@article{3913,
  abstract     = {Many invasive ant species, such as the Argentine ant or the red imported fire ant, have huge colonies with thousands of mass-foraging workers, which quickly monopolise resources and therefore represent a considerable threat to the native ant fauna. Cardiocondyla obscurior and several other species of this myrmicine genus have similarly been transferred throughout the tropics by human activities. However, because their colonies are tiny and workers forage solitarily, Cardiocondyla are often not recognized as successful invaders. Here, we document that the life history of Cardiocondyla closely resembles that of the more conspicuous tramp species, with polygyny, intranidal mating, budding, worker sterility, low genetic variability, and possibly also unicoloniality. Given that introduced Cardiocondyla may locally reach a very high population density, the effects of these stealthy invaders on the native arthropod fauna should receive more attention.},
  author       = {Heinze, Jürgen and Cremer, Sylvia and Eckl, Norbert and Schrempf, Alexandra},
  issn         = {1420-9098},
  journal      = {Insectes Sociaux},
  number       = {1},
  pages        = {1 -- 7},
  publisher    = {Springer Nature},
  title        = {{Stealthy invaders: the biology of Cardiocondyla tramp ants}},
  doi          = {10.1007/s00040-005-0847-4},
  volume       = {53},
  year         = {2006},
}

@article{3918,
  abstract     = {Wingless (ergatoid) males of the tramp ant Cardiocondyla minutior attack and kill their young ergatoid rivals and thus attempt to monopolize mating with female sexuals reared in the colony. Because of the different strength of local mate competition in colonies with one or several reproductive queens, we expected the production of new ergatoid males to vary with queen number. Sex ratios were mostly female-biased, but in contrast to the sympatric species C. obscurior (Cremer and Heinze, 2002) neither the percentage of ergatoid males nor of female sexuals among the first 20 sexuals produced varied considerably with queen number. As in C. obscurior, experimental colony fragmentation led to the production of winged males, whereas in unfragmented control colonies only ergatoid males eclosed.},
  author       = {Heinze, Jürgen and Böttcher, A. and Cremer, Sylvia},
  issn         = {1420-9098},
  journal      = {Insectes Sociaux},
  number       = {3},
  pages        = {275 -- 278},
  publisher    = {Springer Nature},
  title        = {{Production of winged and wingless males in the ant, Cardiocondyla minutior}},
  doi          = {10.1007/s00040-004-0740-6},
  volume       = {51},
  year         = {2004},
}

@article{3924,
  abstract     = {Males of the ant Cardiocondyla show a dispersal dimorphism of a winged and wingless morph. The loss of flight has lead to morphological reductions in the wingless (ergatoid) males and also affected body size, eye size and pigmentation. As ergatoid males mate exclusively inside the maternal nest, they underlie increased male-male competition and therefore have also evolved additional changes in behaviour and physiology: in contrast to winged males, ergatoid males are highly aggressive towards each other and their spermatogenesis is prolonged compared to all other hymenopteran males. In addition to these two male morphs, we found males with an intermediate appearance. These "intermorphic" males provide a transitional stage between normal males in most investigated morphological and physiological parameters. As they are produced extremely rarely and only in colonies that switch between pure ergatoid to mixed male production, we argue that they likely represent a developmental mistake. Parallels between the determination of male morphs and female castes (queen-worker dimorphism and worker polymorphism) might help to understand how the large potential of phenotypic plasticity in both sexes of social insects is realised during development.},
  author       = {Cremer, Sylvia and Lautenschläger, Birgit and Heinze, Jürgen},
  issn         = {0020-1812},
  journal      = {Insectes Sociaux},
  number       = {3},
  pages        = {221 -- 228},
  publisher    = {Springer},
  title        = {{A transitional stage between the ergatoid and winged male morph in the ant Cardiocondyla obscurior}},
  doi          = {10.1007/s00040-002-8305-z},
  volume       = {49},
  year         = {2002},
}