Avaliação do potencial inseticida e metabolômica microbiana de extratos orgânicos de isolados de fungos Entomopatogênicos metarhizium spp.

Abstract

The expansion of cultivated areas in Brazil, associated with climatic conditions and indiscriminate use of pesticides, selects insect resistant pests. The stink bug Dichelops melacanthus (Dallas, 1851) (hemiptera: pentatomidae) causes damage to the growth of maize crops, slowing yields and impairing their growth and reproduction by decreasing the number of plants per cultivated area. Some fungi synthesize secondary metabolites and enzymes that act as agents without biological pest control in agriculture. A metabolic analysis is the study of secondary metabolites with low molecular masses produced by fungi and other microorganisms. One of the analytical tools that allow this analysis is the liquid chromatography coupled to mass spectrometry, which enables both quantitative and qualitative analysis, providing structural information of molecules from mass data. The objectives of this work were to perform a bioinsecticide test against the D. melacanthus stink bug and to identify the possible genus of the six fungal isolates through the metabolomic analysis. Six isolates were obtained from insects Spheciformes sp. (Wasp), Anthophila sp. (Bee), Formica sp. (Ant), Amblytelus sp (Beetle). The organic extracts produced by the isolates were extracted using organic solvent ethyl acetate and methanol. To perform the bioinsecticide test the bed bugs were in the fifth instar of growth. There were 14 treatments with 5 repetitions. Each treatment was carried out in an acrylic box containing 5 bed bugs, with a restricted diet, and average humidity of 60% per box in a 14 hour photoperiod. The treatments were sprayed on each box according to the respective treatment. After the tenth day of analysis, the Tukey test for mortality analysis was performed. The metabolites analysis was obtained according to the molecular mass obtained in UHPLC (Ultra High Pressure Liquid Chromatography) at a concentration of 0.1 mg / ml, from the fungal extracts. Morphologically identified fungal spores belonging to the genus Aspergillus sp. The insecticide test did not present significant mortality data from fungal isolates extracts and spores, due to the average mortality of the controls and control are close to the results of the other treatments. In the metabolomic analysis, 24 metabolites synthesized by fungi were identified, being 17 destruxins and 7 aflatoxins produced by Metarhizium and Aspergillus respectively. The identification of fungi by these analyzes were complementary, besides allowing the creation of a database of fungal molecules using mass spectrometry.