This work was supported by the National Key Research and Development Program of China (No. 2019YFC1200503), by the National Science Foundation of China (No. 32072385), and by Youth Innovation Promotion Association CAS (2021084).

1. SBPH maintenance
<ol>
	<li>Rear the viruliferous and RSV-free SBPH individuals in a glass incubator (65 x 200 mm) with 5-6 rice (Oryza sativa cv. Nipponbare) seedlings per glass chamber in the laboratory. Grow the rice plants at 25 &#176;C under a 16 h light / 8 h dark photoperiod. 
	NOTE: The viruliferous and RSV-free SBPH individuals were initially caught in Jiangsu Province, China.</li>
	<li>Detect RSV in SBPH by dot-enzyme-linked immunosorbent assay (dot-ELISA) with a rabbit RSV-specific polyclonal...

<ol>
	<li>Cheng, X., Zhu, L., He, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Towards+understanding+of+molecular+interactions+between+rice+and+the+brown+planthopper.">Towards understanding of molecular interactions between rice and the brown planthopper.</a> Molecular Plant. 6 (3), 621-634 (2013).</li><li>Cho, W. K., Lian, S., Kim, S. M., Park, S. H., Kim, K. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Current+insights+into+research+on+Rice+Stripe+Virus.">Current insights into research on Rice Stripe Virus.</a> The Plant Pathology Journal. 29 (3), 223-233 (2013).</li><li>He, M., Guan, S. Y., He, C. Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evolution+of+rice+stripe+virus.">Evolution of rice stripe virus.</a> Molecular Phylogenetics and Evolution. 109, 343-350 (2017).</li><li>Wu, 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=Nonstructural+protein+NS4+of+Rice+Stripe+Virus+plays+a+critical+role+in+viral+spread+in+the+body+of+vector+insects.">Nonstructural protein NS4 of Rice Stripe Virus plays a critical role in viral spread in the body of vector insects.</a> PLoS One. 9 (2), 88636 (2014).</li><li>Huo, Y., 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=Transovarial+transmission+of+a+plant+virus+is+mediated+by+vitellogenin+of+its+insect+vector.">Transovarial transmission of a plant virus is mediated by vitellogenin of its insect vector.</a> PLoS Pathogens. 10 (3), 1003949 (2014).</li><li>Taning, C. N., Andrade, E. C., Hunter, W. B., Christiaens, O., Smagghe, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Asian+citrus+psyllid+RNAi+pathway-RNAi+evidence.">Asian citrus psyllid RNAi pathway-RNAi evidence.</a> Scientific Reports. 6, 38082 (2016).</li><li>Garbutt, J. S., Bell&#233;s, X., Richards, E. H., Reynolds, S. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Persistence+of+double-stranded+RNA+in+insect+hemolymph+as+a+potential+determiner+of+RNA+interference+success:+evidence+from+Manduca+sexta+and+Blattella+germanica.">Persistence of double-stranded RNA in insect hemolymph as a potential determiner of RNA interference success: evidence from Manduca sexta and Blattella germanica.</a> Journal of Insect Physiology. 59 (2), 171-178 (2013).</li><li>Huo, Y., 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=Artificial+feeding+Rice+Stripe+Virus+enables+efficient+virus+infection+of+Laodelphax+striatellus.">Artificial feeding Rice Stripe Virus enables efficient virus infection of Laodelphax striatellus.</a> Journal of Virological Methods. 235, 139-143 (2016).</li><li>Huo, Y., 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=Insect+tissue-specific+vitellogenin+facilitates+transmission+of+plant+virus.">Insect tissue-specific vitellogenin facilitates transmission of plant virus.</a> PLoS Pathogens. 14 (2), 1006909 (2018).</li><li>Huo, Y., 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=Rice+Stripe+Virus+hitchhikes+the+vector+insect+vitellogenin+ligand-receptor+pathway+for+ovary+entry.">Rice Stripe Virus hitchhikes the vector insect vitellogenin ligand-receptor pathway for ovary entry.</a> Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences. 374, 20180312 (2019).</li><li>Bao, Y. Y., 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=De+novo+intestine-specific+transcriptome+of+the+brown+planthopper+Nilaparvata+lugens+revealed+potential+functions+in+digestion,+detoxification+and+immune+response.">De novo intestine-specific transcriptome of the brown planthopper Nilaparvata lugens revealed potential functions in digestion, detoxification and immune response.</a> Genomics. 99 (4), 256-264 (2012).</li><li>Elzinga, D. A., 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=The+role+of+protein+effectors+in+plant-aphid+interactions.">The role of protein effectors in plant-aphid interactions.</a> Current Opinion In Plant Biology. 16 (4), 451-456 (2013).</li><li>Chung, S. 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=Herbivore+exploits+orally+secreted+bacteria+to+suppress+plant+defenses.">Herbivore exploits orally secreted bacteria to suppress plant defenses.</a> Proceedings of the National Academy of Sciences of the United States of America. 110 (39), 15728-15733 (2013).</li><li>Bos, J. I., 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=A+functional+genomics+approach+identifies+candidate+effectors+from+the+aphid+species+Myzus+persicae+(green+peach+aphid).">A functional genomics approach identifies candidate effectors from the aphid species Myzus persicae (green peach aphid).</a> PLoS Genetics. 6 (11), 1001216 (2010).</li><li>Liu, X., Zhou, H., Zhao, J., Hua, H., He, Y. <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+the+secreted+watery+saliva+proteins+of+the+rice+brown+planthopper,+Nilaparvata+lugens+(St&#229;l)+by+transcriptome+and+Shotgun+LC-MS/MS+approach.">Identification of the secreted watery saliva proteins of the rice brown planthopper, Nilaparvata lugens (St&#229;l) by transcriptome and Shotgun LC-MS/MS approach.</a> Journal of Insect Physiology. 89, 60-69 (2016).</li><li>Cao, T. T., L&#252;, J., Lou, Y. G., Cheng, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Feeding-induced+interactions+between+two+rice+planthoppers,+Nilaparvata+lugens+and+Sogatella+furcifera+(Hemiptera:+Delphacidae):+effects+on+feeding+and+honeydew+excretion.">Feeding-induced interactions between two rice planthoppers, Nilaparvata lugens and Sogatella furcifera (Hemiptera: Delphacidae): effects on feeding and honeydew excretion.</a> Environmental Entomology. 42 (6), 1281-1291 (2013).</li><li>De Vos, M., 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=Myzus+persicae+(green+peach+aphid)+salivary+components+induce+defence+responses+in+Arabidopsis+thaliana.">Myzus persicae (green peach aphid) salivary components induce defence responses in Arabidopsis thaliana.</a> Plant, Cell &amp; Environment. 32 (11), 1548-1560 (2009).</li><li>Wang, 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=Understanding+the+immune+system+architecture+and+transcriptome+responses+to+southern+rice+black-streaked+dwarf+virus+in+Sogatella+furcifera.">Understanding the immune system architecture and transcriptome responses to southern rice black-streaked dwarf virus in Sogatella furcifera.</a> Scientific Reports. 6, 36254 (2016).</li><li>Wang, Y., 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=Penetration+into+rice+tissues+by+brown+planthopper+and+fine+structure+of+the+salivary+sheaths.">Penetration into rice tissues by brown planthopper and fine structure of the salivary sheaths.</a> Entomologia Experimentalis et Applicata. 129 (3), 295-307 (2008).</li><li>Wang, 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=Armet+is+an+effector+protein+mediating+aphid-plant+interactions.">Armet is an effector protein mediating aphid-plant interactions.</a> FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology. 29 (5), 2032-2045 (2015).</li><li>Chaudhary, R., Atamian, H. S., Shen, Z., Briggs, S. P., Kaloshian, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=GroEL+from+the+endosymbiont+Buchnera+aphidicola+betrays+the+aphid+by+triggering+plant+defense.">GroEL from the endosymbiont Buchnera aphidicola betrays the aphid by triggering plant defense.</a> Proceedings of the National Academy of Sciences of the United States of America. 111 (24), 8919-8924 (2014).</li><li>Ma, R., Chen, J. L., Cheng, D. F., Sun, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Activation+of+defense+mechanism+in+wheat+by+polyphenol+oxidase+from+aphid+saliva.">Activation of defense mechanism in wheat by polyphenol oxidase from aphid saliva.</a> Journal of Agricultural and Food Chemistry. 58 (4), 2410-2418 (2010).</li><li>Zheng, L., Seon, Y. J., McHugh, J., Papagerakis, S., Papagerakis, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clock+genes+show+circadian+rhythms+in+salivary+glands.">Clock genes show circadian rhythms in salivary glands.</a> Journal of Dental Research. 91 (8), 783-788 (2012).</li><li>Huang, H. J., Lu, J. B., Li, Q., Bao, Y. Y., Zhang, C. X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Combined+transcriptomic/proteomic+analysis+of+salivary+gland+and+secreted+saliva+in+three+planthopper+species.">Combined transcriptomic/proteomic analysis of salivary gland and secreted saliva in three planthopper species.</a> Journal of Proteomics. 172, 25-35 (2018).</li><li>Huang, H. J., Liu, C. W., Xu, H. J., Bao, Y. Y., Zhang, C. X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mucin-like+protein,+a+saliva+component+involved+in+brown+planthopper+virulence+and+host+adaptation.">Mucin-like protein, a saliva component involved in brown planthopper virulence and host adaptation.</a> Journal of Insect Physiology. 98, 223-230 (2017).</li><li>Shangguan, X., 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=A+mucin-like+protein+of+planthopper+is+required+for+feeding+and+induces+immunity+response+in+plants.">A mucin-like protein of planthopper is required for feeding and induces immunity response in plants.</a> Plant Physiology. 176 (1), 552-565 (2018).</li><li>Petrova, A., Smith, C. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immunodetection+of+a+brown+planthopper+(Nilaparvata+lugens+St&#229;l)+salivary+catalase-like+protein+into+tissues+of+rice,+Oryza+sativa.">Immunodetection of a brown planthopper (Nilaparvata lugens St&#229;l) salivary catalase-like protein into tissues of rice, Oryza sativa.</a> Insect Molecular Biology. 23 (1), 13-25 (2014).</li><li>Zhu, J., 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=Genome+sequence+of+the+small+brown+planthopper,+Laodelphax+striatellus.">Genome sequence of the small brown planthopper, Laodelphax striatellus.</a> GigaScience. 6 (12), 1-12 (2017).</li><li>Van Bel, A. J., Will, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+evaluation+of+proteins+in+watery+and+gel+saliva+of+aphids.">Functional evaluation of proteins in watery and gel saliva of aphids.</a> Frontiers In Plant Science. 7, 1840 (2016).</li><li>Perez-Vilar, J., Hill, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+structure+and+assembly+of+secreted+mucins.">The structure and assembly of secreted mucins.</a> The Journal of Biological Chemistry. 274 (45), 31751-31754 (1999).</li><li>Pitino, M., Hogenhout, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aphid+protein+effectors+promote+aphid+colonization+in+a+plant+species-specific+manner.">Aphid protein effectors promote aphid colonization in a plant species-specific manner.</a> Molecular Plant-Microbe Interactions: MPMI. 26 (1), 130-139 (2013).</li><li>Zhang, F., Zhu, L., He, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differential+gene+expression+in+response+to+brown+planthopper+feeding+in+rice.">Differential gene expression in response to brown planthopper feeding in rice.</a> Journal of Plant Physiology. 161 (1), 53-62 (2004).</li><li>Hogenhout, S. A., Ammar, E. -. D., Whitfield, A. E., Redinbaugh, M. 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Successful rearing of insects on artificial diets was first reported in 1962 when Mittler and Dadd described the Paraffin membrane technique to hold an artificial diet29,30. And this method has been explored in many aspects of insect biology and behavior, for example, nutrient supplement, dsRNA feeding, and virus acquisition. Based on the requirements of saliva analysis, 5% sucrose is used as the general artificial diet to collect saliva of SBPH in this study. Fo...

Rice stripe virus (RSV), a negative-stranded RNA virus in the genus Tenuivirus, causes severe diseases in rice production in East Asia1,2,3. Transmission of RSV from infected rice plants to healthy ones depends on insect vectors, mainly Laodelphax striatellus, which transmits RSV in a persistent-propagative manner. SBPH acquires the virus after feeding on RSV-infected plants. Once inside the insect, RSV infects the midgut epithelial cell one day after feeding and then passes through the midgut barrier to penetrate the hemolymph. Subsequently, RSV spreads into different tissues via the hemolymph and then propagates. After a latent period of about 10-14 days post-acquisition, the virus inside the salivary gland can be transmitted to the healthy host plants via the secreted saliva while SBPH sucks sap from the phloem4,5,6,7,8,9,10. An efficient feeding process and various factors in the saliva are essential for the spread of RSV from the insect to the host plant.
Insect saliva secreted by salivary glands is believed to mediate insects, viruses, and host plants.Hemipteran insects usually produce two types of saliva: gelling saliva and watery saliva11,12,13. Gelling saliva is mainly secreted into the apoplasm to sustain the movement of the stylet among host cells and is also related to overcoming plant resistance and immune responses14,15,16,17. At the probing stage of feeding, insects intermittently secrete gelling saliva that immediately gets oxidized to form a surface flange. Then, single or branched sheaths encase the stylet to reserve a tubular channel18,19,20. The surface flange on the epidermis is presumed to facilitate penetration of the stylet by serving as an anchor point, while the sheaths around the stylet may provide mechanical stability and lubrication16,21,22,23. Nlshp was identified as an essential protein for salivary sheath formation and successful feeding of brown planthopper (Nilaparvata lugens, BPH). Inhibition of the expression of the structural sheath protein (SHP) secreted by the aphid Acyrthosiphon pisum reduced its reproduction by disrupting feeding from host sieve tubes24. Moreover, in some insect species, gel saliva factors are supposed to trigger plant immune responses by forming so-called herbivore-associated molecular patterns (HAMPs). In N. lugens, NlMLP, a mucin-like protein related to sheath formation, induces plant defenses against feeding, including cell death, the expression of defense-related genes, and callose deposition 25,26. Also, some gel saliva factors in aphids have been proved to trigger plant defense responses via gene-to-gene interactions similar to pathogen-associated molecular patterns12,15,27.
For studying the saliva factors essential for insect feeding and/or pathogen transmission, it is necessary to analyze secreted saliva. Here, artificial feeding and collection methods to obtain sufficient amounts of saliva are described for further analysis. Using a medium containing only a single nutritional element, many saliva proteins were collected and analyzed by silver staining and western blotting. This method will be helpful in further research on factors in saliva that are essential for RSV transmission by SBPH.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>10-KD centrifugal filter</td>
			<td>Merck Millipore</td>
			<td>R5PA83496</td>
			<td>For concentration</td>
		</tr>
		<tr>
			<td>10x Protein Transfer Buffer(wet)</td>
			<td>macGENE</td>
			<td>MP008</td>
			<td>Transfer buffer for western blotting</td>
		</tr>
		<tr>
			<td>10x TBST buffer</td>
			<td>Coolaber</td>
			<td>SL1328-500mL&#215;10</td>
			<td>Wash buffer for western blotting</td>
		</tr>
		<tr>
			<td>Azure c600 biosystems</td>
			<td>Azure Biosystems</td>
			<td>Azure c600</td>
			<td>Imaging system for western blotting and silver staining</td>
		</tr>
		<tr>
			<td>Color Prestained protein ladder</td>
			<td>GenStar</td>
			<td>M221-01</td>
			<td>Protein marker for western blotting</td>
		</tr>
		<tr>
			<td>ECL&#160;western blotting detection reagents</td>
			<td>GE Healthcare</td>
			<td>RPN2209</td>
			<td>Western blotting detection</td>
		</tr>
		<tr>
			<td>Enchanced HRP-DAB Chromogenic Kit</td>
			<td>TIANGEN</td>
			<td>#PA110</td>
			<td>Chromogenic reaction</td>
		</tr>
		<tr>
			<td>Horseradish peroxidase-conjugated goat anti-rabbit antibodies</td>
			<td>Sigma</td>
			<td>401393-2ML</td>
			<td>Polyclonal secondary antibody for western blotting</td>
		</tr>
		<tr>
			<td>Immobilon(R)-P Polyvinylidene difluoride membrane</td>
			<td>Merck Millipore</td>
			<td>IPVH00010</td>
			<td>Transfer membrane for western blotting</td>
		</tr>
		<tr>
			<td>iTaq Universal SYBR Green Supermix</td>
			<td>Bio-Rad</td>
			<td>1725125</td>
			<td>For quantitative real-time PCR (qRT-PCR)</td>
		</tr>
		<tr>
			<td>KIT,iSCRIPT cDNA SYNTHES</td>
			<td>Bio-Rad</td>
			<td>1708891</td>
			<td>For Reverse-transcriptional PCR (RT-PCR)</td>
		</tr>
		<tr>
			<td>Millex-GP Filter, 0.22 &#181;m</td>
			<td>Merck Millipore</td>
			<td>SLGP033RB</td>
			<td>For filtration</td>
		</tr>
		<tr>
			<td>Mini-PROTEAB TGX Gels</td>
			<td>Bio-Rad</td>
			<td>4561043</td>
			<td>For SDS-PAGE</td>
		</tr>
		<tr>
			<td>NanoDrop One</td>
			<td>Thermo Scientific</td>
			<td>ND-ONEC-W</td>
			<td>Detection of protein concentration</td>
		</tr>
		<tr>
			<td>Nylon membrane</td>
			<td>PALL</td>
			<td>T42754</td>
			<td>Membrane for dot-ELISA</td>
		</tr>
		<tr>
			<td>Parafilm M Membrane</td>
			<td>Sigma</td>
			<td>P7793-1EA</td>
			<td>Making artifical diet sandwichs</td>
		</tr>
		<tr>
			<td>Rabbit anti-LssgMP polyclonal antibody against LssgMP peptides</td>
			<td>Genstript</td>
			<td></td>
			<td>Rabbit primary anti-LssgMP polyclonal antibody for western blotting</td>
		</tr>
		<tr>
			<td>Rabbit anti-RSV polyclonal antibody</td>
			<td>Genstript</td>
			<td></td>
			<td>Rabbit primary anti-RSV polyclonal antibody for western blotting and dot-ELISA</td>
		</tr>
		<tr>
			<td>RNAprep pure Micro Kit</td>
			<td>TIANGEN</td>
			<td>DP420</td>
			<td>For RNA Extraction</td>
		</tr>
	</tbody>
</table>

two-layered membrane sandwich method for laodelphax striatellus saliva collection

Rice stripe virus (RSV), which causes significant economic loss of agriculture in East Asia, entirely depends on insect vectors for its effective transmission among host rice. Laodelphax striatellus (small brown planthopper, SBPH) is the primary insect vector that horizontally transmits RSV while sucking sap from the phloem. Saliva plays a significant role in insects' feeding behavior. A convenient method that will be useful for research on insects' saliva with piercing-sucking feeding behavior is described here. In this method, insects were allowed to feed on an artificial diet sandwiched between two stretched paraffin film layers. The diet containing the saliva was collected each day, filtered, and concentrated for further analysis. Finally, the quality of collected saliva was examined by protein staining and immunoblotting. This method was exemplified by detecting the presence of RSV and a mucin-like protein in the saliva of SBPH. These artificial feeding and saliva collection method will lay a foundation for further research on factors in insect saliva related to feeding behavior and virus transmission.

Schematics of artificial feeding installation and saliva collection 
Figure 1A depicts the glass cylinder (15 cm x 2.5 cm) used as a feeding chamber to collect the saliva. Firstly, the SBPH larvae were starved for several hours to improve the collection efficiency and then immobilized by chilling for 5 min. After the insects were transferred into the glass cylinder, both open ends of the chamber were covered with stretched Paraffin membrane. At one end, 200 &#181;L of 5...

Watch this Scientific Journal Video about Two-layered Membrane Sandwich Method for Laodelphax striatellus Saliva Collection at JoVE.com

Two-layered Membrane Sandwich Method for Laodelphax striatellus Saliva Collection

The present protocol describes a method to collect sufficient saliva from piercing-sucking insects using an artificial medium. This is a convenient method for collecting insect saliva and studying salivary function on insect feeding behavior and vector-borne virus transmission.

Two-layered Membrane Sandwich Method for Laodelphax striatellus Saliva Collection

Rice stripe virus (RSV), which causes significant economic loss of agriculture in East Asia, entirely depends on insect vectors for its effective ...

Artificial feeding and saliva collection provide a direct method for detecting effectors in insect saliva. However, this has not be described in detail before. This protocol is effective for saliva collection from saprophytic insects.Additionally, it's a simple technique, as we use medium containing only sucrose as a artificial diet. Saprophytic insects'saliva may affect against the host's immune system to benefit feeding behavior and transmit pathogens. This medicine that can be used for insect behavior and the insect bone path research.This is a simple method to perform. However, this suggest the mounting of clean experimental environment as saliva is being collected for further research. Begin by preparing a 5%sucrose solution for the artificial diet, and filter the solution through a 0.22 micron filter to remove bacterial contamination and impurities.Starve approximately 200 small brown plant hopper larvae for three to five hours before introducing them into a feeding chamber. Next, to prepare the glass cylinders as feeding chambers, cover one open end of the chamber with a paraffin membrane before introducing the experimental insects, then transfer the insects into the glass cylinder and cover the other end of the chamber with stretched paraffin membrane. Add 200 microliters of artificial diet on the membrane, then cover the liquid with another layer of stretched paraffin membrane.Finally, cover the chamber with aluminum foil, leaving the end with the artificial diet device exposed to the light. After 24 hours, collect the SBPH saliva by cooling the cylinder at four degrees Celsius to immobilize the insects, then uncover the outer film and collect the artificial diet into 1.5 milliliter sterile tubes using a sterile pipette. Keep the collected saliva at minus 80 degrees Celsius until analysis.Next, rinse the inner membrane with 50 microliters of fresh artificial diet three times by pipetting softly, and collect the artificial washing diet into 1.5 milliliter sterile tubes. After the three rinses, add fresh artificial diet on the inner membrane and place a freshly stretched paraffin membrane on top. Finally, filter the collected samples through a 0.22 micron filter unit to remove microbes and other contaminants.Transfer the collective saliva samples in a 500 microliter, 10 kilodalton centrifugal filter. Centrifuge the sample. Collect the supernatant and bring up the final volume to 100 microliters.To measure the concentration of the collected saliva, turn on the UV visible spectrophotometer and wash the pedestals three times with double-distilled water. Select the options on the screen in the following order, proteins, protein A280. Select type and one absorbance unit equal to one milligram per milliliter.Then check the box for baseline correction, 340 nanometers. Next, load two microliters of 5%sucrose aqueous solution as blank, then touch Blank at the bottom of the screen. Finally, after setting the standards, load two microliters of the collected saliva and record the protein concentration.When feeding on 5%sucrose, more than 80%of SBPH survived for the first four days. However, from the fifth day onward, mortality increased quickly to 40%and on the seventh day, less than half of the SBPH survived. An SDS page analysis showed the concentrated saliva samples from RSV-infected SBPH saliva contained many more proteins than the 5%sucrose negative control.In a Western blot analysis for detection of the RSV capsid protein, a non-infected and viruliferous insects. The RSV capsid protein was successfully detected in the viruliferous sample, an antibody designed against the LssgMP gene product detected a 78 kilodalton protein in non-infected and viruliferous samples, demonstrating that LssgMP is a saliva protein. A QRT PCR analysis of LssgMP transcript levels in different tissues showed that the Lssg transcript levels in the salivary gland was 20-fold higher than in the whole body and gut, confirming the specific expression of LssgMP in the salivary gland.Starving the experimental insects before introducing them into chamber is necessary to ensure the efficiency of our saliva collection. Besides, an artificial medium should be collected and exchanged every 24 hours to reduce microbial contamination in the collected sample. This technique provides a direct method to study the function of saliva in transmitting pathogens.Additionally, it can help study insect pathogen host interaction.

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Research

JoVE Journal

Biology

2.2K visualizações.  Chinese Academy of Sciences. A alimentação artificial e a coleta de saliva fornecem um método direto para detectar efeitos na saliva de insetos. No entanto, isso não foi descrito em detalhes antes. Este protocolo é eficaz para a coleta de saliva de insetos saprofíticos.Além disso, é uma técnica simples, pois usamos meio contendo apenas sacarose como uma dieta artificial. A saliva de insetos saprofíticos pode afetar contra o sistema imunológico do hospedeiro para beneficiar o comportamento alimentar e tr...