Second Diapause in Spruce Budworm from Eastern Canada

1961 ◽  
Vol 93 (7) ◽  
pp. 594-602 ◽  
Author(s):  
George T. Harvey

In eastern Canada larvae of the spruce budworm, Choristoneura fumiferana (Clem.), complete their development in one year, undergoing only one period of winter diapause in the second instar, whereas in certain parts of British Columbia, at high altitudes, two years are normally required for development, the larvae spending a second period of winter diapause in the fourth instar (3, 9). Among laboratory-reared eastern budworm there are a few individuals that enter a similar second diapause (7). The low incidence and somewhat irregular occurrence of this second diapause in eastern budworm, even in laboratory rearings, have hitherto made detailed studies almost impossible, but unusual storage times and treatments used recently in rearing experiments had the unexpected effect of increasing the incidence of this tvpe of behaviour to a level where experimental analysis became possible. This paper describes these larvae and their behaviour; an account of the effects of various conditions upon the incidence of second diapause will be presented later.

1960 ◽  
Vol 36 (4) ◽  
pp. 362-374 ◽  
Author(s):  
G. T. Silver

An outbreak of the one-year cycle spruce budworm, Choristoneura fumiferana (Clem.), on Douglas fir, Pseudotsuga menziesii (Mirb.) Franco, which lasted six years before collapsing, is described. Population trends and seasonal development, effect of defoliation on the host trees and parasites of the insect are discussed.


1958 ◽  
Vol 36 (4) ◽  
pp. 453-462 ◽  
Author(s):  
H. C. Coppel

Phorocera incrassala Smith, which was transferred from Western to Eastern Canada for release against the spruce budworm, Choristoneura fumiferana (Clem.), deposits microtype eggs on leaves, which are later ingested by the host. Eggs hatch immediately after ingestion, but the parasite does not develop beyond the first instar until the host pupates. The larva then develops rapidly, matures in 10 days, and forms its puparium within the host pupal case. The adult emerges in 12 to 14 days. No information is available on the overwintering habits. Among the important characters for identifying the immature stages of P. incrassala are the buccopharyngeal apparatus and the anterior and posterior spiracles.


1976 ◽  
Vol 108 (4) ◽  
pp. 383-386 ◽  
Author(s):  
G. G. Wilson

AbstractThe mass production of Nosema fumiferanae spores using second, third, and fourth instar larvae of Choristoneura fumiferana is described. In general, second instar larvae inoculated with 2 × 105 spores per millilitre of suspension resulted in a maximum spore yield of 1.3 × 108 spores per larva. A spore concentration of 2 × 107 reduced larval weights and increased larval mortality.


1984 ◽  
Vol 60 (5) ◽  
pp. 273-279 ◽  
Author(s):  
David A. MacLean

Effects of spruce budworm (Choristoneura fumiferana (Clem.)) outbreaks on the productivity and stability of forests in eastern Canada are reviewed and discussed. Defoliation results in reduced growth of trees, widespread tree mortality, and loss of wood production, and thereby causes major forest management problems. At present, the only feasible method for limiting damage and losses from budworm outbreaks over large areas is to apply chemical or biological insecticides periodically to kill larvae and protect the forest from defoliation and tree mortality. Although budworm outbreaks definitely disrupt the wood-producing capacity of forests (or the short-term "stability of forests for human usage"), in terms of overall ecological stability, outbreaks apparently act as a cycling mechanism that allows advance fir-spruce regeneration to succeed the fir-spruce overstory.


1972 ◽  
Vol 104 (7) ◽  
pp. 1051-1054
Author(s):  
J. F. Stewart ◽  
N. R. Brown

AbstractA series of low-volume spray treatments were conducted to study the contact and residual effect of two concentrations of the insecticide phosphamidon to fourth instar spruce budworm, Choristoneura fumiferana (Clem.), on balsam fir, Abies balsamea (L.) Mill, and red spruce, Picea rubens Sarg. Treatment of sprayed larvae on sprayed trees, unsprayed larvae on sprayed trees, and sprayed larvae on unsprayed trees, resulted in two principal conclusions: (a) Higher concentrations of phosphamidon (1% versus 0.5% active) accelerated mortality in all instances and (b) no statistical difference (P = 0.1%) was found in the final mortalities between treatments in which only the foliage was treated and where both larvae and foliage were treated with phosphamidon.


1957 ◽  
Vol 35 (5) ◽  
pp. 581-592 ◽  
Author(s):  
H. C. Coppel ◽  
B. C. Smith

Omoloma fumiferanae (Tot.), a parasite of a small number of Lepidoptera in North America and the most common of the native tachinid parasites of Choristoneura fumiferana (Clem.) in British Columbia, deposits macrotype eggs on the integument of the host. The time from oviposition (on a host about to pupate) to puparial formation was 8 to 12 days at 23 °C. and a relative humidity of 60%. Approximately 25% of puparia produce adults the same year. The fate of these adults is not known. The remainder of the puparia produce adults the following spring. Among the important characters for identifying the immature stages of O. fumiferanae are the buccopharyngeal apparatus and the anterior and posterior spiracles.


2013 ◽  
Vol 43 (12) ◽  
pp. 1181-1195 ◽  
Author(s):  
David R. Gray

The spruce budworm (Choristoneura fumiferana Clemens) is perhaps the single most important disturbance agent in Canada’s eastern forests. Climate and forest composition are dominant factors in spruce budworm outbreak dynamics through their direct influences on the pest, its natural enemies, and its hosts, and through their influence on the multitrophic interactions that are important in outbreak dynamics. A combination of four climate variables, three forest composition variables, and one location variable explained 60% of the multivariate variability in outbreak characteristics (duration and severity) in eastern Canada. Outbreak duration was most strongly influenced by April–May accumulation of degree-days; outbreak severity was most strongly influenced by the extreme maximum temperatures of April–May. The basal area of balsam fir had a stronger influence than that of black spruce on duration and on severity. Both outbreak characteristics declined in more northerly locations. Under a projected future (2011–2040) climate scenario the largest increases in outbreak duration and severity are predicted to occur on the Gaspé Peninsula and the north shore of the St. Lawrence River (Quebec). The largest decreases in duration and severity are predicted to occur in southern Ontario and along the Bay of Fundy in New Brunswick and Nova Scotia. The predicted average change in outbreak duration is around –1.3 years. The predicted average change in outbreak severity is only slightly different from zero (around –1.5% defoliation).


2009 ◽  
Vol 85 (4) ◽  
pp. 625-630 ◽  
Author(s):  
Alan J Thomson

Temperature records from weather stations across eastern Canada were used with published data on degree-day requirements for spruce budworm larval emergence and balsam fir bud flush to estimate historical patterns of larval emergence and timing of bud flush. The pattern of association was studied using Response Surface Analysis and was found to vary from west to east. April values of the Pacific/North American (PNA) pattern, Pacific Decadal Oscillation (PDO) and Northern Annular Mode (NAM) climate indices showed the most significant relationship to both emergence and bud flush in the 2 Ontario stations, while May values of the PDO and Eastern Pacific (EP) indices were most significant in the 4 Quebec and New Brunswick locations. Key words: phenology, balsam fir, teleconnections


2018 ◽  
Author(s):  
Melbert T. Schwarz ◽  
Daniel Kneeshaw ◽  
Steven W. Kembel

ABSTRACTMicrobial communities have been shown to play an important role for host health in mammals, especially humans. It is thought that microbes could play an equally important role in other animal hosts such as insects. A growing body of evidence seems to support this, however most of the research effort in understanding host-microbe interactions in insects has been focused on a few well-studied groups such as bees, cockroaches and termites. We studied the effects of the gut-associated microbial community on the growth and survival of the eastern spruce budworm Choristoneura fumiferana, an economically important lepidopteran forest pest in eastern Canada and the northeastern United States. Contrary to our expectations, the gut microbial community of spruce budworm larvae does not appear to influence host growth or survival. Our results agree with the hypothesis that lepidopteran larvae lack resident microbial communities and are not nutritionally dependent on bacterial symbionts.


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