-The objective of this work was to evaluate if the immunosuppressant Sandimmun Neoral enhances the activity of Metarhizium anisopliae against the leaf-cutting ant Atta sexdens. The vulnerability to the pathogen was measured by comparing the mortality rate of worker ants subjected to the following treatments: immunosuppressant+control, immunosuppressant+M. anisopliae, excipient+control, excipient+M. anisopliae, control+M. anisopliae, and control. Worker ants treated with immunosuppressant+M. anisopliae showed the highest mortality rate in comparison with those subjected to all other treatments. The use of the immunosuppressant together with entomopathogenic fungus controlled leaf-cutting ants in laboratory conditions. Index terms: biological control, Formicidae, immunity, immunosuppression. Suscetibilidade de operárias de Atta sexdens tratadas com o imunossupressor Sandimmun Neoral a Metarhizium anisopliaeResumo -O objetivo deste trabalho foi avaliar se o imunossupressor Sandimmun Neoral favorece a atividade de Metarhizium anisopliae contra a formiga cortadeira Atta sexdens. A vulnerabilidade ao patógeno foi medida ao se comparar a mortalidade de operárias expostas aos seguintes tratamentos: imunossupressor+controle, imunossupressor+M. anisopliae, excipiente+controle, excipiente+M. anisopliae, controle+M. anisopliae e controle. Operárias tratadas com imunossupressor+M. anisopliae apresentaram a maior taxa de mortalidade em comparação às submetidas a todos os outros tratamentos. O uso do imunossupressor juntamente com fungo entomopatogênico controlou as formigas cortadeiras em condições de laboratório.Termos para indexação: controle biológico, Formicidae, imunidade, imunossupressão.

The aim of the study was to test the effects of various concentrations of zinc sulfate (ZnSO4) on the radial growth of Trichoderma harzianum and Leucoagaricus gongylophorus in Petri dishes. In addition, we investigated the acceptance of baits containing live propagules of the encapsulated T. harzianum fungus and baits containing ZnSO4 by foraging leafcutter worker ants, A. sexdens, as well as their effects on the colonies of these ants. For the in vitro test, the design was completely randomized using ten replicates of a 2 × 7 factorial scheme: two species of fungi (T. harzianum and L. gongylophorus) and seven concentrations of ZnSO4. For bait acceptance tests, four treatments were used: baits without the mycelium and ZnSO4 (T1, control), baits containing encapsulated T. harzianum mycelium (T2), baits containing ZnSO4 (T3), and baits containing zinc sulfate and the encapsulated T. harzianum (T4). Each treatment was tested in duplicates using eight colonies. In the in vitro test, a ZnSO4 concentration of 0.25 g/L was sufficient to completely inhibit the development of L. gongylophorus without affecting the development of T. harzianum. In the bait acceptance test, the workers accepted ~55% of the bait combination of ZnSO4 and T. harzianum. This suggests the potential of treatment T4 in controlling leafcutter ants. Moreover, treatment T4 is environmentally friendly.