The Effects of UV Radiation on Metarhizium anisopliae

Abstract

The development of fungal insecticides as biological control agents provides a safer, more natural approach to pest control than chemical insecticides. Metarhizium anisopliae, one of the most widely used mycoinsecticides, is one fungal species of high economic potential in current use. However, a rapid decrease in pathogen activity in the field due to ultraviolet radiation presents a problem for further production. The present study seeks to determine if certain strains of M. anisopliae are more tolerant of UV radiation, thus providing the potential for higher effectiveness in the field. Utilizing a novel method for examining fungal persistence that is more conducive to real-world scenarios of fungicide application to crops, fungi were applied on leaf disks rather than agar plates. Leaf disks were then exposed to UV-A and UV-B from an artificial source at UV intensity equivalent to mid-day June or July. After being exposed to UV irradiation, the conidia were removed and subjected to a germination test as a measure of the lethality of the UV exposure. This study examined 15 strains of M. anisopliae obtained from the Sidney, Montana, USDA-ARS collection of entomopathogenic fungal cultures.