White-backed Planthopper Research Articles

Biology and lifetable of whitebacked planthopper Sogatella furcifera (Horvath) on rice

Whitebacked planthopper Sogatella furcifera (Horvath) is an important insect pest causing economic damage to rice. Studies on its biology in West Bengal revealed that the fecundity was 197± 13.37 eggs/ female. The incubation period was 7.6± 0.69 days in October, with nymphal duration being 16.2± 0.85 days; and longevity of male macropterous ones was 9.5± 2.06, while for brachypterous it was 7.3± 1.33 days; and female brachypterous lived for 13.50± 1.08 days. The net fecundity rate, intrinsic rate of increase, gross reproductive rate, generation time, doubling time, finite rate of increase and net reproductive rate were 31.30, 0.122, 108.60, 29.29, 5.68 days, 1.129 and 64.91, respectively. The seasonal abundance when studied on rice in rainy season revealed that slight incidence occurred at 60 days, and its peak was at 32.00 and 34.20/ hill at 120 DAT during second week of November. Then it disappeared from the third week of November with the onset of winter during 2019 and 2020.

Threonyl-tRNA synthetase gene, a potential target for RNAi-based control of three rice planthoppers.

RNA interference (RNAi) has potential as a new strategy for pest control. However, the current overemphasis on the control of a single pest increased control costs. The aim of this study was to find a green method of controlling several pests without affecting the natural enemies with a single target gene. One possible RNAi target is the threonyl-tRNA synthetase (ThrRS), which is conserved and plays a significant role in protein biosynthesis. In this study, one threonyl-tRNA synthetase gene (NlthrS) was identified from the brown planthopper (Nilaparvata lugens). Spatio-temporal expression pattern analysis showed that NlthrS was highly expressed in the ovary, late embryogenesis, nymphs and female adults. In addition, RNAi-mediated knockdown of NlthrS caused 85.6% nymph mortality, 100% female infertility, molting disorder, extended nymph duration and shortened adult longevity. Target-specific results were obtained when dsNlthrS was used to interfere with the whiteback planthopper (Sogatella furcifera), small brown planthopper (Laodelphax striatellus), zig-zag winged leafhopper (Inazuma dorsalis) and their natural enemy (green mirid bug, Cyrtorhinus lividipennis). In addition, dsNlthrS could cause high mortalities of three species of planthoppers (85.6-100%), while only dsNlthrS-1 led to the death (97.3%) of I. dorsalis that was not affected by dsNlthrS-2. Furthermore, neither dsNlthrS-1 nor dsNlthrS-2 could influence the survival of C. lividipennis. The results reveal the biological functions of ThrRS in N. lugens in addtion toits protein synthesis, deepening our understanding of tRNA synthase in insects and providing a new method for the control of several rice pests via one dsRNA design. © 2022 Society of Chemical Industry.

Molecular Characterization of UDP-N-Acetylglucosamine Pyrophosphorylase and Its Role in the Growth and Development of the White-Backed Planthopper Sogatella furcifera (Hemiptera: Delphacidae).

UDP-N-acetylglucosamine pyrophosphorylase (UAP) is a key enzyme in the chitin biosynthesis pathway of insects. Here, we described the gene SfUAP in the white-backed planthopper Sogatella furcifera (Horváth) with an open reading frame of 1470 bp. Quantitative real-time polymerase chain reaction (qPCR) suggested that SfUAP exhibits a different developmental expression pattern and a higher expression after molting. The highest expression of SfUAP was observed in the integument tissues of adults, whereas head tissues showed negligible expression. RNAi-based gene silencing decreased the mRNA transcript levels in S. furcifera nymphs injected with double-stranded RNA of SfUAP. Finally, SfUAP silencing led to 84% mortality and malformed phenotypes in nymphs. Thus, our results can help better understand the role of SfUAP in S. furcifera.

Sogatella furcifera Saliva Mucin-like Protein Is Required for Feeding and Induces Rice Defences.

The white-backed planthopper (WBPH), Sogatella furcifera, is one of the most important piercing-sucking pests of rice (Oryza sativa) in Asia. Mucin-like salivary protein (SFMLP) is highly expressed in the salivary glands of WBPH, which plays an important role in WBPH feeding. In this study, WBPH injected with dsSFMLP had difficulty in sucking phloem sap from rice plants, which significantly reduced their food intake, weight, and survival. In contrast, the knockdown of the SFMLP gene had only a marginal effect on the survival of WBPH fed an artificial diet. Further studies showed that silencing SFMLP resulted in the short and single-branched salivary sheaths secretion and less formation of salivary flanges in rice. These data suggest that SFMLP is involved in the formation of the salivary sheath and is essential for feeding in WBPH. Overexpression of the SFMLP gene in rice plants promoted the feeding of WBPH, whereas silencing the gene in rice plants significantly decreased WBPH performance. Additionally, it was found that overexpression of SFMLP in rice plants elicited the signalling pathway of SA (salicylic acid) while suppressing JA (jasmonic acid); in contrast, silencing of the SFMLP gene in rice plants showed the opposite results. This study clarified the function of SFMLP in WBPH feeding as well as mediating rice defences.

Does solar light trap reduce the cost of pesticides used in rice field?

Pesticide application against insect pest infestation is environmentally unsafe and costly. An attempt was taken to evaluate the solar light trap as ecofriendly and cost-effective approach in Transplanted Aman rice (BRRI dhan32) field at Barhatta Upazila (Sub-district) in Netrokona district of Bangladesh. It was found that rice pest like Rice yellow stem borer, Rice leaf roller, Green leaf hopper, Brown plant hopper, Rice leaf miner, Rice gall midge, White leafhopper, Rice bug, Rice ear cutting caterpillar, White-backed planthopper, Rice caseworm, Grasshopper, Rice skipper and Rice beetle were the major insects that captured under the solar light traps. Some beneficial insects were also attracted by the trap these were Ladybird beetle, Water scavenger, Giant water bug, Ground beetle, Rove beetle, Damsel fly. All the harmful and the beneficial insects were belonging the order of Lepidoptera, Hemiptera, Orthoptera, Coleoptera, Diptera and Odonata. Though the mean yield of rice was statistically insignificant in both fields, the light trap installed fields required the less frequency of pesticides than the control fields which ultimately rendered the low pesticides cost in a great extent. On an average 1,034 BDT was reduced in per hectare. SAARC J. Agric., 20(1): 171-183 (2022)

Discovery of Pyrido[1,2-a]pyrimidine Mesoionic Compounds Containing Benzo[b]thiophene Moiety as Potential Pesticide Candidates.

The increasing evolution of insect resistance has made it challenging for traditional insecticides to control the bean aphid (Aphis craccivora Koch). To address this pending issue, a range of pyrido[1,2-a]pyrimidine mesoionic compounds containing benzo[b]thiophene were designed and synthesized. The biological activity test results of the target compounds indicated that they had moderate to outstanding insecticidal activity against the bean aphid (Aphis craccivora) and moderate insecticidal activity against the white-backed planthopper (Sogatella furcifera). Compound L14 exhibited significant insecticidal activity against A. craccivora, with an LC50 value of 1.82 μg/mL, which was superior to triflumezopyrim (LC50 = 4.76 μg/mL). The results of enzyme activity assay showed that compound L14 had a definite inhibitory effect on ATPase. Moreover, the proteomics and docking findings of compound L14 suggested that it may act on the central nervous system of aphids and interact with nicotinic acetylcholine receptors. Therefore, compound L14 is a potentially novel insecticide candidate for further utilization.

Non-Preference Mechanism of Resistance in Rice Germplasm Accessions to Whitebacked Planthopper Sogatella furcifera (Horvath)

Non-Preference Mechanism of Resistance in Rice Germplasm Accessions to Whitebacked Planthopper Sogatella furcifera (Horvath)

Immigration Pathways of White-Backed Planthopper in the Confluence Area of the Two Monsoon Systems.

The white-backed planthopper, WBPH, Sogatella furcifera (Horváth) is a plant pest that migrates long-distances. The migration pathway of WBPH in eastern China coincides with the north-south round trip of the East Asian monsoon. However, in Yunnan China, which is affected by two monsoon systems, the migration pathway is unclear. Light-trap data and analysis of female ovarian development showed that the peak period of immigration of WBPH into western Yunnan was earlier than in eastern Yunnan. Using meteorological reanalysis data and flight parameters of WBPH, trajectory modeling showed that there are two immigration pathways to Yunnan. One is from Myanmar to western Yunnan, and the other is from Vietnam and Laos to eastern Yunnan. The reason for the differences in source areas and immigration pathways between eastern and western Yunnan is that the west wind prevails in western Yunnan and is controlled by South Asian monsoon, while southwesterly winds prevail in eastern Yunnan due to the combined influence of South Asian monsoon and East Asian monsoon. The results indicate that WBPH invades Yunnan via two pathways under a two-monsoon system. These data will allow earlier prediction and population management of WBPH.

Identification of Alien Introgression Lines Resistant to White Backed Planthopper, Sogatella furcifera (Horvath) in Rice

Introgression lines of wide cross derivatives were screened to identify resistant/tolerant entries for WBPH biotypes under artificial condition. The main objective of this study is to provide breeders with more ‘attractive’ plant genetic resources that are easier to use, i.e. resistance sources in acceptable genetic background; or inbreeding tolerant forms disomic lines for inbred or hybrid rice breeding programme. Forty six pre-breeding lines were evaluated against White Backed Plant Hopper (WBPH) under glasshouse condition over a period of two years (2019 and 2020). Out of these, seven pre-breeding lines are moderately resistant to WBPH having score 5. Three pre-breeding lines are moderately susceptible to WBPH having score 7 and rest thirty four pre-breeding lines are highly susceptible to WBPH with a score of 9.

Identification of resistance of Guangxi (Oryza rufipogon Griff.) to white-backed planthopper with stem evaluation method

Identification of resistance of Guangxi (Oryza rufipogon Griff.) to white-backed planthopper with stem evaluation method

The Dark Septate Endophyte, Phialocephala fortinii J2PC4, Mitigates Southern Rice Black-Streaked Dwarf Disease and Impacts the Mortality of White Back Planthopper

Southern rice black-streaked dwarf disease (SRBSDD), caused by the southern rice black-streaked dwarf virus (SRBSDV) and transmitted by the white-backed planthopper (WBPH), is a severe disease responsible for significant yield losses in Southeast Asia, including China. The present study investigated utilization of dark septate endophyte (DSE) fungi against SRBSDD and WBPHas a new, effective approach for managing this disease. An isolate of the DSE fungus, Phialocephala fortinii J2PC4, was selected based on its effective symbiosis with rice. Phialocephala fortinii J2PC4 significantly promoted the growth of the rice, increasing plant height (14.8%), fresh weight (59.5%), and dry weight (60.5%) relative to the untreated control in growth-promotion experiments. In experiments assessing disease and pest suppression, growth of rice plants P. fortinii J2PC4 also promoted growth, increasing plant height(22.4%), fresh weight (74.0%), and dry mass (32.4%). Plants infested with WBPH for 48 hours exhibited a WBPH mortality rate of 8.2% in P. fortinii J2PC4 treated plants compared to 1.5% in the control plants. Disease incidence of SRBSDD in the plants treated with P. fortinii J2PC4 exhibited a 28.5% reduction in SRBSDD disease incidence compared to control plants. P. fortinii J2PC4 colonization of rice seedlings decreased the malondialdehyde (MDA) content, increased the superoxide dismutase (SOD) and peroxidase (POD) activity in rice leaves and induced the expression of the resistance-related genes, AOS, PR1a, and PR1b. In contrast POX1 and OsSAUR2 were down-regulated, relative to control plants. Larval production by WBPH in P. fortinii J2PC4 treated plants was also 24.7% lower than control plants in the pest resistance experiment. Our results provide new insights on use of the DSE fungus, P. fortinii J2PC4, as a biofertilizer and a biocontrol agent, which can potentially be applied as a new, safe and effective treatments for growth stimulation and disease and pest control in rice plants.

Design, Synthesis, and Insecticidal Activity of Novel Pyrido[1, 2-a]pyrimidinone Mesoionic Compounds Containing an Indole Moiety as Potential Acetylcholine Receptor Insecticides.

In this study, a series of novel mesoionic pyrido[1,2-a]pyrimidinone compounds containing a natural skeleton indole were designed and synthesized, and the insecticidal activities of the target compounds were tested. The results showed that the target compounds had good to excellent insecticidal activities against white-backed planthoppers (Sogatella furcifera) and bean aphids (Aphis craccivora). Among them, compound 7 showed outstanding insecticidal activities against both S. furcifera and A. craccivora, with LC50 values of 0.86 and 0.85 μg/mL, respectively. The insecticidal activity against bean aphids (A. craccivora) was superior to that of triflumezopyrim (LC50 = 3.67 μg/mL). Proteomics and quantitative real-time polymerase chain reaction (qRT-PCR) results revealed that compound 7 may interact with α1 and α7 nAChR subunits of S. furcifera. The results of enzyme activities indicated that compound 7 was an inhibitor of AChE in S. furcifera. This study provides new ideas for the discovery of new mesoionic pyrido[1,2-a]pyrimidinone insecticides.

Silencing the Autophagy-Related Genes ATG3 and ATG9 Promotes SRBSDV Propagation and Transmission in Sogatella furcifera.

Simple SummaryPlant viruses are mostly transmitted by insects and cause severe damage to crops. The southern rice black-streaked dwarf virus is a rice virus exclusively transmitted by a planthopper, Sogatella furcifera. Autophagy is usually initiated as an adaptive response for cell survival in unfavorable conditions, such as pathogen invasion. The invasion of the virus in the vector may elicit autophagy and may subsequently function to suppress or promote virus propagation and transmission in the insect vector. Here, we annotated two key autophagy-related genes, SfATG3 and SfATG9, in the planthopper vector and found that the genes are conserved among various insects. Interestingly, exposure of the vector to the virus activated the expression of SfATG3 and SfATG9, and silencing SfATG3 or SfATG9 promoted propagation and transmission rates of the virus. These results indicate that the expression of autophagy-related genes is initiated in the vector following exposure to the virus and that autophagy-related genes functions to suppress SRBSDV propagation and transmission.Autophagy plays diverse roles in the interaction among pathogen, vector, and host. In the plant virus and insect vector system, autophagy can be an antiviral/pro-viral factor to suppress/promote virus propagation and transmission. Here, we report the antiviral role of autophagy-related genes ATG3 and ATG9 in the white-backed planthopper (Sogatella furcifera) during the process of transmitting the southern rice black-streaked dwarf virus (SRBSDV). In this study, we annotated two autophagy-related genes, SfATG3 and SfATG9, from the female S. furcifera transcriptome. The cDNA of SfATG3 and SfATG9 comprised an open reading frame (ORF) of 999 bp and 2295 bp that encodes a protein of 332 and 764 amino acid residues, respectively. SfATG3 has two conserved domains and SfATG9 has one conserved domain. In S. furcifera females exposed to SRBSDV, expression of autophagy-related genes was significantly activated and shared similar temporal patterns to those of SRBSDV S9-1 and S10, all peaking at 4 d post viral exposure. Silencing the expression of SfATG3 and SfATG9 promoted SRBSDV propagation and transmission. This study provides evidence for the first time that S. furcifera autophagy-related genes ATG3 and ATG9 play an antiviral role to suppress SRBSDV propagation and transmission.

Bioefficacy of ethiprole + pymetrozine against the white-backed planthopper Sogatella furcifera (Howard), in rice (ADT – 46)

The nymphs and adults of white-backed planthoppers (Sogatella furcifera, Howard) remove plant sap resulting in yield loss. Indiscriminate use of insecticides, results in the development of resistance by insects and ill effects on the environment opening the new era of chemicals with novel modes of action with good bioefficacy, higher selectivity, low mammalian toxicity and safety to the environment. Therefore, the introduction of newer insecticide molecules with alternate modes of action will play a serious role in pest management programs. Hence, an experiment was conducted to evaluate the bioefficacy of ethiprole + pymetrozine against white-backed planthopper of rice (ADT – 46) under laboratory and field conditions at Annamalai University, Chidambaram during 2018-20. Ethiprole + pymetrozine @ (T1 - 36.91 + 138), (T2 - 40.13 + 150) and (T3 - 45.47 + 170) g a.i ha-1 with standard checks T4 - pymetrozine @ (150) g a.i ha-1, T5 - buprofezin @ (200) g a.i ha-1 and T6 - ethiprole + imidacloprid @ (50 + 50) g a.i ha-1 were evaluated against white-backed planthopper. The standard checks were of positive control i.e., reference insecticides which is in common use The results revealed that T3 recorded the lowest population of white-backed planthopper/hill at 15 day after spraying (1.13 hoppers/hill in August – December 2018 and 1.79 hoppers/hill in August – December 2019 respectively) giving better yield. The population of natural enemies was comparatively lower in all insecticidal treatments than in the control.

Flotillin 2 Facilitates the Infection of a Plant Virus in the Gut of Insect Vector.

ABSTRACTMost plant viruses require insect vectors for transmission. One of the key steps for the transmission of persistent-circulative plant viruses is overcoming the gut barrier to enter epithelial cells. To date, little has been known about viral cofactors in gut epithelial cells of insect vectors. Here, we identified flotillin 2 as a plasma membrane protein that facilitates the infection of rice stripe virus (RSV) in its vector, the small brown planthopper. Flotillin 2 displayed a prominent plasma membrane location in midgut epithelial cells. The nucleocapsid protein of RSV and flotillin 2 colocalized on gut microvilli, and a nanomolar affinity existed between the two proteins. Knockout of flotillin 2 impeded the entry of virions into epithelial cells, resulting in a 57% reduction of RSV levels in planthoppers. The knockout of flotillin 2 decreased disease incidence in rice plants fed by viruliferous planthoppers from 40% to 11.7%. Furthermore, flotillin 2 mediated the infection of southern rice black-streaked dwarf virus in its vector, the white-backed planthopper. This work implies the potential of flotillin 2 as a target for controlling the transmission of rice stripe disease.IMPORTANCE Plant viral diseases are a major threat to world agriculture. The transmission of 80% of plant viruses requires vector insects, and 54% of vector-borne plant viruses are persistent-circulative viruses, which must overcome the barriers of gut cells with the help of proteins on the cell surface. Here, we identified flotillin 2 as a membrane protein that mediates the cell entry of rice stripe virus in its vector insect, small brown planthopper. Flotillin 2 displays a prominent cellular membrane location in midgut cells and can specifically bind to virions. The loss of flotillin 2 impedes the entry of virions into the midgut cells of vector insects and substantially suppresses viral transmission to rice. Therefore, flotillin 2 may be a promising target gene for manipulation in vector insects to control the transmission of rice stripe disease and perhaps that of other rice virus diseases in the future.

Toxicity of Thiamethoxam 25WG and Sulfoxaflor 21.8SC tTo Rice White Backed Planthopper sogatella furcifera (Horvath)

Baseline toxicity of neonicotinoid insecticides viz., thiamethoxam 25WG and sulfoxaflor 21.8SC was assessed in the field collected populations of the rice white backed planthopper Sogatella furcifera (Horvath). The major rice growing regions of Tamil Nadu when studied revealed that the field populations vary in their susceptibility. Coimbatore and Bhavani populations were more susceptible compared to the Nagapattinam one. Baseline toxicity of thiamethoxam 25WG was relatively high with narrow variation (LC50 - 0.3130 to 1.7882 ppm; LC95 - 1.0993 to 6.3840 ppm); LC50 of sulfoxaflor 21.8SC ranged from 1.3121 to 3.8392 ppm, while the LC95 values were 3.1507 to 5.2754 ppm. The resistance ratios varied among the populations viz., thiamethoxam 25WG (2.5 to 5.6 folds) and sulfoxaflor 21.8SC (1.8 to 2.9 folds). Thus, the population from Nagapattinam exhibited maximum resistance.

Efficacy of Benzpyrimoxan 10SC Against Rice Planthoppers

The efficacy of foliar application of benzpyrimoxan 10SC @ 50, 75, 100, 125 and 150 g a.i./ ha besides the insecticidal checks imidacloprid 17.8SL @ 25 g a.i./ha and buprofezin 25SC @ 187.5 g a.i./ha was evaluated against the brown planthopper (BPH) Nilaparvata lugens (Stal.) and the white backed planthopper (WBPH) Sogatella furcifera (Horvath) on rice during kharif 2017 and 2018 at the Punjab Agricultural University, Ludhiana. Experimental design consisted of random blocks in three replications. Two years data revealed that benzpyrimoxan 10SC @ 100 g a.i./ha is significantly superior against the N. lugens and S. furcifera complex. Benzpyrimoxan 10SC @ 100 g a.i./ha gave significantly higher yield (34.17 q/ ha) than its lower doses but was statistically at par with its higher doses. Non-significant differences in number of spiders/hill among treated plots and untreated check at 10- and 15-DAS indicated the safety of benzpyrimoxan.

Intracellular Ca2+ accumulation triggered by caffeine provokes resistance against a broad range of biotic stress in rice.

Chemical pesticides are still frequently overused to diminish such crop loss caused by biotic stress despite the threat to humans and the environment. Thus, it is urgent to find safer and more effective defense strategies. In this study, we report that caffeine, implanted through a transgenic approach, enhances resistance against variable biotic stresses in rice without fitness cost. Caffeine-producing rice (CPR) was generated by introducing three N-methyltransferase genes involved in the biosynthesis of caffeine in coffee plants. The CPR plants have no differences in morphology and growth compared to their wild-type counterparts, but they show strongly enhanced resistance to both bacterial leaf blight, rice blast, and attack of white-backed planthoppers. Caffeine acts as a repellent agent against rice pathogens. Moreover, caffeine triggers a series of Ca2+ signalling-like processes to synthesize salicylic acid (SA), a hormone associated with plant resistance. In CPR, phosphodiesterase was inhibited by caffeine, cAMP and cGMP increased, intracellular Ca2+ increased, phenylalanine lyase (PAL) was activated by OsCPK1, and SA synthesis was activated. This finding is a novel strategy to improve resistance against the biotic stresses of crops with a special type of defense inducer.

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.