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The Regulation of European Spruce Sawfly Numbers in the Maritime Provinces of Canada from 1937 to 19631

Published online by Cambridge University Press:  31 May 2012

M. M. Neilson
Affiliation:
Forest Entomology and Pathology Laboratory, Fredericton, New Brunswick
R. F. Morris
Affiliation:
Forest Entomology and Pathology Laboratory, Fredericton, New Brunswick

Abstract

The European spruce sawfly, Diprion hercyniae (Htg.), was first discovered in Canada in 1930 and in the next few years attained outbreak proportions in spruce forests over large areas in the Gaspé Peninsula and New Brunswick. The accidental introduction of a polyhedrosis in the early 1930’s was responsible for the rapid decline of the infestation, and under the influence of both disease and introduced parasites, densities throughout the range of the sawfly have been fluctuating at very low levels for the past 20 years. Population studies have been conducted on this insect in New Brunswick since 1938 and data are now available for 50 consecutive generations over a 25-year period. Morris’ key-factor approach, using parasites, disease and weather as the key factors, has been used in the analyses of the data. Although disease obscured the effect of other control factors, during high sawfly densities, larval parasites have been largely responsible for maintaining the low densities experienced in New Brunswick for the past 20 years. A pronounced change in the relative importance of the different parasite species and in the amount of cocoon predation attributable to small mammals and wireworms has occurred during the change from high to low host densities.

Type
Articles
Copyright
Copyright © Entomological Society of Canada 1964

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References

Balch, R. E., and Bird, F. T.. 1944. A disease of the European spruce sawfly, Gilpinia hercyniae (Htg.), and its place in natural control. Sci. Agric. 26: 6580.Google Scholar
Bird, F. T., and Burk, J. M.. 1961. Artificially disseminated virus as a factor controlling the European spruce sawfly, Diprion hercyniae (Htg.), in the absence of introduced parasites. Canad. Ent. 93: 228238.CrossRefGoogle Scholar
Holling, C. S. 1959a. The components of predation as revealed by a study of small mammal predation of the European pine sawfly. Canad. Ent. 91: 293320.CrossRefGoogle Scholar
Holling, C. S. 1959b. Some characteristics of simple types of predation and parasitism. Canad. Ent. 91: 385398.CrossRefGoogle Scholar
Morris, R. F. 1949. Differentiation by small mammal predators between sound and empty cocoons of the European spruce sawfly. Canad. Ent. 81: 114120.CrossRefGoogle Scholar
Morris, R. F. 1951. The larval Elateridae of eastern spruce forests and their role in the natural control of Gilpinia hercyniae (Htg.). Canad. Ent. 83: 133147.CrossRefGoogle Scholar
Morris, R. F. 1959. Single-factor analysis in population dynamics. Ecology 40: 580588.CrossRefGoogle Scholar
Morris, R. F. 1963. Predictive population equations based on key factors. pp. 16–21. In LeRoux, E. J. et al. , Population dynamics of agricultural and forest insect pests. Mem. ent. Soc. Can. 32, 103 pp.Google Scholar
Prebble, M. L. 1941. The diapause and related phenomena in Gilpinia polytoma (Hartig) in eastern Canada. Canad. J. Res. (D) 19: 295–322; 323–346; 350–362; 417–436; 437454.CrossRefGoogle Scholar
Prebble, M. L. 1943. Sampling methods in population studies of the European spruce sawfly, Gilpinia hercyniae (Htg.), in eastern Canada. Trans. roy. Soc. Can. 37: 93126.Google Scholar
Reeks, W. A. 1953. The establishment of introduced parasites of the European spruce sawfly, Diprion hercyniae (Htg.), in the Maritime Provinces. Canad. J. agric. Sci. 33: 405429.Google Scholar
Varley, G. C. 1963. The interpretation of change and stability in insect populations. Proc. R. ent. Soc. Lond. (C) 27: 5257.Google Scholar