Production of thermotolerant entomopathogenic Isaria fumosorosea SFP-198 conidia in corn-corn oil mixture.
Low thermotolerance of entomopathogenic fungi is a major impediment to long-term storage and effective application of these biopesticides under seasonal high temperatures. The effects of high temperatures on the viability of an entomopathogenic fungus, Isaria fumosorosea SFP-198 (KCTC 0499BP), produced on different substrates amended with various additives were explored. Ground corn was found to be superior in producing the most thermotolerant conidia compared to yellow soybean, red kidney bean, and rice in a polyethylene bag production system. Using ground corn mixed with corn oil as a substrate resulted in only 7% reduction in germination compared to ground corn alone (67% reduction) after exposure of conidia to 50 degrees C for 2 h. Corn oil as an additive for ground corn was followed by inorganic salts (KCl and NaCl), carbohydrates (sucrose and dextrin), a sugar alcohol (sorbitol), and plant oils (soybean oil and cotton seed oil) in ability to improve conidial thermotolerance. Unsaturated fatty acids, such as linoleic acid and oleic acid, the main components of corn oil, served as effective additives for conidial thermotolerance in a dosage-dependent manner, possibly explaining the improvement by corn oil. This finding suggests that the corn-corn oil mixture can be used to produce highly thermotolerant SFP-198 conidia and provides the relation of unsaturated fatty acids as substrates with conidial thermotolerance.
Entomology Research Laboratory, Department of Plant and Soil Science, University of Vermont, 661 Spear Street, Burlington, VT 05405-0105, USA. jae-su.kim@uvm.edu
Jae Su
JS
Kim
Yeon Ho
YH
Je
Jong Yul
JY
Roh
D003314:Corn Oil / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry; D006358:Hot Temperature; D006999:Hypocreales / Q000502:physiology* / Q000528:radiation effects*; D050296:Microbial Viability / Q000528:radiation effects*; D013172:Spores, Fungal / Q000502:physiology* / Q000528:radiation effects*
D003470:Culture Media; D003314:Corn Oil