Facultative polygyny in Ectatomma tuberculatum (Formicidae, Ectatomminae)

Abstract

Polygyny, the presence of several mated queens within the same colony, is widespread in insect societies. This phenomenon is commonly associated with ecological constraints such as limited nest sites. In habitats where solitary nest foundation is risky, monogynous colonies can reintegrate young daughter queens (secondary polygyny). We studied the reproductive structure (i.e. queen number) of the ectatommine ant Ectatomma tuberculatum from Bahia State, Brazil. This species was found to present facultative polygyny: out of a total of 130 colonies collected, 39.2% were monogynous, while 43.8% were polygynous. Polygynous colonies had significantly more workers than monogynous ones. Queen number in polygynous colonies ranged from 2 to 26, with an average of 4 ± 4 queens per colony. All nestmate queens were egg-layers with no apparent dominance hierarchy or agonistic behavior. Non-nestmate queens were adopted by monogynous colonies suggesting that polygyny is secondary, originating through queen adoption. This species is characterized by an open recognition system, which probably allows a switch from monogynous to polygynous colonies. The behavioral acts of queens showed that resident queens remained frequently immobile on or near the brood, contrarily to alien or adopted queens and gynes. In addition, monogynous queens showed no behavioral or physiological (i.e. by ovarian status) differences in comparison with polygynous ones. Secondary or facultative polygyny, probably associated with queen adoption, may have been favored in particular environmental conditions. Indeed, by increasing colony productivity (i.e. number of workers) and territory size (by budding and polydomy), polygyny could uphold E. tuberculatum as a dominant species in the mosaic of arboreal ants in Neotropical habitats.

Juvenile hormone downregulates vitellogenin production in Ectatomma tuberculatum (Hymenoptera: Formicidae) sterile workers

“…Ectatomma tuberculatum (Olivier 1792) (Ectatomminae) makes small colonies of up to 400 workers with one or many morphologically differentiated queens (Hora et al, 2001;Hora et al, 2005). The workers are morphologically identical, and the tasks they perform within the colony vary according to age (Champalbert and Lachaud, 1990;Fénéron et al, 1996;Hora et al, 2001).…”

Behavioral Differentiation and Ovarian Development of Unmated Gynes, Queens, and Workers ofEctatomma vizottoiAlmeida 1987 (Formicidae, Ectatomminae)

“…The presence of several queens may be the result of adoption, as described for E. permagnum [12], E. ruidum [15], and E. tuberculatum, which, in this case, show facultative polygyny [17]. However, queens and unmated gynes showed a clear behavioral differentiation, in which queens played the role of reproducers and unmated gynes performed activities belonging to the worker repertoire.…”

“…Unmated gynes have never been observed laying fertilized eggs and performing activities related to "colony maintenance", and therefore show a repertoire which is more similar to the workers' than to the queen's. However, even if there are several reproductive castes in a colony, a functional monogyny occurs, in which only one queen lays fertilized eggs [17].…”

“…As discussed by Brandão [11] there is a clear division of labor between queen and workers in monogynic colonies, in which the workers are responsible for most of the tasks; some examples are Ectatomma permagnum Forel [12] and Ectatomma planidens Borgmeier [13] (erroneously identified as Ectatomma edentatum Roger [14]). The subfamily Ectatomminae also includes several polygynous species, such as E. ruidum [15], Gnamptogenys striatula Mayr [16], and E. tuberculatum [17]. Also, social organization has been studied in some species of Ectatomma Smith, including E. tuberculatum [18], E. permagnum [12], Ectatomma brunneum (=quadridens) Smith [19], E. ruidum [20,21], E. planidens [13], and Ectatomma opaciventre (Roger) [22,23].…”

Assessing the Proteomic Activity of the Venom of the AntEctatomma tuberculatum(Hymenoptera: Formicidae: Ectatomminae)

“…Additional information on the biology of this species in cacao plantations can be found in Delabie and Hora and collaborators [26,27]. In the laboratory, 100 workers were anesthetized with CO 2 and dissected for extraction of venom glands.…”