Production of trophic eggs by virgin workers in the ponerine ant Gnamptogenys menadensis

Most colonies (thirty-five out of thirty-seven) of the ant Gnamptogenys men adensis (Mayr) (Hymenoptera: Formicidae: Ponerinae) lack queens. Mated work ers produce reproductive eggs, whereas virgin workers can lay only smaller trophic eggs (350 ovipositions observed). These two egg types are morpholog ically distinct (e.g. in the pattern of oogenesis and ultrastructure of mem branes and micropyle) and relate to different ovarian characteristics (ovar iole length, number of yolky oocytes and yellow bodies). When reproductives are removed, a small number of virgin workers switch to producing reproduc tive eggs, although only 3% of these develop into larvae. Once workers are mated, up to 50% of their eggs develop further. Trophic eggs are generally absent in social insects lacking physical castes, and we review adaptive ex planations of its occurrence in G. menadensis.