Toxicity of foliage extracts of Tithonia diversifolia (Asteraceae) on Atta cephalotes (Hymenoptera: Myrmicinae) workers

Leaf-cutting ants (Formicidae: Myrmicinae) have been considered herbivorous generalists; however, some plant species escape their attack because of the presence of secondary metabolites. The main objective of this study was to determine the insecticide effect of foliage extracts of Tithonia diversifolia on Atta cephalotes workers (Hymenoptera: Myrmicinae) and define the potential application ways and concentrations. Extracts were obtained from fresh and dry T. diversifolia foliage, using ethanol as solvent. The principal metabolic compounds were identified and the extracts in three concentrations (0.5 ml/l, 1.5 ml/l, and 3 ml/l) were applied to the ants in two manners: ingestion and contact. Results showed that crude extract of T. diversifolia was toxic to the ants in all concentrations and methods tested; however, dry extracts applied for contact at 1.5-ml/l concentration produced the most efficient toxic effect to A. cephalotes workers. The study contributes to identifying an environmental sound control strategy for the leaf-cutting ant, A. cephalotes. (C) 2012 Elsevier B.V. All rights reserved.