Population Dynamics of the California Red Scale, Aonidiella aurantii Maskell, and Its Parasitoid, Aphytis melinus (Howard), in Grapefruit Orchards in Turkey

2008 ◽  
Vol 43 (3) ◽  
pp. 291-299 ◽  
Author(s):  
Sevcan Oztemiz ◽  
Ferda Yarpuzlu ◽  
Mehmet Karacaoglu
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
Early Spring ◽  
Aonidiella Aurantii ◽  
Parasitization Rate ◽  
Aphytis Melinus ◽  
Second Stage

The purpose of this study was to define the population dynamics of the California red scale, Aonidiella aurantii Maskell (Heteroptera: Homoptera: Diaspididae), and its parasitoid, Aphytis melinus (Howard) (Hymenoptera: Aphelinidae), released to control the scale in grapefruit orchards in Turkey. Results revealed that A. aurantii exhibited 3 generations in the spring, summer, and autumn each year for 2004 and 2005. The highest population density of second-stage larvae occurred on leaves at densities of 18 and 46 individuals per 4 cm2 with the lowest density occurring on stems at levels of 7 and 8 individuals per cm2 in grapefruit in both years. Parasitoid populations increased in the summer and into autumn. Parasitation rate was increased by releasing A. melinus adults in the orchards. In 2004 and 2005, respectively, the highest parasitization rate occurred on infested leaves with 60.8% and 40.8%, followed by infested fruits at 25% and 54.5%, on infested shoots with 36.4% and 19.3%, and on infested stems with 8.33% and 15.4%. Second-stage and unmated females of red scale were most dense during the spring, summer and autumn each year, thus, appearing to be the best time for release of parasitoids. These results suggest that in releasing A. melinus in grapefruit orchards in Turkey, 50% of the parasitoids should be released in early spring, 25% in summer, and 25% in autumn.

Effects of crop sequence and rainfall on population dynamics of Fusarium solani f.sp. phaseoli in soil

1992 ◽  
Vol 70 (10) ◽  
pp. 2005-2008 ◽  
Author(s):  
Robert Hall ◽  
Lana Gay Phillips
Keyword(s):  
Population Dynamics ◽  
Phaseolus Vulgaris ◽  
Population Density ◽  
Fusarium Solani ◽  
Population Densities ◽  
Total Rainfall ◽  
Colony Forming Units ◽  
Bean Crop ◽  
Previous Summer ◽  
Crop Sequence

Evidence is presented that population dynamics of Fusarium solani f.sp. phaseoli in soil depend on the effects of crop sequence and rainfall on parasitic activities of the pathogen. In a rotation trial started in 1978 and conducted over 14 years, population densities (colony-forming units/g) of the fungus in soil remained below 50 in treatments (fallow, repeated corn, repeated soybean) where the preferred host plant (common bean, Phaseolus vulgaris) was not grown. Where bean was grown every 3rd year or every year, population densities reached 475 and 660, respectively, by 1984. Thereafter, population densities of the fungus fluctuated widely from year to year in both rotation and repeated bean treatments. In the rotation treatment, peaks in population density of the pathogen coincided with the years of bean production. In repeated bean plots between 1985 and 1991, population density of the fungus in June was significantly correlated (r = 0.77, p = 0.04) with total rainfall received during the previous summer (June–August). It is postulated that higher rainfall during the growing season of the bean crop stimulated root growth and root infection, leading to the accumulation of higher levels of potential inoculum in infected tissue and the release of higher levels of inoculum into the soil by the following June. Key words: Fusarium solani f.sp. phaseoli, bean, Phaseolus vulgaris, rainfall, crop rotation.

PREDATION BY INSECTS AND SPIDERS INHABITING COLONIAL WEBS OF HYPHANTRIA CUNEA

1972 ◽  
Vol 104 (8) ◽  
pp. 1197-1207 ◽  
Author(s):  
R. F. Morris
Keyword(s):  
Population Dynamics ◽  
Nova Scotia ◽  
North America ◽  
Population Density ◽  
New Brunswick ◽  
Numerical Response ◽  
Initial Number ◽  
Hyphantria Cunea ◽  
The North ◽  
The Mean

AbstractThe number of predators inhabiting nests of Hyphantria cunea Drury was recorded annually for 13 years in four areas in New Brunswick and two areas on the coast of Nova Scotia. The most common groups were the pentatomids and spiders, which sometimes reproduced within the nests, but the mean number per nest was low in relation to the number of H. cunea larvae in the colonies. The rate of predation on fifth-instar larvae was low. Small or timid predators appeared to prey largely on moribund larvae or small saprophagans during the principal defoliating instars of H. cunea.No relationship could be detected between the number of larvae reaching the fifth instar and the number of predators in the colony; nor could any functional or numerical response of the predators to either the initial number of larvae per colony or the population density of colonies be found. It is concluded that the influence of the nest-inhabiting predators is small and relatively stable, and may be treated as a constant in the development of models to explain the population dynamics of H. cunea.H. cunea is a pest in parts of Europe and Asia, where it has been accidentally introduced from North America. The introduction to other continents of the North American predator, Podisus maculiventiis (Say), is discussed briefly.

scholarly journals Climatic Factors, Reproductive Success and Population Dynamics in the Montane Vole Microtus Montanus

2005 ◽  
Vol 29 ◽  
pp. 49-51
Author(s):  
Alita Pinter
Keyword(s):  
Population Dynamics ◽  
Reproductive Success ◽  
Population Density ◽  
Climatic Factors ◽  
Small Rodents ◽  
Microtus Montanus ◽  
Small Measure ◽  
Long Term Studies

A variety of hypotheses has been proposed to explain multiannual fluctuations in population density ("cycles") of small rodents (for reviews see Finerty 1980, Taitt and Krebs 1985). Doubtless, such cycles - known since antiquity (Elton 1942) - result from an interaction of a multitude of factors. However, the inability of extant hypotheses, alone or in combination, to explain the causality of cycles rests in no small measure with the fact that long-term studies of the phenomenon are notoriously uncommon.

Population dynamics and production of a brine shrimp, Parartemia zietziana Sayce (Crustacea : Anostraca), in two salt lakes in westren Victoria, Australia

1977 ◽  
Vol 28 (4) ◽  
pp. 417 ◽  
Author(s):  
R Marchant ◽  
WD Williams
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
Temperature Stress ◽  
Brine Shrimp ◽  
Dry Weight ◽  
Salt Lakes ◽  
Confidence Limits ◽  
Length Frequency ◽  
Population Densities ◽  
The Mean

Quantitative samples of P. zietziana were taken monthly for two years from Pink Lake and Lake Cundare. Shrimps were usually contagiously distributed. To reduce error, samples were stratified resulting in confidence limits of 40-50% for the mean population density. Despite this variability, stable trends emerged, and variation was not so great as to mask significant differences. Length-frequency analyses distinguished cohorts; a regression was established between length and dry weight, enabling growth to be estimated from samples. By combining growth with population densities in Allen curves, production was computed. In Pink Lake and Lake Cundare mean pro- duction was 11.3 and 1.0 g dry weight m-2 year-1 respectively. Generally there were two or three generations per year, but time and extent of recruitment were not predictable. Each generation suffered continuous mortality, the death of young shrimps accounting for most of the production. This mortality remains unexplained; there are no significant predators and salinity and temperature stress would occur only during summer.

Paddlefish Management, Propagation, and Conservation in the 21st Century

2009 ◽  
Keyword(s):  
Growth Rate ◽  
Population Dynamics ◽  
Mortality Rate ◽  
Population Density ◽  
21St Century ◽  
High Growth ◽  
High Growth Rate ◽  
Demographic Groups ◽  
Annual Mortality ◽  
Remnant Population

<em>Abstract</em>.—Paddlefish <em>Polyodon spathula </em>vanished from areas of the upper Tombigbee River basin in Mississippi and Alabama during the 1950s, long before channelization and damming associated with construction of the Tennessee-Tombigbee Waterway (TTW) were completed in 1984. This study was undertaken to assess distribution and population dynamics of any remaining stock. Paddlefish were not captured in upstream impoundments, but an unexploited remnant population was located in the downstream impoundment: Demopolis Lake, Alabama. Paddlefish in Demopolis Lake were characterized by a population density of 2.6 fish/ha, high growth rate relative to more northern populations, and natural annual mortality rate (<em>A </em>= 0.406) similar to other southern populations. Two wintering habitats (cutoff bendways) were heavily utilized by paddlefish. Large males primarily inhabited the more lotic bendway while females and small males were more common in the more lentic bendway, indicating differential importance of habitats among demographic groups. The restricted distribution of TTW paddlefish and demographic differences between habitats suggest that areas heavily utilized by paddlefish should be protected from further degradation. Sedimentation has resulted in reductions of bendway depth and reduced connectivity of backwaters, reducing availability of suitable paddlefish habitat. Restoring connectivity of bendways through dredging could reverse this trend and provide other benefits to fisheries.

Population Dynamics of Municipalities in Central Russia

2017 ◽  
Vol 2017 (6) ◽  
pp. 97-124
Author(s):  
Irina Kalabikhina ◽  
Denis Mokrensky
Keyword(s):  
Population Dynamics ◽  
Elderly Population ◽  
Population Change ◽  
Population Decline ◽  
The Elderly ◽  
Second Stage ◽  
Central Russia ◽  
Population Concentration ◽  
Population Reduction ◽  
Demographic Policy

In this paper we present the results of the analysis of the population change in nonmetropolitan city municipalities by components and concentration of population in the municipalities were investigated, their typologization was developed in accordance with the contribution of various components to population dynamics. The article discusses the limitations of municipal statistics. The methods of average values, the balance equation, and the measures of population concentration are used. The main conclusions confirm the trends of population decline at the second stage of demographic policy, territorial unevenness and concentration of population in administrative centers and the closest settlements to them. Less than 2% of the municipalities in question demonstrate both natural and migratory growth, and in 70% of municipalities both migration and natural components make a contribution to population reduction. The relatively high proportion of the elderly population was observed in the studied municipalities; crude birth and death rates were worse than the average in the district.

scholarly journals Human impact and population dynamics in the Neolithic and Bronze Age: Multi-proxy evidence from north-western Central Europe

The Holocene ◽  
2019 ◽  
Vol 29 (10) ◽  
pp. 1596-1606 ◽  
Author(s):  
Ingo Feeser ◽  
Walter Dörfler ◽  
Jutta Kneisel ◽  
Martin Hinz ◽  
Stefan Dreibrodt
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
Bronze Age ◽  
Human Impact ◽  
Central Europe ◽  
Human Activity ◽  
Temporal Distribution ◽  
Relative Population ◽  
Erosion History ◽  
North Western

This paper aims at reconstructing the population dynamics during the Neolithic and Bronze Age, c. 4500–500 cal. BC, in north-western Central Europe. The approach is based on the assumption that increased population density is positively linked with human activity and human impact on the environment, respectively. Therefore, we use archaeological 14C dates and palaeoenvironmental data from northern Germany and south-western Denmark to construct and compare independent proxies of human activity. The latter involves relative quantification of human impact based on pollen analysis and soil erosion history inferred from summarizing of dated colluvial layers. Concurring patterns of changes in human activity are frequently recorded on a multi-centennial scale. Whereas such multi-proxy patterns are interpreted to indicate relative population changes, divergent patterns are discussed in the context of proxy-related uncertainties and potential biases. Patterns of temporal distribution of increasing and decreasing human activity are understood as ‘boom and bust’ phases in population density/size. Based on the comparison of the three proxies, we identify five phases of growing (boom) and four phases of decreasing (bust) population. The boom phases date to ca. 4000–3500, 3000–2900, 2200–2100, 1450–1300 and 1000–750 cal. BC. The bust phases to ca. 3200–3000, 2400–2300, 1650–1500 and 1200–1100 cal. BC.

The population dynamics of Cardiaspina albitextura (Psyllidae).

1964 ◽  
Vol 12 (3) ◽  
pp. 362 ◽  
Author(s):  
LR Clark
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
Population Study ◽  
Intraspecific Competition ◽  
Limited Availability ◽  
Host Trees ◽  
Increase With Increase ◽  
Numerical Stabilization ◽  
Environmental Agencies ◽  
Population Numbers

During the last 16 years, the numbers of Cavdiaspina albitextura rose from low to high in many places, and either remained high or eventually resumed their original levels. In other places, the numbers of the psyllid remained low although they fluctuated considerably. The results of a population study which began in 1952 suggest that, in parts of the woodland colonized by C. albitextura, the stabilization of psyllid numbers occurred temporarily - in some areas at low mean levels of population density and in others at high mean levels. In other parts of the woodland, psyllid numbers changed progressively with time. The occurrence of numerical stabilization appeared to depend upon the extent of the mortality caused directly or indirectly by certain environmental agencies whose "deciding" or "conditioning" influence determined when and where stabilization was possible. At low psyllid densities, the principal conditioning agencies were probably the whole complex of species predacious on psyllid nymphs and eggs, and weather. At high psyllid densities, the conditioning agencies were the density of host trees, and wind. Providing that sufficient mortality was caused by the conditioning agencies, negative feed-back mechanisms were able to implement stabilization. At low psyllid densities, birds predacious on adult psyllids appeared to be the operative or "density-governing" agency. The intensity of their attacks, which tended to increase with increase in psyllid density, operated in a probabilistic manner to limit increase in population numbers. At high psyllid densities, food and space favourable for oviposition were the operative agencies. The limited availability of food and space brought into action a stabilizing mechanism which functioned automatically through forms of intraspecific competition.

Population dynamics of plant parasitic nematodes in Queensland pineapple fields and the effects of these nematodes on pineapple production

1993 ◽  
Vol 33 (2) ◽  
pp. 197 ◽  
Author(s):  
GR Stirling ◽  
A Nikulin
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
Parasitic Nematodes ◽  
Plant Parasitic Nematodes ◽  
Root Knot Nematode ◽  
Ratoon Crop ◽  
Original Population ◽  
Ethylene Dibromide ◽  
Nematode Population Density ◽  
Plant Parasitic

Twelve pineapple fields with various densities of root-knot nematode were selected during a ratoon crop. Nematode populations were monitored regularly after the crop was ploughed out. Regardless of the original population density, rootknot nematodes were almost nondetectable at the end of the subsequent 3-6-month fallow intercycle period. In the absence of nematicide treatment there were marked differences between sites in the manner in which rootknot nematodes increased in the newly planted crop. At some sites, they were detectable 9-15 months after planting, whereas at other sites, nematodes were not observed at 15 months. Increases in ratoon crop yield following application of ethylene dibromide or fenamiphos were related to root-knot nematode population density. Significant increases in yield were not obtained at sites where the nematode was not detectable at 15 months. The results suggest that some pineapple growers are needlessly applying nematicides and that nematode diagnostic services should be developed to provide growers with advice on their nematode management programs.

The role of seed reproduction in the dynamics of established populations of Hieracium floribundum and a comparison with that of vegetative reproduction

1975 ◽  
Vol 53 (24) ◽  
pp. 3022-3031 ◽  
Author(s):  
A. G. Thomas ◽  
H. M. Dale
Keyword(s):  
Population Dynamics ◽  
Seedling Establishment ◽  
Vegetative Reproduction ◽  
Soil Surface ◽  
Growing Season ◽  
Population Based ◽  
Early Spring ◽  
Viable Seed ◽  
Density Patch

In the crowded parts of patches of Hieracium floribundum Wimm. and Grab., which were established for at least a decade in an ungrazed pasture, 7–10% of the population (3700 individuals/m2) flowered. Of the plants that flowered, 94% were alive a year later, but only 5% of these flowered. Abortion of flower heads was common; one half of all those which were initiated in early June had aborted by flowering time in early July. Freshly dispersed seed had a viability of 57%, which was reduced to 17% a year later, after its storage close to the soil surface. Less than 6% of the viable seed was innately dormant. Dry, laboratory-stored seed retained its viability for the year but was slower to germinate than soil-stored seed. In field conditions, germination was temperature inhibited during most of the growing season. Maximum daytime microsite temperatures of less than 32 °C, which is necessary for germination, were found to occur only in early spring and late fall. Successful seedling establishment accounts for 1% of the individuals in a crowded population. Based on the maximum sexual reproduction from plants in crowded populations, a seed has a probability of 1 in 20 000 of becoming an established seedling. A model of population dynamics in a high-density patch traces the fate of seedling establishment, surviving adults, and stolon-derived rosettes for a single year.

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