EFFECTS OF TEMPERATURE AND SOLAR-RADIATION INTERACTIONS ON THE SURVIVAL OF QUIESCENT CONIDIA OF THE ENTOMOPATHOGENIC HYPHOMYCETE PAECILOMYCES-FUMOSOROSEUS (WIZE) BROWN AND SMITH

The detrimental effect of solar radiation on the survival of conidia o f the entomopathogenic fungus Paecilomyces fumoroseus was studied by m onitoring germinability and ability to form colonies (CFU) of conidia irradiated at two temperatures, 25 and 35 degrees C, harmless to shade d conidia. There was no apparent effect when spores were exposed to a high level of artificial radiation (0.66 W m(-2) UVB). However, at a l ower level of irradiance (0.33 W m(-2)), effects of radiation occurred more quickly at 35 degrees C than at 25 degrees C. Under natural sola r radiation, the rate of decrease in germinability or viability was do ubled at 35 degrees C as compared to 25 degrees C, indicating an inter action between temperature and radiation effects under natural conditi ons. This interaction was not detected in indoor experiments, indicati ng that the spectral distribution of W radiation has to be taken in ac count as well as its irradiance when studying its effects.