Selectivity of Workers of the Grass-Cutting Ants Atta bisphaerica and Atta capiguara (Hymenoptera: Formicidae) to Vegetable Oils

The grass-cutting ants Atta capiguara Goncalves, 1941 and Atta bisphaerica Forel, 1908, have great economic importance as regards pastures and various agricultural cultivations in Brazil. These are ants which are difficult control, generally rejecting toxic baits, the main control method, in the field. In this work the reactions of the workers of A. capiguara and A. bisphaerica to vegetable oils in neutral substrates were observed, aiming to select the most attractive for the formulation of bait matrixes. Three field experiments were conducted. In the first experiment conducted for A. capiguara, the following treatments were used: corn oil, soy oil, cotton oil, canola oil, sesame oil, sunflower oil and control (distilled water). For the other experiments, conducted for both species of ant, the following treatments were used: cotton oil, rice oil, canola oil, sesame oil, sunflower oil, corn oil, soy oil, bait pellets without active ingredient, distilled water and cellulose (not immersed in water or oil). The data presented in this work affirms that soy oil, present in commercial baits,probably contributes to its attractiveness. Corn and rice oil presented potential as substitutes for soy oil in relation to the development of new bait matrixes for A. capiguara.