W. Jan A. Volney
Natural Resources Canada, Canadian Forest Service, Edmonton

Keith Knowles
Manitoba Conservation, Winnipeg

SERG Project #2003/09
Year of Project: 2003
Report Received: 2005

Recent attempts to control spruce budworm in northwestern Manitoba in mixed stands of white and black spruces were frustrated by the apparent differences in developmental rates between insect populations feeding on different hosts. This study was conducted to determine if there was a difference in development of host shoots as well as to compare the phenological development of the spruce budworm on the two hosts. The year 2003 was one in which most spruces in western Canada flowered profusely. As a consequence budworm survival to feeding site establishment on the vegetative shoots was unusually high, resulting to complete destruction of the current year’s foliage by the fourth spruce budworm instar. During this highly unusual year there seemed to be little biologically significant differences in development of shoots on the two hosts. There were also no biologically significant differences in the development rates of the spruce budworm population on the two hosts. While this is interesting biologically, these conditions are highly unusual. This argues for a repetition of the work in a year when flowering is expected to be low and thus more typical of conditions under which budworm control operations would be undertaken.