A Review of the Important Insects Affecting the Spruce-Fir Forest in the Maritime Provinces

Morris, R. F.

doi:10.5558/tfc34159-2

Cited by 18 publications

(18 citation statements)

References 27 publications

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“…A study of the predation by tits during the outbreak of winter moth in Wytham in 1948 revealed that only 2-5% of the caterpillars were taken (Betts 1955, Varley andGradwell 1962a) . There is substantial evidence in the literature for the inability of bird predators to prevent insect outbreaks (e.g., Morris 1958, Clark 1964.…”

Section: Introductionmentioning

confidence: 99%

Seasonal Changes in Oak Leaf Tannins and Nutrients as a Cause of Spring Feeding by Winter Moth Caterpillars

Feeny

1970

Ecology

1,761

1,268

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Abstract. Concentration in the spring of feeding by caterpillars of the winter moth, Operophtera brumata L., and other species of Lepidoptera on oak trees in England is believed to be related to seasonal changes in the texture and chemical composition of the leaves. Increasing leaf toughness is a proximate, though probably not ultimate, factor preventing late larval feeding by the winter moth, the commonest spring species on oak. Early feeding coincides with maximum leaf protein content and minimum leaf sugar content, which suggests that availability of nitrogen, rather ·than of carbohydrate, may be a limiting factor for spring-feeding larvae. The content of oak leaf tannins, which inhibit the growth of winter moth larvae, increases during the summer and may render leaves less suitable for' insect growth by further reducing the availability of nitrogen and perhaps also by influencing leaf palatability. Oak trees are extensively damaged by insect attack, and it is likely that leaf tannins have a defensive function against insects as well as against other herbivores and against pathogens.

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Section: Introductionmentioning

confidence: 99%

Seasonal Changes in Oak Leaf Tannins and Nutrients as a Cause of Spring Feeding by Winter Moth Caterpillars

Feeny

1970

Ecology

1,761

1,268

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“…A I acre site is simulated in the model but infestations of blackheaded budworm may extend over much larger areas (Morris 1958). This is a valid criticism; however, a sensitivity analysis of the model showed that its basic qualitative behavior was not significantly altered under wide ranges in the values of the various parameters.…”

Section: Discussionmentioning

confidence: 99%

A Process Model for Eastern Blackheaded Budworm (Lepidoptera: Tortricidae)

McNamee

1979

Can Entomol

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Can. Enr. I I 1: 55-66(1979) A theory for the population behavior of the eastern blackheaded budwom is presented. The qualitative properties and key processes of the system are identified and a description of the theory as a simulation model is given. Two domains of stability exist for the insect; one is caused by bird predation, the second by the effects of food limitation. The model predicts that the budworm's cyclical population fluctuations are produced by the disappearance and reappearance of these stable domains and consequent movement of densities to new levels. Parasitism is identified as the principal mechanism causing this behavior. A qualitative comparison of model behavior with historical behavior is made and a critical field experiment to test the validity of the theory is proposed. Finally it is suggested that the population behavior of many forest defoliators may be explained using this theory.Takahashi (1964) proposed a model which suggested a mechanism by which a discrete-generation insect species could exhibit rapid changes in population density. Using stock-recruitment curves (Ricker 1954), he postulated the existence of two stable equiIibrium densities for the insect, one endemic, the other epidemic, with an unstable equilibrium at some intermediate density (Fig. 1). Onset and collapse of outbreaks were viewed as changes in the population level from one stable density across the unstable equilibrium to the other stable density. HolIing (1973) extended this concept and defined "domains of stability," regions of stable population density separated by unstable equilibria. Therefore, in Fig. 1, there are two stable domains: d l and d2. Peterman et al. (in press) described the dynamics of multi-stabIe systems; as a consequence of processes in the system, stability domains can disappear and reappear and result in rapid shifts in density.This paper presents a model that has been developed for the eastern blackheaded budworm, Acleris variana (Fern.). The model was constructed using the identified key processes of the system and then used to investigate its real-world behavior. The theory proposes that the system has two domains of attraction and the population fluctuations of the insect can be characterized by the collapse and reappearance of these stable regions.

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“…Spruce budworm outbreaks are a natural pnenomenon associated with the vegetative climax of the spruce-fir forest (Blais 1952). Mature stands of balsam fir are one prerequisite for the development of these outbreaks, and, generally, it is only when this condition prevails over extensive areas that endemic populations of the insect become epidemic (Prebble and Morris 1951, Morris 1958). The destruction of a considerable amount of fir, and, to a lesser extent, white spruce and red spruce is a natural consequence of these outbreaks.…”

Section: Pouvait Varier Et Que Sur Un Total De 17 Intervalles Entre mentioning

confidence: 99%

The policy of keeping trees alive via spray operations may hasten the recurrence of spruce budworm outbreaks

Blais¹

1974

The Forestry Chronicle

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A Review of the Important Insects Affecting the Spruce-Fir Forest in the Maritime Provinces

Cited by 18 publications

References 27 publications

Seasonal Changes in Oak Leaf Tannins and Nutrients as a Cause of Spring Feeding by Winter Moth Caterpillars

Seasonal Changes in Oak Leaf Tannins and Nutrients as a Cause of Spring Feeding by Winter Moth Caterpillars

A Process Model for Eastern Blackheaded Budworm (Lepidoptera: Tortricidae)

The policy of keeping trees alive via spray operations may hasten the recurrence of spruce budworm outbreaks

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