Experimental aerial application of a new isolate of the nucleopolyhedrovirus, CfMNPV against choristoneura fumiferana (Lepidoptera: Tortricidae)

Abstract A new isolate of spruce budworm ( Choristoneura fumiferana ) multicapsid nucleopolyhedrovirus called Tortrivirus and designated Cf MNPV-T3 was field tested in 1998–1999 to evaluate its efficacy against C. fumiferana . A double application of the virus was sprayed aerially at 5.0×10 11 occlusion bodies in 2.5 l of diluent carrier per hectare. Following the application in 1998, viral infection of spruce budworm larvae increased significantly but there were no linear relationships between spray deposit, larval infection and insect population reduction and no epizootic was initiated. As a consequence, larval infection reverted to incipient levels in 1999. Spruce budworm population reductions that could be attributed to the virus were Cf MNPV-T3 was not therefore, as effective in controlling C. fumiferana populations as laboratory studies had suggested it would be.