavioral development as witnessed from the age of first performance of feed larva, build, bring pulp and bring food. We conclude therefore that in R.marginata, juvenile hormone has retained its function of modulating reproductive division of labor and has not acquired the function of modulating age polyethism.