February 15, 2011
An indigenous nematode species, that apparently paralyzes and kills emerald ash borer (EAB) by injecting either a bacteria or a toxic substance, has been found in old outbreak sites in Ontario.

The nematodes were found living within dead and dried adult and larval borers underneath the bark of infested and dead ash trees. Although the finding is preliminary, it is felt that the nematode shows high reproductive potential on EAB, making it a suitable candidate for mass production and subsequent use as a control agent.

Tests will take place to better understand the mechanism by which this organism kills EAB and other insect species. Great Lakes Forestry Centre researcher Dr. George Kyei-Poku has been studying the nematodes. The Centre is administered by the Canadian government.

The doctor’s search has taken him to southwestern Ontario near Sarnia, Windsor and London. Kyei-Poku and his team have also identified four native fungi with the potential to kill EAB. These are common fungi already living in Canadian soils. A first step in examining the potential of these fungi as a large scale control method is to find out how fast they will kill this pest.

Spreading these fungi among EAB populations is another huge challenge. A method currently under consideration is placing the pathogen in traps laden with lures that only attract EAB. The theory is that contaminated EAB will fly off from the traps and mate with others, which will in turn contaminate the bodies of those mates, thereby spreading the disease. At a minimum the fungi will kill any EAB that flies into the trap, thus reducing their spread into non-infested ash trees.

If successful, this research may lead to the establishment of production facilities to mass-produce the most effective pathogens that can then be safely released into the environment near known EAB infestations.

To date, millions of ash trees have succumbed to EAB in Ontario, Quebec and several states in the U.S. Control measures to date have consisted of the use of a systemic insecticide (TreeAzin for individual treatment of high-value trees), silvicultural practices (tree removal and shredding) and imposed quarantines to restrict movement of infested wood.