PREVALENCE OF SPIDERS AND THEIR IMPORTANCE AS PREDATORS IN ONTARIO PEACH ORCHARDS

1967 ◽  
Vol 99 (2) ◽  
pp. 160-170 ◽  
Author(s):  
W. L. Putman
Keyword(s):  
Population Density ◽  
Paper Chromatography ◽  
Panonychus Ulmi ◽  
Single Tree ◽  
Minor Peak ◽  
Satisfactory Method ◽  
Form Part ◽  
Mite Density ◽  
A Minor

AbstractPhilodromus spp., especially praelustris Keyserlmg, and sometimes Theridion murarium were the only abundant spiders in peach orchards, though small numbers of many other species were present. No satisfactory method of sampling the population density of all species was discovered. The spider population as a whole reached a minor peak in June and a much higher peak in early August. A single tree may contain more than 200 spiders. When fed only on Panonychus ulmi (Koch), young P. praelustris eventually died without moulting; young of T. murarium moulted once or twice but their development was slower than that of those in the orchards. Chironomids were the commonest prey of P. praelustris and apparently of other spiders in the orchards.Spiders collected from peach plots with different densities of P. ulmi and Bryobia arborea Morgan and Anderson were examined for pigments of these mites by paper chromatography. Some spiders in all collections had fed on the mites, and the percentage that had done so usually varied directly with mite density in the plots. Spiders form part of the complex of minor predators that aid the major predators in regulating the density of P. ulmi at endemic levels.

Effects of phytoseiid predators on the sex ratio of the spider mite Panonychus ulmi

1991 ◽  
Vol 69 (1) ◽  
pp. 208-212 ◽  
Author(s):  
Dan L. Johnson ◽  
Heather C. Proctor
Keyword(s):  
Population Density ◽  
Sex Ratio ◽  
Spider Mite ◽  
Total Population ◽  
Panonychus Ulmi ◽  
Encounter Rate ◽  
Male Mortality ◽  
Adult Sex Ratio ◽  
Biased Sex Ratio ◽  
Male Activity

The effect of predator presence on the adult sex ratio of a spider mite (Panonychus ulmi) was examined in a field experiment. Phytoseiid predators (chiefly Typhlodromus occidentalis) were removed from 32 trees harboring P. ulmi populations, and allowed to remain at natural levels on 32 other trees. Both total population density and proportion of males in the prey population were significantly higher in predator-free trees. Mechanisms that could explain the increase in the proportion of males are examined. The most probable is that greater male activity results in a higher encounter rate between predator and prey, and that subsequent higher male mortality when predators are present exaggerates the female-biased sex ratio. The theoretical effects of sex-biased predation on diplo-diploid and haplo-diploid organisms are discussed.

Some aspects of the ecology of bagrid catfishes in a southern Nigerian river

1991 ◽  
Vol 7 (2) ◽  
pp. 221-232 ◽  
Author(s):  
George Idodo-Umeh ◽  
Reginald Victor
Keyword(s):  
Spatial Distribution ◽  
Species Composition ◽  
Rainy Season ◽  
Major Peak ◽  
Fish Yield ◽  
Southern Nigeria ◽  
Minor Peak ◽  
A Minor ◽  
Principal Species ◽  
Dry And Rainy Seasons

ABSTRACTSome aspects of the ecology of bagrid catfishes in River Ase, southern Nigeria were studied for a period of two years. Nine species of Bagridae were recorded and these accounted for 15.0% of the number and 24.4% of the weight of all fish captured. Chrysichthys nigrodigitatus and Chrysichthys auratus longifilis were the principal species. C. nigrodigitatus was a rainy season species, while C. auratus longifilis was abundant in both dry and rainy seasons. Both species showed a major peak in catches between 0600 and 0900 h. C. nigrodigitatus exhibited a minor peak in catches between 1500 and 2100h, while C. auratus longifilis showed a minor peak between 1500 and 1800h. The spatial distribution of C. nigrodigitatus and C. auratus longifilis populations was heterogeneous. Bagrid fishes were an important component in the fish yield of the study river and its species composition has been compared with those of other Nigerian waters. The distribution and abundance of C. nigrodigitatus and C. auratus longifilis are discussed in detail.

The Contribution of Amphipoda to the Diet of Certain Inshore Fish Species in Kames Bay, Millport

1997 ◽  
Vol 77 (3) ◽  
pp. 907-910 ◽  
Author(s):  
D.J. Beare ◽  
P.G. Moore
Keyword(s):  
Population Density ◽  
Fish Species ◽  
Amphipod Species ◽  
Sand Goby ◽  
Flatfish Species ◽  
Sublittoral Zone ◽  
Minor Part ◽  
A Minor

Thirteen species of Amphipoda have been recorded from the stomachs of plaice and 11 species from dabs, with Perioculodes longimanus the most notable prey oedicerotid in both flatfish species sampled from the shallow sublittoral zone (<-6 m depth) at Kames Bay, Millport. Plaice took mostly bivalve siphon tips (Angulus sp.). Polychaetes were more numerous in larger plaice. Sand gobies specialized on small crustaceans, taking 13 amphipod species inter alia (with P. longimanus again the most notable oedicerotid). Amphipod numbers in sand goby stomachs increased with the length of the fish. Neither dabs nor sand gobies consumed bivalve siphon tips and only rarely consumed polychaetes. Although amphipods formed only a minor part of the diet of plaice, at the population density known for this species in this bay, its depredations would still constitute an important selective agency governing patterns of activity in epibenthic oedicerotids.

The Role of Predators and Other Biotic Agents in Regulating the Population Density of Phytophagous Mites in Ontario Peach Orchards

1966 ◽  
Vol 98 (8) ◽  
pp. 808-820 ◽  
Author(s):  
W. L. Putman ◽  
D. H. C. Herne
Keyword(s):  
Population Density ◽  
Population Growth ◽  
Tetranychus Urticae ◽  
Considerable Extent ◽  
Panonychus Ulmi ◽  
Apple Orchards ◽  
Rapid Population Growth ◽  
One Year ◽  
Heavy Mortality

AbstractMore than 40 species of insects and arachnids attack Panonychus ulmi (Koch), Tetranychus urticae Koch, T. canadensis (McGregor), Bryobia arborea Morgan and Anderson, or Aculus cornutus (Banks) in peach orchards of the Niagara Peninsula. The most effective predators attacking P. ulmi are Typhlodromus caudiglans Schuster, Haplothrips faurei Hood, Stethorus punctillum Weise, and Chrysopa spp. Peach orchards lack the predatory mirids characteristic of apple orchards. A condition, presumably disease, caused heavy mortality in one year. Endemic densities of P. ulmi are maintained in that state by predators, chiefly T. caudiglans, that subsist to a considerable extent on other sources of food, whereas epidemics of P. ulmi are reduced largely by other predators, chiefly H. faurei and S. punctillum, that increase in numbers by feeding on the mite during its period of rapid population growth but exert their greatest effect later in the season by destroying the winter eggs.

scholarly journals Use of glycyl-l-phenylalanine 2-naphthylamide, a lysosome-disrupting cathepsin C substrate, to distinguish between lysosomes and prelysosomal endocytic vacuoles

1994 ◽  
Vol 300 (1) ◽  
pp. 229-236 ◽  
Author(s):  
T O Berg ◽  
P E Strømhaug ◽  
T Løvdal ◽  
P O Seglen ◽  
T Berg
Keyword(s):  
Acid Phosphatase ◽  
Degradation Products ◽  
Rat Hepatocytes ◽  
Endocytic Pathway ◽  
Marker Enzyme ◽  
Major Peak ◽  
Isolated Rat Hepatocytes ◽  
Cathepsin C ◽  
Minor Peak ◽  
A Minor

Lysosome-disrupting enzyme substrates have been used to distinguish between lysosomal and prelysosomal compartments along the endocytic pathway in isolated rat hepatocytes. The cells were incubated for various periods of time with 125I-labelled tyramine cellobiose (125I-TC) covalently coupled to asialoorosomucoid (AOM) (125I-TC-AOM); this molecule is internalized by receptor-mediated endocytosis and degraded in lysosomes, where the degradation products (acid-soluble, radio-labelled short peptides) accumulate, Glycyl-L-phenylalanine 2-naphthylamide (GPN) and methionine O-methyl ester (MOM), which are hydrolysed by lysosomal cathepsin C and a lysosomal esterase respectively, both diffused into hepatocytic lysosomes after electrodisruption of the cells. Intralysosomal accumulation of the hydrolysis products (amino acids) of these substrates caused osmotic lysis of more than 90% of the lysosomes, as measured by the release of acid-soluble radioactivity derived from 125I-TC-AOM degradation. The acid-soluble radioactivity coincided in sucrose-density gradients with a major peak of the lysosomal marker enzyme acid phosphatase at 1.18 g/ml; in addition a minor, presumably endosomal, acid phosphatase peak was observed around 1.14 g/ml. The major peak of acid phosphatase was almost completely released by GPN (and by MOM), while the minor peak seemed unaffected by GPN. Acid-insoluble radioactivity, presumably in endosomes, banded (after 1 h of 125I-TC-AOM uptake) as a major peak at 1.14 and a minor peak at 1.18 g/ml in sucrose gradients, and was not significantly released by GPN. GPN thus appears to be an excellent tool by which to distinguish between endosomes and lysosomes. MOM, on the other hand, released some radioactivity and acid phosphatase from endosomes as well as from lysosomes.

A survey of microorganisms for thermonuclease production

1980 ◽  
Vol 26 (4) ◽  
pp. 532-535 ◽  
Author(s):  
C. E. Park ◽  
A. de Melo Serrano ◽  
M. Landgraf ◽  
J. C. Huang ◽  
Z. Stankiewicz ◽  
...  
Keyword(s):  
The Other ◽  
Major Peak ◽  
Coagulase Negative Staphylococci ◽  
Ph Profile ◽  
Streptococcus Faecalis ◽  
Heat Stable ◽  
Minor Peak ◽  
A Minor ◽  
Group D ◽  
Coagulase Positive Staphylococci

A total of 1204 cultures comprising 16 genera were surveyed for production of thermonuclease (TNase) in milk. Cultures other than Staphylococcus capable of TNase production were restricted to two genera, Streptococcus and Bacillus. Nineteen percent of 338 group D streptococci comprising four species (85% of which were Streptococcus faecalis) and 17% of 60 streptococci belonging to other groups produced TNase. Nine percent of 130 Bacillus cultures comprising six species produced the enzyme. On the other hand, 99% of coagulase-positive staphylococci produced TNase and only 18% of the coagulase-negative staphylococci produced the enzyme. The amount of TNase produced by streptococci and bacilli was significantly lower than that produced by coagulase-positive staphylococci. The pH profile of the streptococci and Bacillus TNases was similar to that of the staphylococcal TNase; each enzyme exhibited a minor peak at pH 7.0 and a broad major peak ranging from pH 8.5 to 10. The nuclease produced by coagulase-positive Staphylococcus was more heat stable than the nucleases produced by Streptococcus and Bacillus; there was little loss in activity of the staphylococcal enzyme after 60 min at 100 °C, whereas 50% of the activity of the streptococcal and Bacillus nucleases was destroyed in 40–60 min and 60–80 min, respectively.

scholarly journals Allium cepa L. responses when Gaeolaelaps aculeifer Canestrini and Parasitus bituberosus Karg are used to control Thrips tabaci Lindeman

2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Mayerly Alejandra Castro-López ◽  
John Wilson Martínez-Osorio
Keyword(s):  
Population Density ◽  
Allium Cepa ◽  
Plant Development ◽  
Insect Pest ◽  
Predatory Mites ◽  
Thrips Tabaci ◽  
Physiological Variables ◽  
Allium Cepa L ◽  
Mite Density ◽  
Chlorophyll Index

Thrips tabaci Lindemann is the main insect pest of Allium cepa L., causing both direct and indirect damage to crops. T. tabaci is controlled by applying chemically synthesized products; however, this insect has already developed resistance to organophosphates, carbamates, and pyrethroids. This study evaluated the effect of soil predatory mites (Gaeolaelaps aculeifer Canestrini and Parasitus bituberosus Karg) on the population density of T. tabaci in potted bulb onion (Allium cepa L.) plants and on the response of physiological variables related to photosynthesis and plant development. Seven treatments were evaluated that released 50, 75 or 100 G. aculeifer or P. bituberosus adults, along with a control without predatory mites. Significant differences (P≤0.05) in the population density of T. tabaci were observed for 13 weeks, with a 78% reduction of individuals in the presence of G. aculeifer and a 72% reduction with P. bituberosus, regardless of mite density, as compared to the control. In addition, the relative chlorophyll index, foliar area, dry leaf weight and fresh bulb weight increased, as compared to the control. The application of 100 individuals of the two species recorded the highest values in the evaluated variables. These results indicate that G. aculeifer and P. bituberosus controls should be explored as an option for integrated T. tabaci management.

Non L.T.E. Populations and Related Quantities for H-H+-e Plasmas as a Function of the Cut-off Level

1974 ◽  
Vol 29 (10) ◽  
pp. 1507-1509 ◽  
Author(s):  
M. Cacciatore ◽  
M. Capitelli
Keyword(s):  
Population Density ◽  
Radiative Recombination ◽  
Excited Level ◽  
Ground Level ◽  
Numerical Results ◽  
Free Electrons ◽  
Direct Excitation ◽  
Minor Influence ◽  
A Minor ◽  
The Continuum

Abstract The influence of the choice of the cut-off level n* of the evaluation of the coefficients of quasistationary plasmas has been studied. The numerical results show that the coefficient r1(i) which represents the contribution of the population density of the ith excited level by direct excitation from the ground level, is strongly affected by the choice of n*. A minor influence is observed 1) on the coefficient r0(i) which represents the contribution to the population density of the ith level from the continuum of free electrons 2) on the collisional-radiative recombination (α) and ionization (S) coefficients'.

scholarly journals Distribution of membranes, especially of plasma-membrane fragments, during zonal centrifugations of homogenates from glucose-repressed Saccharomyces Cerevisiae

1976 ◽  
Vol 154 (3) ◽  
pp. 751-763 ◽  
Author(s):  
T Nurminen ◽  
L Taskinen ◽  
H Suomalainen
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Plasma Membrane ◽  
High Speed ◽  
Membrane Vesicles ◽  
Appreciable Amount ◽  
Main Peak ◽  
Mitochondrial Density ◽  
Minor Peak ◽  
Smooth Membrane ◽  
A Minor

1. The distributions of several enzymes and other marker components were examined after zonal centrifugations of whole homogenates from glucose-repressed Saccharomyces cerevisiae on sucrose and iso-osmotic Ficoll, and the composition and morphology of the fractions were investigated. 2. After high-speed zonal centrifugation most of the protein, acid and alkaline phosphatases, alkaline pyrophosphatase, adenosine monophosphatase, β-fructofuranosidase, α-mannosidase, NADPH-cytochrome c oxidoreductase and an appreciable amount of phospholipid and sterol were non-sedimentable, i.e. were at densities below 1.09 (g/cm3). Most of the RNA was at p=1.06-1.08 in Ficoll and at p=1.09-1.11 in sucrose. 3. The bulk of the Mg2+-dependent adenosine triphosphatase (Mg-ATPase) was coincident with the main peak of phospholipid and sterol, at median density 1.10, which was also rich in smooth-membrane vesicles. In Ficoll, a minor peak of phospholipid and sterol at p-1.12-1.15 contained a smaller part of the oligomycin-insensitive Mg-ATPase and heavy membrane fragments. In sucrose, several minor peaks of Mg-ATPase were in the mitochondrial density range, and a peak of oligomycin-insensitive Mg-ATPase coincident with a minor peak of phospholipid and sterol at around p-1.25 contained heavy membrane fragments of high carbohydrate content, especially mannose. 4. Further purification of the oligomycin-insensitive Mg-ATPase containing membrane preparations was performed on Urografin gradients. 5. It is argued that the oligomycin-insensitive Mg-ATPase containing membranes are fragments of the plasma membrane, but have different densities because they contain different amounts of glycoprotein particles.

scholarly journals NUCLEIC ACID AND PROTEIN METABOLISM DURING THE MITOTIC CYCLE IN VICIA FABA

1961 ◽  
Vol 9 (2) ◽  
pp. 445-462 ◽  
Author(s):  
John Woodard ◽  
Ellen Rasch ◽  
Hewson Swift
Keyword(s):  
Vicia Faba ◽  
Total Protein ◽  
Mitotic Cycle ◽  
Mitotic Division ◽  
Fast Green ◽  
Cytoplasmic Rna ◽  
Minor Peak ◽  
Histone Synthesis ◽  
A Minor ◽  
Nucleolar Rna

In order to investigate some of the cytochemical processes involved in interphase growth and culminating in cell division, a combined autoradiographic and microphotometric study of nucleic acids and proteins was undertaken on statistically seriated cells of Vicia faba root meristems. Adenine-8-C14 and uridine-H3 were used as ribonucleic acid (RNA) precursors, thymidine-H3 as a deoxyribonucleic acid (DNA) precursor, and phenylalanine-3-C14 as a protein precursor. Stains used in microphotometry were Feulgen (DNA), azure B (RNA), pH 2.0 fast green (total protein), and pH 8.1 fast green (histone). The autoradiographic data (representing rate of incorporation per organelle) and the microphotometric data (representing changes in amounts of the various components) indicate that the mitotic cycle may be divided into several metabolic phases, three predominantly anabolic (net increase), and a fourth phase predominantly catabolic (net decrease). The anabolic periods are: 1. Telophase to post-telophase during which there are high rates of accumulation of cytoplasmic and nucleolar RNA and nucleolar and chromosomal total protein. 2. Post-telophase to preprophase characterized by histone synthesis and a diphasic synthesis of DNA with the peak of synthesis at mid-interphase and a minor peak just preceding prophase. The minor peak is coincident with a relatively localized DNA synthesis in several chromosomal regions. This period is also characterized by minimal accumulations of cytoplasmic RNA and chromosomal and nucleolar total protein and RNA. 3. Preprophase to prophase in which there are again high rates of accumulation of cytoplasmic RNA, and nucleolar and chromosomal total protein and RNA. The catabolic phase is: 4. The mitotic division during which there are marked losses of cytoplasmic RNA and chromosomal and nucleolar total protein and RNA.

Sign in / Sign up

Export Citation Format

Share Document