Forest Insect Populations

Graham, Samuel A.

doi:10.2307/1943231

Cited by 22 publications

(6 citation statements)

References 2 publications

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“…"We simply do not understand exactly why populations of, say, a Pentatomid bug, a grasshop per, a moth caterpillar, a vole, a rabbit, and an ungulate should be able to draw upon the same common resource (grass land vegetation) and yet... form a stable animal community over long periods of years." Forests contain hun dreds of potentially injurious animal species in economically insignificant numbers (Graham, 1939). As stated by Darwin in his "Origin of Species," the face of nature remains for long periods uniform because the mortality of a species and its tendency to increase are in the long run so nicely balanced.…”

Section: Introductionmentioning

confidence: 99%

Prey-predator interactions in self-balanced laboratory populations

Flanders¹,

Badgley²

1963

Hilg

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The establishment of a self-perpetuating animal association in an environment that is abiotically uniform appears to be essential for ascertaining and understanding the principles of biotic regulation of populations. If this association so established is of a simple type, such as that of a plant-feeding insect under regulation by one of its natural enemies, the isolation of basic regulatory factors and a study of the operation of each, free of the extraneous or secondary factors which confuse relationships under natural conditions, is possible.Organisms that are eminently suitable for this purpose because they perform as well in the laboratory as in nature are the flour moth, Anagasta kühniella (Zeil.); the predatory mite, Blattisocius tarsalis (Berlese) and the parasitic wasp, Exidechthis canescens (Grav.).Populations of these animals, when placed together, are selfperpetuating and self-regulating and form a permanent ecosystem if periodically provided with adequate amounts of nonviable plant material, such as processed grains of wheat. The ecosystem then consists of one or two "food chains/' the wheat being fed upon by the caterpillar and the caterpillar being fed upon by the parasite; the caterpillar that escapes parasitic attack becomes a moth whose eggs are fed upon by the predatory mite.In the Anagasta ecosystem, the population of each organism attains a numerical balance with its numbers fluctuating around an average density. This average density, however, varies not only with the kind of organism but with the type of regulatory mech anism which may be either the amount of food (food depletion), predatism or parasitism. These mechanisms and the sequence in which they operate can be manipulated by modifying the abiotic environmental factors that determine the extent and frequency of contact between prey and natural enemy. Consequently, the inter action of such populations may be rendered either numerically regulative or numerically nonregulative. The operation of one mechanism may either preclude or supplement the operation of another.continued Inside back cover

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Section: Introductionmentioning

confidence: 99%

Prey-predator interactions in self-balanced laboratory populations

Flanders¹,

Badgley²

1963

Hilg

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“…Unbiased estimates of sex ratios for local populations are difficult to obtain because of gender‐specific behavioural differences that influence trap catch data. Sex ratios from multiple different sampling procedures were not markedly different from 1 : 1 (Miller, ; Rhainds & Heard, ; but see Graham, ), therefore, if we assume that approximately half our surviving population were females, we can infer fecundity. It has previously been shown that the potential fecundity of females from spruce trees increased by an average of 69 eggs for each 1‐mm increase in fore wing length (Thomas et al ., ).…”

Section: Discussionmentioning

confidence: 94%

Interguild interactions between a non‐native phloem feeder and a native outbreaking defoliator

MacDonnell¹,

Edwards

Heard

et al. 2020

Ecological Entomology

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1. Competitive and synergistic interactions directly or indirectly drive community dynamics of herbivorous insects. Novel interactions between non-native and native insects are unpredictable and not fully understood.2. We used manipulative experiments on mature red spruce trees to test interactions between a non-native phloem feeding insect, the brown spruce longhorn beetle (BSLB), and an outbreaking native defoliator, the spruce budworm. We subjected treatment trees to defoliation by three densities of spruce budworm larvae. Treatment trees were: stressed by (i) girdling (to mimic beetle feeding) or (ii) girdling + BSLB before spruce budworm larvae were introduced on branches in sleeve cages. Budworm larvae then fed on foliage and developed to pupation. We assessed all branches for budworm performance, defoliation, shoot production and shoot growth.3. Shoot length did not differ in response to stress from girdling or BSLB infestation. Neither stress from girdling, nor interactions with BSLB feeding affected spruce budworm performance or defoliation. Intraspecific impacts on performance and defoliation in relation to budworm density were stronger than the effects of tree stress.4. Prior infestation of red spruce by BSLB in our experimental set-up did not influence spruce budworm performance. BSLB is a successful invader that has blended into its novel ecological niche because of ecological and phylogenetic similarities with a native congener, Tetropium cinnamopterum. 5. Outbreaks by BSLB will not likely impede or facilitate spruce budworm outbreaks if they co-occur. It would be useful to evaluate the reverse scenario of BSLB success after defoliation stress by spruce budworm.

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“…Many stands in New Brunswick reached this condition at least two or three decades before the present outbreak. Swaine (1928) and Graham (1939) suspected that favorable climatic conditions for several successive years might bi a necessary prelude to the development of budworm outbreaks. Evidence to support such a relation has been provided by Wellington et al (1950) in Ontario and Greenbank (1956) in New Brunswick.…”

Section: Figurementioning

confidence: 99%

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

Morris¹

1958

The Forestry Chronicle

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After graduating from tlze Faculty o f Forestry, University of New Brunswick, in 1938, R. Franklin Morris was awarded a special scholarship by the Canadian Pulp and Paper Association for post-graduate studies in entomology. He received his M . Sc. from Syracuse in I940 and Ph. D. from the Universio of Michigan in I947. His present work, and interests, are concerned almost entirely with basic research in the population dynamics of forest insects and other organisms.

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Forest Insect Populations

Cited by 22 publications

References 2 publications

Prey-predator interactions in self-balanced laboratory populations

Prey-predator interactions in self-balanced laboratory populations

Interguild interactions between a non‐native phloem feeder and a native outbreaking defoliator

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

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