Population Dynamics of the Larch Sawfly

1964 ◽  
Vol 96 (1-2) ◽  
pp. 160-161 ◽  
Author(s):  
Keyword(s):  
Biological Control ◽  
Population Dynamics ◽  
Life Table ◽  
Quantitative Methods ◽  
Population Data ◽  
Natural Control ◽  
Mortality Factors ◽  
Ecological Relationships ◽  
Pristiphora Erichsonii ◽  
Larch Sawfly

The larch sawfly, Pristiphora erichsonii (Htg.), has been studied in Manitoba for over 50 years, since the first outbreaks led to the introduction of the European parasite, Mesoleius tenthredinis Morley. This parasite was credited with reducing the severity of early outbreaks but when host populations again increased in the early 1940's, it was found that M. tenthredinis was ineffective due to the ability of host larvae to encapsulate parasite eggs. Intensive studies of individual mortality factors were initiated at the Winnipeg Laboratory as staff and facilities were expanded in the late 1940's. Development of the life-table concept of recording population data (Morris and Miller 1954) led to co-ordination of several projects until by 1955 a team of research officers was engaged in comprehensive studies of general ecological relationships, parasitism, vertebrate predation, and the effect of defoliation on host stands. Members of the team currently engaged in population dynamics studies and responsible for this exhibit are: Dr.C. H. Buckner, vertebrate predators; W. G. H. Ives, quantitative methods and natural control; L. D. Nairn, interrelations with host tree; Dr. W. J. Turnock, natural and biological control, bioclimatology. Other Winnipeg officers working on related larch sawfly projects are Dr. R. J. Heron, physiological studies, and J. A. Muldrew, biological control with particular reference to immunity to M. tenthredinis.

Mortality of Cocoons of the Larch Sawfly, Pristiphora erichsonii (Htg.), in Relation to Distance from Small-Mammal Tunnels

1959 ◽  
Vol 91 (9) ◽  
pp. 535-542 ◽  
Author(s):  
C. H. Buckner
Keyword(s):  
Small Mammals ◽  
Small Mammal ◽  
Natural Mortality ◽  
Mortality Factors ◽  
Forest Reserve ◽  
Pristiphora Erichsonii ◽  
Larch Sawfly ◽  
The Relationship

The relationship between the fate of cocoons of the larch sawfly, Pristiphora erichsonii (Htg.), and distance from small-mammal tunnels was studied during 1958 in the Whiteshell Forest Reserve of eastern Manitoba. The objects were to determine the distance that small mammals can detect cocoons and to observe possible effects of the interactions of small-mammal predation and other natural mortality factors of the insect. Additional analyses of the data provided information on the behaviour of the predators and the ecology of the prey insect.

Major Factors in Survival of the Immature Stages of Pieris rapae (L.)

1966 ◽  
Vol 98 (6) ◽  
pp. 653-662 ◽  
Author(s):  
D. G. Harcourt
Keyword(s):  
Population Dynamics ◽  
Survival Rate ◽  
Pieris Rapae ◽  
Pupal Stage ◽  
Population Data ◽  
Life Tables ◽  
Immature Stages ◽  
Mortality Factors ◽  
Key Factor ◽  
Major Factors

AbstractDetailed studies on the population dynamics of the imported cabbageworm, Pieris rapae (L.), have been carried out at Merivale, Ontario, since 1959. A method for preparing life tables is described and a mean life table is presented for 18 generations of the species on cabbage. Population data for the preadult period show that there are three age intervals during which extensive mortality may occur: (1) between hatching and the second moult, (2) instars three to five, and (3) during the pupal stage. The analysis of successive age-interval survivals in relation to generation survival showed that the latter is largely determined by the survival rate for (2). Examination of the life tables revealed that a granulosis of the larvae caused by a capsule virus is the key factor in generation survival. Major mortality factors include rainfall and parasites.

Estimation of Adult Populations of the Larch Sawfly, Pristiphora erichsonii (Htg.)

1960 ◽  
Vol 92 (9) ◽  
pp. 659-662 ◽  
Author(s):  
W. J. Turnock
Keyword(s):  
Mortality Factors ◽  
Pristiphora Erichsonii ◽  
Larch Sawfly

This paper is one in a series on techniques for estimating populations of various stages of the larch sawfly (Ives, 1055; Ives and Prentice, 1958; Ives and Turnock, 1959) to provide's basis for the evaluation of mortality factors. The larch sawfly overwinters in a cocoon in the soil and adults emerge during the spring and summer (Turnock, 1960). This paper describes the methods and results of sampling adults as they emerge from the soil.

Contemporaneous Mortality Factors in Population Dynamics

1965 ◽  
Vol 97 (11) ◽  
pp. 1173-1184 ◽  
Author(s):  
R. F. Morris
Keyword(s):  
Population Dynamics ◽  
Statistical Inference ◽  
Direct Observation ◽  
General Equation ◽  
Population Data ◽  
Interaction Coefficient ◽  
Field Population ◽  
Population Trend ◽  
Mortality Factor ◽  
Mortality Factors

AbstractThe effect of any mortality factor on population trend is influenced greatly by other factors that operate contemporaneously within the same age interval, and by the extent to which it interacts with these other factors. A general equation which makes provision for different degrees of interaction is proposed as a simplified first step in the study of interaction, and some theoretical examples are presented to illustrate the importance of the interaction coefficient. Methods for obtaining estimates of the coefficient, both through statistical inference from field population data and through direct observation and experimentation, are discussed.

History of Larch Sawfly Outbreaks and their Effect on Tamarack Stands in Manitoba and Saskatchewan

1962 ◽  
Vol 94 (3) ◽  
pp. 242-255 ◽  
Author(s):  
L. D. Nairn ◽  
W. A. Reeks ◽  
F. E. Webb ◽  
V. Hildahl
Keyword(s):  
Life Table ◽  
Annual Reports ◽  
Forest Insect ◽  
Forest Reserve ◽  
Pristiphora Erichsonii ◽  
Larch Sawfly ◽  
History Of ◽  
Insect Survey

The larch sawfly, Pristiphora erichsonii (Htg.), has been under observation in Manitoba and Saskatchewan since early in the present century. Recorded observations were somewhat fragmentary until 1937; since then systematic and detailed annual reports have been provided by the Forest Insect Survey and since 1948 intensive ecological and life table studies have been conducted by staff of the Winnipeg Laboratory at the Whiteshell Forest Reserve, Manitoba.

Estimation of Cocoon Populations of the Larch Sawfly, Pristiphora erichsonii (Hartig)

1959 ◽  
Vol 91 (10) ◽  
pp. 650-661 ◽  
Author(s):  
W. G. H. Ives ◽  
W. J. Turnock
Keyword(s):  
Soil Sampling ◽  
The Other ◽  
Host Tree ◽  
Accurate Estimation ◽  
Mortality Factors ◽  
Factors Affecting ◽  
Pristiphora Erichsonii ◽  
Larch Sawfly

This paper is one in a series on techniques used in estimating populations of various stages of the larch sawfly (Ives, 1955b; Ives and Prentice, 1958). This insect spends most of the year in cocoons in the soil beneath the host tree. The objective of accurate estimation of the cocoon population is to provide a basis for the evaluation of mortality factors affecting this stage. Two methods of estimation are considered in this paper. One is based on soil sampling (Part I) and the other on the number of cocoons formed in traps for falling larvae (Part 11).

Evaluation of Mortality During the Cocoon Stage of the Larch Sawfly, Pristiphora erichsonii (Htg.)

1962 ◽  
Vol 94 (9) ◽  
pp. 897-902 ◽  
Author(s):  
W. J. Turnock ◽  
W. G. H. Ives
Keyword(s):  
Research Team ◽  
Life Tables ◽  
Current Work ◽  
Population Estimates ◽  
Individual Factors ◽  
Mortality Factors ◽  
Factors Affecting ◽  
Pristiphora Erichsonii ◽  
Larch Sawfly ◽  
Unbiased Estimates

This is one of a series of papers on the development of life tables for the larch sawfly, Pristiphora erichsonii (Htg.), by a research team at Winnipeg. Previous papers have described techniques for obtaining population estimates for eggs, cocoons, and adults (Ives, 1955; Ives and Turnock, 1959; Turnock, 1960), and current work is concerned with the development of methods of segregating and evaluating the mortality factors affecting each stage. This paper describes the methods used to evaluate the amount of mortality caused by individual factors in the cocoon stage and discusses the problems of obtaining accurate and unbiased estimates.

scholarly journals The influence of two wildfires and biological control agents on the population dynamics of Melaleuca quinquenervia in a seasonally inundated wetland

2021 ◽  
Vol 14 (1) ◽  
pp. 3-8
Author(s):  
Philip W. Tipping ◽  
Melissa R. Martin ◽  
Jeremiah R. Foley ◽  
Ryan M. Pierce ◽  
Lyn A. Gettys
Keyword(s):  
Biological Control ◽  
Population Dynamics ◽  
Seedling Recruitment ◽  
Additional Treatment ◽  
Seed Rain ◽  
The Other ◽  
Melaleuca Quinquenervia ◽  
Biological Control Agents ◽  
Seedling Mortality ◽  
Sapling Growth

AbstractThe potential of Melaleuca quinquenervia (Cav.) S.T. Blake to reinvade cleared areas was evaluated over a 13-yr period that included two wildfires and the introduction of biological control agents. The first wildfire occurred in 1998 and was followed by a mean of 591.5 recruited seedlings m−2. Recruits from that fire were cleared 7 yr later in July 2005 for a second experiment to evaluate seedling recruitment into cleared areas. Seed rain, seedling recruitment and mortality, and sapling growth rates were measured in four plots located around individual large reproductive trees. A second natural wildfire in 2007 burned through those plots, leading to increases in seed rain followed by a pulse in recruitment of 21.04 seedlings m−2, 96.5% fewer than after the 1998 fire. Recruits in half of the plots around each tree were then treated with regular applications of an insecticide to restrict herbivory by biological control agents, while herbivory was not restricted in the other half. There was no difference in seedling mortality between treatments 1,083 d post-fire (2007) with 96.6% seedling mortality in the unrestricted herbivory treatment and 89.4% mortality in the restricted herbivory treatment. Recruits subjected to the restricted herbivory treatment grew taller than those in the unrestricted herbivory treatment, 101.3 cm versus 37.4 cm. Many of the recruits were attacked by the biological control agents, which slowed their growth. Although solitary M. quinquenervia trees retain some capacity to reinvade areas under specific circumstances, there was a downward trend in their overall invasiveness at this site, with progressively smaller recruitment cohorts due to biological control agents. Land managers should prioritize removing large reproductive trees over treating recently recruited populations, which can be left for many years for the biological control agents to suppress before any additional treatment would be needed.

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