Research on microorganisms for the control of pests and pathogens is increasing. Such organisms display antagonistic effects on pests and pathogens, at the same time, they do not interfere with the sustainable development processes and are environmentally safe for human populations. Thus, bioprospection of fungi from restinga ecosystems is of interest as a novel source of microorganism and a yet unexplored source of chemical structures. This study selected endophytic fungi and fungi from the

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... tinga soil samples to investigate their biological activity against insects. Fifty-three fungal isolates were used in screening bioassays against Atta sexdens rubropilosa leaf-cutting ant workers via direct contact of the insects with sporulating fungi cultures. This assay indicated that Trichoderma caused the highest mortality. Extracts from Trichoderma were then assessed for biological activity via ingestion, contact or exposure to fungal volatiles. Results showed that one Trichoderma sp. isolate (TR1) caused 50% mortality in 2, 1.5 and 4 days when ingested, sprayed onto the ants or by exposing ants to volatiles, respectively. Although this fungus is not known to be entomopathogenic, it could have potential use as an additional tool for pest control as it produces metabolites with antagonistic effects.