Submitted to: Biological Control
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/14/2005
Publication Date: 5/11/2005
Citation: Mcguire, M.R., Ulloa, M., Park, Y.H., Hudson, N. 2005. Biological and molecular characteristics of beauveria bassiana isolates from california lygus hesperus (hemiptera:miridae) populations. Biol. Cont. 3:307-314. Interpretive Summary: The Western tarnished plant bug (WTPB) is a particularly devastating pest of cotton and other crops. Although chemical pesticides are frequently used for control of the WTPB, these pesticides may also affect predators and parasites that affect pests other than WTPB. These other pests may then become problems later in the season. The creation of an effective biopesticide that affects only WTPB would be beneficial to the industry. A fungus called Beauveria bassiana infects and kills WTPB. We discovered certain, naturally occurring isolates of the fungus in the San Joaquin Valley of California and these isolates may be very effective agents against WTPB. The manuscript details evidence of infectivity and growth of the fungus at high temperatures in comparison with other isolates. Four isolates in particular were highly effective and could grow at temperatures commonly occurring in the San Joaquin Valley. In addition, molecular work detailed the uniqueness of the isolates. The information will be of value to other scientists and, eventually to growers attempting to control WTPB.
Technical Abstract: Lygus hesperus is an important pest of many crops grown in the Western U.S. 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 L. hesperus populations were screened for their ability to grow at high temperatures and for their ability to infect and kill L. hesperus adults under laboratory conditions. No isolate grew at 37°C but most isolates were able to grow at 35°C. B. bassiana isolated from a commercial product was not able to grow at 35°C. In addition, several L. hesperus isolates were more efficacious than the commercial isolate. LC50 of four isolates were more than 10 times lower than the commercial isolate. Microsatellite markers were used to determine that selected isolates could be distinguished from other isolates. Preliminary information suggested 82 isolates of B. bassiana were closely related to each other but distantly related to the commercial isolate.