Biological control is based on the use of microorganisms to combat populations of a specific pathogen. Nematophagous fungi have shown to be promising agents to combat nematode parasites of plants and animals. These organisms produce special structures along the hyphae, named traps, which are responsible for capturing and killing the nematode pre-parasitic stages. The growth of the isolates I31 of Arthrobotrys robusta and NF34a of Monacrosporium thaumasium was studied after submission to four different methods of preservation during eighteen months. The isolates were stored at 4ºC and cryopreserved with or without addition of cryoprotectants and stored in silica gel. The isolates did not present variation in radial growth when stored at 4ºC and frozen with or without addition of cryoprotectants. There was no significant difference between the dry mycelial mass of the isolates stored at 4ºC and those frozen after the addition of cryoprotectants. Storage in silica gel and freezing without cryoprotection interfered negatively in the capacity of the fungi to produce mycelial mass. This characteristic also was observed for sporulation of the two isolates. The behaviour of the isolates when maintained for prolonged periods under laboratory conditions is an important factor for selection of the most efficient method of preservation.
nematophagous fungi; biological control; preservation of microorganisms
