Population studies of the citrus psylla,Trioza erytreae: Factors influencing population size

1991 ◽  
Vol 19 (3) ◽  
pp. 183-193 ◽  
Author(s):  
M. A. van den Berg ◽  
Susan H. Anderson ◽  
Valerie E. Deacon
Keyword(s):  
Population Size ◽  
Population Studies ◽  
Factors Influencing ◽  
Trioza Erytreae ◽  
Citrus Psylla

Population studies of the citrus psylla,trioza erytreae: factors influencing dispersal

1991 ◽  
Vol 19 (4) ◽  
pp. 283-289 ◽  
Author(s):  
M. A. Van Den Berg ◽  
Susan H. Anderson ◽  
Valerie E. Deacon
Keyword(s):  
Population Studies ◽  
Factors Influencing ◽  
Trioza Erytreae ◽  
Citrus Psylla

scholarly journals Distribution of mountain hawkweeds (Hieracium s. str.) in the Hrubý Jeseník Mountains

2017 ◽  
Vol 66 (3) ◽  
pp. 193-229
Author(s):  
Jiří Kocián ◽  
Jindřich Chrtek
Keyword(s):  
Population Size ◽  
Current Distribution ◽  
Factors Influencing ◽  
Historical Distribution ◽  
New Localities ◽  
Field Revision

Abstract Field revision of current distribution of mountain hawkweeds (Hieracium s. str.) in the Hrubý Jeseník Mts was undertaken. Hieracium atratum, H. chlorocephalum, H. engleri, H. grabowskianum and H. plumbeum, whose last occurrence was documented many decades or even a century ago, were rediscovered. H. plumbeum was even found in new localities. The occurrence of H. alpinum, H. bifidum, H. chrysostyloides, H. inuloides, H. nigritum, H. prenanthoides, H. silesiacum, H. stygium and H. villosum was ascertained at many of their historical localities and a few new localities were found too. A neophyte species H. mixtum was discovered. Hieracium moravicum was not found. Accurate locality description and population size are provided for each finding. Herbarium revision and excerption of crucial literature were performed to provide historical distribution. Distributional changes as well as threatening and beneficial factors influencing Hieracium species in the Hrubý Jeseník Mts are discussed.

Factors influencing the production of turbidity by goldfish (Carassius auratus)

1992 ◽  
Vol 70 (8) ◽  
pp. 1585-1589 ◽  
Author(s):  
Michael J. Richardson ◽  
Frederick G. Whoriskey
Keyword(s):  
Population Size ◽  
Carassius Auratus ◽  
Small Fish ◽  
Large Fish ◽  
Goldfish Carassius Auratus ◽  
Factors Influencing ◽  
Poor Predictor ◽  
Size Population ◽  
The Impact ◽  
Successful Colonization

Experiments were conducted to determine the effect of body size, population size and structure, and temperature upon the level of turbidity generation by goldfish foraging in laboratory pools. Water temperature correlated with turbidity generation, which peaked at 25 °C but declined at 30 °C. Goldfish exhibited diurnal activity at all temperatures except 25 °C, where nocturnal behaviour predominated. Both body length and population size positively influenced turbidity production. Groups of a few large fish produced significantly more turbidity than groups of many small fish of equal biomass. Biomass was therefore a poor predictor of the level of turbidity, making it difficult to predict the impact of goldfish upon multispecific pond communities following successful colonization.

The importance of parasite mortality in regulating the population size of the AcanthocephalanPomphorhynchus laevisin goldfish

Parasitology ◽  
1974 ◽  
Vol 68 (1) ◽  
pp. 93-101 ◽  
Author(s):  
C. R. Kennedy
Keyword(s):  
Growth Rate ◽  
Feedback Control ◽  
Mortality Rate ◽  
Population Size ◽  
Population Densities ◽  
Time Intervals ◽  
Pomphorhynchus Laevis ◽  
Factors Influencing ◽  
Natural Hosts ◽  
The Stability

Experiments to study the mortality rate of the acanthocephalanPomphorhynchus laevisin goldfish are described. Infections with different population densities of parasite were given to fish on one occasion only and on several occasions with different time intervals between infection.The parasites established and grew in the experimental hosts at rates comparable to those in natural hosts on all occasions. The proportion establishing did not decrease with increasing population size and bore no relationship to the presence of an existing infection. The greatest loss of parasites occurred during the period of establishment. Thereafter, mortality was gradual, and the proportion of the population lost was not related to either the density of infection or to the intervals between infections. No evidence of reduced growth rate was found at the higher population densities.It is concluded that parasite mortality does not function as a feedback control and so is relatively unimportant in regulating the population size of fish acanthocephalans. Both field and laboratory evidence indicate that this is controlled by factors influencing recruitment. The equation of mortality and recruitment rates observed in many field populations must therefore be a matter of chance, and the implications of this with respect to the stability of fish-acanthocephalan systems is discussed.

Interactions between citrus psylla,Trioza erytreae (Hem. Triozidae), and spiders in an unsprayed citrus orchard in the transvaal lowveld

Entomophaga ◽  
1992 ◽  
Vol 37 (4) ◽  
pp. 599-608 ◽  
Author(s):  
M. A. Berg ◽  
Ansie S. Dippenaar-Shoeman ◽  
Valerie E. Deacon ◽  
Susan H. Anderson
Keyword(s):  
Citrus Orchard ◽  
Trioza Erytreae ◽  
Citrus Psylla

scholarly journals MODELING URBAN CRIME PATTERNS USING SPATIAL SPACE TIME AND REGRESSION ANALYSIS

2019 ◽  
Vol XLII-4/W16 ◽  
pp. 247-254 ◽  
Author(s):  
H. Hashim ◽  
W. M. N. Wan Mohd ◽  
E. S. S. M. Sadek ◽  
K. M. Dimyati
Keyword(s):  
Population Density ◽  
Population Size ◽  
Hot Spot ◽  
Space Time ◽  
Urban Crime ◽  
Ols Regression ◽  
Crime Patterns ◽  
Factors Influencing ◽  
Size Population ◽  
Crime Pattern

Abstract. The population size, population density and rate of urbanization are often crediting to contributing increasing a crime pattern specially in city. Urbanism model stating that the rise in urban crime and social problems is based on three population indicators namely; size, density and heterogeneity. The objective of this paper is to identify crime patterns of the hot spot urban crime location and the factors influencing the crime pattern relationship with population size, population density and rate of urbanization population. This study employed the ArcGIS Pro 2.4 tool such as Emerging Hot Spot Analysis (Space Time) to determine a crime pattern and Ordinary Least Squares (OLS) Regression to determine the factors influencing the crime patterns. By using these analyses tools, this study found that 54 (53%) out of 102 total neighbourhood locations (2011–2017 years) had a 99 percent significance confidence level where z-score exceeded +2.58 with a small p-value (p < 0.01) as the hot spot crime location. The result of data analysis using OLS regression explains that combination of exploratory variable model rate of urbanization and population size contributes 56 percent (R2 = 0.559) variance in crime index rate incident [F (3,39) = 18.779, p < 0.01). While the population density (β = 0.045, t = 0.700, p > 0.10) is not a significance contributes to the change in crime index rate in Petaling and Klang district. The importance of the study is useful information for encouraging government and law enforcement agencies to promote safety and reduce risk of urban population crime areas.

A bibliography of the citrus psylla,Trioza Erytreae (Del Guercio) (Hemiptera: Triozidae), up to 1987

1988 ◽  
Vol 16 (1) ◽  
pp. 47-61 ◽  
Author(s):  
M. A. Van Den Berg ◽  
Cecelia D. Fletcher
Keyword(s):  
Trioza Erytreae ◽  
Citrus Psylla
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