Comparing methods of preservation for cultures of entomopathogenic fungi

Abstract

Nine species of entomopathogenic fungi were tested for viability after they had been stored with deionized water, mineral oil, or silica gel or frozen at –20 or –80°C. Species tested included members of the Hyphomycetes, Entomophthorales, Trichomycetes, and Oomycetes. The fungal cultures were maintained up to 1.5 years and were checked at 3, 6, 12, and 18 months. For all species evaluated, Paecilomyces fumosoroseus demonstrated the best results, surviving through 18 months when stored with water or mineral oil and when frozen at –80°C. For the majority of other fungal species tested, except the trichomycete Smittium culisetae and oomycete Leptolegnia chapmanii, freezing at –80°C was the best storage method and storage with silica gel was the worst. In addition to culture viability, infectivity against Aedes aegypti larvae was evaluated after 18 months of storage for L. chapmanii and S. culisetae. The simplest and least expensive methods, using water or mineral oil, were the only successful methods for maintaining viability and infectivity of L. chapmanii and S. culisetae.Key words: entomopathogenic fungi, preservation, storage, viability.