ENVIRONMENTAL-FACTORS AFFECTING PERSISTENCE OF ENTOMOPATHOGENS

This symposium review will focus on the impact of environmental factors (primarily sunlight, temperature, humidity-water) on the field persistence of selected representative species of entomopathogens (bacteria, fungi, protozoans, viruses). Sunlight is probably the most destructive environmental factor affecting the persistence of entomopathogens and commercial microbial pesticides. Temperatures prevalent in most agro-ecosystems (ca. 10 to 40-degrees-C) generally do not adversely affect entomopathogens. Effects at temperature extremes, however, might be obtained when the entomopathogens are stressed by other factors (e.g., light, water, chemicals). The effect of humidity or water on entomopathogens also is difficult to separate from its combination with other environmental factors. Humidity or water per se generally does not directly affect the activity or viability of viral or bacterial entomopathogens, respectively. In contrast, lack of moisture reduces the infectivity of many protozoan spores and moisture generally is a primary requirement for germination of conidia and survival of entomopathogenic fungi.