Formicidal activity of essential oils of Myrcia lundiana chemotypes on Acromyrmex balzani

Essential oils (EOs) from plants have been considered as a viable alternative to the use of synthetic insecticides for the control of insect pests. In the current study, we evaluated the formicidal activity of essential oils of two Myrcia lundiana (Myrtaceae) chemotypes, their major compounds and their binaries mixtures on Acromyrmex balzani (Emery, 1980) (Hymenoptera: Formicidae). The effects of essential oils on A. balzani were evaluated by fumigation toxicity bioassays and behavioral tests. The major concentration of isopulegol and citral in the essential oils characterized the two M. lundiana chemotypes, with 1,8-cineol being the second compound with the highest concentration. The essential oils and their major compounds were toxic to A. balzani workers. The isolated isopulegol and citral were around 14 and four times more toxic than the essential oils of their respective chemotypes. The mixture of the major compounds with 1,8-cineol resulted in an antagonistic effect. The treatments provoked rapid mortality and altered the walking behavior of A. balzani. Isopulegol resulted the highest toxicity, while the citral chemotype showed a more persistent repellent effect on A. balzani. The EOs of the M. lundiana chemotypes allow to obtain compounds for the development of new insecticides for the program management of leaf-cutting ants.