EFFECTS OF TEMPERATURE ON THE VIABILITY OF THE CONIDIA OF METARHIZIUM-FLAVOVIRIDE IN OIL FORMULATIONS

The effects of temperature on the survival of conidia of the entomopat hogenic Metarhizium flavoviride in oil formulations for ultra low volu me application were investigated. High temperature treatments caused d elay in germination as well as death; drying conidia by adding dried s ilica gel to oil formulations greatly increased temperature tolerance. Conidia were more tolerant to temperature extremes than suggested fro m previous work with > 80% germination recorded from dried conidia exp osed to 60-degrees-C for 90 min and 59% and 20% surviving 8 and 42 d, respectively, at 55-degrees. Under some circumstances reduced germinat ion following high temperature exposure was reversed by a subsequent s torage period at lower temperatures. Conidia produced at 30-degrees we re more tolerant of high temperature than conidia produced at 26-degre es and increasing the sucrose content of the growth media from 2% to 8 % reduced tolerance.