Submitted to: Journal of Entomological Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/1/2006
Publication Date: 5/15/2007
Citation: Dara, S.K., Mcguire, M.R., Kaya, H.K. 2007. Isolation and evaluation of beauveria bassiana (deuteromycotina: hyphomycetes) for the suppression of glassy-winged sharpshooter, homalodisca coagulata (homoptera: cicadellidae). Journal of Entomological Science. 42(1):56-65. Interpretive Summary: The glassy winged sharpshooter (GWSS) was introduced into California where it is particularly efficient at transmitting a bacterium that causes disease in grapes, almonds, and other economically important crops. Like many pests that are introduced into a new environment, many of its natural enemies were not introduced, thus populations can increase rapidly. One type of natural enemy is a fungus called Beauveria bassiana that kills insects. The purpose of the work reported in this manuscript was to evaluate if B. bassiana is present in GWSS populations in California and to determine if other isolates of the fungus can cause infections in the insect. No naturally occurring fungal pathogens were found in California GWSS populations despite extensive searches. However, fungi isolated from GWSS in Texas and Florida, as well as some other isolates of B. bassiana from other California insects and soil samples, could infect GWSS. This work should be of interest to pest control practitioners, scientists studying novel methods of insect control and companies that produce fungi that infect insects.
Technical Abstract: The glassy-winged sharpshooter, Homalodisca coagulata, is of great importance to California agriculture as a vector of Pierce’s disease causing bacterium, Xylella fastidiosa. Researchers aim at developing control strategies that mitigate vector populations and prevent the spread of the disease. One of the potential means of controlling the sharpshooter is the use of entomopathogenic fungi. In an attempt to discover naturally occurring fungal pathogens that are adapted to the sharpshooter and its habitats, soil samples from citrus and pomegranate orchards in Tulare and Riverside counties in southern California were screened for the presence of pathogens. Using a modified Galleria bait method that required small quantities of soil samples, 124 isolates of Beauveria bassiana (Balsamo) Vuillemin and four isolates of Metarhizium anisopliae (Metschnikoff) Sorokin were recovered from organic citrus and conventional pomegranate orchards. Additionally, 22 isolates of B. bassiana were recovered by plating soil suspensions on selective growth media. Natural fungal infections were not seen in H. coagulata populations from periodical sampling in Kern, Riverside and Ventura counties in southern California. However, isolates of B. bassiana were recovered from other insect hosts in Fresno and Kern counties. Some of the B. bassiana isolates recovered from soil and insect hosts were evaluated against H. coagulata along with other fungal pathogens isolated from H. coagulata in Texas, Mississippi and Florida. Growth of the selected isolates was also evaluated at 15, 23, 28 and 32 oC. The Texas isolate and two California isolates of B. bassiana were virulent against H. coagulata and warrant further study.