Evaluation of the antifungal activity of propolis extracts from stingless bees on phytopathogenic fungi

The bees of the Meliponini tribe, known as stingless bees (SB), elaborate a distinct type of propolis, whose application potential is largely unexplored. Currently, there is some knowledge of the pharmacological activities of the propolis from Apis mellifera, however, little is known about the diversity and antimicrobial activity of Meliponini propolis, especially in relation to pathogens of agricultural importance. This study aimed to investigate the antimicrobial activity of the alcoholic extract of propolis from T. clavipes (Borá), S. bipunctata (Tubuna), and T. angustula (Jataí), comparing with the ethanolic extract from A. mellifera propolis. The autoclaved and non-autoclaved extracts were evaluated at the concentrations of zero, 1.6 %; 3.2 %; 6.4 %, and 12.0 % v/v. Fungal development was determined by measuring the mycelial diameter up to the fourteenth day of inoculation, with five replicates; the growth inhibition was calculated relative to the control. According to the results, the highest concentration of phenolic compounds and flavonoids was present in the ethanolic extract of A. mellifera propolis when compared to the SB extracts. The results indicated an inhibitory effect on the growth of the phytopathogens Colletotrichum gloeosporioides, Fusarium sp., Botryosphaeria sp., and Botrytis sp., mainly from 6.4 % and 12.0 % v/v when evaluated in the non-autoclaved medium, followed by the autoclaved medium. The fungus Botrytis sp. was the phytopathogen that suffered greater inhibition from 3.2 mL∙L-1, with the T. angustula propolis extract. The obtained results demonstrate that the alcoholic extracts of propolis from SB have the potential to control phytopathogenic fungi of agricultural interest.