Chemical analysis and hydroalcoholic extract activity of ferns on the mutualist fungus of leafcutter ants

Abstract

Leafcutter ants are among the most important agricultural and forest pests in the Neotropical region, given that they use plant matter as substrate for the growth of their mutualist fungus Leucoagaricus gongylophorus. Plant-based insecticides and fungicides have shown potential for controlling these ants. The present study assessed the hydroalcoholic extract activity of four fern fronds (dry and rainy periods) on the mutualist fungus of leafcutter ants. Fungal mycelium suspensions were seeded on the surface of tubes containing fern extracts at a concentration of 5 mg/mL and 100 μg/mL. The chemical profile of the extracts was analyzed by thin layer chromatography (TLC). Extracts (dry period) at a concentration of 5 mg/mL inhibited the growth of the fungus: Macrothelypteris torresiana and Dicksonia sellowiana (less than 20%), Niphidium crassifolium (approximately 40%), Parapolystichum effusum extract (100%). None of the extracts (dry and rainy periods) inhibited fungal growth at a concentration of 100 μg/mL. The chemical profile analysis of the extracts indicated the presence of beta-sitosterol, friedelinol, rutin, and kaempferol. The crude extracts of P. effusum and N. crassifolium were the most promising in future formulations of antifungal products. Thus, ferns are potential plants in the search for environmentally-friendly substances for sustainable agriculture.

Key words:
antifungals; biological interactions; Leucoagaricus gongylophorus; pteridophytes.