Name: visualization of flow field around a vibrating pipeline within an equilibrium scour hole
Uploaded: 2019-08-26T14:00:00
Description: Watch this Scientific Journal Video about Visualization of Flow Field Around a Vibrating Pipeline Within an Equilibrium Scour Hole at JoVE.com

This work was supported by the Young Scientists Fund of the National Natural Science Foundation of China (51709082) and the Fundamental Research Funds for the Central Universities (2018B13014).

1. Laboratory safety check
<ol>
	<li>Review the safety rules relating to the use of the laser and flume system.</li>
	<li>Ensure that the safety training requirements of the laboratory have been met. 
	NOTE: In this experiment, a set of 5W air-cooling continuous wave laser with a wavelength of 532 nm and a glass-sided straight flume (Figure 1) with dimensions of 11 m length, 0.6 m width, and 0.6 m depth are used. The basic safety recommendations for these two apparatuses are as follow...

<ol>
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The protocol presented in this paper describes a method for visualization of the two-dimensional flow fields and determination of the near-boundary flow stress fields around a forced vibrating pipeline in an equilibrium scour hole by using the PIV techniques. Since the designed pipeline motion is one-dimensional along the y direction, preparing and adjusting the pipeline model and vibration system to fulfill this objective are critical prerequisites for a successful outcome. Any undesirable motions of the pipeli...

Subsea pipelines are widely used in offshore environments for the purpose of fluid or hydro-carbon products conveyance. When a pipeline is placed on an erodible seabed, a scour hole around the pipeline is likely to form because of the waves, currents or dynamic motions of the pipeline itself (forced-vibration or vortex-induced-vibration)1,2. To improve the understanding of the scour mechanism around a subsea pipeline, measurements of the turbulent flow fields and estimations of the bed shear and normal stresses within the pipeline-fluid-seabed interaction region are essential in addition to measurements of the scour hole dimension1,2,3,4,5,6,7. In an environment where the bed shear and normal stresses are extremely difficult to be determined because the flow field is unsteady and the bottom boundary is rough, measured instantaneous near-boundary stresses (at approximately 2 mm above the boundary) could be used as their surrogate8,9. In the past few decades, scour around a vibrating pipeline has been studied and published without quantitatively presenting the values of the sophisticated flow fields around the pipeline within the scour hole3,4,5,10,11,12,13,14,15,16,17,18. Therefore, the goal of this method paper is to provide a novel experimental protocol for visualizing the detailed flow fields and to determine the near-boundary shear and normal stresses within an equilibrium scour hole induced by a forced vibrating pipeline. It should be noted that the pipeline-fluid-seabed interaction process in this study is in a quiescent water environment rather than those with unidirectional currents and waves.
This experimental method consists of two important components, namely, (1) simulation of pipeline (forced) vibrations; and (2) measurements of the flow fields around the pipeline. In the first component, the vibrating pipeline was simulated in an experimental flume by using a vibrating system, which has a servo motor, two connecting springs, and pipeline supporting frames. Different vibration frequencies and amplitudes can be simulated by adjusting the motor speed and location of the connecting springs. In the second component, the time-resolved particle image velocimetry (PIV) and wavelet transform techniques were adopted to obtain high temporal and spatial resolution flow field data at different pipeline vibration phases. The time-resolved PIV system consists of a continuous wave laser, a high-speed camera, seeding particles, and cross-correlation algorithms. Although PIV techniques have been widely used in obtaining steady turbulent flow fields19,20,21,22,23,24,25, applications in complex unsteady flow field conditions, such as cases of pipeline-fluids-seabed interaction, are relatively limited8,9,26,27. The reason probably is because traditional single-time-interval cross-correlation algorithm of PIV techniques is unable to accurately capture the flow features in unsteady flow fields where a relatively high velocity gradient is present9,20. The method described in this paper can solve this problem by using the multiple-time-interval cross-correlation algorithm9,28.

<table border="0" cellpadding="0" cellspacing="0" style="width:1299px;" width="1298">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:211px;">Camera control software</td>
			<td style="width:359px;">Vision Research</td>
			<td style="width:175px;">Phantom PCC 2.6</td>
			<td style="width:555px;">Camera control, image data acquisition and processing</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:211px;">Camera lens</td>
			<td style="width:359px;">Nikon Chiyoda</td>
			<td style="width:175px;"></td>
			<td>Nikor&#160; 60mm, f=2.8 prime lens</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Continuous wave laser&#160;</td>
			<td style="width:359px;">Beijing Laserwave optoelectronics technology co. ltd.</td>
			<td style="width:175px;"></td>
			<td>PIV Laser source; Nd:YAG laser, 532 nm; air-cooling</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:211px;">High-speed camera</td>
			<td style="width:359px;">Vision Research</td>
			<td style="width:175px;">Phantom Miro 120</td>
			<td>Image data recording</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:211px;">Laser sheet forming optics&#160;</td>
			<td style="width:359px;">Thorlabs Inc</td>
			<td style="width:175px;"></td>
			<td>Transform the point laser to a thin laser sheet</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Pipeline model</td>
			<td style="width:359px;">ZONCEPZ SOLUTIONS</td>
			<td style="width:175px;"></td>
			<td>Acrylic cylinder with a diameter of 35 mm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Pipeline vibration system</td>
			<td style="width:359px;">ZONCEPZ SOLUTIONS</td>
			<td style="width:175px;"></td>
			<td>Consists of a sever motor, two connecting springs and pipeline supporting frames.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:211px;">PIV calcuation software</td>
			<td>AXESEA Engineering Technology Limited Co.</td>
			<td style="width:175px;">PISIOU</td>
			<td>Image data processing for obtaining flow fields and pipeline displacements</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:211px;">PIV seeding materials</td>
			<td style="width:359px;">Shimakyu</td>
			<td style="width:175px;"></td>
			<td>Aluminum powder with a diameter of 10um</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:211px;">Recirculating flume&#160;</td>
			<td style="width:359px;">SZU ENGINEERING PTE LTD</td>
			<td style="width:175px;"></td>
			<td>Glass-sided, 11 m long, 0.6 m wide, and 0.6 m deep</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:211px;">Tri-pod</td>
			<td style="width:359px;">MANFROTTO</td>
			<td style="width:175px;">SKU MT190GOC4US 410</td>
			<td>Camara supporting</td>
		</tr>
	</tbody>
</table>

visualization of flow field around a vibrating pipeline within an equilibrium scour hole

An experimental method is presented in this paper to facilitate visualization of the detailed flow fields and determination of the near-boundary shear and normal stresses within an equilibrium scour hole induced by a vibrating pipeline. This method involves the implementation of a pipeline vibration system in a straight flume, a time-resolved particle image velocimetry (PIV) system for pipeline displacement tracking and flow fields measurements. The displacement time-series of the vibrating pipeline are obtained by using the cross-correlation algorithms. The steps for processing raw particle laden images obtained by using the time-resolved PIV are described. The detailed instantaneous flow fields around the vibrating pipeline at different vibrating phases are calculated by using a multiple-time-interval cross-correlation algorithm to avoid displacement bias error in the flow regions with a large velocity gradient. By applying the wavelet transform technique, the captured images that have the same vibrating phase are accurately cataloged before the phase-averaged velocity fields are obtained. The key advantages of the flow measurement technique described in this paper are that it has a very high temporal and spatial resolution and can be simultaneously used to obtain the pipeline dynamics, flow fields, and near-boundary flow stresses. By using this technique, more in-depth studies of the 2-dimensional flow field in a complex environment, such as that around a vibrating pipeline, can be conducted to better understand the associated sophisticated scour mechanism.

An example of the comparison between the raw image and processed image of the pipeline displacements tracking and instantaneous velocity calculation is shown in Figure 3. As shown in Figure 3b, the seeding particles and noise in the raw image are filtered out and the shining pipeline edge is retained to obtain the displacement time series. As shown in Figures 3c, light scatters/reflections around the seeding particles, pipeline ...

Watch this Scientific Journal Video about Visualization of Flow Field Around a Vibrating Pipeline Within an Equilibrium Scour Hole at JoVE.com

Visualization of Flow Field Around a Vibrating Pipeline Within an Equilibrium Scour Hole

The goal of the protocol is to enable visualization of the detailed flow fields and determination of the near-boundary shear and normal stresses within an equilibrium scour hole induced by a vibrating pipeline.

An experimental method is presented in this paper to facilitate visualization of the detailed flow fields and determination of the near-boundary shear and ...

This experimental protocol is to visualize the detail flow fields and the near boundary share in normal stresses within an equilibrium scour hole induced by a forced vibrating pipeline. The key advantage of this measurement technique is its capacity to simultaneously obtain pipeline dynamics, flow fields and near boundary flow stresses in high resolution. By using this technique, more in-depth studies of the two dimensional flow field in a complex environment can be conducted to better understand the scour mechanism.The experiment takes place in a flume 11 meters long. The cross section is square with side length of 0.6 meters. This schematic view of the flume provides additional details including the location of an erodible seabed model.The water level is 0.4 meters above the seabed. In the seabed model, use uniformly distributed medium sand that has been compacted and leveled. Have the structure for the vibration system in place over the flume.This consists of a fixed frame that is locked on the top rails of the flume. The fixed frame has a moveable pole that supports an aluminum frame. The aluminum supporting the frame holds the pipeline model above the seabed model in the flume.This schematic provides an overview of the setup. Note that there are four bearings that ensure the aluminum supporting frame can only vibrate vertically. A connecting rod between the movable pole and a servo motor drives the motion of the aluminum frame.The setup depends on the pipe geometry. This duplicate of the acrylic pipeline model has a diameter of 35 millimeters. Adjust the supporting frame and pole so the bottom of the pipeline is one diameter above the initial seabed surface.Respect all laser safety protocols and begin working with the laser. Place the 532 nanometer laser and optics for velocimetry on top of the flume. The optics include elements to form a sheet of illumination.With the laser on, adjust the optics so that a flat sheet of illumination is formed in the field of interest in the flume. The sheet should be along the flume center and parallel to its side walls. These schematic front and side views indicate the position of the laser and optics and the created laser sheet in the setup.Next, set up the camera of the particle image velocimetry apparatus. Use a high speed camera with the appropriate focal length directed perpendicularly to the laser sheet. Connect the camera to a computer with the correct control software.With the camera on, adjust the field of view to ensure the pipeline fluid seabed region is visible and the image is clear. To calibrate the setup, begin with the seeding particles. This aluminum powder provides particles with a diameter of 10 microns.Add about 20 grams of seeding particles to the test section of the flume. Verify that the camera brings the seeding particles into sharp focus. Then, place a calibration ruler inside the field of view on the laser sheet plane and capture a calibration image.After choosing a sampling rate for data collection, turn off the laser and camera. For the experiment, obtain a transparent acrylic plate. Support it over the test bed below the laser source and on the water surface to suppress surface fluctuations.This diagram provides details of the use of strings attached to the flume rails to support the plate in this setup. Next, turn on the servo motor on the frame. This will begin to induce forced vibrations on the pipeline model.Keep the vibration system running for 24 hours. After 24 hours, turn on the laser to create the light sheet. Start the camera and its control software using the calibrated settings.Then, turn off the lights and begin data collection. Once the data is collected, check that the seeding particle density for 32 by 32 pixel interrogation window is greater than eight before collecting additional datasets. Once all of the datasets have been collected, begin data processing.Work with the particle image velocimetry software with the calibration image opened. Next, go to the toolbar and click the scale setup button. Move the cross hairs to a mark on the ruler's image and tag it.Next, tag a second mark on the ruler's image. In the dialogue box that opens, enter the distance between the marks according to the ruler. Note the scale that is computed.Return to the toolbar and click the origin button. From there, use the mouse to set the origin of the coordinates for all of the data images. Click yes when done.Then, click on the file menu and load the first of the raw images that were collected as data. Check that the other files are accessible but return to the first file. Next, click on the parameter menu.In the dialogue box, enter the number of data files and the sample rate to load all the images. Save the values and close the box. Now, go to the image filter menu.There, apply the low pass filter. In the toolbar, click the PTV module. Follow this by clicking tracing point.Then in the image, find the center point at the right half of the pipeline circumference and select it. Okay the selection before clicking on PTV tools in the toolbar. In the dialogue box that opens, adjust the gamma, light gate and median filter settings to single out the pipeline outline in the image.After approving the changes, click the object tracking button. Use the mouse to select an identifiable portion of the pipeline on the processed image. Once this is done, the software tracks the displacement in the images and records the time series.After the data is saved, go to and click on PTV tools. In the dialogue box, click the default button and OK to recover the raw image for subsequent analysis. Click on PTV module to deactivate the module.Remain in the toolbar and open the parameter panel. Verify the velocity vector calculation parameter and others before closing the dialogue box. Then, go to the image filter menu.Apply a laplacian filter function to the raw images to highlight the seeding particles and filter out undesired scattered light. Now, go back to the toolbar and click on boundary. Use the mouse to set the geometric mask on the images to exclude the seabed region.Confirm that the boundary has been set. When done, click boundary save to save the boundary data. Finally, go to the toolbar and click the run button to calculate the instantaneous velocity fields using the cross correlation method.Export and save the instantaneous velocity field's data for further analysis. This an image of a quasi-equilibrium scour profile and vibrating pipeline taken after 24 hours of pipeline vibration. The origin for analysis is set at the intersection point at the original seabed surface and the pipeline vertical center line.Seeding particles are visible but very few sediment particles are suspended in the flow, suggesting the system is in a quasi-equilibrium stage. Data collected with the protocol allows visualization of the phase averaged velocity field and vorticity dynamics. This video consists of 72 frames of flow fields from one pipeline vibration cycle.This method can also be applied to investigate vortex induced vibration processes such as pipeline vibration induced by asymmetry vortex shedding.

visualization-flow-field-around-vibrating-pipeline-within-an

Research

JoVE Journal

Environment

Surface Renewal: An Advanced Micrometeorological Method for Measuring and Processing Field-Scale Energy Flux Density Data

Advanced micrometeorological methods have become increasingly important in soil, crop, and environmental sciences. For many scientists without formal training in atmospheric science, these techniques are relatively inaccessible. Surface renewal and other flux measurement methods require an understanding of boundary layer meteorology and extensive training in instrumentation and multiple data management programs. To improve accessibility of these techniques, we describe the underlying theory of surface renewal measurements, demonstrate how to set up a field station for surface renewal with eddy covariance calibration, and utilize our open-source turnkey data logger program to perform flux data acquisition and processing. The new turnkey program returns to the user a simple data table with the corrected fluxes and quality control parameters, and eliminates the need for researchers to shuttle between multiple processing programs to obtain the final flux data. An example of data generated from these measurements demonstrates how crop water use is measured with this technique. The output information is useful to growers for making irrigation decisions in a variety of agricultural ecosystems. These stations are currently deployed in numerous field experiments by researchers in our group and the California Department of Water Resources in the following crops: rice, wine and raisin grape vineyards, alfalfa, almond, walnut, peach, lemon, avocado, and corn.

Surface renewal is a micrometeorological method that is being used increasingly to determine energy fluxes, but its technical complexity makes it inaccessible to a broad audience. We describe the steps needed to set up and calibrate a surface renewal field station, to acquire and process data, and to correctly interpret results.

Advanced micrometeorological methods have become  increasingly important in soil, crop, and environmental sciences.  For many scientists without formal ...

Technique for Studying Arthropod and Microbial Communities within Tree Tissues

Phloem tissues of pine are habitats for many thousands of organisms. Arthropods and microbes use phloem and cambium tissues to seek mates, lay eggs, rear young, feed, or hide from natural enemies or harsh environmental conditions outside of the tree. Organisms that persist within the phloem habitat are difficult to observe given their location under bark. We provide a technique to preserve intact phloem and prepare it for experimentation with invertebrates and microorganisms. The apparatus is called a &#8216;phloem sandwich&#8217; and allows for the introduction and observation of arthropods, microbes, and other organisms. This technique has resulted in a better understanding of the feeding behaviors, life-history traits, reproduction, development, and interactions of organisms within tree phloem. The strengths of this technique include the use of inexpensive materials, variability in sandwich size, flexibility to re-open the sandwich or introduce multiple organisms through drilled holes, and the preservation and maintenance of phloem integrity. The phloem sandwich is an excellent educational tool for scientific discovery in both K-12 science courses and university research laboratories.

We provide a technique to preserve intact tree phloem and prepare it for observation. We create an apparatus called a phloem sandwich that allows for the introduction and observation of arthropods, microbes, and other organisms that inhabit phloem tissues.

Phloem tissues of pine are habitats for many thousands of organisms.  Arthropods and microbes use phloem and cambium tissues to seek mates, lay eggs, rear ...

Spotting Cheetahs: Identifying Individuals by Their Footprints

The cheetah (Acinonyx jubatus) is Africa's most endangered large felid and listed as Vulnerable with a declining population trend by the IUCN1. It ranges widely over sub-Saharan Africa and in parts of the Middle East. Cheetah conservationists face two major challenges, conflict with landowners over the killing of domestic livestock, and concern over range contraction. Understanding of the latter remains particularly poor2. Namibia is believed to support the largest number of cheetahs of any range country, around 30%, but estimates range from 2,9053 to 13,5204. The disparity is likely a result of the different techniques used in monitoring.
Current techniques, including invasive tagging with VHF or satellite/GPS collars, can be costly and unreliable. The footprint identification technique5 is a new tool accessible to both field scientists and also citizens with smartphones, who could potentially augment data collection. The footprint identification technique analyzes digital images of footprints captured according to a standardized protocol. Images are optimized and measured in data visualization software. Measurements of distances, angles, and areas of the footprint images are analyzed using a robust cross-validated pairwise discriminant analysis based on a customized model. The final output is in the form of a Ward's cluster dendrogram. A user-friendly graphic user interface (GUI) allows the user immediate access and clear interpretation of classification results.
The footprint identification technique algorithms are species specific because each species has a unique anatomy. The technique runs in a data visualization software, using its own scripting language (jsl) that can be customized for the footprint anatomy of any species. An initial classification algorithm is built from a training database of footprints from that species, collected from individuals of known identity. An algorithm derived from a cheetah of known identity is then able to classify free-ranging cheetahs of unknown identity. The footprint identification technique predicts individual cheetah identity with an accuracy of &gt;90%.

The cheetah (Acinonyx jubatus) is an iconic, endangered species, but conservation efforts are challenged by habitat shrinkage and conflict with commercial farmers. The footprint identification technique, a robust, accurate and cost-effective image classification system, is a new approach to monitoring cheetahs.

The cheetah (Acinonyx jubatus) is Africa's most endangered large felid and listed as Vulnerable with a declining population trend by the IUCN1. It ranges ...

Watershed Planning within a Quantitative Scenario Analysis Framework

There is a critical need for tools and methodologies capable of managing aquatic systems within heavily impacted watersheds. Current efforts often fall short as a result of an inability to quantify and predict complex cumulative effects of current and future land use scenarios at relevant spatial scales. The goal of this manuscript is to provide methods for conducting a targeted watershed assessment that enables resource managers to produce landscape-based cumulative effects models for use within a scenario analysis management framework. Sites are first selected for inclusion within the watershed assessment by identifying sites that fall along independent gradients and combinations of known stressors. Field and laboratory techniques are then used to obtain data on the physical, chemical, and biological effects of multiple land use activities. Multiple linear regression analysis is then used to produce landscape-based cumulative effects models for predicting aquatic conditions. Lastly, methods for incorporating cumulative effects models within a scenario analysis framework for guiding management and regulatory decisions (e.g., permitting and mitigation) within actively developing watersheds are discussed and demonstrated for 2 sub-watersheds within the mountaintop mining region of central Appalachia. The watershed assessment and management approach provided herein enables resource managers to facilitate economic and development activity while protecting aquatic resources and producing opportunity for net ecological benefits through targeted remediation.

There is a critical need for tools and methodologies capable of managing aquatic systems in the face of uncertain future conditions. We provide methods for conducting a targeted watershed assessment that enables resource managers to produce landscape-based cumulative effects models for use within a scenario analysis management framework.

There is a critical need for tools and methodologies capable of managing aquatic systems within heavily impacted watersheds. Current efforts often fall ...

Experimental Protocol for Biodiesel Production with Isolation of Alkenones as Coproducts from Commercial Isochrysis Algal Biomass

The need to replace petroleum fuels with alternatives from renewable and more environmentally sustainable sources is of growing importance. Biomass-derived biofuels have gained considerable attention in this regard, however first generation biofuels from edible crops like corn ethanol or soybean biodiesel have generally fallen out of favor. There is thus great interest in the development of methods for the production of liquid fuels from domestic and superior non-edible sources. Here we describe a detailed procedure for the production of a purified biodiesel from the marine microalgae Isochrysis. Additionally, a unique suite of lipids known as polyunsaturated long-chain alkenones are isolated in parallel as potentially valuable coproducts to offset the cost of biodiesel production. Multi-kilogram quantities of Isochrysis are purchased from two commercial sources, one as a wet paste (80% water) that is first dried prior to processing, and the other a dry milled powder (95% dry). Lipids are extracted with hexanes in a Soxhlet apparatus to produce an algal oil (&#34;hexane algal oil&#34;) containing both traditional fats (i.e., triglycerides, 46-60% w/w) and alkenones (16-25% w/w). Saponification of the triglycerides in the algal oil allows for separation of the resulting free fatty acids (FFAs) from alkenone-containing neutral lipids. FFAs are then converted to biodiesel (i.e., fatty acid methyl esters, FAMEs) by acid-catalyzed esterification while alkenones are isolated and purified from the neutral lipids by crystallization. We demonstrate that biodiesel from both commercial Isochrysis biomasses have similar but not identical FAME profiles, characterized by elevated polyunsaturated fatty acid contents (approximately 40% w/w). Yields of biodiesel were consistently higher when starting from the Isochrysis wet paste (12% w/w vs. 7% w/w), which can be traced to lower amounts of hexane algal oil obtained from the powdered Isochrysis product.

Experimental Protocol for Biodiesel Production with Isolation of Alkenones as Coproducts from Commercial Isochrysis Algal Biomass

Detailed methods are presented for the production of biodiesel along with the co-isolation of alkenones as valuable coproducts from commercial Isochrysis microalgae.

The need to replace petroleum fuels with alternatives from renewable and more environmentally sustainable sources is of growing importance. ...

Kinematic History of a Salient-recess Junction Explored through a Combined Approach of Field Data and Analog Sandbox Modeling

Within fold-thrust belts, the junctions between salients and recesses may hold critical clues to the overall kinematic history. The deformation history within these junctions is best preserved in areas where thrust sheets extend from a salient through an adjacent recess. We examine one such junction within the Sevier fold-thrust belt (western United States) along the Leamington transverse zone, northern Utah. Deformation within this junction took place by faulting and cataclastic flow. Here, we describe a protocol that examines these fault patterns to better understand the kinematic history of the field area. Fault data is supplemented by analog sandbox experiments. This study suggests that, in detail, deformation within the overlying thrust sheet may not directly reflect the underlying basement structure. We demonstrate that this combined field-experimental approach is easy, accessible, and may provide more details to the deformation preserved in the crust than other more expensive methods, such as computer modeling. In addition, the sandbox model may help to explain why and how these details formed. This method can be applied throughout fold-thrust belts, where upper-crustal rocks are well preserved. In addition, it can be modified to study any part of the upper crust that has been deformed via elastico-frictional mechanisms. Finally, this combined approach may provide more details as to how fold-thrust belts maintain critical-taper and serve as potential targets for natural resource exploration.

Kinematic histories of fold-thrust belts are typically based on careful examinations of high-grade metamorphic rocks within a salient. We provide a novel method of understanding fold-thrust belts by examining salient-recess junctions. We analyze the oft-ignored upper crustal rocks using a combined approach of detailed fault analysis with experimental sandbox modeling.

Within fold-thrust belts, the junctions between salients and recesses may hold critical clues to the overall kinematic history. The deformation history ...

Modification and Application of a Leaf Blower-vac for Field Sampling of Arthropods

Rice fields host a large diversity of arthropods, but investigating their population dynamics and interactions is challenging. Here we describe the modification and application of a leaf blower-vac for suction sampling of arthropod populations in rice. When used in combination with an enclosure, application of this sampling device provides absolute estimates of the populations of arthropods as numbers per standardized sampling area. The sampling efficiency depends critically on the sampling duration. In a mature rice crop, a two-minute sampling in an enclosure of 0.13 m2 yields more than 90% of the arthropod population. The device also allows sampling of arthropods dwelling on the water surface or the soil in rice paddies, but it is not suitable for sampling fast flying insects, such as predatory Odonata or larger hymenopterous parasitoids. The modified blower-vac is simple to construct, and cheaper and easier to handle than traditional suction sampling devices, such as D-vac. The low cost makes the modified blower-vac also accessible to researchers in developing countries.

Assessment of arthropod abundance in crops is critical for investigating population dynamics and species interactions. Here we describe the modification and application of a leaf blower-vac for suction sampling of arthropods in rice.

Rice fields host a large diversity of arthropods, but investigating their population dynamics and interactions is challenging. Here we describe the ...

Reliable Method for Assessing Seed Germination, Dormancy, and Mortality under Field Conditions

We describe techniques for approximating seed bank dynamics over time using Helianthus annuus as an example study species. Strips of permeable polyester fabric and glue can be folded and glued to construct a strip of compartments that house seeds and identifying information, while allowing contact with soil leachate, water, microorganisms, and ambient temperature. Strips may be constructed with a wide range of compartment numbers and sizes and allow the researcher to house a variety of genotypes within a single species, different species, or seeds that have experienced different treatments. As opposed to individual seed packets, strips are more easily retrieved as a unit. While replicate packets can be included within a strip, different strips can act as blocks or can be retrieved at different times for observation of seed behavior over time. We used a high temperature glue gun to delineate compartments and sealed the strips once the seed and tags identifying block and removal times were inserted. The seed strips were then buried in the field at the desired depth, with the location marked for later removal. Burrowing animal predators were effectively excluded by use of a covering of metal mesh hardware cloth on the soil surface. After the selected time interval for burial, strips were dug up and seeds were assessed for germination, dormancy and mortality. While clearly dead seeds can often be distinguished from ungerminated living ones by eye, dormant seeds were conclusively identified using a standard Tetrazolium chloride colorimetric test for seed viability.

Here we present a protocol for assessing seed survivorship, germination and dormancy under field conditions using buried, labeled seed strips and tetrazolium chloride (TZ) viability testing.

We describe techniques for approximating seed bank dynamics over time using Helianthus annuus as an example study species. Strips of permeable polyester ...

Field Experiments of Pollination Ecology: The Case of Lycoris sanguinea var. sanguinea

Plant-pollinator interactions have been studied for approximately one hundred years. During that time, many field methods have been developed to clarify the pollination effectiveness of each pollinator for visited flowers. Pollinator observations have been one of the most common methods to identify pollinators, and bagging and cage experiments have been conducted to show the effectiveness of specific pollinators. In a previous study of Lycoris sanguinea var. sanguinea, its effective pollinators, the visitation frequencies of each floral visitor, and its reproductive strategies were not identified. This study reports the observation that small bees visited flowers that were partially opened (breaking buds). To the best of our knowledge, this phenomenon has not been reported previously. Further, this study investigates the hypothesis that small bees can pollinate at that flowering stage. This study demonstrates the basic methods of field experiments in pollination ecology using L. sanguinea var. sanguinea. Pollinator observations and digital video showed the visitation frequencies of each floral visitor. Bagging and cage experiments revealed that these flowers could be pollinated fully and that breaking-bud pollination could be important for the pollination of this plant species. The advantages and disadvantages of each method are discussed, and recent developments, including laboratory experiments, are described.

Field Experiments of Pollination Ecology: The Case of Lycoris sanguinea var. sanguinea

To reveal the pollinator effectiveness of a given plant species, multiple methods of field experiments have been developed. This study demonstrates the basic methods of field experiments for pollination ecology using the case study of Lycoris sanguinea var. sanguinea and the novel pollination mechanism, breaking-bud pollination.

Plant-pollinator interactions have been studied for approximately one hundred years. During that time, many field methods have been developed to clarify ...

Development of Metarhizium anisopliae as a Mycoinsecticide: From Isolation to Field Performance

A major concern when developing commercial mycoinsecticides is the kill speed compared to that of chemical insecticides. Therefore, isolation and screening for the selection of a fast-acting, highly virulent entomopathogenic fungus are important steps. Entomopathogenic fungi, such as Metarhizium, Beauveria, and Nomurea, which act by contact, are better suited than Bacillus thuringiensis or nucleopolyhedrosis virus (NPV), which must be ingested by the insect pest. In the present work, we isolated 68 Metarhizium strains from infected insects using a soil dilution and bait method. The isolates were identified by the amplification and sequencing of the ITS1-5.8S-ITS2 and 26S rDNA region. The most virulent strain of Metarhizium anisopliae was selected based on the median lethal concentration (LC50) and time (LT50) obtained in insect bioassays against III-instar larvae of Helicoverpa armigera. The mass production of spores by the selected strain was carried out with solid-state fermentation (SSF) using rice as a substrate for 14 days. Spores were extracted from the sporulated biomass using 0.1% tween-80, and different formulations of the spores were prepared. Field trials of the formulations for the control of an H. armigera infestation in pigeon peas were carried out by randomized block design. The infestation control levels obtained with oil and aqueous formulations (78.0% and 70.9%, respectively) were better than the 63.4% obtained with chemical pesticide.

Development of Metarhizium anisopliae as a Mycoinsecticide: From Isolation to Field Performance

Here, we report the different stages involved in the knowledge-based development of an effective mycoinsecticide, including the isolation, identification, screening, and selection of the "best-fit" entomopathogenic fungus, Metarhizium anisopliae, for the control of insect pests in agriculture.