Toxicity and behavioral alterations of essential oils of Eplingiella fruticosa genotypes and their major compounds to Acromyrmex balzani

Eplingiella fruticosa is an endemic plant to the coastal region of northeastern Brazil with biological activities with potential as organosynthetic insecticides for control of agricultural and forest pests, such as leaf-cutting ants, belonging to the genus Acromyrmex. This study aimed to evaluate the acute toxicity, by fumigation, essential oils of four E. fruticosa genotypes and their major compounds on Acromyrmex balzani workers and the behavioral changes caused to this species when exposed to these compounds. The essential oils used in this work were selected from previous studies and according to chemical grouping. The essential oils from genotypes EPF303 and EPF1103 showed higher mean levels of monoterpenes (43.6%, with camphor and 1,8-cineol as major compounds) in relation to genotypes EPF202 and EPF901 (17.4%). The latter consisted mainly of sesquiterpenes (82.6%, with caryophyllene oxide and β-caryophyllene as major compounds). The essential oils from all E. fruticosa genotypes were toxic to A. balzani workers with concentrations required to cause 50% mortality to the insects ranged from 4.54 to 6.78 μL.L−1. When applied alone, camphor and 1,8-cineol were more potent than essential oils with higher average levels of monoterpenes. Conversely, the major sesquiterpenes (β-caryophyllene and caryophyllene oxide) were less toxic than essential oils consisting mainly of sesquiterpenes. The treatments used reduced A. balzani survival over the exposure time. The LT50 for all treatments were less than 15 h. The essential oils and their respective major compounds affected the walking behavior and caused repellency to A. balzani workers. The present results showed the potential of E. fruticosa essential oils and their major compounds for the development of new efficient products in the control of A. balzani.