MONOGYNY AND REGULATION OF WORKER MATING IN THE QUEENLESS ANT DINOPONERA QUADRICEPS

The morphologically specialized queen caste has been lost in various p onerine ants, and mated workers ('gamergates') reproduce instead of qu eens. Unlike previous reports in the literature, we found only one gam ergate in each colony of Dinoponera quadriceps. We documented monogyny by dissecting ovaries and spermathecae in 914 workers from 15 colonie s, and by observing mating in the laboratory. In colonies without a ga mergate, aggressive interactions among some of the unmated nestmates l ed to the behavioural differentiation of a top-ranking worker ('alpha' ), which laid almost all the eggs. Only the alpha went outside the nes t at night, and mated if foreign males were present (N=11 tests), thus becoming a gamergate. The alpha was sexually attractive even when her ovaries were not yet active. After intromission, the male remained li nked to the alpha while she severed the end of his abdomen. Pieces of the male genitalia remained attached to her genital tract, and she rem oved them after 30 +/- 18 min ((X) over bar SD; N=9). We interpret thi s to be a mating plug, preventing other males from fathering her offsp ring. None of these newly inseminated gamergates continued to go outsi de the nest, and, when tested, they never re-mated (N=4). Thus, gamerg ates of D. quadriceps probably mate only once. In queenless ant specie s, comparative evidence indicates that worker mating is often regulate d in monogynous species, while unrestricted mating of young individual s is typical of polygynous species (oviposition is regulated subsequen tly). Furthermore, the occurrence of either monogyny or polygyny influ ences the mating strategies of males, and mating plugs have been repor ted only in some monogynous species. (C) 1998 The Association for the Study of Animal Behaviour.