Queens Survival during Pleometrosis in Monogynous and Polygynous Ant Species (Hymenoptera, Formicidae)

Abstract

The objective of this study is to examine the survival rates of queens in pleometrotic groups of two ant species: Lasius paralienus Seifert, 1992 (a monogynous species) and Solenopsis fugax (Latreille, 1798) (a polygynous species). The study was conducted in 2020 and 2021 in Odesa, Ukraine. After the nuptial flight, 45 gynes of S. fugax and 64 of L. paralienus were captured. Solenopsis fugax were seated in groups of 5 (9 experiments in total), L. paralienus in groups of 5 (8 experiments) and 3 specimens (8 experiments). For L. paralienus, the effect of pleometrotic group size on the queens was tested. Maximum duration of the experiment was 115 days for S. fugax and 293 days for L. paralienus (until only one queen remains or the number of queens does not change significantly). The number of queens (alive, dead and killed), workers and brood were counted once a week. There were no significant differences in mortality between groups of 3 and 5 queens of Lasius paralienus ants (p = 0.06). The period of main queen mortality occurs shortly after founding of the pleometrotic group. Mortality continues to rise after the emergence of a group of 10–30 workers until only 1 queen remains in group of Lasius. When L. paralienus queens died naturally, the average number of workers was 7.5, the average number of larvae was 3.32 and the average number of pupae was 5.16. However, when they died due to fights, the average number of workers was 23.89, the average number of larvae was 8.89 and the average number of pupae was 13.89. In the case of S. fugax, when queens died naturally, the average number of workers was 5.43. A comparison of the total queen mortality in the pleometrotic groups of the two ant species showed that most queens survive in the polygynous S. fugax, whereas all but one die in the monogynous Lasius.