Atividade inseticida do óleo essencial de Cymbopogon spp. (Poaceae) em operárias e colônias de Atta sexdens (Formicidae: Attini)

Abstract

Leafcutter ants (Formicidae: Attini) are defoliating insects; they are one of the most prominent pests in the Neotropical region, due the damage they may cause in both agricultural and forest crops. They are abundant and widely distributed and cut fresh parts of plants to use as a substrate for the symbiotic fungi they grow inside their nests. Currently, the main method for controlling these insect pests is through the use of toxic baits. However, the search for new anticide compounds has steadily increased, including plant compounds with insecticidal activity, mostly due to the presumed safety of these compounds for human beings and the environment. Therefore, the aim of this study was to evaluate the insecticidal activity and the sublethal effects of Cymbopogon citratus, Cymbopogon martinii, and Cymbopogon nardus essential oils on Atta sexdens worker ants exposed to topical application through contact and through fumigation, and to evaluate the insecticidal activity of C. citratus essential oil through nebulization on Atta sexdens colonies under laboratory conditions. The study was performed in the Forest Entomology Laboratory of the Department of Forestry Sciences at the Universidade Federal de Sergipe in São Cristóvão, Sergipe, Brazil. The C. citratus essential oil showed significant insecticidal activity, whereas the insecticidal activity of C. martinii and C. nardus was less. However, all the species (essential oils) affected Atta sexdens worker ant behavior and movement. The C. citratus essential oil showed insecticidal activity for control of leafcutter ants, as well as fungicidal activity against the symbiotic fungi. This essential oil caused considerable loss in the weight of fungal mass in the colonies, along with mortality of the queen and worker ants, which proves to be promising for development of new insecticides for management of this insect pest.

Leafcutter ants (Formicidae: Attini) are defoliating insects; they are one of the most prominent pests in the Neotropical region, due the damage they may cause in both agricultural and forest crops. They are abundant and widely distributed and cut fresh parts of plants to use as a substrate for the symbiotic fungi they grow inside their nests. Currently, the main method for controlling these insect pests is through the use of toxic baits. However, the search for new anticide compounds has steadily increased, including plant compounds with insecticidal activity, mostly due to the presumed safety of these compounds for human beings and the environment. Therefore, the aim of this study was to evaluate the insecticidal activity and the sublethal effects of Cymbopogon citratus, Cymbopogon martinii, and Cymbopogon nardus essential oils on Atta sexdens worker ants exposed to topical application through contact and through fumigation, and to evaluate the insecticidal activity of C. citratus essential oil through nebulization on Atta sexdens colonies under laboratory conditions. The study was performed in the Forest Entomology Laboratory of the Department of Forestry Sciences at the Universidade Federal de Sergipe in São Cristóvão, Sergipe, Brazil. The C. citratus essential oil showed significant insecticidal activity, whereas the insecticidal activity of C. martinii and C. nardus was less. However, all the species (essential oils) affected Atta sexdens worker ant behavior and movement. The C. citratus essential oil showed insecticidal activity for control of leafcutter ants, as well as fungicidal activity against the symbiotic fungi. This essential oil caused considerable loss in the weight of fungal mass in the colonies, along with mortality of the queen and worker ants, which proves to be promising for development of new insecticides for management of this insect pest.