scholarly journals Different Hatching Rates of Floodwater Mosquitoes Aedes sticticus, Aedes rossicus and Aedes cinereus from Different Flooded Environments

Insects ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 279
Author(s):  
Anders Lindström ◽  
Disa Eklöf ◽  
Tobias Lilja
Keyword(s):  
Tap Water ◽  
Soil Samples ◽  
Mosquito Larvae ◽  
Retaining Structures ◽  
Retaining Structure ◽  
Large Numbers ◽  
Random Samples ◽  
Nuisance Species ◽  
Flooding Events ◽  
Hatching Rates

In the lower Dalälven region, floodwater mosquitoes cause recurring problems. The main nuisance species is Aedes (Ochlerotatus) sticticus, but large numbers of Aedes (Aedes) rossicus and Aedes (Aedes) cinereus also hatch during flooding events. To increase understanding of which environments in the area give rise to mosquito nuisance, soil samples were taken from 20 locations from four environmental categories: grazed meadows, mowed meadows, unkept open grassland areas and forest areas. In each location 20 soil samples were taken, 10 from random locations and 10 from moisture retaining structures, such as tussocks, shrubs, piles of leaves, logs, and roots. The soil samples were soaked with tap water in the lab, and mosquito larvae were collected and allowed to develop to adult mosquitoes for species identification. Fewer larvae hatched from mowed areas and more larvae hatched from moisture retaining structure samples than random samples. The results showed that Aedes cinereus mostly hatch from grazed and unkept areas and hatched as much from random samples as from structures, whereas Aedes sticticus and Aedes rossicus hatched from open unkept and forest areas and hatch significantly more from structure samples. When the moisture retaining structures in open unkept areas where Aedes sticticus hatched were identified it was clear that they hatched predominantly from willow shrubs that offered shade. The results suggest that Ae. sticticus and Ae. cinereus favor different flooded environments for oviposition.

Macrostructural and Microstructural Properties of Residual Soils as Engineered Landfill Liner Materials

2021 ◽  
Author(s):  
Lee Li Yong ◽  
Vivi Anggraini ◽  
Mavinakere Eshwaraiah Raghunandan ◽  
Mohd. Raihan Taha
Keyword(s):  
Tap Water ◽  
Chemical Precipitation ◽  
Soil Samples ◽  
Residual Soil ◽  
Diffuse Double Layer ◽  
Microstructural Properties ◽  
Residual Soils ◽  
Soil Leachate ◽  
Landfill Liner ◽  
X Ray

ABSTRACT This study assessed the performance of residual soils with regard to their macrostructural and microstructural properties and compatibility with leachate in pursuit of exploring alternative cost-effective and efficient landfill liner materials. A series of laboratory investigations was conducted on three residual soil samples by using tap water and leachate as permeation fluid to achieve the objectives of the study. The zeta potential measurements revealed that the presence of multivalent cations in the leachate decreased the diffuse double layer (DDL) thickness around the soil particles. The reduced DDL thickness caused a decrease in Atterberg limits of soil-leachate samples and changes in the classification of fine fractions. Additionally, the effects of pore clogging attributed to chemical precipitation and bioclogging were responsible for the reduction in measured hydraulic conductivities of soil-leachate samples. These effects can be clearly observed from the field-emission scanning electron microscopy images of soil-leachate samples with the appearance of less visible voids that led to a more compact and dense structure. The formation of new non-clay minerals and associated changes in the Al and Si ratio as reflected in the x-ray diffraction diffractograms and energy-dispersive x-ray analyses, respectively, were attributed to the effects of chemical precipitation. This study concluded that S1 and S2 residual soil samples are potential landfill liner materials because they possess adequate grading characteristics, adequate unconfined compressive strength, low hydraulic conductivity, and good compatibility with leachate. In contrast, the S3 sample requires further treatment to enhance its properties in order to comply with the requirements of landfill liner materials.

scholarly journals Distribution of Bacillus thuringiensis subsp. israelensis in Soil of a Swiss Wetland Reserve after 22 Years of Mosquito Control

2011 ◽  
Vol 77 (11) ◽  
pp. 3663-3668 ◽  
Author(s):  
Valeria Guidi ◽  
Nicola Patocchi ◽  
Peter Lüthy ◽  
Mauro Tonolla
Keyword(s):  
Spatial Distribution ◽  
Bacillus Thuringiensis ◽  
Confidence Interval ◽  
Quantitative Pcr ◽  
Mosquito Control ◽  
Soil Samples ◽  
Sampling Point ◽  
Content Type ◽  
Large Numbers ◽  
Continuous Accumulation

ABSTRACTRecurrent treatments withBacillus thuringiensissubsp.israelensisare required to control the floodwater mosquitoAedes vexansthat breeds in large numbers in the wetlands of the Bolle di Magadino Reserve in Canton Ticino, Switzerland. Interventions have been carried out since 1988. In the present study, the spatial distribution of restingB. thuringiensissubsp.israelensisspores in the soil was measured. TheB. thuringiensissubsp.israelensisconcentration was determined in soil samples collected along six transects covering different elevations within the periodically flooded zones. A total of 258 samples were processed and analyzed by quantitative PCR that targeted an identical fragment of 159 bp for theB. thuringiensissubsp.israelensis cry4Aaandcry4Bagenes.B. thuringiensissubsp.israelensisspores were found to persist in soils of the wetland reserve at concentrations of up to 6.8 log per gram of soil. Continuous accumulation due to regular treatments could be excluded, as the decrease in spores amounted to 95.8% (95% confidence interval, 93.9 to 97.7%). The distribution of spores was correlated to the number ofB. thuringiensissubsp.israelensistreatments, the elevation of the sampling point, and the duration of the flooding periods. The number ofB. thuringiensissubsp.israelensistreatments was the major factor influencing the distribution of spores in the different topographic zones (P< 0.0001). These findings indicated thatB. thuringiensissubsp.israelensisspores are rather immobile after their introduction into the environment.

scholarly journals Timber sheet pile-vegetation model for stream bank retaining structure

2019 ◽  
Vol 92 ◽  
pp. 12013 ◽  
Author(s):  
Abhijith Kamath ◽  
Wolfgang Gard ◽  
Jan-Willem Van de Kuilen
Keyword(s):  
Riparian Vegetation ◽  
Root Systems ◽  
Physical Parameters ◽  
Preliminary Estimate ◽  
Sheet Pile ◽  
Vegetation Model ◽  
Mechanical Reinforcement ◽  
Retaining Structures ◽  
Retaining Structure ◽  
Stream Bank

Timber sheet piles are widely used to protect canal and stream banks. Quite often, riparian vegetation also grows along these retaining structures. Roots of riparian vegetation mechanically reinforce the soil with their root systems. A timber sheetpile- vegetation model is developed taking into account the mechanical reinforcement of the vegetation roots. The model uses easy to obtain physical parameters, which makes it suitable to have a preliminary estimate of how the forces on the bio engineered structure would evolve.

Laboratory Tests of Insecticides on Mosquito Larvae in Polluted and Tap Water

1963 ◽  
Vol 56 (6) ◽  
pp. 834-835
Author(s):  
Lawrence L. Lewallen ◽  
William H. Wilder
Keyword(s):  
Laboratory Tests ◽  
Tap Water ◽  
Mosquito Larvae

Diving beetles (Dytiscidae) as predators of mosquito larvae (Culicidae) in field experiments and in laboratory tests of prey preference

2003 ◽  
Vol 93 (3) ◽  
pp. 219-226 ◽  
Author(s):  
E. Lundkvist ◽  
J. Landin ◽  
M. Jackson ◽  
C. Svensson
Keyword(s):  
Body Length ◽  
Negative Correlation ◽  
Laboratory Tests ◽  
Field Experiments ◽  
Mosquito Larvae ◽  
Natural Control ◽  
Large Numbers ◽  
Diving Beetles ◽  
The Mean ◽  
Artificial Ponds

AbstractField experiments were performed in artificial ponds to evaluate how the density of predatory diving beetles (Dytiscidae) would affect the population levels of mosquito larvae (Culicidae). Mosquitoes colonizing the ponds were predominantly species of the genus Culex. In 2000, most of the dytiscids colonizing the ponds were small (Hydroporus spp.), and these predators had no impact on the size of larval mosquito populations, not even in ponds with added dytiscids. In 2001, larger beetles (Ilybius, Rhantus, and Agabus spp.) were more common, and there were significantly fewer mosquito larvae in ponds with the highest numbers of dytiscids. There was a negative correlation between numbers of diving beetles in the ponds and the mean body length of mosquito larvae. In neither year could dytiscid densities be maintained above a certain level owing to emigration. In laboratory tests, there were marked differences between three common dytiscid species in regard to preferences for Daphnia and Culex species as prey: Colymbetes paykulli Erichson chose mosquito larvae more often, whereas both Ilybius ater (De Geer) and I. fuliginosus (Fabricius) preferred Daphnia spp. All of the tested dytiscids consumed large numbers of prey. Since some dytiscid species can efficiently decrease populations of mosquito larvae, they are probably important in the natural control of these dipterans.

An automatic, multichamber soil-washing apparatus for removing fungal spores from soil

1972 ◽  
Vol 18 (9) ◽  
pp. 1399-1404 ◽  
Author(s):  
J. Bissett ◽  
P. Widden
Keyword(s):  
Fungal Spores ◽  
Soil Washing ◽  
Soil Samples ◽  
Cross Contamination ◽  
Vegetative Mycelium ◽  
Soil Particles ◽  
Large Numbers

An automatic soil-washing apparatus is described which enabled the washing of fungus spores out of large numbers of soil samples simultaneously. Tests of the apparatus indicated that superficial spores were removed from most of the soil particles. This allowed organisms growing in soil as vegetative mycelium to be isolated more readily without the serious competition commonly encountered from organisms sporulating heavily in the soil. Virtually no cross-contamination of soil samples occurred in the multichambered apparatus.

scholarly journals Comparison of Genetic Diversity in Core and Whole Germplasm Collections for Phaseolus vulgaris L.

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 772E-772
Author(s):  
J. Nienhuis ◽  
P. Skroch ◽  
M. Sass ◽  
S. Beebe ◽  
J. Tohme ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Phaseolus Vulgaris ◽  
Phaseolus Vulgaris L ◽  
The Core ◽  
Germplasm Collections ◽  
Large Numbers ◽  
Random Samples ◽  
Two Samples ◽  
Marker Frequency ◽  
Seed Characteristics

The number of Phaseolus vulgaris germplasm accessions numbers more than 30,000. While the large numbers of accessions increase the probability of preserving genetic variability they simultaneously limit the efficient and routine utilization of this resource. From the approximately 4000 P. vulgaris accessions in the C.I.A.T. whole collection that were collected in Mexico, a core collection of 400 accessions was developed based on variation for agronomic performance, ecological adaptation, and seed characteristics. Random samples of 90 accessions each were drawn from the core and whole collections and evaluated for 224 polymorphic RAPD bands. Based on analysis of the RAPD data there were no significant differences in genetic diversity between the two samples. The correlation of marker frequency for the two samples was 0.984 confirming that the two samples represent the same population.

Survival of a lowland heathland seed bank after a 33-year burial

1997 ◽  
Vol 7 (4) ◽  
pp. 409-411 ◽  
Author(s):  
Ken Thompson ◽  
Stuart R. Band
Keyword(s):  
Seed Bank ◽  
Land Surface ◽  
Calluna Vulgaris ◽  
Soil Samples ◽  
Large Numbers ◽  
First Time

AbstractSoil samples were collected from the original land surface beneath an experimental earthwork, constructed in 1963 at Morden Bog, Dorset, England, and excavated in 1996. Large numbers of seeds of Calluna vulgaris, Erica cinerea and E. tetralix germinated from the samples, but other species present in the original flora, including Ulex minor and several grasses, were absent. The results confirm the previously-documented longevity of Calluna and E. tetralix, and for the first time demonstrate similar longevity in E. cinerea.

A Method of testing Oils and other Chemical Agents for Killing Mosquito Larvae

1936 ◽  
Vol 27 (4) ◽  
pp. 649-652
Author(s):  
J. Cauchi ◽  
W. Sellers ◽  
J. D. Bunkall
Keyword(s):  
Mosquito Larva ◽  
Laboratory Experiments ◽  
Fourth Instar ◽  
Mosquito Larvae ◽  
Mineral Oils ◽  
Chemical Agents ◽  
Large Numbers ◽  
Southern Nigeria ◽  
Wet Weather ◽  
Comparability Of Results

In 1933, the late Dr. Drysdale Anderson made a series of laboratory experiments at Onitsha, Southern Nigeria, to study the mosquito larva-killing properties of a number of mineral oils and of some mixtures of these oils. For the experiments he used fresh fourth instar larvae of Anopheles costalis, Giles, which is the most common malaria-carrying species in Nigeria; these larvae he obtained from two temporary pools in the bush, which produced large numbers of larvae in wet weather but dried up after a period of 48 hours without rain.For his experiments Dr. Anderson used plates marked at a diameter of 19-5 cm. (giving a depth of fluid of 2-5 cm.) with 20 to 30 larvae for each plate and one observer for every 3 plates. An experiment consisted of an average of 200 larvae. The oil was applied by discharging 0·65 cc. from a pipette.It was suggested that confirmatory experiments in the field were required to check the results of these laboratory experiments. This led to the methods described below being devised by us for testing the efficiency of larvicides under conditions as nearly natural as practicable.To ensure comparability of results we dug our own breeding-pits, each approximately 2 feet by 2 feet square, on low-lying ground where the ground water is very near the surface. The pits were made of such a depth as to contain 8–12 inches of water and are kept under observation for breeding, and when this occurs its intensity is recorded by measuring out a definite number of dips taken along the four sides of the pit and by counting the larvae captured.For this “dipping” we made our own rectangular dishes of zinc sheeting with sloping sides 2 inches from rim to bottom, 9 inches by 5½ inches in area at rim level, and 8 inches by 4½ inches in area at the bottom. In practice, such dishes collect about 30 fluid ounces at each complete dip.

Sign in / Sign up

Export Citation Format

Share Document