Sobrevivência em um período crítico: análises do evento reprodutivo e da fase de fundação de colônias de Acromyrmex subterraneus

Abstract

The nuptial flight and foundation period are the most critical periods in the life-cycle of ants, since factors such as predation, dissection, contamination and countless others can interfere with the dispersion and mating of the reproductive individuals, and in the digging and foraging of queens. The mortality rate is very high, so the decisions made should favor the survival and success of the individuals. Therefore, this study aims to investigate some aspects of the initial period of the life-cycle of Acromyrmex subterraneus in order to: i) clarify the advantages of the premature flight, as well as if its occurrence is smaller yet common to many colonies, or smaller due to the participation of less colonies; ii) evaluate the effect of the mass of queens on the survival and productivity of the incipient colonies; iii) evaluate the foraging cost to the queens in terms of energy and fitness during the colony foundation period. Genetic and morphological data revealed that the premature nuptial flight is an event restricted to a few colonies, and that the genetic factor must act in the development period of the individuals, accelerating this process and resulting in smaller individuals that reach maturity and depart for flight quicker. The reduction of competition for nesting sites and of potential conflict through greater kinship between the individuals could both be factors that favor the occurrence of this event. By evaluating the mass of young, founder queens, it was possible to verify that lighter queens have less chance of survival, and that the production of offspring is similar, regardless of presented initial mass. This indicates that intrinsic factors, such as the initial mass of queens at the moment of foundation, could also have significant influence on their mortality rate. Finally, it was revealed that the search for food does not affect the survival of the queens, and that the foraging cost during the foundation period is not directly linked to the lipid expenditure. Rather that at the time of caring for offspring, where queens that don’t need to leave the colony to search for food, they supposedly have more time to invest in raising and maintaining the colony, making it more populous more quickly.