Toxicity and behavioral alterations caused by essential oils of Croton tetradenius and their major compounds on Acromyrmex balzani

Leafcutter ant Acromyrmex balzani is a species responsible for causing important losses in agricultural crops, pastures and forest plantations. Croton tetradenius, an aromatic plant of wide occurrence in northeastern Brazil, is a plant that has great potential as a botanical insecticide for control of leafcutter ants. The present study evaluates the toxicity and sublethal effects of essential oils of C. tetradenius plants from natural populations in the state of Sergipe, Brazil, and their major compounds, applied by fumigation, on A. balzani workers. The essential oils used in the study were obtained from five plants of C. tetradenius and their major compounds - 1,8-cineole, alpha-pinene, camphor, (E)-pinocarveol and p-cymene-, acquired commercially. All treatments exhibited formicidal activity, with LC50 values ranging from 1.47 to 2.40 mu L.L-1 for the essential oils and 0.45-11.20 mu L-1 for the major compounds. Camphor was the most toxic tested compound. After exposure, there was a reduction in the survival of A. balzani. The highest observed LT50 was 42.91 h for essential oils of plant CRT042. The essential oils and their major compounds repelled and affected the walking behavior of A. balzani workers. The formicidal activity of C. tetradenius essential oil and its major compounds was verified, and we demonstrated that it has potential as a natural insecticide to control A. balzani.