Bionomics of the Aspen Leaf Miner, Phyllocnistis populiella Cham. (Lepidoptera: Gracillariidae)

1964 ◽  
Vol 96 (6) ◽  
pp. 857-874 ◽  
Author(s):  
S. F. Condrashoff
Keyword(s):  
Populus Tremuloides ◽  
Leaf Surface ◽  
Climatic Factors ◽  
Population Decline ◽  
Instar Larva ◽  
Leaf Miner ◽  
Permanent Sample Plots ◽  
The Individual ◽  
New Generation ◽  
Phyllocnistis Populiella

AbstractThe aspen leaf miner, Phyllocnistis populiella Cham., has recently become common and very abundant in western North America, and has been authoritatively identified only from trembling aspen, Populus tremuloides Michx. Overwintered adults lay eggs on young aspen leaves in spring, and new-generation moths emerge in about two months. Only the single epidermal cell layer is mined on the upper or lower leaf surface, most of the feeding being done by the third-instar larva in about a week. Heavy attack results in defoliation by mid-summer. Activities of breeding populations are affected by temperature (50-55°F. is optimal for copulation, 54-56°F. for feeding, and 52-58°F. for oviposirion) and developmental stage of aspen leaves. Eggs are laid singly near the apex of the leaf and tend to be evenly spaced. Distribution of eggs between leaves tends to be uniform in a particular level of the tree, although more eggs are laid in the lower crown. A female moth can develop more than 40 eggs, but only about 7 are usually laid because of limited opportunities. Mortality in the larval and pupal stages is often high; population decline usually follows mortalities above 70%. Parasitism sometimes plays an important role, but the independence of population changes between broad geographic areas suggests that numbers of P. populiella may be strongly influenced by climatic factors. Population trends and damage can be assessed conveniently for large geographic areas and for specific sites by continuing studies in permanent sample plots. Expected damage may be predicted from estimates of new-generation adult populations. Because inter-tree variation exceeds intra-tree variation, more trees and fewer branches per tree should be taken to increase sampling efficiency. Also, greater precision is attained by the use of the individual leaf surface rather than the leaf as a basic sample unit.

Population decline of Globodera rostochiensis in Western Serbia

Nematology ◽  
2017 ◽  
Vol 19 (2) ◽  
pp. 185-195
Author(s):  
Nikola Grujić ◽  
Milan Radivojević
Keyword(s):  
Climatic Factors ◽  
Population Decline ◽  
Potato Cultivar ◽  
Potato Production ◽  
Globodera Rostochiensis ◽  
Initial Population ◽  
Management Procedures ◽  
Before And After ◽  
New Generation ◽  
Annual Decline

Annual decline rates of potato cyst nematode (PCN) populations have been extensively studied. They vary considerably due to many factors, including potato cultivar, initial PCN density and climatic factors. Information is needed on PCN decline in potato fields in the specific conditions of Western Serbia, which is the centre for most of the local potato production, especially seed potato. We investigated the decline of Globodera rostochiensis over 1 or 2 years under the influence of PCN-resistant potato cv. Agria in the field and microplots. Decline was compared with fallow in Ponikve, near the original record of G. rostochiensis. Population decline in the field after cv. Agria was approximately 80%. In two parts of the field where potato cv. Agria was cropped once or twice with fallow before and after, the viable PCN population declined over 9 years to about 1% of initial values. In a third part of the field, left fallow for 9 years, 15% of the initial population was still viable, after an annual decline rate of 9.4%. The influence of volunteer potatoes on maintaining PCN populations was also examined. In the microplots, with a higher density of volunteers compared to the field, PCN decline under resistant potato cv. Agria was 70%. At crop harvest a new generation was recorded, suggesting its possible formation on susceptible volunteer potato. The full cysts represented 1% of all cysts examined and 13% of total second-stage juveniles found in the samples. The information will be useful for improvement of management procedures.

Variable extrafloral nectary expression and its consequences in quaking aspen

2007 ◽  
Vol 85 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Patricia Doak ◽  
Diane Wagner ◽  
Adam Watson
Keyword(s):  
Populus Tremuloides ◽  
Natural Variation ◽  
Leaf Miner ◽  
Quaking Aspen ◽  
Insect Community ◽  
Interior Alaska ◽  
Leaf Mining ◽  
Secretory Glands ◽  
The Relationship ◽  
Phyllocnistis Populiella

Extrafloral nectaries (EFNs) are secretory glands most commonly linked to defensive mutualisms. Both a plant’s need for defense and the strength of defense provided by mutualists will vary with plant condition and local insect community. Thus, the benefit of EFNs may vary spatially and temporally. However, little attention has been paid to natural variation in the presence and abundance of EFNs within and among individuals of the same species. Quaking aspen, Populus tremuloides Michx., bear EFNs on a subset of their leaves. Here, we describe patterns of EFN expression on shoots within ramets, among ramets, and among putative clones in interior Alaska. We also examine the relationship between EFN presence and herbivory by both the very abundant aspen leaf miner, Phyllocnistis populiella Chambers, and less common chewing herbivores. The proportion of leaves bearing EFNs varied from 33% to 87% among distinct aspen stands. Within stands, short (1–2 m height) ramets had higher EFN frequency than their taller (>4 m) neighbors. Patterns of herbivory also differed between short and tall ramets. Compared with leaves without EFNs, those with EFNs suffered less mining damage on short ramets but slightly higher damage on tall ramets. Tall ramets suffered more chewing damage than short ramets, but this damage was unrelated to the presence of EFNs. Our results suggest that variable EFN expression may be explained by variation in the benefits of EFNs. Leaves with EFNs on short ramets benefit through reduction in leaf mining, but this benefit does not extend to tall ramets or other forms of herbivory.

scholarly journals Can the relation between fat and protein in milk be changed by selective breeding

1947 ◽  
Vol 19 (1) ◽  
pp. 8-21
Author(s):  
T. Lonka
Keyword(s):  
Milk Yield ◽  
Climatic Factors ◽  
Production Capacity ◽  
General Rule ◽  
Regression Equation ◽  
Fat Percentage ◽  
Protein Percentage ◽  
Coefficient Of Correlation ◽  
Rule Set ◽  
The Individual

In Finland the protein content of the feeds is in general so low that it restricts the milk yield particularly in herds of high production capacity. This is especially significant for the reason that owing primarily to climatic factors the quality of the feeds cannot be notably improved in this respect. Therefore an effort should be made to change the composition of milk by means of breeding in such a way that it would correspond to the possibilities of feed cultivation in Finland better than at present. This would mean that it should be endeavoured to breed cows whose milk is very fat-rich but at the same time poor in protein, in which case more of the commercially valuable butterfat could be produced on the feed grown on the estate. Since a correspondingly greater amount of milk of poor protein percentage could be produced than that of protein rich milk, the breeding of such cows would not decrease the yield of protein, which is of such great food value, but as great an amount in kilograms of milk protein would be available as earlier for domestic purposes as well as dairies. We have aimed at this goal in our country in general by endeavouring to raise the fat percentage of the milk by means of breeding. It is known that protein percentage does not increase exactly as markedly as the fat percentage, wherefore the protein yield per kilogram of fat decreases as the percentage rises. The influence of breeding would however be incomparably greater if low protein percentage were selected simultaneously with high fat percentage. In the investigation we have dealt with the possibilities of such selection in Finnish cattle, in connection with which we have striven to make clear how much the protein percentage of the milk varies independently of the fat percentage. The material comprises 54 West-Finnish Native cows; the fat and protein percentages of their milk yield has been determined once a month during one lactation. The relation of fat and protein is not the same throughout the whole lactation, but it changes so that at the end of the lactation the protein percentage as compared with the fat percentage is relatively greater than at the beginning of the period (Table and Figure 1). The averages of the fat and protein percentages and likewise the correlation between them depend consequently upon the length of the calving interval. Therefore the said averages have been estimated only on the basis of 2—7 production months. Fy means of these averages r = +0.60 ± 0.09 was derived as the coefficient of correlation between the fat and protein percentages y = 1.53 + 0.39 x as the regression equation, x = fat percentage and y = protein percentage. The individual cows diverge very much from the general rule set by the regression equation, which can be concluded already from the comparatively low value of the coefficient of correlation. The protein percentage of the milk yield of the West- Finnish Native cows diverges at least about one per cent independently of the fat percentage when judging on the basis of the extreme divergencies in the material. Although a part of the divergency evidently is caused by external factors, the role of the genetic factors is nevertheless so great that there appear to be great possibilities for breeding cows producing fat-rich milk by means of breeding but having a protein which would be considerably lower than the present average.

scholarly journals China's Rural Migrant Workers, the State, and Labor Politics

2017 ◽  
Author(s):  
Jenny Chan ◽  
Mark Selden
Keyword(s):  
Migrant Workers ◽  
The State ◽  
Labor Politics ◽  
Rural Migrant ◽  
Industrial Labor ◽  
Class Power ◽  
The Individual ◽  
New Generation ◽  
The Impact ◽  
Rural Migrant Workers

The proletarianization of rural migrants is distinctive to contemporary China's development model, in which the state has fostered the growth of a “semi-proletariat” numbering more than 200 million to fuel labor-intensive industries and urbanization. Drawing on fieldwork in Guangdong and Sichuan provinces between 2010 and 2014, supplemented with scholarly studies and government surveys, the authors analyze the precarity and the individual and collective struggles of a new generation of rural migrant workers. They present an analysis of high and growing levels of labor conflict at a time when the previous domination of state enterprises has given way to the predominance of migrant workers as the core of an expanding industrial labor force. In particular, the authors assess the significance of the growing number of legal and extra-legal actions taken by workers within a framework that highlights the deep contradictions among labor, capital, and the Chinese state. They also discuss the impact of demographic changes and geographic shifts of population and production on the growth of working-class power in the workplace and the marketplace.

scholarly journals TEACHING LANGUAGE THROUGH TECHNOLOGY

2019 ◽  
Vol 1 (2) ◽  
pp. 4-5
Author(s):  
Malathy P
Keyword(s):  
Modern Technology ◽  
Teaching Materials ◽  
Technology In The Classroom ◽  
Teaching Language ◽  
Full Attention ◽  
The Individual ◽  
New Generation ◽  
Teaching Time ◽  
Vast Range

Teaching is demanding, exciting and gratifying. Students arrive in the classroom to learn and the task of the teacher becomes easier. Maintaining motivation then becomes the main objective. Brian O’Connell says “Without motivation, learning doesn’t take place.” Before teaching a class, it is essential to prepare and collect enough materials to cover the allocated teaching time. Teaching materials are used to promote learning, to maintain interest, to add variety to the lesson and to relate one subject to other subjects. There is a vast range of materials for teachers to use, although some are more readily available in certain countries than in others. Teachers always need more and more materials to keep up to date, and to renew worn items. It is useful to be aware of the applications of Modern Technology in the classroom although it is not readily available in many colleges or not available at all. Students enjoy variety in classroom and welcome the introduction of any form of film and screen presentations. The novelty factor immediately gains the full attention of the individual. And a highly professional studio production almost guarantees interest that will be maintained throughout the screening. Thus teaching through Technologies becomes a pleasurable experience for the students to learn. Modern appliances like Computers, Projectors, CD Player can be used in teaching. But all kind of Technologies still need the  presence of a teacher, his smile, his heart and his motivation. The aim must be to produce a new generation full of humanity and life and not Computer – like students.

PRESIDENT'S ADDRESS

PEDIATRICS ◽  
1953 ◽  
Vol 11 (1) ◽  
pp. 1-6
Author(s):  
WARREN W. QUILLIAN
Keyword(s):  
Social Progress ◽  
Basic Principles ◽  
University Of Wisconsin ◽  
School Of Medicine ◽  
The People ◽  
Differences Of Opinion ◽  
High Standards ◽  
The Individual ◽  
The University ◽  
New Generation

Economic and social progress in our practice depends upon the sustained interest and the effort of the individual physician. Courage and faith are necessary foundations for action in this critical year of decision, and there is every reason to believe that the new generation of pediatricians has every qualification necessary to continue the quest for better health among children. His adventure in "practical idealism" will not be an easy one. But, fortified by the assurance of his noble heritage of accomplishment and adherence to high standards, he will accept the challenge of the future with a deep sense of responsibility. He will keep faith with those who have gone before, and attempt to retain the confidence and trust of the people as did our fathers, by holding high the banner of service. The price of success in this undertaking involves a determination to reach our objectives regardless of adverse circumstances, concentration on the immediate problems, and by long range plans for fulfilling our obligations to the children of America. Frustration and differences of opinion are inevitable. Changing conditions require flexibility in our adaptation to existing needs. Let us keep our eyes upon the stars, but our feet upon the ground! Our responsibilities are great. The Dean of the School of Medicine at the University of Wisconsin, Dr. William S. Middleton, recently stated the challenge in these words: "Make no small plans; they have no magic to stir man's soul!" Medicine progresses, even in a troubled world. Changes in governments, in laws and controls, have not interfered with this progress. Civilizations of the past have been destroyed by the decay and infamy and greed within their own structure. Let us renew our faith in the simple basic principles, which have characterized the growth and development of the Academy for 22 years.

scholarly journals Towards an Evolutionary Understanding of the Current Global Socio-economic Crisis and Restructuring: From a Conjunctural to a Structural and Evolutionary Perspective

2018 ◽  
Vol 9 (1) ◽  
pp. 15 ◽  
Author(s):  
Charis Michael Vlados ◽  
Nikolaos Deniozos ◽  
Demosthenes Chatzinikolaou ◽  
Michail Demertzis
Keyword(s):  
Economic Crisis ◽  
Chaos Theory ◽  
Economic Research ◽  
Global Dynamics ◽  
Evolutionary Perspective ◽  
Economic Perspective ◽  
System Science ◽  
Methodological Principles ◽  
The Individual ◽  
New Generation

The current global socio-economic crisis and restructuring reshapes the terms of study of the global dynamics as a whole. A new generation of interdisciplinary socio-economic research on the matter in question seems to be progressively emerging in international literature.Against this background, it gradually emerges the understanding, that any attempt to interpret the individual contemporary socio-economic phenomena, which relate to the crisis and the attempt to restructure globalization, can only be inadequate and ineffective, since it fails to fully approach the current dynamics of globalization in synthetic, holistic terms.In this direction, new interpretative approaches seem to intensify interpenetration and conceptual syntheses between the different fields of socio-economic sciences, in an increasingly unified perspective, by extensively "borrowing" –in a direct and indirect way– methods and theoretical "lenses" derived from system science, chaos theory, and evolutionary economics.In the depth of this methodological rearrangement, according to the position put forward in the following paper, it is crucial that an effort is made to move from a conjunctural to a structural perception of the crisis. Ultimately, the great challenge for the field of study of global dynamics nowadays is the transition from the methodological principles of the traditional mechanistic interpretative method to a coherent and integrated evolutionary socio-economic perspective.

Are We Justified in Conducting Invasive Research on Captive Apes for Their Wild Counterparts?

2018 ◽  
Vol 26 (6) ◽  
pp. 598-615
Author(s):  
Katlin Kraska
Keyword(s):  
Animal Rights ◽  
Power Relations ◽  
Wild Population ◽  
Population Decline ◽  
Conservation Policy ◽  
Wild Animals ◽  
Wildlife Species ◽  
Asymmetrical Power ◽  
Species Membership ◽  
The Individual

Abstract Wildlife species are threatened for a variety of reasons; research on captive individuals of the same species can, in some circumstances, prevent wild population decline. Such decisions pit conservationists and animal rights advocates against one another—the former are interested in survival of the species and the latter in individual rights. I argue that invasive research on captive animals for the sake of wild animals is justifiable in cases of emergency only if it is the lesser of two evils. This requires that the individual chimpanzee be compensated for harms incurred. I then argue this logic generally does not apply to human beneficiaries of invasive research conducted on chimpanzees. This is not because species membership is morally significant, but because asymmetrical power relations characterized by dependency and vulnerability will always exist between the groups if human interests are at stake. The argument focuses on federal chimpanzee conservation policy.

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