White-backed Planthopper Research Articles

Sublethal effects of nitenpyram on the biological traits and metabolic enzymes of the white-backed planthopper, Sogatella furcifera (Hemiptera: Delphacidae)

Neonicotinoid insecticide nitenpyram is widely used in controlling rice hoppers including Sogatella furcifera (Horváth). At present, the effects of nitenpyram on the biological traits and metabolic enzymes of S. furcifera remain unclear. In this study, we applied an age-stage, two-sex life table to evaluate the sublethal effects of nitenpyram on S. furcifera under one- or multi-generation exposure. Fecundity of F0 individuals was significantly decreased in the LC25 treatment group compared to the control. Additionally, in contrast to control, the preadult period, male adult longevity, female adult longevity, longevity, total preoviposition period (TPOP), oviposition days and fecundity were significantly decreased in the F1 and F6 generations, while the development time of the 1st, 3rd and 5th -instar in the F6 generation were significantly shorter than the control and (or) the F1 generation. Moreover, except for the mean generation time (T) that was significantly decreased in the F1 and F6 generations, other population parameters such as the intrinsic rate of increase (ri), finite rate of increase (λ) and net reproductive rate (R0) were not influenced by nitenpyram exposure. The P450 and EST were both significantly increased in the F0 and F6 individuals after nitenpyram (LC25) treatment, and the P450 showed a higher activity in the F6 generation than F0. The mRNA levels of four P450 genes (CYP4CE3, CYP417A4, CYP439A3 and CYP6FJ3) were induced by nitenpyram (LC25) treatment in both the F0 and F6 generation, and these four P450 genes were also significantly upregulated in the F6 generation compared with F0. Our findings are useful for developing rational application strategies for using pesticides and understanding the metabolic resistance of nitenpyram in S. furcifera.

Recombinase polymerase amplification assay for sensitive and rapid detection of southern rice black-streaked dwarf virus in plants

Southern rice black-streaked dwarf virus (SRBSDV) naturally infects rice and maize plants through white-backed planthopper (Sogatella furcifera) causing significant crop losses in China and Vietnam. Thus, rapid and accurate detection methods for SRBSDV are urgently needed. Recombinase polymerase amplification (RPA) is a novel technique for rapid and sensitive detection of nucleic acids. In this research, a reverse transcription (RT)-RPA-based method was developed for the detection of SRBSDV. A pair of RPA primers targeting the conserved sequences within the SP10 (major coat protein) gene on genomic RNA S10 of SRBSDV were designed. The assay was performed in a single tube at 39 °C for 20 min and demonstrated that the RPA assay is an efficient alternative for rapid detection of SRBSDV.

Sogatella vibix (white-backed planthopper)

This datasheet on Sogatella vibix covers Identity, Distribution, Hosts/Species Affected, Natural Enemies, Further Information.

A cytorhabdovirus-based expression vector in Nilaparvata lugens, Laodelphax striatellus, and Sogatella furcifera

The brown planthopper (BPH, Nilaparvata lugens), the small brown planthopper (SBPH, Laodelphax striatellus), and the white-backed planthopper (WBPH, Sogatella furcifera) are problematic insect pests and cause severe yield losses through phloem sap-sucking and virus transmission. Barley yellow striate mosaic virus (BYSMV), a plant cytorhabdovirus, has been developed as versatile expression platforms in SBPHs and cereal plants. However, bio-safe overexpression vectors based on recombinant BYSMV (rBYSMV) remain to be developed and applied to the three kinds of planthoppers. Here, we found that rBYSMV was able to infect SBPHs, BPHs and WBPHs through microinjection with crude extracts from rBYSMV-infected barley leaves. To ensure bio-safety of the rBYSMV vectors, we generated an rBYSMV mutant by deleting the accessory protein P3, a putative viral movement protein. As expected, the resulting mutant abolished viral systemic infection in barley plants but had no effects on BYSMV infectivity in insect vectors. Subsequently, we used the modified rBYSMV vector to overexpress iron transport peptide (ITP) in the three kinds of planthoppers and revealed the potential functions of ITP. Overall, our results provide bio-safe overexpression platforms to facilitate functional genomics studies of planthoppers.

Establishment of White-Backed Planthopper Cell Lines.

The first continuous cell line of leafhopper was established over 50years ago. Since then, leafhopper cell monolayers have been used extensively to assay the infectivity of plant viruses that multiply in their insect vectors and to elucidate the viral determinants for virus transmission via insects. We have established continuous insect cell lines of three rice planthoppers, which have been used to study the mechanisms for replication and spread of rice viruses. The notable advantage of the vector cell monolayer system is that it can reach a uniform infection rate of 100% of the cells in the culture inoculated with diluted viruses, and thus allows for synchronous virus multiplication. The self-propagative nature of leafhopper and planthopper cell lines under favorable conditions ensures the system both dynamic and stable for viral infection. The vector cell monolayer systems and molecular probes, along with reliable traditional methods, certainly facilitate studies on interactions between plant viruses and insect vectors at molecular and cellular levels.

Discovery of Pyrido[1,2-a]pyrimidinone Mesoionic Compounds Incorporating a Dithioacetal Moiety as Novel Potential Insecticidal Agents.

A series of novel mesoionic pyrido[1,2-a]pyrimidinone compounds incorporating a dithioacetal skeleton were designed and synthesized for use as insecticidal agents. The biological activity of the title compounds indicated good to excellent insecticidal activities against bean aphids (Aphis craccivora) and white-backed planthoppers (Sogatella furcifera). Compound 34 showed excellent insecticidal activity against bean aphids (A. craccivora) with an LC50 value of 2.80 μg/mL, exceeding the insecticidal activity of trifluoropyrimidine (LC50 = 4.20 μg/mL). Proteomics and molecular docking results indicated that compound 34 could act on nicotinic acetylcholine receptors. This study provides support for the application of mesoionic pyrido[1,2-a]pyrimidinone compounds containing dithioacetal as novel insecticidal agents.

Biological Efficacy of Cochlioquinone-9, a Natural Plant Defense Compound for White-Backed Planthopper Control in Rice.

Simple SummaryThis study investigated the biological efficacy of cochlioquinone-9 (cq-9), a plant secondary metabolite, for controlling white-backed planthopper (WBPH) and compared the gene expression levels following cq-9 treatment. The results show that cq-9 enhances plant growth against WBPH and is associated with aromatic amino acid-related plant defense genes. This demonstrates the potential of cq-9 to replace chemical pesticides and suggests a new method for controlling WBPH.Rice is exposed to various biotic stresses in the natural environment. The white-backed planthopper (Sogatella furcifera, WBPH) is a pest that causes loss of rice yield and threatens the global food supply. In most cases, pesticides are used to control WBPH. However, excessive use of pesticides increases pesticide resistance to pests and causes environmental pollution. Therefore, it is necessary to develop natural product-based pesticides to control WBPH. Plants produce a variety of secondary metabolites for protection. Secondary metabolites act as a defense against pathogens and pests and are valuable as pesticides and breeding materials. Cochlioquinone is a secondary metabolite that exhibits various biological activities, has a negative effect on the growth and development of insects, and contributes to plant defense. Here, we compared plant growth after treatment with cochlioquinone-9 (cq-9), a quinone family member. cq-9 improved the ability of plants to resist WBPH and had an effect on plant growth. Gene expression analysis revealed that cq-9 interacts with various defense-related genes to confer resistance to WBPH, suggesting that it is related to flavonoid compounds. Overall, this study provides insight into the mechanisms of WBPH resistance and suggests that cq-9 represents an environmentally friendly agent for WBPH control.

Rice Resistance Buffers against the Induced Enhancement of Brown Planthopper Fitness by Some Insecticides

The brown planthopper, Nilaparvata lugens (Stål)[BPH], is a damaging pest of rice in Asia. Insecticides and rice varietal resistance are widely implemented BPH management practices. However, outbreaks of BPH have been linked to excessive insecticide use—challenging the compatibility of these two management practices. IR62 is a variety with resistance against BPH, the whitebacked planthopper, Sogatella furcifera Horváth [WBPH], and the green leafhopper, Nephotettix virescens (Distant)[GLH]. We compared BPH responses to IR62 and to the susceptible variety IR64 treated with buprofezin, carbofuran, cartap hydrochloride, cypermethrin, deltamethrin, fipronil, or thiamethoxam + chlorantraniliprole. In greenhouse bioassays, cypermethrin, fipronil and thiamethoxam + chlorantraniliprole reduced egg laying on both varieties, and, together with buprofezin, reduced nymph survival to zero. Buprofezin, carbofuran, and cartap hydrochloride stimulated egg laying, and carbofuran increased nymph biomass, but these effects were reduced on IR62. Planthopper populations were ten times higher on deltamethrin-treated rice than untreated rice in a screenhouse experiment. Host resistance failed to buffer against this insecticide-induced resurgence in BPH and WBPH. However, IR62 reduced the effect in GLH. Rice treated with cypermethrin and fipronil had reduced yields compared to untreated controls, suggesting possible phytotoxic effects. We found little evidence of synergies between the two management practices; but host resistance did buffer against the undesirable effects of some insecticides.

Efficacy of Biopesticides Against Plant Hoppers in Direct Seeded Rice

This study evaluates the field efficacy of some biopesticides i.e., azadirachtin 1%EC @ 250, 500 & 750 ml, Bacillus thuringiensis @1500, 2000 & 2500 g, Beauveria bassiana 10%SC @2000, 2250 & 2500 ml and chlorpyriphos 20EC @2500 ml (check)/ha against the brown plant hopper Nilaparvata lugens (Stål) and white backed plant hopper, Sogatella furcifera (Horváth) in direct seeded rice. The experiment was carried out at the Punjab Agricultural University, Ludhiana and Punjab Agricultural University Regional Research Station, Gurdaspur during 2017-18. It was observed that all tested biopesticides were found significantly effective. Beauveria bassiana @2500 ml/ha was the most effective, while the maximum cost-benefit ratio was obtained with chlorpyriphos 20EC @2500 ml (standard check) followed by azadirachtin 1% EC @250 and 500 ml/ha. Despite less cost benefits, biopesticides can be safer to environment.

Effect of Ecological Engineering on Incidence of Key Rice Pests

Incidence of rice pests like white backed planthopper (WBPH) Sogatella furcifera, leaf folder Cnaphalocrocis medinalis, whorl maggot Hydrellia sasakii and stem borers - yellow stem borer Scirpophaga incertulas and the pink stem borer Sesamia inferens were studied in ecologically engineered rice fields during kharif 2019 and 2020. The WBPH population significantly reduced in fields planted with mixture of crop and flowering plants (0.66 ± 0.25 and 0.83 ± 0.44 WBPH/hill) during kharif 2019 and 2020, respectively. Rice plots planted with crops and flowering plants had lowest leaf folder damage in both the seasons (0.64 ± 0.11% and 0.54 ± 0.35%). Similarly, whorl maggot damage in mixture of crop and flowering plants found significantly reduced than control plots in both the seasons. Reduced pest activity in ecologically engineered fields significantly increased rice yield, particularly in rice plots planted with crops and flowering plants (5.60 ± 0.24 and 5.27 ± 0.06 mt/ ha). Study revealed that planting of crop and flowering plants around the rice field increased the natural enemy activity and reduced incidence of rice pests which eventually reduced the yield losses caused by insect pests and increased the rice grain yield.

Insecticide Resistance Monitoring in Field Populations of the Whitebacked Planthopper Sogatella furcifera (Horvath) in China, 2019-2020.

Simple SummaryThe whitebacked planthopper (WBPH), Sogatella furcifera (Horváth), is one of the most destructive pests that seriously threatens the high-quality and safe production of rice. Overuse of chemical insecticides has led to varying levels of resistance to insecticides in the field population of S. furcifera. In this study, we measured the susceptibility of 18 populations to 10 insecticides by the rice-seedling dip method. Enzyme assays were performed to measure the levels of esterase (EST), glutathione S- transferase (GST) and cytochrome P450 monooxygenase (P450). A risk of cross-resistance between some insecticides were found by pairwise correlation, and EST may be contributed to the resistance to nitenpyram, thiamethoxam and clothianidin in S. furcifera. Overall, our findings will help inform the effective insecticide resistance management strategies to delay the development of insecticide resistance in S. furcifera.Monitoring is an important component of insecticide resistance management. In this study, resistance monitoring was conducted on 18 field populations in China. The results showed that S. furcifera developed high levels of resistance to chlorpyrifos and buprofezin, and S. furcifera showed low to moderate levels of resistance to imidacloprid, thiamethoxam, dinotefuran, clothianidin, sulfoxaflor, isoprocarb and ethofenprox. Sogatella furcifera remained susceptible or low levels of resistance to nitenpyram. LC50 values of nitenpyram and dinotefuran, imidacloprid, thiamethoxam, clothianidin and chlorpyrifos exhibited significant correlations, as did those between dinotefuran and thiamethoxam, clothianidin, sulfoxaflor, imidacloprid, isoprocarb and buprofezin. Similarly, significant correlations were observed between thiamethoxam and clothianidin, sulfoxaflor and imidacloprid. In addition, the activity of EST in field populations of S. furcifera were significantly correlated with the LC50 values of nitenpyram, thiamethoxam and clothianidin. These results will help inform effective insecticide resistance management strategies to delay the development of insecticide resistance in S. furcifera.

A New Mitochondrial Genome of Sogatella furcifera (Horváth) (Hemiptera: Delphacidae) and Mitogenome-Wide Investigation on Polymorphisms.

Simple SummaryWe completed one mitogenome of white-backed planthopper (WBPH), Sogatella furcifera (Horváth), with finding heteroplasmy phenomenon confirmed by PCR reaction and Sanger sequencing method. This heteroplasmy was not observed in WBPHs (n = 24) collected from the fields, suggesting that it may be uncommon in fields. We also analyzed single nucleotide polymorphisms, insertion and deletions, and simple sequence repeats among three currently available WBPH mitogenomes of Korea and China, suggesting that identified intraspecific variations could be potential candidates for developing markers to distinguish geographical populations of WBPH including Korean and Chinese. Phylogenetic analysis of 32 mitogenomes of Delphacidae including the three WBPH mitogenomes suggested that Delphacinae seems to be monophyletic and Sogatella species including WBPH are clearly formed as one clade.White-backed planthopper (WBPH), Sogatella furcifera (Horváth), is one of the major sap-sucking rice pests in East Asia. We have determined a new complete mitochondrial genome of WBPH collected in the Korean peninsula using NGS technology. Its length and GC percentages are 16,613 bp and 23.8%, respectively. We observed one polymorphic site, a non-synonymous change, in the COX3 gene with confirmation heteroplasmy phenomenon within individuals of WBPH by PCR amplification and Sanger sequencing, the first report in this species. In addition, this heteroplasmy was not observed in wild WBPH populations, suggesting that it may be uncommon in fields. We analyzed single nucleotide polymorphisms, insertion, and deletions, and simple sequence repeats among the three WBPH mitogenomes from Korea and China and found diverse intraspecific variations, which could be potential candidates for developing markers to distinguish geographical populations. Phylogenetic analysis of 32 mitogenomes of Delphacidae including the three WBPH mitogenomes suggested that Delphacinae seems to be monophyletic and Sogatella species including WBPH are clearly formed as one clade. In the future, it is expected that complete mitogenomes of individuals of geographically dispersed WBPH populations will be used for further population genetic studies to understand the migration pathway of WBPH.

Silencing a Simple Extracellular Leucine-Rich Repeat Gene OsI-BAK1 Enhances the Resistance of Rice to Brown Planthopper Nilaparvata lugens.

Many plant proteins with extracellular leucine-rich repeat (eLRR) domains play an important role in plant immunity. However, the role of one class of eLRR plant proteins—the simple eLRR proteins—in plant defenses against herbivores remains largely unknown. Here, we found that a simple eLRR protein OsI-BAK1 in rice localizes to the plasma membrane. Its expression was induced by mechanical wounding, the infestation of gravid females of brown planthopper (BPH) Nilaparvata lugens or white-backed planthopper Sogatella furcifera and treatment with methyl jasmonate or abscisic acid. Silencing OsI-BAK1 (ir-ibak1) in rice enhanced the BPH-induced transcript levels of three defense-related WRKY genes (OsWRKY24, OsWRKY53 and OsWRKY70) but decreased the induced levels of ethylene. Bioassays revealed that the hatching rate was significantly lower in BPH eggs laid on ir-ibak1 plants than wild-type (WT) plants; moreover, gravid BPH females preferred to oviposit on WT plants over ir-ibak1 plants. The exogenous application of ethephon on ir-ibak1 plants eliminated the BPH oviposition preference between WT and ir-ibak1 plants but had no effect on the hatching rate of BPH eggs. These findings suggest that OsI-BAK1 acts as a negative modulator of defense responses in rice to BPH and that BPH might exploit this modulator for its own benefit.

Expression Analyses of Vitellogenin and Target of Rapamycin of Sogatella furcifera (Hemiptera: Delphacidae), and Their Effects on Reproduction.

Vitellogenin (Vg) and the target of rapamycin (TOR) are important genes involved in insect reproduction regulation. In this work, the full lengths of the Vg (SfVg) and TOR (SfTOR) genes of the white-backed planthopper Sogatella furcifera were cloned. The expression pattern in females showed that SfVg was highly expressed in fat bodies, and SfTOR was highly expressed in Malpighian tubules. After silencing SfVg or SfTOR, female adults did not deposit eggs. Their ovarian development was delayed, and yolk protein deposition in the oocytes was reduced. However, wild-type females mated with SfTOR-silenced males could lay eggs and produce offsprings normally. The dissections of testes and accessory glands of males with SfTOR knockdown showed that their development was not affected. Therefore, the silencing of the SfVg or SfTOR genes can effectively inhibit female reproduction, but SfTOR knockdown has no significant effect on male reproductive capacity. Furthermore, silencing SfTOR can cause SfVg expression to decrease significantly. All of the above results revealed that SfVg and SfTOR are essential for white-backed planthopper reproduction and may provide a potential target for pest control.

The Quantitative Trait Loci Mapping of Rice Plant and the Components of Its Extract Confirmed the Anti-Inflammatory and Platelet Aggregation Effects In Vitro and In Vivo.

Unpredictable climate change might cause serious lack of food in the world. Therefore, in the present world, it is urgent to prepare countermeasures to solve problems in terms of human survival. In this research, quantitative trait loci (QTLs) were analyzed when rice attacked by white backed planthopper (WBPH) were analyzed using 120 Cheongcheong/Nagdong double haploid lines. Moreover, from the detected QTLs, WBPH resistance-related genes were screened in large candidate genes. Among them, OsCM, a major gene in the synthesis of Cochlioquinone-9 (cq-9), was screened. OsCM has high homology with the sequence of chorismate mutase, and exists in various functional and structural forms in plants that produce aromatic amino acids. It also induces resistance to biotic stress through the synthesis of secondary metabolites in plants. The WBPH resistance was improved in rice overexpressed through map-based cloning of the WBPH resistance-related gene OsCM, which was finally detected by QTL mapping. In addition, cq-9 increased the survival rate of caecal ligation puncture (CLP)-surgery mice by 60%. Moreover, the aorta of rat treated with cq-9 was effective in vasodilation response and significantly reduced the aggregation of rat platelets induced by collagen treatment. A cq-9, which is strongly associated with resistance to WBPH in rice, is also associated with positive effect of CLP surgery mice survival rate, vasodilation, and significantly reduced rat platelet aggregation induced by collagen treatment. Therefore, cq-9 presents research possibilities as a substance in a new paradigm that can act on both Plant-Insect in response to the present unpredictable future.

Over-Expression of Chorismate Mutase Enhances the Accumulation of Salicylic Acid, Lignin, and Antioxidants in Response to the White-Backed Planthopper in Rice Plants.

The white-backed planthopper (WBPH) is a serious pest of rice crop and causes sever yield loss each year, especially in Asian countries. In this study, we used chorismate mutase (CM) transgenic line to examine the defense mechanism of rice plants against WBPH. The survival rate of WBPHs, infestation rate of plants, lignin biosynthesis, transcriptional regulation of related genes, salicylic acid (SA) accumulation and signaling and antioxidants regulation were investigated. The WBPH population decreased by 67% in OxCM-t, and the plant infestation rate was 3.5-fold higher in wild-type plants compared with transgenic plants. A substantial increase in lignin was found in the transgenic line (742%) and wild-type (417%) plants. Additionally, CM, phenylalanine ammonia lyase (PAL), chalcone synthase (CHS), and chalcone isomerase (CHI) showed significant increases in their relative expression level in the transgenic line. Salicylic acid was significantly enhanced in the transgenic line compared with WBPH infestation. SA can activate pathogenesis related proteins-1 (PR1), PR2, antioxidants, and the expression of their related genes: superoxide dismutase (SOD) and catalase (CAT). WBPH infestation reduced the chlorophyll contents of both transgenic and wild-type plants, but the reduction was great in wild-type than transgenic plants. The sugar content was only significantly increased in the transgenic line, indicating that sugars are not heavily involved in WBPH stress. Phenylalanine, proline, aspartic acid, and total amino acids were increased in the transgenic line and reduced in the wild-type plants. Taken together, all the results suggest that overexpression of CM gene regulates the defense mechanisms and enhances the rice toward WBPH stress.

Cloning and Functional Verification of CYP408A3 and CYP6CS3 Related to Chlorpyrifos Resistance in the Sogatella furcifera (Horváth) (Hemiptera: Delphacidae)

Simple SummaryAs an important enzyme system in organisms, P450 multi-functional oxidase not only participates in the metabolism and synthesis of substances in organisms but can also maintain the normal physiological functions of organisms under stress. As one of the important rice pests, the harm caused by white-backed planthoppers has been increasing in recent years. Although the application of chemical pesticides as one of the prevention and control measures can slow down the harm of white-backed planthoppers, its resistance is also rising rapidly. Among them, the generation of metabolic resistance dominated by the P450 enzyme is more common. In this study, we measured the expression of ten P450 gene in vivo situations with a background of chlorpyrifos resistance in white-backed planthoppers. After selecting the two genes with the highest expression, the function of these two genes in the pesticide resistance process was verified by RNA interference and provided a theoretical basis for a follow-up study of the molecular mechanism of the P450 gene mediated by pesticide resistance formation.The white-back planthopper (WBPH), Sogatella furcifera, mainly harms rice and occurs in most rice regions in China and Asia. With the use of chemical pesticides, S. furcifera has developed varying degrees of resistance to a variety of pesticides. In our study, a chlorpyrifos-resistant population (44.25-fold) was built through six generations of screening with a sublethal dose of chlorpyrifos (LD50) from a field population. The expression levels of ten selected resistance-related P450 genes were analyzed by RT-qPCR and found that CYP408A3 and CYP6CS3 were significantly more expressed in the third instar nymphs of the XY17-G5 and XY17-G6 populations, about 25-fold more than the Sus-Lab strain, respectively (p < 0.01). To elucidate their molecular function in the development of resistance towards chlorpyrifos, we cloned two P450 full lengths and predicted their tertiary protein structures. CYP408A3 and CYP6CS3 were also downregulated after injecting dsCYP408A3, dsCYP6CS3, or their mixture compared to the control group. Moreover, the mortality rates of the dsCYP6CS3 (91.7%) and the mixture injection treatment (93.3%) treated by the LC50 concentration of chlorpyrifos were significantly higher than the blank control group (51.7%) and dsCYP408A3 injection treatment (69.3%) at 72 h (p < 0.01). Meanwhile, the P450 enzyme activities in the dsRNA treatments were lower than that in the control (XY17-G6) (p < 0.01). Therefore, the P450 gene CYP6CS3 may be one of the main genes in the development of chlorpyrifos resistance in S. furcifera.

Southern rice black-streaked dwarf virus hijacks SNARE complex of its insect vector for its effective transmission to rice.

Vesicular trafficking is an important dynamic process that facilitates intracellular transport of biological macromolecules and their release into the extracellular environment. However, little is known about whether or how plant viruses utilize intracellular vesicles to their advantage. Here, we report that southern rice black‐streaked dwarf virus (SRBSDV) enters intracellular vesicles in epithelial cells of its insect vector by engaging VAMP7 and Vti1a proteins in the soluble N‐ethylmaleimide‐sensitive factor attachment protein receptor (SNARE) complex. The major outer capsid protein P10 of SRBSDV was shown to interact with VAMP7 and Vti1a of the white‐backed planthopper and promote the fusion of vesicles into a large vesicle, which finally fused with the plasma membrane to release virions from midgut epithelial cells. Downregulation of the expression of either VAMP7 or Vti1a did not affect viral entry and accumulation in the gut, but significantly reduced viral accumulation in the haemolymph. It also did not affect virus acquisition, but significantly reduced the virus transmission efficiency to rice. Our data reveal a critical mechanism by which a plant reovirus hijacks the vesicle transport system to overcome the midgut escape barrier in vector insects and provide new insights into the role of the SNARE complex in viral transmission and the potential for developing novel strategies of viral disease control.

Sphingolipid composition and metabolism differ in three auchenorrhynchous pests of rice

• A total of 28, 27 and 25 sphingolipid species were detected in SBPH, WBPH and GRLH. • No C14 sphingoid-base was detected in GRLH. • The category of sphingomyelins varies in the three insect species. • The leafhopper possessed more SMase gene isoforms than planthoppers. Sphingolipids (SPLs), a group of membrane and intracellular lipids, mediate numerous cellular processes. The composition and metabolism of sphingolipids varies according to species and the sphingolipid studies of insects, as compared to mammals, are not yet clear. In the current study, we subjected three auchenorrhynchous insects, including whitebacked planthopper (WBPH), Sogatella furcifera , small brown planthopper (SBPH), Laodelphax striatellus, and green rice leafhopper (GRLH), Nephotettix cincticeps , as representative rice pests for sphingolipid analysis. We performed sphingolipid species profiling using UPLC-Q-TOF-MS/MS and isolated sphingolipid metabolic genes from their transcriptomic data. C14-, C16-, C18- and C20-sphingoid base were detected in both planthoppers, but no C14- sphingoid base was found in GRLH. The planthoppers had more abundant sphingosine-1-phosphates (Sph-1-P) and ceramides than leafhopper. A total of 14, 13 and 16 sphingomyelin species were found in SBPH, WBPH and GRLH, respectively. The composition of sphingomyelin species varied in three insects. Coordinated with the abundance in sphingomyelin species, the leafhopper possessed more sphingomyelinase ( SMase ) gene isoforms for metabolism of different sphingomyelins than planthoppers. The phylogenetic analysis showed the three tested insects all possessed one potential neutral-SMase homologue, whereas SBPH and GRLH both had another potential acid-SMase homologue. This study is a comprehensive sphingolipidomic analysis, suggesting that sphingolipid profiles significantly differed among the three insects. By providing information of sphingolipid metabolic gene homologues of these three insects, our findings will contribute to the further sphingolipid studies of auchenorrhynchous insects and provide a research foundation for rice pest management.

Resistance Evaluation of Dominant Varieties against Southern Rice Black-Streaked Dwarf Virus in Southern China.

Southern rice black-streaked dwarf virus (SRBSDV), a Fijivirus in the Reoviridae family, is transmitted by the white-backed planthopper (Sogatella furcifera, WBPH), a long-distance migratory insect, and presents a serious threat to rice production in Asia. It was first discovered in China’s Guangdong Province in 2001 and has been endemic in the south of China and north of Vietnam for two decades, with serious outbreaks in 2009, 2010, and 2017. In this study, we evaluated the resistance of 10 dominant rice varieties from southern China, where the virus overwinters and accumulates as a source of early spring reinfection, against this virus by artificial inoculation. The results showed that in all tested varieties there was no immune resistance, but there were differences in the infection rate, with incidence rates from 21% to 90.7%, and in symptom severity, with plant weight loss from 66.71% to 91.20% and height loss from 34.1% to 65.06%. Additionally, and valuably, the virus titer and the insect vector virus acquisition potency from diseased plants were significantly different among the varieties: an over sixfold difference was determined between resistant and susceptible varieties, and there was a positive correlation between virus accumulation and insect vector virus acquisition. The results can provide a basis for the selection of rice varieties in southern China to reduce the damage of SRBSDV in this area and to minimize the reinfection source and epidemics of the virus in other rice-growing areas.