Morphological and physiological correlates of the colony foundation mode and reproductive role differentiation in Belonogaster juncea juncea (Vespidae, Polistinae)

Abstract

A study on the reproductive status of Belonogaster juncea juncea individuals was conducted in Cameroon on 21 pre- and 15 post-emergence colonies. We compared the females’ size and ovarian development, and verified if they were inseminated or not. Dominant females were inseminated, had well developed ovaries, and were the largest individuals in pre-emergence colonies; in post-emergence colonies their size did not differ significantly from that of non-dominant females. Most subordinate females of both pre- and post-emergence colonies had thread-like ovaries, but a few had well developed ovaries. In pre-emergence colonies 13 subordinates had thread-like ovaries and several yellow bodies indicating that they had already laid eggs. We deduced that subordinates with well developed ovaries joined the foundations shortly before our study, while those with several yellow bodies had arrived some time before and their ovaries had regressed. At the end of the post-emergence phase appear non-dominant females with well developed ovaries. They are the future foundresses. Some females can disperse just after emergence and join a new foundation without mating. Nevertheless, most co-foundresses were inseminated when they joined the foundations, and so had the potential to reproduce, negating the hypothesis of swarm founding in B. j. juncea.