Fatal attraction: Engineering and selecting beauveria bassiana fungal strains for targeted biocontrol of Mountain Pine Beetle (Dendroctonus ponderosae)

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The mountain pine beetle (Dendroctonus ponderosae) has killed >50% of mature lodgepole pine trees (Pinus contorta) across >16 million ha of British Columbia. It has now crossed the Rocky Mountains into Alberta, where it infests lodgepole, jack (P. banksiana) & lodgepole × jack pine hybrid forests. Its attack on jack pine is of special concern as this common species extends across the boreal forest to Canada's East Coast. Beetles preferentially attack mature trees where they feed & reproduce below the bark. Beetles introduce blue stain fungi (Grosmannia clavigera, Leptographium longiclavatum) that block water & nutrient transport, limit trees defensive responses, & provide nutrients to beetle offspring. Control efforts are limited to destruction of infested trees. Since 2006, the Alberta government has spent nearly $500 million to detect & eradicate the beetles. Beauveria bassiana is a fungus that attacks beetles & kills them. Although the species can colonize a wide variety of arthropods, some strains have narrow spectra of activity. This fungus is already in use as a biological insecticide against other insects. Although B. bassiana is lethal to D. ponderosae & other bark beetles in the lab, field tests often fail to demonstrate propagation of the mycosis or control of beetle populations. However, B. bassiana was successful in field tests with European spruce bark beetle (Ips typographus) due to its persistence in forest litter. Canada's forests influence climate, contribute to CO2 uptake, provide wildlife habitat, clean water & other ecosystem services. They accounted for $19.8 billion of Canada's GDP in 2013. This application requests funding to examine selection, generation & testing of fungal strains of B. bassiana that are environmentally robust, specifically lethal to the mountain pine beetle & readily deployed for direct control. The project will engineer into the fungus: (i) enhanced UV & drought tolerance to improve field applications; & (ii) pine beetle sex pheromone production to attract the insects to infected individuals. Lab tests of efficacy will be followed by controlled field trials to evaluate biocontrol of the insect by the fungus under natural conditions & examine nonspecific lethality to desirable (e.g. pollinating) insects.