Decision-making in Pheidole oxyops Forel, 1908 (Formicidae: Myrmicinae) facing different types of resources.
Felipe Pereira da Rocha, Felipe Pereira da Rocha , Diego Santana Assis , Fábio Santos do Nascimento
Departamento de Biologia Animal, Universidade Estadual de Campinas, Campinas, Brasil.; Departamento de Biologia Animal, Universidade Estadual de Campinas, Campinas, Brasil. ; Departamento de Biologia, Universidade de São Paulo, Ribeirão Preto, Brasil. ; Departamento de Biologia, Universidade de São Paulo, Ribeirão Preto, Brasil.
Decision-making for an organism means to choose how to allocate time and energy to different life tasks. In resource-limited environments, making decisions is essential to ensure survival. Ants have many foraging strategies adapted to their environment and modulated by the decisions they make facing resources. Thus, the present work intends to test the basic decision-making rules taken by ants during foraging and recruitment, and relate resource quantity with recruitment velocity and exit rate of foragers. We test whether resources differing in quality and quantity elicit different responses on foragers, that seek the best exploring strategy. Colonies of Pheidole oxyops were presented with items of two qualities (Sardine and Crackers) and weights (0,4g and 2g) and their behaviour was filmed. The videos were analysed, and many established parameters were measured for decision-making analysis. Simple and mixed linear models and its Akaike values were done, G tests were done to look for differences between foragers' decisions. Individual decision to accept the items were more frequent, as well as recruiting the colony for item transport. The items were rejected few times, mostly crackers. The items were taken most of the time, only the big sardine that was explored mainly where it was found, and the big cracker which did not have a significant difference between taking the item or not. Time of food finding was random; but analysis, return to the colony, and colony's reaction time were all significant, for at least one item. Exiting rate of foragers did not have a relation with item size, but recruitment velocity did. Our results show that foragers make decisions based on item nutritional value, colony current state and item transportability. Decision-making follows basic local rules, and do not need some kind of central control. Ants are able to make decisions that affect and optimize the strategies used by the colony, important to maximize colony' fitness.