Influence of Cultivar, Nitrogen, and Frequency of Insecticide Application on Vegetable Leafminer (Diptera: Agromyzidae) Population Density and Dispersion on Snap Beans

1987 ◽  
Vol 80 (1) ◽  
pp. 107-110 ◽  
Author(s):  
H. Y. Hanna ◽  
R. N. Story ◽  
A. J. Adams
Keyword(s):  
Population Density ◽  
Insecticide Application ◽  
Snap Beans

scholarly journals KEPADATAN POPULASI PREDATOR, PESAING, DAN SIMBION KUTUDAUN PADA TANAMAN KACANG PANJANG PASCAAPLIKASI INSEKTISIDA

2004 ◽  
Vol 4 (2) ◽  
pp. 62-68
Author(s):  
Nur Yasin ◽  
Listianingsih Listianingsih ◽  
Lestari Wibowo ◽  
F. X. Susilo
Keyword(s):  
Population Density ◽  
Growing Season ◽  
Insecticide Application ◽  
Randomized Design ◽  
Completely Randomized Design

The population density of Aphis sp., their predators, competitors, and symbionts in longbean field treated with insecticide.  This study was aimed to determine the effect of profenofos insecticide application on 1) the population density of Aphis sp., their predators (coccinellids and syrphids), competitor (Empoasca sp.) and symbionts (ants), and 2) the interactions between the aphid and the predator, the aphid and the symbiont, and the aphid and the competitor in the longbean field.  The experiment was arranged in completely randomized design with three levels of profenofos treatments (P1= profenofos sprayed weekly, P2= profenofos sprayed biweekly, and K= unsprayed). Each treatment was replicated six times.  Population density (insect number/longbean hill) was observed three times a week, totaling 16 observations during the growing season.  The result showed that profenofos spray decreased the population density of Aphis sp.  Profenofos treatment also suppressed coccinellid, syrphid, Empoasca sp., and ant population.  However, the insecticide did not affect the correlation either between Aphis sp. and ant, between Aphis sp. and Empoasca sp.,  between ant and Empoasca sp., between ant and coccinellids/syrphids, or between Empoasca sp. and  coccinellids/syrphids.  It was clear from this study that profenofos strengthened the interaction between Aphis sp. and coccinellids.  Aphis sp.—syrphid interaction was weekened by biweekly spray of profenofos, but was replenished by weekly spray of the insecticide.

Convergence of regional population density in Russia over 120 years

2020 ◽  
pp. 133-158
Author(s):  
K. A. Kholodilin ◽  
Y. I. Yanzhimaeva
Keyword(s):  
Population Density ◽  
Spatial Dependence ◽  
Population Distribution ◽  
Regional Level ◽  
Capital City ◽  
County Level ◽  
Spatial Effects ◽  
Russian Regions ◽  
Regional Population ◽  
Regional Population Density

A relative uniformity of population distribution on the territory of the country is of importance from socio-economic and strategic perspectives. It is especially important in the case of Russia with its densely populated West and underpopulated East. This paper considers changes in population density in Russian regions, which occurred between 1897 and 2017. It explores whether there was convergence in population density and what factors influenced it. For this purpose, it uses the data both at county and regional levels, which are brought to common borders for comparability purposes. Further, the models of unconditional and conditional β-convergence are estimated, taking into account the spatial dependence. The paper concludes that the population density equalization took place in 1897-2017 at the county level and in 1926—1970 at the regional level. In addition, the population density increase is shown to be influenced not only by spatial effects, but also by political and geographical factors such as climate, number of GULAG camps, and the distance from the capital city.

Extension of the Spatial PDI Model to Three Dimensions

1997 ◽  
Vol 84 (1) ◽  
pp. 176-178
Author(s):  
Frank O'Brien
Keyword(s):  
Population Density ◽  
Dimensional Space ◽  
Finite Lattice ◽  
Three Dimensional ◽  
Upper Bounds ◽  
Three Dimensions ◽  
Lower And Upper Bounds ◽  
Density Index ◽  
Three Dimensional Space

The author's population density index ( PDI) model is extended to three-dimensional distributions. A derived formula is presented that allows for the calculation of the lower and upper bounds of density in three-dimensional space for any finite lattice.

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