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.

scholarly journals Population dynamics of Saissetia oleae. II. Life-tables and key-factor analysis

2017 ◽  
Vol 8 ◽  
pp. 59 ◽  
Author(s):  
E. T. Kapatos ◽  
E.T. Stratopoulou
Keyword(s):  
Factor Analysis ◽  
Population Dynamics ◽  
Population Change ◽  
Life Tables ◽  
Population Fluctuations ◽  
Mortality Factors ◽  
Population System ◽  
Key Factor ◽  
Key Factor Analysis ◽  
Table Data

A series of life-tables for the population of Saisselia oleae (Oliv.) (Homoptera: Coccidae) during five yearly generations (1981-86) were constructed in Corfu. Key-factor analysis carried out on the life-table data indicated that mortality of young stages during summer, caused mainly by the high temperatures, and mortality during spring, caused mainly by predation, determine total population change within each generation. These two mortality factors are the predominant factors of the population dynamics of S. oleae determining population fluctuations. The other mortality factors of the population system of S. oleae were less important. Summer parasites and egg predators, in particular, do not play any significant role on the population dynamics of S. oleae.

Design of a Sampling Plan for Studies on the Population Dynamics of the Imported Cabbageworm, Pieris rapae (L.) (Lepidoptera: Pieridae)

1962 ◽  
Vol 94 (8) ◽  
pp. 849-859 ◽  
Author(s):  
D. G. Harcourt
Keyword(s):  
Population Dynamics ◽  
Pieris Rapae ◽  
Sampling Plan ◽  
Immature Stages ◽  
Mortality Factors ◽  
Term Study ◽  
Factors Affecting ◽  
Long Term Study ◽  
Successive Generations

In 1958, intensive studies on the population dynamics of the imported cabbageworm, Pieris rapae (L.), on cabbage were initiated in long-term study plots at Merivale, Ontario. The object was to construct ecological life tables for successive generations of the species, and ultimately, to develop mathematical models describing survival of field populations. This paper reports on the variation between samples of immature stages of the insect, and between some of the mortality factors affecting its abundance; it further illustrates the use of these data in designing a sampling plan with acceptable limits of precision.

MAJOR FACTORS IN SURVIVAL OF THE IMMATURE STAGES OF FENUSA PUSILLA IN SOUTHWESTERN QUEBEC

1970 ◽  
Vol 102 (8) ◽  
pp. 995-1002 ◽  
Author(s):  
H. H. Cheng ◽  
E. J. LeRoux
Keyword(s):  
Population Dynamics ◽  
Leaf Miner ◽  
Immature Stages ◽  
Key Factors ◽  
Larval Stages ◽  
Fenusa Pusilla ◽  
Two Generations ◽  
Key Factor ◽  
Major Factors ◽  
Old Trees

AbstractIntensive studies on the population dynamics of the birch leaf miner, Fenusa pusilla (Lepeletier), were carried out in two stands of blue birch at the Morgan Arboretum, Macdonald College, Que., from 1964 to 1966. Life tables for nine and two generations, respectively, showed that mortality of the immature stages was lower on 3- to 5-year-old trees than on 9-year-old trees. The analysis of successive age-interval survivals in relation to generation survival revealed that predation during the late larval stages was the key factor in generation survival of the insect on the younger trees. Desiccation of the leaf during the early larval stages along with predation were key factors on the older trees.

scholarly journals Snow physical properties may be a significant determinant of lemming population dynamics in the high Arctic

2018 ◽  
Vol 4 (4) ◽  
pp. 813-826 ◽  
Author(s):  
Florent Domine ◽  
Gilles Gauthier ◽  
Vincent Vionnet ◽  
Dominique Fauteux ◽  
Marie Dumont ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Basal Layer ◽  
Population Data ◽  
High Arctic ◽  
Population Fluctuations ◽  
Snow Modeling ◽  
Animal Populations ◽  
Key Factor ◽  
Snow Conditions ◽  
The Many

Cyclic population fluctuations are common in boreal and Arctic species but the causes of these cycles are still debated today. Among these species, lemmings are Arctic rodents that live and reproduce under the snow and whose large cyclical population fluctuations in the high Arctic impact the whole tundra food web. We explore, using lemming population data and snow modeling, whether the hardness of the basal layer of the snowpack, determined by rain-on-snow events (ROS) and wind storms in autumn, can affect brown lemming population dynamics in the Canadian high Arctic. Using a 7-year dataset collected on Bylot Island, Nunavut, Canada over the period 2003–2014, we demonstrate that liquid water input to snow is strongly inversely related with winter population growth (R2 ≥ 0.62) and to a lesser extent to lemming summer densities and winter nest densities (R2 = 0.29–0.39). ROS in autumn can therefore influence the amplitude of brown lemming population fluctuations. Increase in ROS events with climate warming should strongly impact the populations of lemmings and consequently those of the many predators that depend upon them. Snow conditions may be a key factor influencing the cyclic dynamics of Arctic animal populations.

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.

Something old, something new: revisiting the diamondback moth (Lepidoptera: Plutellidae) life table after 65 years

2019 ◽  
Vol 152 (1) ◽  
pp. 70-88 ◽  
Author(s):  
Tina Dancau ◽  
Tim Haye ◽  
Naomi Cappuccino ◽  
Peter G. Mason
Keyword(s):  
Population Dynamics ◽  
Diamondback Moth ◽  
Total Mortality ◽  
Sampling Technique ◽  
Life Tables ◽  
Mortality Factors ◽  
Destructive Sampling ◽  
Moth Population ◽  
Central Experimental Farm ◽  
History Of

AbstractNearly 65 years ago, D.G. Harcourt developed the first of 74 life tables of the diamondback moth, Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae), on the Central Experimental Farm in Ottawa, Ontario, Canada and at nearby sites. This work is cited whenever authors discuss the life history of the diamondback moth and its parasitoids in Canada. Since Harcourt’s study, climate change, urbanisation, and crop diversity may have altered the population dynamics of both the diamondback moth and its natural enemy community in the original study area. To follow up on Harcourt’s work, we used two approaches to build life tables to describe mortality factors in the field and the natural enemies attacking diamondback moth in Ottawa: destructive sampling of mature cabbage, Brassica oleracea Linnaeus (Brassicaceae), plants similar to Harcourt’s approach and a modern sentinel-based approach with an enemy exclusion cage treatment. After 65 years, the primary parasitoids attacking diamondback moth remained the same, although more parasitoid diversity was revealed by the destructive sampling technique. Total mortality and parasitism levels also remained similar. In one notable difference, we attributed more diamondback mortality to predation. Overall, however, diamondback moth population dynamics have changed little in Ottawa in the decades since Harcourt’s studies.

The effect of Bombylius pulchellus (Diptera; Bombyliidae) and other mortality factors upon the biology of Halictus ligatus (Hymenoptera; Halictidae) in southern Ontario

1988 ◽  
Vol 66 (3) ◽  
pp. 611-616 ◽  
Author(s):  
Laurence Packer
Keyword(s):  
Survival Rate ◽  
Fungal Infection ◽  
Brood Cell ◽  
Immature Stages ◽  
Microbial Infection ◽  
Mortality Factors ◽  
Southern Ontario ◽  
Two Factors ◽  
Halictus Ligatus ◽  
Reproductive Brood

Two factors were important in causing brood mortality in a southern Ontario population of Halictus ligatus: parasitism by larvae of the bombyliid Bombylius pulchellus and various forms of microbial infection of bee immatures or their pollen ball food. Bombyliid larvae consumed host prepupae or, less commonly, young pupae, restricted their attack mostly to the reproductive brood, and were contagiously distributed within the nest population. All immature stages were susceptible to fungal infection or disease but such pathogens did not seem to spread among cells within nests, indicating that bees may be able to prevent the spread of disease from one brood cell to another. Filling affected cells with earth may accomplish this brood hygiene. The survival rate of worker and reproductive brood immatures approximated 90%. Reproductive brood mortality affected females more than males. Reproductive brood mortality was probably underestimated: filled-in cells that may represent brood mortality were not included in these estimates.

MAJOR FACTORS IN SURVIVAL OF THE IMMATURE STAGES OF HYLEMYA BRASSICAE (DIPTERA: ANTHOMYIIDAE) ON CABBAGE

1971 ◽  
Vol 103 (5) ◽  
pp. 717-728 ◽  
Author(s):  
M. K. Mukerji
Keyword(s):  
Sampling Error ◽  
Pupal Stage ◽  
Density Dependent ◽  
Mortality Process ◽  
Key Factor ◽  
Pupal Parasitism ◽  
Hylemya Brassicae ◽  
Table Data ◽  
Cabbage Maggot ◽  
Major Factors

AbstractStudies on the population dynamics of the cabbage maggot, Hylemya brassicae (Bouché), on cabbage were carried out at two locations in Ontario from 1967 to 1970. Analysis of life-table data for nine generations showed that extensive mortalities occurred during the following age intervals: (1) egg stage; (2) between hatching and the second moult; (3) third-instar larvae; (4) pupal stage. Density dependent mortality occurred only during the latter period. The analysis of age interval survivals and graphical key factor analysis showed that "misadventure" of the larvae between hatching and the second moult was the key factor. The overall mortality process from egg to adult eclosion was density dependent, revealing the importance of pupal parasitism as a stabilizing factor. A predictive model based on density relationships was found to explain 62% of the variance in generation survival. The remainder of the variance is unexplained and may be due to sampling error and/or the influence of factors not measured.

Design of a Sampling Plan for Studies on the Population Dynamics of the Diamondback Moth, Plutella maculipennis (Curt.) (Lepidoptera: Plutellidae)

1961 ◽  
Vol 93 (9) ◽  
pp. 820-831 ◽  
Author(s):  
D. G. Harcourt
Keyword(s):  
Population Dynamics ◽  
Diamondback Moth ◽  
Sampling Plan ◽  
Immature Stages ◽  
Mortality Factors ◽  
Term Study ◽  
Factors Affecting ◽  
Long Term Study ◽  
Successive Generations

In 1958, intensive studies on the population dynamics of the diamondback moth, Plutella maculipennis (Curt.), on cabbage were initiated in long-term study plots at Merivale, Ontario. The object was to construct ecological life tables (Morris and Miller, 1954) for successive generations of the insect, and, ultimately, to develop a mathematical model describing survival of field populations. This paper reports on the variation between samples of immature stages of the moth, and between some of the mortality factors affecting its abundance, and on the use of these data in designing a sampling plan with acceptable limits of precision.

scholarly journals Population dynamics of Saissetia oleae. Ι. Assessments of ροpulation and mortality

2017 ◽  
Vol 8 ◽  
pp. 53 ◽  
Author(s):  
E. T. Stratopoulou ◽  
Ε.Τ. Kapatos
Keyword(s):  
Overall Survival ◽  
Population Dynamics ◽  
Survival Rate ◽  
High Temperatures ◽  
Mortality Rates ◽  
Overall Survival Rate ◽  
Population Changes ◽  
Mortality Factors ◽  
Saissetia Oleae ◽  
Heavy Mortality

The population dynamics of Saisselia oleae (Oliv.) (Homoptera: Coccidae) was studied in Corfu during five successive yearly generations (1981-1986). Successive estimates of the population of S. oleae were obtained within each of the five yearly generations and survivorship curves were constructed showing the progressive re­duction of the living population within each generation and population changes from generation to generation. The calculated mortality rates indicate that the population of S. oleae suffers heavy mortality. The major mortality factors were high temperatures during summer, the action of predators, particularly during spring, and mortality of crawlers during summer. Overall survival rate was very low and corresponded to total generation mortality that ranged from 99.693% to 99.987%. It is assumed that variation in the action of mortality factors cause considerable I’l Uctuations of the S. oleae population.

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