Optimization of Beauveria bassiana in a spray formulation against Choristoneura fumiferana

Most mycoinsecticides require a carrier of natural or synthetic oils for them to be effective when sprayed on forest-defoliating caterpillars such as the eastern spruce budworm (Choristoneura fumiferana (Clemens)). Two isolates of Beauveria bassiana conidia were formulated in natural (vegetable) and synthetic (mineral) oils and tested against late instar larvae of the budworm. Topical application showed the ARSEF 1850 isolate to be more effective than a commercially available strain. Additional laboratory spray trials using a hand-held spinning disc sprayer showed that the ARSEF 1850 natural oil formulation significantly increased mortality when compared with controls. The use of oil-formulated B. bassiana conidia should be considered for future budworm management under the integrated pest management of this pest in North America.