This project was funded by the Government of Canada through Genome Canada and the Ontario Genomics Institute (OGI-046), and Ontario Research Fund&#8211;Global Leadership in Genomics and Life Sciences GL2-01-035 (to M.G. and V.G.). T.V.L. is a postdoctoral fellow of the Fund for Scientific Research Flanders (FWO).

1. Maintenance of the Spider Mite Population
NOTE: Spider mites are reared on California red kidney beans (Phaseolus vulgaris).
<ol>
	<li>Grow bean plants from seeds for 2-3 weeks prior to infestation.</li>
	<li>Intermix these plants with infested plants; adult mites will rapidly colonize fresh plant material.</li>
	<li>Remove old infested bean plants every 7-10 days,&#160;replacing them with fresh plants.</li>
</ol>
2. Collecting Adult Female Mites
<ol>
	<li>Mite Collection using the Washing Method
	<ol>
		<li>To collect mites, place a fresh bean plant in contact with infested plants 1 to 2 days prior to the experiment.</li>
		<li>Use 20 to 30 fresh bean plants to collect 1,000 to 2,000 adult female mites.</li>
		<li>Prepare a solution of Tween 20 at 0.001% using tap water at RT.</li>
		<li>Wash infested bean plants in the Tween 20 solution, using 2&#160;to 3&#160;plants at a&#160;time.</li>
		<li>Each plant is washed 2-3x to collect all mites from leaves.</li>
		<li>Complete step 2.1.4 within 10 min&#160;to avoid mite mortality.</li>
	</ol>
	</li>
	<li>Isolation of Adult Female Mites by Filtration of the Mite Suspension through Sieves of Defined Mesh Size
	<ol>
		<li>Prepare sieves of the following mesh sizes: 500 &#181;m (to remove debris) and 300 &#181;m (to collect female adult mites) (Figure&#160;1A).</li>
		<li>Filter the suspension through the 500 &#181;m sieve.</li>
		<li>Refilter the suspension through the 300 &#181;m sieve. Adult female mites will be retained.</li>
		<li>Dip a 300 &#181;m sieve with adult female mites in clean tap water to remove the Tween 20.</li>
		<li>Spread mites in a single layer at the bottom of the sieve.</li>
		<li>Use paper towel to remove excess water from the mesh and sides of the sieve. NOTE: This is done because mites need to dry quickly in order to recover.</li>
		<li>Prepare an assembly as shown in Figure&#160;1B; this will allow mites to move freely, but will prevent them from escaping.</li>
		<li>Place the sieve with mites on top of the sieve that is used as a support.</li>
		<li>Surround bottom sieve with water to prevent mites from dispersing. NOTE: Mites will start recovering after approximately 5 min. After approximately 30 min, the number of moving mites is sufficient to start collection (Figure&#160;1D). Mites should be collected within 1 hr, as they produce silk that will interfere with the collection.</li>
	</ol>
	</li>
</ol>
3. Plant Infestation with Mites
NOTE: Once adult female mites have recovered, they can be used for plant infestation. There are 2&#160;methods used to infest experimental plants with adult female mites: a) using a fine brush (protocol section 3.1) and b) using a pump or vacuum line (protocol section 3.2).
<ol>
	<li>Mite Infestation using a Brush 
	NOTE: Spider mite infestation with a brush is used for application of up to 30 mites per plant.
	<ol>
		<li>Use a soft hair round art brush of size 00 or finer.</li>
		<li>Wet the brush with RT tap water.</li>
		<li>Gently pick up mites from the sieve using the brush tip and transfer them to the plant.</li>
	</ol>
	</li>
	<li>Mite Infestation using a Pump 
	NOTE: Plant infestation with mites collected by a pump/vacuum line is used when more than 30 mites are applied. For this method, a vacuum pump for microelectronic components pickup or a vacuum line can be used. It is important to keep the airflow constant and of sufficient strength (2-4 psi).
	<ol>
		<li>Attach a 1 ml&#160;pipette tip to the tube that connects to the pump or vacuum line by using a 1.5 ml&#160;centrifuge tube cut at the bottom as an adapter between the pump/vacuum tube and the tip.</li>
		<li>Place a piece of paper towel between the pipette tip and the adapter (1.5 ml&#160;centrifuge tube). NOTE: the purpose of this is to trap mites inside the pipette tip during the aspiration process and also to reduce the airflow (Figure&#160;1C).</li>
		<li>Collect mites directly from the sieve using the pipette tip.</li>
		<li>Alternatively, collect mites one by one from infested leaves using a stereoscope.</li>
		<li>When the required number of mites has been collected, remove the pipette tip from the tube, making sure that the piece of paper towel at the back of the pipette tip is undisturbed.</li>
		<li>Collect mites by tapping the pipette tip and clumping the mites together. Then, place them on the leaf; within seconds, the mites will start to disperse on the leaf.</li>
	</ol>
	</li>
</ol>
4. Recording and Assessing Plant Damage
<ol>
	<li>Recording Plant Damage 
	NOTE: For A. thaliana, plant damage is assessed after 4&#160;days of mite feeding. Damage is recorded as the&#160;total surface area of chlorotic spots. For damage measurement, the entire rosette is cut and scanned. Scanning parameters described are for an Epson V30 scanner but will act as a good starting point for any similar flatbed scanner. Keep scan parameters constant for all experiments allowing comparison between individual experiment runs.
	<ol>
		<li>Cover scanner bed with transparency sheet to prevent contaminating scanner surface with plant material.</li>
		<li>Cut an entire rosette and place on the scanner bed so adaxial (upper) side of leaves are facing the scanner light source and capture element. Alternatively, if rosettes are too dense to capture individual leaves without overlap, dissect the rosette into individual leaves or groups of non-overlapping leaves with fine scissors before placing on the scanner bed. Multiple rosettes can be scanned simultaneously.</li>
		<li>Cover rosettes or leaves with a piece of white paper to prevent adherence to and contamination of the scanner cover.</li>
		<li>Close scanner cover and perform a scan with the following parameters: Resolution: 1,200 dpi; Color mode: Adobe RGB; Brightness: +25; File type: maximum quality JPEG.</li>
		<li>Save image files for subsequent damage analysis.</li>
	</ol>
	</li>
	<li>Plant Damage Quantification 
	NOTE: The area of damage is manually calculated using Photoshop. Due to large differences in leaf shape and intensity of color of the symptoms as a result of the mite feeding, automatic methods were unreliable. Thus, a grid method is used to assess plant damage:
	<ol>
		<li>Open the image of the plant with Photoshop.</li>
		<li>Create a new layer, then overlay scanned image with a grid of 0.25 mm x 0.25 mm divisions (View or Display &#8211; Show &#8211; Grid, keyboard shortcut Ctrl + &#8216;).</li>
		<li>On an overlaid layer, mark damaged leaf areas using a dot (use the &#8220;Pencil Tool&#8221;, keyboard shortcut B). Use one single dot for each square of the grid below which there is damage covering more than one half of the grid unit. The size of the dot is defined in pixels (i.e., 52 pixels per dot).</li>
		<li>When all squares of the grid that show plant damage covering at least half of the grid unit are marked with a dot, use the histogram tool (Window - Histogram) to determine the total number of pixels on the layer. The histogram tool permits one to measure the number of pixels. Since each dot is represented by a constant and known number of pixels, the histogram tool will measure the total number of pixels, representing the total number of dots, and, by extension, the total number of marked squares.</li>
		<li>Calculate the number of &#8220;dots&#8221; marked by using the formula: 
		Number of dots = total number of pixels/number of pixel per dot.</li>
		<li>Calculate the total area of damage by multiplying the number of marked dots on the image by the area of 1&#160;square of the grid, as one dot corresponds to one square of the grid.</li>
	</ol>
	</li>
</ol>

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	<li>Jeppson, L. R., Keifer, H. H., Baker, E. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Mites injurious to economic plants. , (1975).</li><li>Migeon, A., Dorkeld, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spider+Mites+Web:+a+comprehensive+database+for+the+Tetranychidae.">Spider Mites Web: a comprehensive database for the Tetranychidae.</a> http://www.montpellier.inra.fr/CBGP/spmweb. , (2013).</li><li>Croft, B. A., Vandebaan, H. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ecological+and+Genetic-Factors+Influencing+Evolution+of+Pesticide+Resistance+in+Tetranychid+and+Phytoseiid+Mites.">Ecological and Genetic-Factors Influencing Evolution of Pesticide Resistance in Tetranychid and Phytoseiid Mites.</a> Exp Appl Acarol. 4, 277-300 (1988).</li><li>Van Leeuwen, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mitochondrial+heteroplasmy+and+the+evolution+of+insecticide+resistance:+Non-Mendelian+inheritance+in+action.">Mitochondrial heteroplasmy and the evolution of insecticide resistance: Non-Mendelian inheritance in action.</a> Proceedings of the National Academy of Sciences of the United States of America. 105, 5980-5985 (2008).</li><li>Van Leeuwen, T., Vontas, J., Tsagkarakou, A., Dermauw, W., Tirry, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acaricide+resistance+mechanisms+in+the+two-spotted+spider+mite+Tetranychus+urticae+and+other+important+Acari:+A+review.">Acaricide resistance mechanisms in the two-spotted spider mite Tetranychus urticae and other important Acari: A review.</a> Insect Biochem Molec. 40, 563-572 (2010).</li><li>Dermauw, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+cys-loop+ligand-gated+ion+channel+gene+family+of+Tetranychus+urticae:+Implications+for+acaricide+toxicology+and+a+novel+mutation+associated+with+abamectin+resistance.">The cys-loop ligand-gated ion channel gene family of Tetranychus urticae: Implications for acaricide toxicology and a novel mutation associated with abamectin resistance.</a> Insect Biochem Molec. 42, 455-465 (2012).</li><li>Van Leeuwen, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Population+bulk+segregant+mapping+uncovers+resistance+mutations+and+the+mode+of+action+of+a+chitin+synthesis+inhibitor+in+arthropods.">Population bulk segregant mapping uncovers resistance mutations and the mode of action of a chitin synthesis inhibitor in arthropods.</a> Proceedings of the National Academy of Sciences. 109, 4407-4412 (2012).</li><li>Dearden, P. K., Donly, C., Grbic, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Expression+of+pair-rule+gene+homologues+in+a+chelicerate:+early+patterning+of+the+two-spotted+spider+mite+Tetranychus+urticae.">Expression of pair-rule gene homologues in a chelicerate: early patterning of the two-spotted spider mite Tetranychus urticae.</a> Development. 129, 5461-5472 (2002).</li><li>Khila, A., Grbic, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gene+silencing+in+the+spider+mite+Tetranychus+urticae:+dsRNA+and+siRNA+parental+silencing+of+the+Distal-less+gene.">Gene silencing in the spider mite Tetranychus urticae: dsRNA and siRNA parental silencing of the Distal-less gene.</a> Development genes and evolution. 217, 241-251 (2007).</li><li>Grbic, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mity+model:+Tetranychus+urticae,+a+candidate+for+chelicerate+model+organism.">Mity model: Tetranychus urticae, a candidate for chelicerate model organism.</a> BioEssays : news and reviews in molecular, cellular and developmental biology. 29, 489-496 (2007).</li><li>Grbic, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+genome+of+Tetranychus+urticae+reveals+herbivorous+pest+adaptations.">The genome of Tetranychus urticae reveals herbivorous pest adaptations.</a> Nature. 479, 487-492 (2011).</li><li>Kliebenstein, D., Pedersen, D., Barker, B., Mitchell-Olds, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparative+analysis+of+quantitative+trait+loci+controlling+glucosinolates,+myrosinase+and+insect+resistance+in+Arabidopsis+thaliana.">Comparative analysis of quantitative trait loci controlling glucosinolates, myrosinase and insect resistance in Arabidopsis thaliana.</a> Genetics. 161, 325-332 (2002).</li><li>Abe, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Function+of+jasmonate+in+response+and+tolerance+of+Arabidopsis+to+thrip+feeding.">Function of jasmonate in response and tolerance of Arabidopsis to thrip feeding.</a> Plant &amp; cell physiology. 49, 68-80 (2008).</li><li>Whiteman, N. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mining+the+plant-herbivore+interface+with+a+leafmining+Drosophila+of+Arabidopsis.">Mining the plant-herbivore interface with a leafmining Drosophila of Arabidopsis.</a> Molecular ecology. 20, 995-1014 (2011).</li><li>Goodspeed, D., Chehab, E. W., Min-Venditti, A., Braam, J., Covington, M. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Arabidopsis+synchronizes+jasmonate-mediated+defense+with+insect+circadian+behavior.">Arabidopsis synchronizes jasmonate-mediated defense with insect circadian behavior.</a> Proc Natl Acad Sci U S A. 109, 4674-4677 (2012).</li><li>Kim, J. H., Lee, B. W., Schroeder, F. C., Jander, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+of+indole+glucosinolate+breakdown+products+with+antifeedant+effects+on+Myzus+persicae+(green+peach+aphid).">Identification of indole glucosinolate breakdown products with antifeedant effects on Myzus persicae (green peach aphid).</a> The Plant journal : for cell and molecular biology. 54, 1015-1026 (2008).</li><li>Adio, A. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biosynthesis+and+defensive+function+of+Ndelta-acetylornithine,+a+jasmonate-induced+Arabidopsis+metabolite.">Biosynthesis and defensive function of Ndelta-acetylornithine, a jasmonate-induced Arabidopsis metabolite.</a> Plant Cell. 23, 3303-3318 (2011).</li><li>Li, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+tomato+homolog+of+CORONATINE-INSENSITIVE1+is+required+for+the+maternal+control+of+seed+maturation,+jasmonate-signaled+defense+responses,+and+glandular+trichome+development.">The tomato homolog of CORONATINE-INSENSITIVE1 is required for the maternal control of seed maturation, jasmonate-signaled defense responses, and glandular trichome development.</a> Plant Cell. 16, 126-143 (2004).</li><li>Kant, M. R., Ament, K., Sabelis, M. W., Haring, M. A., Schuurink, R. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differential+timing+of+spider+mite-induced+direct+and+indirect+defenses+in+tomato+plants.">Differential timing of spider mite-induced direct and indirect defenses in tomato plants.</a> Plant Physiol. 135, 483-495 (2004).</li><li>Schneider, C. A., Rasband, W. S., Eliceiri, K. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=NIH+Image+to+ImageJ:+25+years+of+image+analysis.">NIH Image to ImageJ: 25 years of image analysis.</a> Nat Methods. 9, 671-675 (2012).</li></ol>

The authors have nothing to disclose.

This video demonstrates protocols used to isolate and to infest plants with large numbers of adult female mites. Although we presented this protocol using A. thaliana, it can be used for any plant-spider mite interaction system and is currently being successfully applied also on tomato and grapevine (Vitis vinifera) plants. The protocol yields reproducible results, indicating that collected mites are of comparable physiological state (Figure&#160;3).
While th...

Plant-pest interaction is a topic of great scientific and economic importance. It was historically studied using both crop plants (such as tomato) and the model plant, A. thaliana. In both cases, susceptibility of plant to herbivore could be measured either directly through assessment of plant phenotype after herbivore attack or indirectly through the assessment of pest performance.
Direct measurements of plant susceptibility were utilized previously for a number of insect pest species using a range of methods. For example, herbivory of lepidopteran larvae is measured as an estimation of the portion of plant tissue consumed by either Plutella xylostella (diamondback moth)&#160;or Trichoplusia ni (cabbage looper)&#160;by the naked eye with the help of a grid12. Also, there are methods that utilize digital imaging of leaf damage with subsequent quantitative image analysis. Such methods were used in studies of A. thaliana interaction with Frankliniella occidentalis (western flower thrips)13, Scaptomyza flava (leaf-mining drosophila)14, and T. ni15.
Indirect measurements of plant susceptibility are widely used in studies of plant-pest interaction. For example, susceptibility of A. thaliana to peach aphid Myzus persicae herbivory is typically assessed through analysis of pest fecundity and description of the gross morphology of a plant after interaction16,17. Another typical indirect indicator of A. thaliana susceptibility to a pest is a dry or wet weight assessment of the herbivore. This parameter is commonly used to characterize herbivory of lepidoterans, such as Pieris rapae (small white), P. xylostella, or T. ni at their larval or pupal stages15,17.
Spider mites are cell-content feeders. Mite-induced damage is recognized as a collection of chlorotic spots that range in color from white to pale green. The susceptibility of a plant host to spider mite herbivory was previously assessed either indirectly through the analysis of spider mite performance days post-infestation18,19, or directly using gross morphology of plants weeks post-infestation18 or using a digital imaging of leaves exposed to mites for days with subsequent automated image analysis19. These methods were being developed and used for studies of interactions between tomato plants and T. urticae, and&#160;typically used small numbers of spider mites (5-15 per treatment) that were collected from the mixed mite population and were placed on the leaf surface using a soft bristle brush. However, these methods are not suitable for studies where greater numbers of mites need to be applied. In addition, while direct processing of leaf images in image analysis software such as Adobe Photoshop (San Jose, CA) or ImageJ20 can be used for the analysis of tomato damage, these protocols need modification in order to be applied to leaves that have greater reflectivity of surface or are lightly colored and have highly visible trichomes (e.g.,&#160;A. thaliana) that interfere with automated selection of chlorotic spots that mark plant damage. Furthermore, the developmental stage of spider mites that can be readily utilized with the previous methods is limited to the most prevalent and easily identifiable adult females and precludes utilization of other developmental stages.
The first critical step toward high-throughput analysis of plant-spider mite interaction is to establish reproducible, simple and robust protocols to challenge plants with spider mites and reliably assess interaction outcomes.
In this video, an efficient method for quick and easy collection of a large number of adult female mites, their application on an experimental plant host, and the assessment of the plant damage due to spider mite feeding are described. The presented protocol enables fast and efficient collection of hundreds of individuals at any developmental stage (eggs, larvae, nymphs, adult males, and females) that can be used for subsequent experimental application. In addition, these protocols can be applied to any mite host plant, but are specifically demonstrated in the case of A. thaliana.

<table><tbody><tr><td>Plant material:</td><td></td><td></td><td></td></tr><tr><td>California red kidney bean</td><td>Stokes, Thorold, ON, Canada</td><td></td><td>2 week old, well infested with spider mites 2 or 3 days before use. Other cultivars of &lt;em&gt;Phaseolus vulgaris&lt;/em&gt; can be used.</td></tr><tr><td>Chemicals:</td><td></td><td></td><td></td></tr><tr><td>Tween 20</td><td>Sigma-Aldrich</td><td>P9416</td><td>1% stock solution is prepared to simplify aliquoting</td></tr><tr><td>Tap water</td><td></td><td></td><td>At room temperature, heat- and cold-shock affect mite survival rate and performance</td></tr><tr><td>Other materials and equipment:</td><td></td><td></td><td></td></tr><tr><td>Plastic tray</td><td></td><td></td><td></td></tr><tr><td>Set of scissors</td><td></td><td></td><td></td></tr><tr><td>2 L beakers</td><td></td><td></td><td></td></tr><tr><td>Paper towels</td><td></td><td></td><td></td></tr><tr><td>Sets of sieves</td><td>Manufactured in house</td><td></td><td>Detailed instructions are available</td></tr><tr><td>Thin brush</td><td></td><td></td><td></td></tr><tr><td>Pipettes</td><td></td><td></td><td></td></tr><tr><td>Pipette tips</td><td></td><td></td><td>0.2 and 1 ml</td></tr><tr><td>1.5 ml centrifuge tubes</td><td></td><td></td><td></td></tr><tr><td>Air pump</td><td></td><td></td><td>Aquarium type pump with inverted air flow. Vacuum line can be used. Required pressure drop is approx. 2-4 psi</td></tr><tr><td>Stereoscope</td><td></td><td></td><td></td></tr><tr><td>Scanner</td><td>Epson</td><td>V30</td><td>Any flatbed scanner allowing necessary degree of control over scan quality. We use Epson V30 for our experiments.</td></tr><tr><td>Computer</td><td></td><td></td><td>Windows or OS X PC which is compatible with scanner hardware and Adobe Photoshop software.</td></tr><tr><td>Adobe Photoshop software</td><td>Adobe Systems Inc., San Jose, CA, USA</td><td>various</td><td>Any version with Histogram tool included.</td></tr></tbody></table>

application of two-spotted spider mite tetranychus urticae for plant-pest interaction studies

The two-spotted spider mite, Tetranychus urticae, is a ubiquitous polyphagous arthropod herbivore that feeds on a remarkably broad array of species, with more than 150 of economic value. It is a major pest of greenhouse crops, especially in Solanaceae and Cucurbitaceae (e.g., tomatoes, eggplants, peppers, cucumbers, zucchini) and greenhouse ornamentals (e.g., roses, chrysanthemum, carnations), annual field crops (such as maize, cotton, soybean, and sugar beet), and in perennial cultures (alfalfa, strawberries, grapes, citruses, and plums)1,2. In addition to the extreme polyphagy that makes it an important agricultural pest, T. urticae has a tendency to develop resistance to a wide array of insecticides and acaricides that are used for its control3-7.
T. urticae is an excellent experimental organism, as it has a rapid life cycle (7 days at 27 &#176;C) and can be easily maintained at high density in the laboratory. Methods to assay gene expression (including in situ hybridization and antibody staining) and to inactivate expression of spider mite endogenous genes using RNA interference have been developed8-10. Recently, the whole genome sequence of T. urticae has been reported, creating an opportunity to develop this pest herbivore as a model organism with equivalent genomic resources that already exist in some of its host plants (Arabidopsis thaliana and the&#160;tomato Solanum lycopersicum)11. Together, these&#160;model organisms could provide insights into molecular bases of plant-pest interactions.
Here, an efficient method for quick and easy collection of a large number of adult female mites, their application on an experimental plant host, and the assessment of the plant damage due to spider mite feeding are described. The presented protocol enables fast and efficient collection of hundreds of individuals at any developmental stage (eggs, larvae, nymphs, adult males, and females) that can be used for subsequent experimental application.

Using 20 to 30 infested bean plants, one can collect around 2,000 adult female mites using sieves. The time required to infest 10 plants with 20 mites per plant is approximately 15 min&#160;if using a brush to transfer mites. Combinations of collection and application methods are shown in Figure&#160;2.
This protocol generates reproducible results of plant damage, demonstrating that collected mites are of similar physiological state and suitable for plant-spider mite interacti...

Watch this Scientific Journal Video about Application of Two-spotted Spider Mite Tetranychus urticae for Plant-pest Interaction Studies at JoVE.com

Application of Two-spotted Spider Mite Tetranychus urticae for Plant-pest Interaction Studies

Protocols for efficient preparation of homogenous samples of spider mites, infestation of experimental plants, and assessment of plant damage, as required for studies of plant-pest interaction were developed.

Application of Two-spotted Spider Mite Tetranychus urticae for Plant-pest Interaction Studies

The two-spotted spider mite, Tetranychus urticae, is a ubiquitous polyphagous arthropod herbivore that feeds on a remarkably broad array of species, with ...

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17.6K Views.  The University of Western Ontario.  Protocollen voor een efficiënte bereiding van homogene monsters van spintmijten, aantasting van experimentele installaties, en beoordeling van plantaardige schade, zoals vereist voor studies van planten-plaaginteractie werden ontwikkeld. 

Video: Application of Two-spotted Spider Mite Tetranychus urticae for Plant-pest Interaction Studies

Remote Sensing Evaluation of Two-spotted Spider Mite Damage on Greenhouse Cotton

The objective of this study was to evaluate a ground-based multispectral optical sensor as a remote sensing tool to assess foliar damage caused by the two-spotted spider mite (TSSM), Tetranychus urticae Koch, on greenhouse grown cotton. TSSM is a polyphagous pest which occurs on a variety of field and horticultural crops. It often becomes an early season pest of cotton in damaging proportions as opposed to being a late season innocuous pest in the mid-southern United States. Evaluation of acaricides is important for maintaining the efficacy of and preventing resistance to the currently available arsenal of chemicals and newly developed control agents. Enumeration of spider mites for efficacy evaluations is laborious and time consuming. Therefore, subjective visual damage rating is commonly used to assess density of spider mites. The NDVI (Normalized Difference Vegetation Index) is the most widely used statistic to describe the spectral reflectance characteristics of vegetation canopy to assess plant stress and health consequent to spider mite infestations. Results demonstrated that a multispectral optical sensor is an effective tool in distinguishing varying levels of infestation caused by T. urticae on early season cotton. This remote sensing technique may be used in lieu of a visual rating to evaluate insecticide treatments.

This manuscript describes a multispectral optical sensor that effectively detected damage to early season cotton artificially infested with varying densities of the two-spotted spider mite populations.

The objective of this study was to evaluate a ground-based multispectral optical sensor as a remote sensing tool to assess foliar damage caused by the ...

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.

A major concern when developing commercial mycoinsecticides is the kill speed compared to that of chemical insecticides. Therefore, isolation and ...

Detached Leaf Assays to Simplify Gene Expression Studies in Potato During Infestation by Chewing Insect Manduca sexta

The multitrophic nature of gene expression studies of insect herbivory demands large numbers of biological replicates, creating the need for simpler, more streamlined herbivory protocols. Perturbations of chewing insects are usually studied in whole plant systems. While this whole organism strategy is popular, it is not necessary if similar observations can be replicated in a single detached leaf. The assumption is that basic elements required for signal transduction are present within the leaf itself. In the case of early events in signal transduction, cells need only to receive the signal from the perturbation and transmit that signal to neighboring cells which are assayed for gene expression.
The proposed method simply changes the timing of the detachment. In whole plant experiments, larvae are confined to a single leaf which is eventually detached from the plant and assayed for gene expression. If the order of excision is reversed, from last in whole plant studies, to first in the detached study, the feeding experiment is simplified.
Solanum tuberosum var. Kennebec is propagated by nodal transfer in a simple tissue culture medium and transferred to soil for further growth if desired. Leaves are excised from the parent plant and relocated to Petri dishes where the feeding assay is conducted with the larval stages of M. sexta. Damaged leaf tissue is assayed for the expression of relatively early events in signal transduction. Gene expression analysis identified infestation-specific Cys2-His2 (C2H2) transcription factors, confirming the success of using detached leaves in early response studies. The method is easier to perform than whole plant infestations and uses less space.

The presented method creates natural herbivore damaged plant tissue through the application of Manduca sexta larvae to detached leaves of potato. The plant tissue is assayed for expression of six transcription factor homologs involved in early responses to insect herbivory.

The multitrophic nature of gene expression studies of insect herbivory demands large numbers of biological replicates, creating the need for simpler, more ...

Study on the Metabolism of Six Systemic Insecticides in a Newly Established Cell Suspension Culture Derived from Tea (Camellia Sinensis L.) Leaves

A platform for studying insecticide metabolism using in vitro tissues of tea plant was developed. Leaves from sterile tea plantlets were induced to form loose callus on Murashige and Skoog (MS) basal media with the plant hormones 2,4-dichlorophenoxyacetic acid (2,4-D, 1.0 mg L-1) and kinetin (KT, 0.1 mg L-1). Callus formed after 3 or 4 rounds of subculturing, each lasting 28 days. Loose callus (about 3 g) was then inoculated into B5 liquid media containing the same plant hormones and was cultured in a shaking incubator (120 rpm) in the dark at 25 &#177; 1 &#176;C. After 3&#8722;4 subcultures, a cell suspension derived from tea leaf was established at a subculture ratio ranging between 1:1 and 1:2 (suspension mother liquid: fresh medium). Using this platform, six insecticides (5 &#181;g mL-1 each thiamethoxam, imidacloprid, acetamiprid, imidaclothiz, dimethoate, and omethoate) were added into the tea leaf-derived cell suspension culture. The metabolism of the insecticides was tracked using liquid chromatography and gas chromatography. To validate the usefulness of the tea cell suspension culture, the metabolites of thiamethoxan and dimethoate present in treated cell cultures and intact plants were compared using mass spectrometry. In treated tea cell cultures, seven metabolites of thiamethoxan and two metabolites of dimethoate were found, while in treated intact plants, only two metabolites of thiamethoxam and one of dimethoate were found. The use of a cell suspension simplified the metabolic analysis compared to the use of intact tea plants, especially for a difficult matrix such as tea.

Study on the Metabolism of Six Systemic Insecticides in a Newly Established Cell Suspension Culture Derived from Tea Camellia Sinensis L. Leaves

This work presents a protocol for establishing a cell suspension culture derived from tea (Camellia sinensis L.) leaves that can be used to study the metabolism of external compounds that can be taken up by the whole plant, such as insecticides.

A platform for studying insecticide metabolism using in vitro tissues of tea plant was developed. Leaves from sterile tea plantlets were induced to form ...

Biochemistry

Sampling for Estimating Frankliniella Species Flower Thrips and Orius Species Predators in Field Experiments

The western flower thrips, Frankliniella occidentalis (Pergande), is a polyphagous pest that has been spread worldwide. The extensive use of insecticides in attempts to control its populations eliminates natural enemies and competitor flower thrips species, thereby increasing its populations. An unsustainable situation develops with concomitant resistant pest populations, secondary pest outbreaks, and environmental degradation. Integrated pest management utilizes knowledge of pest and natural enemy relationships to implement tactics that are environmentally friendly and sustainable. Minute pirate bugs are the most important worldwide predators of thrips. They can suppress and ultimately control Frankliniella species flower thrips. Flower samples taken at least weekly are needed to understand predator-prey dynamics. Shown here is the sampling of the flowers of fruiting vegetables and companion plants to estimate the densities of individual thrips and minute pirate bug species. Representative data illustrates how the protocol is used to determine the efficacy of management tactics over time and how to evaluate the benefits of predation by minute pirate bugs. The sampling protocol is similarly adaptable to sampling thrips and minute pirate bugs in other plant species hosts.

Sampling for Estimating Frankliniella Species Flower Thrips and Orius Species Predators in Field Experiments

Presented here is a protocol to determine the number of thrips and minute pirate bug predators in crops over multiple dates in field experiments. Also illustrated is how to determine the efficacy of management tactics against thrips and evaluate the benefits of predation by minute pirate bugs.

The western flower thrips, Frankliniella occidentalis (Pergande), is a polyphagous pest that has been spread worldwide. The extensive use of insecticides ...

Leveraging Micro-CT Scanning to Analyze Parasitic Plant-Host Interactions

Micro-CT scanning has become an established tool in investigating plant structure and function. Its non-destructive nature, combined with the possibility of three-dimensional visualization and virtual sectioning, has allowed novel and increasingly detailed analysis of complex plant organs. Interactions among plants, including between parasitic plants and their hosts, can also be explored. However, sample preparation before scanning becomes crucial due to the interaction between these plants, which often differ in tissue organization and composition. Furthermore, the broad diversity of parasitic flowering plants, ranging from highly reduced vegetative bodies to trees, herbs, and shrubs, must be considered during the sampling, treatment, and preparation of parasite-host material. Here two different approaches are described for introducing contrast solutions into the parasite and/or host plants, focusing on analyzing the haustorium. This organ promotes connection and communication between the two plants. Following a simple approach, details of haustorium tissue organization can be explored three-dimensionally, as shown here for&#160;euphytoid, vine, and mistletoe parasitic species. Selecting specific contrasting agents and application approaches also allow detailed observation of endoparasite spread within the host body and detection of direct vessel-to-vessel connection between parasite and host, as shown here for an obligate root parasite. Thus, the protocol discussed here can be applied to the broad diversity of parasitic flowering plants to advance the understanding of their development, structure, and functioning.

Micro-CT is a non-destructive tool that can analyze plant structures in three dimensions. The present protocol describes the sample preparation to leverage micro-CT to analyze parasitic plant structure and function. Different species are used to highlight the advantages of this method when coupled with specific preparations.

Micro-CT scanning has become an established tool in investigating plant structure and function. Its non-destructive nature, combined with the possibility ...

Bioassays for Monitoring Insecticide Resistance

Pest resistance to pesticides is an increasing problem because pesticides are an integral part of high-yielding production agriculture. When few products are labeled for an individual pest within a particular crop system, chemical control options are limited. Therefore, the same product(s) are used repeatedly and continual selection pressure is placed on the target pest. There are both financial and environmental costs associated with the development of resistant populations. The cost of pesticide resistance has been estimated at approximately $ 1.5 billion annually in the United States. This paper will describe protocols, currently used to monitor arthropod (specifically insects) populations for the development of resistance. The adult vial test is used to measure the toxicity to contact insecticides and a modification of this test is used for plant-systemic insecticides. In these bioassays, insects are exposed to technical grade insecticide and responses (mortality) recorded at a specific post-exposure interval. The mortality data are subjected to Log Dose probit analysis to generate estimates of a lethal concentration that provides mortality to 50% (LC50) of the target populations and a series of confidence limits (CL's) as estimates of data variability. When these data are collected for a range of insecticide-susceptible populations, the LC50 can be used as baseline data for future monitoring purposes. After populations have been exposed to products, the results can be compared to a previously determined LC50 using the same methodology.

This manuscript demonstrates and discusses techniques used to survey pesticide susceptibility and detect resistance to contact and systemic pesticides in arthropod pests.

Pest resistance to pesticides is an increasing problem because pesticides are an integral part of high-yielding production agriculture. When few products ...

Biology

Artificial Host Parasitization by Trichogramma dendrolimi and Venom Extraction

Extracting Venom from the Parasitoid Wasp Trichogramma dendrolimi Using an Artificial Host

Parasitoid wasps are a diverse group of hymenopteran insects that serve as invaluable resources for pest biocontrol. To ensure successful parasitism, parasitoid wasps inject venom into their hosts to suppress their hosts&#39; immunity, modulate hosts&#39; development, metabolism, and even behavior. With over 600,000 estimated species, the diversity of parasitoid wasps surpasses that of other venomous animals, such as snakes, cone snails, and spiders. Parasitoid wasp venom is an underexplored source of bioactive molecules with potential applications in pest control and medicine. However, collecting parasitoid venom is challenging due to the inability to use direct or electrical stimulation and the difficulty in dissection because of their small size. Trichogramma is a genus of tiny (~0.5 mm) egg parasitoid wasps that are widely used for the biological control of lepidopteran pests in both agriculture and forests. Here, we report a method for extracting venom from T. dendrolimi using artificial hosts. These artificial hosts are created with polyethylene film and amino acid solutions and then inoculated with Trichogramma wasps for parasitism. The venom was subsequently collected and concentrated. This method enables the extraction of large amounts of Trichogramma venom while avoiding contamination from other tissues caused by dissection, a common issue in venom reservoir dissection protocols. This innovative approach facilitates the study of Trichogramma venom, paving the way for new research and potential applications.

Author Spotlight: Efficient Venom Extraction Method from Trichogramma Parasitoid Wasps 

Here, we present a protocol for extracting venom from Trichogramma dendrolimi using an artificial host created with polyethylene film and amino acid solution.

Parasitoid wasps are a diverse group of hymenopteran insects that serve as invaluable resources for pest biocontrol. To ensure successful parasitism, ...

Characterizing Herbivore Resistance Mechanisms: Spittlebugs on Brachiaria spp. as an Example

Plants can resist herbivore damage through three broad mechanisms: antixenosis, antibiosis and tolerance1. Antixenosis is the degree to which the plant is avoided when the herbivore is able to select other plants2. Antibiosis is the degree to which the plant affects the fitness of the herbivore feeding on it1.Tolerance is the degree to which the plant can withstand or repair damage caused by the herbivore, without compromising the herbivore's growth and reproduction1. The durability of herbivore resistance in an agricultural setting depends to a great extent on the resistance mechanism favored during crop breeding efforts3.
We demonstrate a no-choice experiment designed to estimate the relative contributions of antibiosis and tolerance to spittlebug resistance in Brachiaria spp. Several species of African grasses of the genus Brachiaria are valuable forage and pasture plants in the Neotropics, but they can be severely challenged by several native species of spittlebugs (Hemiptera: Cercopidae)4.To assess their resistance to spittlebugs, plants are vegetatively-propagated by stem cuttings and allowed to grow for approximately one month, allowing the growth of superficial roots on which spittlebugs can feed. At that point, each test plant is individually challenged with six spittlebug eggs near hatching. Infestations are allowed to progress for one month before evaluating plant damage and insect survival. Scoring plant damage provides an estimate of tolerance while scoring insect survival provides an estimate of antibiosis. This protocol has facilitated our plant breeding objective to enhance spittlebug resistance in commercial brachiariagrases5.

Characterizing Herbivore Resistance Mechanisms: Spittlebugs on Brachiaria spp. as an Example

This video explains mechanisms of host plant resistance to herbivory and demonstrates a no-choice test that estimates the relative contributions of antibiosis and tolerance to spittlebug resistance in Brachiaria spp.

Plants can resist herbivore damage through three broad mechanisms: antixenosis, antibiosis and tolerance1. Antixenosis is the degree to which the plant is ...

Molecule Delivery in Plants Using a Direct Infusion Device

Direct Infusion Device for Molecule Delivery in Plants

Testing the function of therapeutic compounds in plants is an important component of agricultural research. Foliar and soil-drench methods are routine but have drawbacks, including variable uptake and the environmental breakdown of tested molecules. Trunk injection of trees is well-established, but most methods for this require expensive, proprietary equipment. To screen various treatments for Huanglongbing, a simple, low-cost method to deliver these compounds to the vascular tissue of small greenhouse-grown citrus trees infected with the phloem-limited bacterium Candidatus Liberibacter asiaticus (CLas) or infested with the phloem-feeding CLas insect vector Diaphorina citri Kuwayama (D. citri) is needed.
To meet these screening requirements, a direct plant infusion (DPI) device was designed that connects to the plant&#39;s trunk. The device is made using a nylon-based 3D-printing system and easily obtainable auxiliary components. The compound uptake efficacy of this device was tested in citrus plants using the fluorescent marker 5,6-carboxyfluorescein-diacetate. Uniform compound distribution of the marker throughout the plants was routinely observed.
Furthermore, this device was used to deliver antimicrobial and insecticidal molecules to determine their effects on CLas and D. citri respectively. The aminoglycoside antibiotic streptomycin was delivered into CLas-infected citrus plants using the device, which resulted in a reduction in the CLas titer from 2 weeks to 4 weeks post treatment. Delivering the neonicotinoid insecticide imidacloprid into D. citri-infested citrus plants resulted in a significant increase in psyllid mortality after 7 days. These results suggest that this DPI device represents a useful system for delivering molecules into plants for&#160;testing and facilitate research and screening purposes.

Author Spotlight: Direct Infusion Device for Molecule Delivery in Plants  

This manuscript describes a novel direct plant infusion device for screening the effectiveness of molecules against the bacteria (Candidatus Liberibacter asiaticus) or its insect vector (Diaphorina citri, Kuwayama) that, in combination, are associated with Huanglongbing citrus disease.

Testing the function of therapeutic compounds in plants is an important component of agricultural research. Foliar and soil-drench methods are routine but ...

Application of Two-spotted Spider Mite Tetranychus urticae for Plant-pest Interaction Studies

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