Forrageamento de Acromyrmex subterraneus molestans Santschi, 1995 (Hymenoptera: Formicidae) em diferentes temperaturas

Abstract

Leaf-cutting ants of the genus Acromyrmex are important Neotropical herbivores and some species are pests of forest plantations in Brazil. They defoliate the plants, causing significant losses in young plantations. The foraging of these ants is considered a complex process, influenced by environmental factors. Temperature is one of the most important. It influences the speed of walking, the intensity of foraging, and the flow of the ants in the trail and the size of the fragment carried by the ants. However, there aren´t studies of this influence for an important species: Acromyrmex subterraneus molestans. Therefore, it is necessary to know the behavior of the ants and how the environmental factors affect this behavior, to create an integrated pest management strategy. Therefore, the objective was to evaluate the influence of temperature on the foraging and locomotor activity of this specie under laboratory conditions. An adult colony of Ac. subterraneus molestans was connected to a foraging arena within a BOD chamber regulated at temperatures of 10, 16, 22, 28, 34 or 40°C. The walking speed, the mass of the loaded fragment, the cephalic width of the ants and the foraging intensity were recorded with a camera. The intensity was measured by counting the number of ants with or without charge in both directions for one minute every five minutes for periods of one hour. The cephalic width of the ants was measured with the ImageJ program. The data were analyzed with generalized linear models using software R. The walking speed, dry mass of the fragment and the transport intensity during the foraging of Ac. subterraneus molestans in the trails increased with the temperature. The walking speed was higher at 40° C for ants with no load, than with loading. The flow of cutters in the foraging trails was higher at temperatures of 34ºC. The mass of fragments foraged by Ac. subterraneus molestans is lower in extreme temperatures (10 and 40ºC) and higher in intermediate (22 and 28ºC). The fragments area it was lower at 28 and 40°C. The width of the cephalic capsule of the Ac. surbeterraneus molestans ants with and without load does not vary with the temperature. Low and high extreme temperatures are inadequate for the foraging of Ac. subterraneus molestans, showing the importance of understanding how climatic changes can affect this ant and its functions in the environment.