The evolution of polygyny in primitively eusocial polistine wasps with special reference to the genus ropalidia

Abstract The eusocial Vespidae can be divided into two broad categories, the primitively eusocial and the highly eusocial. Primitively eusocial species lack morphologically distinct queens. Although their ‘queens’ (inseminated and overwintered females in temperate species and major egg-layers in tropical species) are often larger than ‘workers’, their sizes overlap and workers have opportunities for personal reproduction (Ross and Matthews 1991). On the other hand, queens of highly eusocial species are distinguishable morphologically from workers, and the latter, as a rule, cannot lay diploid, female eggs. Most species of the subfamily Vespinae are highly eusocial (Matsuura 1991), all known species of the subfamily Stenogastrinae are primitively eusocial (Turillazzi 1991), while the subfamily Polistinae contains both primitively and highly eusocial species (Jeanne 1991; Gadagkar 1991; Reeve 1991). Within the Polistinae, we can distinguish two subgroups, the independent-founding species, in which colonies are initiated by one or several inseminated foundresses (queens), independently of any uninseminated females (workers), and the swarm-founding species, in which a colony is founded by a swarm containing a small number of queens and a large number of workers (Jeanne 1980).