Stand breakdown and surface fuel accumulation due to spruce budworm (Choristoneura fumiferana) defoliation in the boreal mixedwood forest of central Canada

2020 ◽  
Vol 50 (6) ◽  
pp. 533-541
Author(s):  
Graham A. Watt ◽  
Brian J. Stocks ◽  
Richard A. Fleming ◽  
Sandy M. Smith
Keyword(s):  
Forest Fires ◽  
Choristoneura Fumiferana ◽  
Spruce Budworm ◽  
Time Frame ◽  
Mixedwood Forests ◽  
Breakdown Time ◽  
Central Canada ◽  
Boreal Mixedwood Forest ◽  
Fuel Accumulation ◽  
The Relationship

Spruce budworm (Choristoneura fumiferana (Clemens)) defoliation has been shown to increase the likelihood of large forest fires in central Canada. However, the time frame of heightened risk based on the duration of spruce budworm defoliation has not yet been quantified. In this article, we document the extent of stand breakdown and surface fuel accumulation after a period of spruce budworm defoliation that occurred between 1972 and 1976. Data on stand characteristics were derived from previous studies at three different locations in the boreal mixedwood forests of central Canada: Aubinadong (B.J. Stocks. 1987. For. Chron. 63: 8–14), Gogama, and Gowganda in Ontario. Stand breakdown was measured using a series of transects set in plots 7 years following aerially mapped defoliation (1977–1983). Results show that during the 4 years following 5 years of defoliation, crown breakage, a typical symptom of defoliation, increased by nearly 200%, and surface fuel increased by 145% from predisturbance levels. The high correlation between crown breakage and surface fuels linked defoliation to fuel buildup. We begin to solve the challenge of measuring fuel structure over the expansive scale of spruce budworm outbreaks by quantifying the relationship among stand breakdown, time since the end of defoliation, and the duration of defoliation so that the expected fuel structure can be modelled from annual defoliation surveys.

Interaction of Apanteles fumiferanae (Hymenoptera: Braconidae) and Nosema fumiferanae (Microsporidia) parasitizing spruce budworm, Choristoneura fumiferana (Lepidoptera: Tortricidae)

1987 ◽  
Vol 65 (8) ◽  
pp. 2047-2050 ◽  
Author(s):  
V. G. Nealis ◽  
S. M. Smith
Keyword(s):  
Choristoneura Fumiferana ◽  
Spruce Budworm ◽  
Dry Weight ◽  
Mass Rearing ◽  
Adult Longevity ◽  
Slight Reduction ◽  
Rate Of Development ◽  
Larval Female ◽  
The Relationship ◽  
Larval Parasites

The relationship between a braconid parasitoid, Apanteles fumiferanae, and a microsporidian pathogen, Nosema fumiferanae, two larval parasites frequently coincident in the spruce budworm, Choristoneura fumiferana, was examined in the laboratory. When Apanteles was reared in spruce budworm infected with high levels of Nosema (i.e., more than 20 × 106 spores/mg dry weight), there was a slight reduction in the within-host rate of development of larval female Apanteles, but survival, within-cocoon rate of development, cocoon weight, and adult longevity were not affected. There was no evidence that any stage of Apanteles was infected with spores of Nosema. A few adult female parasitoids were found to carry spores of Nosema on their integuments but it is unlikely that Apanteles is an important vector of the microsporidian. We conclude that these natural enemies of budworm do not interact significantly in their common host. The implications for population dynamics of the spruce budworm and mass rearing of Apanteles are discussed.

FLIGHT DURATION OF MALE SPRUCE BUDWORM (CHORISTONEURA FUMIFERANA [CLEM.]) AND ATTRACTIVENESS OF FEMALE SPRUCE BUDWORM ARE UNAFFECTED BY MICROSPORIDIAN INFECTION OR MOTH SIZE

1990 ◽  
Vol 122 (3) ◽  
pp. 419-422 ◽  
Author(s):  
C.J. Sanders ◽  
G.G. Wilson
Keyword(s):  
Wind Tunnel ◽  
Choristoneura Fumiferana ◽  
Virgin Female ◽  
Spruce Budworm ◽  
Flight Duration ◽  
Significant Relationships ◽  
Female Attractiveness ◽  
Microsporidian Infection ◽  
The Relationship

AbstractNo correlation was found between the size of male spruce budworm (Choristoneura fumiferana [Clem.]) moths and the duration of their flight in a sustained-flight wind tunnel. The numbers of male moths caught in traps baited with virgin female spruce budworm moths increased as the size of the females increased, but the relationship was significant in only one of eight experiments. Infection with the microsporidium Nosema fumiferanae (Thomson) resulted in smaller insects, but there were no significant relationships between the incidence of infection and male flight duration or female attractiveness.

THE RELATIONSHIP OF THE SPRUCE BUDWORM (CHORISTONEURA FUMIFERANA, CLEM.) TO THE FLOWERING CONDITION OF BALSAM FIR (ABIES BALSAMEA (L.) MILL.)

1952 ◽  
Vol 30 (1) ◽  
pp. 1-29 ◽  
Author(s):  
J. R. Blais
Keyword(s):  
Direct Effect ◽  
Choristoneura Fumiferana ◽  
Abies Balsamea ◽  
Spruce Budworm ◽  
Balsam Fir ◽  
Larval Stages ◽  
Competition For Food ◽  
Relationship Of ◽  
The Relationship

Populations of the spruce budworm were studied on flowering and nonflowering balsam fir trees. Generally more eggs were found on the flowering trees. The flowering balsam fir trees were found to harbor higher populations in the early larval stages owing to the presence on these trees of staminate flowers and flower cups. The behavior of the larvae in relation to staminate flowers and flower cups was studied in both the field and the laboratory. Larvae that fed partially on pollen developed more rapidly than larvae that fed exclusively on foliage. Pollen as a food did not appear to have any direct effect on survival or fecundity. Other experiments showed that mortality was higher, development retarded, and fecundity reduced in insects forced to feed on old foliage in contrast with those fed on the current year's growth. Defoliation was more severe on flowering trees in the earlier stages of the infestation. However, as populations increased, wandering increased owing to competition for food. This resulted in an overflow of larvae from flowering to nonflowering trees.

scholarly journals Spruce Budworm (Choristoneura fumiferana Clem.) Defoliation Promotes Vertical Fuel Continuity in Ontario’s Boreal Mixedwood Forest

Forests ◽  
2018 ◽  
Vol 9 (5) ◽  
pp. 256
Author(s):  
Graham Watt ◽  
Richard Fleming ◽  
Sandy Smith ◽  
Marie-Josée Fortin
Keyword(s):  
Choristoneura Fumiferana ◽  
Spruce Budworm ◽  
Boreal Mixedwood Forest

The Aristocracy in England and Tuscany, 1000 - 1250

2019 ◽  
Author(s):  
Peter Coss
Keyword(s):  
Time Frame ◽  
Grand Narrative ◽  
English History ◽  
Internal Dynamics ◽  
Italian Experience ◽  
English Society ◽  
History Of ◽  
External Stimuli ◽  
The Relationship ◽  
Interpretative Framework

Part I of this book is an in-depth examination of the characteristics of the Tuscan aristocracy across the first two and a half centuries of the second millennium, as studied by Italian historians and others working within the Italian tradition: their origins, interests, strategies for survival and exercise of power; the structure and the several levels of aristocracy and how these interrelated; the internal dynamics and perceptions that governed aristocratic life; and the relationship to non-aristocratic sectors of society. It will look at how aristocratic society changed across this period and how far changes were internally generated as opposed to responses from external stimuli. The relationship between the aristocracy and public authority will also be examined. Part II of the book deals with England. The aim here is not a comparative study but to bring insights drawn from Tuscan history and Tuscan historiography into play in understanding the evolution of English society from around the year 1000 to around 1250. This part of the book draws on the breadth of English historiography but is also guided by the Italian experience. The book challenges the interpretative framework within which much English history of this period tends to be written—that is to say the grand narrative which revolves around Magna Carta and English exceptionalism—and seeks to avoid dangers of teleology, of idealism, and of essentialism. By offering a study of the aristocracy across a wide time-frame and with themes drawn from Italian historiography, I hope to obviate these tendencies and to appreciate the aristocracy firmly within its own contexts.

Derivation of Pheromone-Based Larval Thresholds in Spruce Budworm Accounting for Distance to Defoliated Forest Stands

2021 ◽  
Author(s):  
Marc Rhainds ◽  
Ian DeMerchant ◽  
Pierre Therrien
Keyword(s):  
Boreal Forests ◽  
Large Scale ◽  
Choristoneura Fumiferana ◽  
Intervention Strategy ◽  
Spruce Budworm ◽  
Interactive Effects ◽  
The Novel ◽  
Forest Stands ◽  
General Guideline ◽  
Number Of Males

Abstract Spruce budworm, Choristoneura fumiferana Clem. (Lepidoptera: Tortricidae), is the most severe defoliator of Pinaceae in Nearctic boreal forests. Three tools widely used to guide large-scale management decisions (year-to-year defoliation maps; density of overwintering second instars [L2]; number of males at pheromone traps) were integrated to derive pheromone-based thresholds corresponding to specific intergenerational transitions in larval densities (L2i → L2i+1), taking into account the novel finding that threshold estimates decline with distance to defoliated forest stands (DIST). Estimates of thresholds were highly variable between years, both numerically and in terms of interactive effects of L2i and DIST, which limit their heuristic value. In the context of early intervention strategy (L2i+1 > 6.5 individuals per branch), however, thresholds fluctuated within relatively narrow intervals across wide ranges of L2i and DIST, and values of 40–200 males per trap may thus be used as general guideline.

Weather and Outbreaks of the Spruce Budworm in the Province of Quebec from 1939 to 1956

1961 ◽  
Vol 93 (2) ◽  
pp. 118-123 ◽  
Author(s):  
J. G. Pilon ◽  
J. R. Blais
Keyword(s):  
Choristoneura Fumiferana ◽  
Abies Balsamea ◽  
Spruce Budworm ◽  
Balsam Fir ◽  
The Past ◽  
Forest Regions ◽  
Tree Component ◽  
Gaspe Peninsula ◽  
Gaspé Peninsula

Nearly all forest regions in the Province of Quebec where balsam fir (Abies balsamea (L.) Mill.) is an important tree component have been subjected to severe defoliation by the spruce budworm, Choristoneura fumiferana (Clem.), during the past 20 years. These outbreaks have followed an easterly direction beginning near the Ontario-Quebec border in 1939 and ending in the Gaspé Peninsula in 1958.

GROUND RELEASES OF TRICHOGRAMMA MINUTUM RILEY (HYMENOPTERA: TRICHOGRAMMATIDAE) AGAINST THE SPRUCE BUDWORM (LEPIDOPTERA: TORTRICIDAE)

1987 ◽  
Vol 119 (3) ◽  
pp. 251-263 ◽  
Author(s):  
S.M. Smith ◽  
M. Hubbes ◽  
J.R. Carrow
Keyword(s):  
Optimal Strategy ◽  
Choristoneura Fumiferana ◽  
Spruce Budworm ◽  
Egg Mass ◽  
Northern Ontario ◽  
Inundative Release ◽  
Egg Masses ◽  
Trichogramma Minutum ◽  
Spruce Stands ◽  
Natural Parasitism

AbstractDuring 1982 and 1984, ground releases of Trichogramma minutum Riley were assessed for control of the spruce budworm, Choristoneura fumiferana (Clemens), on 12- to 20-year-old, white spruce stands in northern Ontario. Maximum parasitism of susceptible egg masses was 16 and 87% following the release of 480 000 and 12 million female T. minutum per hectare, respectively. Releases at intervals of 1 week maintained parasitism of susceptible egg masses at constant levels throughout the oviposition period of spruce budworm. When parasitism of susceptible egg masses was maintained above 78.2% during the ovipositional period, total egg mass parasitism averaged 58.0% and resulted in an 80.3% reduction of overwintering 2nd-instar larvae. The optimal strategy for reducing spruce budworm was two releases of T. minutum at an interval of 1 week in the ovipositional period. This allowed a second generation of parasitoids to emerge from the spruce budworm eggs that were more efficient in maintaining high levels of parasitism than those emerging from the standard rearing host. Natural parasitism of spruce budworm egg masses was less than 4% and there was no carryover of parasitism in the years following inundative release. The rate of T. minutum release necessary to achieve effective mortality of spruce budworm during outbreak populations is discussed briefly.

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