Fungos micoparasitas associados a colônias iniciais de Atta sexdens (Linnaeus, 1758) (Hymenoptera: Formicidae)

Abstract

Leaf-cutting ants are considered dominant herbivores of the Neotropical region, being important agricultural and forest pests, causing great economic losses. The control of Atta sexdens, the most severe among cutters, is mainly performed as the use of chemical insecticides, and is often inefficient due to the social behavior of the Formicidae family. In addition, in the field the natural microbial control takes place, being worth highlighting the action of mycoparasite fungi, which were studied with the objective of finding isolates with antagonistic potential to the symbiotic fungus. In this context, 50 soil samples from pans of A. sexdens initial colonies were collected in eucalyptus plantations in the city of Belo Oriente – MG. A total of 98 isolates of fungi were obtained, of which five isolates of genera/species with reports of mycoparasitism (Taralomyces sp., P. lilacinum, Cladosporium sp., Penicillium sp. and Escovopsis sp.) were selected for bioassay. All the isolates used in the experiment were able to inhibit the development of the symbiotic fungus in vitro and also to cause mortality to the workers. Nevertheless, the results were not repeated in the bioassays with subcolonies, where only the isolates of Penicillium sp and Escovopsis sp. were able to cause the collapse of the subcolonies. However, the results obtained stimulate the use of mycoparasite fungi as a control strategy for A. sexdens, showing that virulence is not the onl y factor that should be taken into account when choosing the control method. New studies must be carried out in order to detect microorganisms that present besides virulence, characteristics such as high capacity of dissemination, rapid development and, mainly, resistance to the antimicrobial compounds produced by the colonies.