This work was supported by the National Key R&#38;D Program of China (No. 2022YFD1401700) and by the National Science Foundation of China (No. 32090013 and No. 32072385).

1. Insect rearing
<ol>
	<li>Raise the SBPHs used in this experiment in rice seedlings (Oryza sativa cv. Nipponbare). Plant 20 rice seedlings in an incubator (65 mm x 200 mm), and grow at 25 &#176;C under a 16 h light/8 h dark photoperiod.</li>
</ol>
2. Dissection of the SBPHs for hemolymph collection
<ol>
	<li>Put the SBPHs into a centrifuge tube, and place them in an ice bath for 10-30 min. 
	NOTE: Do not place the SBPHs in the ice bath for less...

Collecting Hemolymph from Small Arthropods

<ol>
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Hemolymph is the medium of the circulatory system in arthropods, and arboviruses can only invade other arthropod tissues if they are able to survive the hostile hemolymph environment. Collecting a high-quality sample of hemolymph is the first step in studying the vector-virus interactions that occur in the hemolymph. It has been reported that insect hemolymph can be obtained from several sites on the insect&#39;s body, including a wound on the front leg, a minor incision in the head area, or a tear wound at the abdomen<s...

Both animal and plant viruses can be transmitted by arthropods, and these viruses pose a severe threat to human health and cause tremendous economic losses in agriculture1,2,3. Importantly, the arthropod hemolymph, which serves as the circulatory system and a vital element of the immune system in arthropods, plays an important role in regulating arboviral transmission. Viruses acquired through the arthropod guts are transported to other tissues only after successfully escaping the adverse hemolymph environment4,5,6,7. The lifecycle of viruses in the arthropod hemolymph involves virus survival in the fluid plasma, entry into the hemocyte, and transport to other tissues, and various virus-vector interaction mechanisms occur in the hemolymph8,9,10,11,12. For example, the vertical transmission of RSV by the SBPH is dependent on a molecular interaction between the SBPH vitellogenin protein and the RSV (rice stripe virus) capsid protein13,14. Some viruses may escape the immune response of the hemolymph by binding specific vector factors15,16,17,18. Therefore, investigating vector-virus interactions in the hemolymph of arthropods is important for developing a better understanding of arbovirus transmission.
The hemolymph of some small insects, such as planthoppers, leafhoppers, and some mosquitoes, is difficult to collect due to their size. To address this issue, several methods have been developed to collect hemolymph, including inserting a syringe needle directly into the insect body to extract a microvolume of the hemolymph, collecting exudate from the wound site with fine-tipped tweezers, and direct centrifugation. These methods have enabled the measurement of relative gene expression levels and viral titers within the hemolymph19,20,21. However, an effective method for quantifying the hemolymph volume, which is necessary for hemocyte counting, protein quantification, and enzyme activity analysis, is currently not available for these small insects.
The SBPH (small brown planthopper) is a type of small insect vector with a body length of about 2-4 mm. The SBPH is capable of transmitting a variety of plant viruses, including RSV, maize rough dwarf virus, and rice black streaked dwarf virus22,23,24. The interaction between the SBPH and RSV has been studied in depth over the past decade. To facilitate working with SBPHs, we developed a novel and simple method of collecting hemolymph. This method, which is based on the principle of capillary forces, uses a capillary with a scale mark to acquire the insect&#39;s hemolymph in a precise and quantifiable manner. This allows us to collect a specific volume of hemolymph from small insects efficiently and to study the hemolymph environment of small vectors in more detail.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>10% SDS-PAGE protein gel</td>
			<td>Bio-rad</td>
			<td>4561035</td>
			<td>Protein separation and detection</td>
		</tr>
		<tr>
			<td>4% paraformaldehyde</td>
			<td>Solarbio</td>
			<td>P1110</td>
			<td>For fixation of the cells or tissues&#160;</td>
		</tr>
		<tr>
			<td>Bradford dye reagent</td>
			<td>Bio-rad</td>
			<td>5000205</td>
			<td>Protein concentration detection</td>
		</tr>
		<tr>
			<td>Capillary</td>
			<td>Hirschmann</td>
			<td>9000101</td>
			<td>For collecting hemolymph</td>
		</tr>
		<tr>
			<td>Cell counting chamber</td>
			<td>ACMEC</td>
			<td>AYA0810</td>
			<td>Hemocytes counting</td>
		</tr>
		<tr>
			<td>Glass slide</td>
			<td>Gitoglas</td>
			<td>10127105A</td>
			<td>For holding insects</td>
		</tr>
		<tr>
			<td>Glass slide coated with silane</td>
			<td>Sigma</td>
			<td>S4651-72EA</td>
			<td>For holding microscope samples</td>
		</tr>
		<tr>
			<td>Gold antifade reagent with DAPI</td>
			<td>Invitrogen</td>
			<td>P36935</td>
			<td>Nucleus staining</td>
		</tr>
		<tr>
			<td>Microscope cover glass</td>
			<td>Gitoglas</td>
			<td>10212424C</td>
			<td>For microscopic observation</td>
		</tr>
		<tr>
			<td>Pipette bulb</td>
			<td>Hirschmann</td>
			<td>9000101</td>
			<td>For collecting hemolymph</td>
		</tr>
		<tr>
			<td>Prism 8.0 software</td>
			<td>GraphPad Software</td>
			<td>/</td>
			<td>Statistical analyses</td>
		</tr>
		<tr>
			<td>Stereomicroscope&#160;</td>
			<td>Motic</td>
			<td>SMZ-168</td>
			<td>For insect dissection</td>
		</tr>
		<tr>
			<td>Tweezers</td>
			<td>Tianld</td>
			<td>P5622</td>
			<td>For insect dissection</td>
		</tr>
		<tr>
			<td>Zeiss inverted microscope</td>
			<td>Zeiss</td>
			<td>Observer Z1</td>
			<td>Hemocytes observation</td>
		</tr>
	</tbody>
</table>

a precise and quantifiable method for collecting hemolymph from small arthropods

Arthropods are known to transmit a variety of viruses of medical and agricultural importance through their hemolymph, which is essential for virus transmission. Hemolymph collection is the basic technology for studying virus-vector interactions. Here, we describe a novel and simple method for the quantitative collection of hemolymph from small arthropods using Laodelphax striatellus (the small brown planthopper, SBPH) as a research model, as this arthropod is the main vector of rice stripe virus (RSV). In this protocol, the process begins by gently pinching off one leg of the frozen arthropod with fine-tipped tweezers and pressing the hemolymph out of the wound. Then, a simple micropipette consisting of a capillary and a pipette bulb is used to collect the transudative hemolymph from the wound according to the principle of capillary forces. Finally, the collected hemolymph can be dissolved into a specific buffer for further study. This new method for collecting hemolymph from small arthropods is a useful and efficient tool for further research on arboviruses and vector-virus interactions.

Author Spotlight: A Precise and Quantifiable Method for Collecting Hemolymph from Small Arthropods  

A Precise and Quantifiable Method for Collecting Hemolymph from Small Arthropods

Our research focuses on arboviruses, insects, and plant interactions. Obtaining hemolymph samples from small arthropods presents a technical challenge for research on insect-borne diseases. This protocol shows a precise and quantifiable technique to counter this issue.Recent research developments in the transmission of arboviruses have discovered that viruses can manipulate several important vector-factors to break through the host barrier. This protocol is a simple, cost-effective and valuable technique that allows for precise quantification of the hemolymph. This method also offers valuable technology for starting the interactions between viruses and vectors.Our upcoming research will focus on understanding the molecular mechanisms of virus transmission by vector-insects while exploring and enhancing new operational techniques.

Micropipette model and hemolymph collection 
We have developed a simple micropipette whose action is based on the capillary forces of the capillary tube. The micropipette is composed of a capillary tube and a pipette bulb (Figure 1A). Capillary tubes are available in different volume sizes ranging from 1 &#181;L to 20 &#181;L, and the capillary tube volumes are selected according to the requirements. Capillary tubes with smaller volumes are not suggested because the ext...

Watch this Scientific Journal Video about A Precise and Quantifiable Method for Collecting Hemolymph from Small Arthropods at JoVE.com

We describe a method to collect quantifiable hemolymph efficiently from small arthropods for subsequent analysis.

Arthropods are known to transmit a variety of viruses of medical and agricultural importance through their hemolymph, which is essential for virus ...

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