Influência da temperatura na seleção de recursos alimentares por espécies de formigas cortadeiras

Abstract

Leaf-cutting ants are widely distributed, occur in the Neotropics and have great ecological importance, as they increase soil fertility and aeration, disperse seeds, in addition to herbivory, which alters the composition and dynamics of the plant community in the habitats where they occur. It is known that the activities of selection of food resources and their foraging by these ants are strongly influenced by climatic conditions, but the influence of temperature on the selection of food resources by the sympatric species Atta laevigata and Atta sexdens is unknown and was the object of this study. Three sub-colonies of each species were connected, by a transparent tube, to a foraging arena inside a BOD with a temperature of 13°, 25° and 38°C, simulating the external environment. Pellets containing sucrose or fat in two concentrations (1% and 10%) were offered to the colonies. A camera was installed above the exit of the foraging arena, to record the foraging of ants during 12 hours, with five replications per sub-colony and temperature. The time to locate and start loading the resources and the loading speed were measured. The location time of resources with fat and sucrose was greater at the highest temperature (38°C), regardless of concentration and species. Atta laevigata is faster in locating and initiating foraging for food resources than A. sexdens at higher temperatures (38°C), probably because it has a wider range of thermal tolerance. The increase in the average global temperature could increase the competitive force for resources of A. laevigata in relation to A. sexdens, implying the exclusion of the latter at the local level. The results help to understand how global warming can change the foraging dynamics of these species, the competition for resources, the competitive exclusion and its implications in their ecological functions.