Biological and molecular characteristics of Beauveria bassiana isolates from California Lygus hesperus (Hemiptera: Miridae) populations

Lygus hesperus is an important pest of many crops grown in the Western US. In addition, other species of Lygus cause damage in other parts of the world. To date, no selective pesticide exists for the control of Lygus spp. and broad spectrum pesticides that also kill natural enemies may lead to secondary pests. Entomopathogenic fungi may offer an alternative to chemical pesticides. Isolates of Beauveria bassiana collected from San Joaquin Valley of California (SJV) L. hesperus populations were screened for their ability to grow at high temperatures and for their ability to infect and kill L. hesperus adults and nymphs under laboratory conditions. No isolate grew at 37 or 35 °C but most isolates were able to grow at 32 °C. In addition, one L. hesperus isolate was more efficacious at higher doses than the commercial isolate. Microsatellite markers were used to determine that selected isolates could be distinguished from other isolates. Preliminary information suggested 82 SJV isolates of B. bassiana were closely related to each other but distantly related to the commercial isolate.