Canadian Forest Service Publications

Evaluation of indigenous Beauveria isolates as potential agents for emerald ash borer management and the development of a diagnostic marker to monitor a post-release isolate. 2013. Kyei-Poku, G.; Johny, S. IOBC-WPRS Bulletin 90:119-124.

Year: 2013

Issued by: Great Lakes Forestry Centre

Catalog ID: 35148

Language: English

Availability: PDF (request by e-mail)

Mark record


To search for effective and safe indigenous biocontrol agents to manage emerald ash borer (EAB), we conducted a survey in 2008-2009 of entomopathogenic fungi (EPF) infecting EAB in outbreak sites in southwestern Ontario, Canada. Many Beauveria spp. isolates were recovered from dead and mycosed EAB cadavers residing in the phloem tissues of dead ash barks, larval frass extracted from feeding galleries under the bark of dead trees. Molecular characterization using sequences of the ITS, 5' end of elongation factor 1 alpha (EFl-a) and intergenic Bloc region fragments revealed that Beauveria bassiana and B. pseudobassiana were commonly associated with EAB in the sampled sites. Initial virulence screening against EAB adults of 23 isolates representing the different clades yielded 8 isolates that produced more than 90% mortality in a single concentration assay. These isolates differed in virulence based on LC50 values estimated from multiple concentration bioassay and based on mean survival times at a conidia concentration of 2 x 106 conidia ml'1. B. bassiana isolate L49-1AA was significantly more virulent and produced more conidia on EAB cadavers compared to the other indigenous isolates and the commercial strain B. bassiana GHA suggesting that L49-1AA may have potential as a control agent against EAB. Studies have been developed to use autocontamination trapping system to disseminate L49-1AA to manage EAB field populations. We targeted the EFl-a gene sequence from L49-1AA to develop an allele/strain specific primer set that will be used to monitor the introduced L49-1AA in terms of its establishment, persistence and virulence in the environment.

Plain Language Summary

In 2008-2009 we surveyed emerald ash borer (EAB) outbreak sites in southwestern Ontario to look for possible native biocontrol agents. We found many species of fungi on the dead EAB and in the insect frass. Using molecular techniques, we identified two species of Beauveria fungi that were most predominant. We tested 23 isolates of these two species for their ability to kill EAB and found one in particular: B. bassiana L49-1AA to be significantly more virulent and able to produce more spores on EAB cadavers than the others. It was also better than the commercial strain of B. bassiana. We then developed field studies using an auto-contamination trapping system to disseminate this fungal isolate to manage EAB populations. We also developed a genetic marker that will be used to monitor its establishment, persistence and virulence in the environment.