White-backed Planthopper Research Articles

A Comparative Analyses of the Complete Mitochondrial Genomes of Fungal Endosymbionts in Sogatella furcifera, White-Backed Planthoppers.

Sogatella furcifera Horvath, commonly known as the white-backed planthoppers (WBPH), is an important pest in East Asian rice fields. Fungal endosymbiosis is widespread among planthoppers in the infraorder Fulgoromorpha and suborder Auchenorrhyncha. We successfully obtained complete mitogenome of five WBPH fungal endosymbionts, belonging to the Ophiocordycipitaceae family, from next-generation sequencing (NGS) reads obtained from S. furcifera samples. These five mitogenomes range in length from 55,390 bp to 55,406 bp, which is shorter than the mitogenome of the fungal endosymbiont found in Ricania speculum, black planthoppers. Twenty-eight protein-coding genes (PCGs), 12 tRNAs, and 2 rRNAs were found in the mitogenomes. Two single-nucleotide polymorphisms, two insertions, and three deletions were identified among the five mitogenomes, which were fewer in number than those of four species of Ophiocordycipitaceae, Ophiocordyceps sinensis, Hirsutella thompsonii, Hirsutella rhossiliensis, and Tolypocladium inflatum. Noticeably short lengths (up to 18 bp) of simple sequence repeats were identified in the five WBPH fungal endosymbiont mitogenomes. Phylogenetic analysis based on conserved PCGs across 25 Ophiocordycipitaceae mitogenomes revealed that the five mitogenomes were clustered with that of R. speculum, forming an independent clade. In addition to providing the full mitogenome sequences, obtaining complete mitogenomes of WBPH endosymbionts can provide insights into their phylogenetic positions without needing to isolate the mtDNA from the host. This advantage is of value to future studies involving fungal endosymbiont mitogenomes.

Utilization of botanical pesticide as rice pests control of in Soporaru Village, North of Tapanuli, Indonesia

Peoples in Soporaru village grows local specific brown rice ‘Kasumbo’ as a source of staple food in North of Tapanuli, Indonesia. The productivity is mostly disturbed by dominant pests, white back leafhoppers, planthopper, stemborer, and stinkbugs. The importance use of plant materials of botanical pesticide can control pests food crops. The method used was purposive random sampling using Yellow Sticky Trap (YST) and applied botanical pesticide, consist of Cosmos caudatus, Tagetes erecta, and Clitoria ternatea at the paddy plantation during May-August 2020 in Soporaru village, North of Tapanuli. The fertilizers used farmer recorded Phosphate, ZA, SP36, and NPK. These results were recorded applied the variance of three botanical pesticide influence the mean population of Sogatella furcipera. Variety pests, such as: S. furcipera, Leptocorisa oratorius, Orseolia oryzae and Nephotettix virescen were identified are quite diverse. Species S. furcipera can detected used by botanical pesticides, C.caudatus/kenikir flower (4-11 individuals), Tagetes erecta L./marigold flower (5-10 individuals) and Clitoria ternatea/butterfly pea flowers (6-13 individuals). Status insects in paddy were three categorized, such 12 species were pests, 7 predators, and only Gryllotalpa orientalis into insect.

Immunofluorescent Labeling of Plant Virus and Insect Vector Proteins in Hemipteran Guts.

Most plant viruses in nature are transmitted from one plant to another by hemipteran insects. A high population density of the vector insects that are highly efficient at virus transmission plays a key role in virus epidemics in fields. Studying virus-insect vector interactions can advance our understanding of virus transmission and epidemics with the aim of designing novel strategies to control plant viruses and their vector insects. Immunofluorescence labeling has been widely used to analyze interactions between pathogens and hosts and is used here in the white-backed planthopper (WBPH, Sogatella furcifera), which efficiently transmits the southern rice black streaked dwarf virus (SRBSDV, genus Fijivirus, family Reoviridae), to locate the virions and insect proteins in the midgut epithelial cells. Using laser scanning confocal microscopy, we studied the morphological characteristics of midgut epithelial cells, cellular localization of insect proteins, and the colocalization of virions and an insect protein. This protocol can be used to study virus activities in insects, functions of insect proteins, and interactions between virus and vector insect.

Excessive Nitrogen Fertilization Favors the Colonization, Survival, and Development of Sogatella furcifera via Bottom-Up Effects.

Fertilization can trigger bottom-up effects on crop plant–insect pest interactions. The intensive use of nitrogen fertilizer has been a common practice in rice production, while the yield has long been challenged by the white-backed planthopper, Sogatella furcifera (Horváth). High nitrogen fertilization can facilitate S. furcifera infestation, however, how nitrogen fertilizer leads to high S. furcifera infestation and the nutritional interactions between rice and S. furcifera are poorly understood. Here, we evaluated the effects of various levels of nitrogen fertilizer application (0–350 kg/ha) on rice, and subsequently on S. furcifera performance. We found that higher nitrogen fertilizer application: (1) increases the preference of infestation behaviors (feeding and oviposition), (2) extends infestation time (adult lifespan), and (3) shortens generation reproduction time (nymph, pre-oviposition, and egg period), which explain the high S. furcifera infestation ratio on rice paddies under high nitrogen conditions. Moreover, high nitrogen fertilizer application increased all tested rice physical indexes (plant height, leaf area, and leaf width) and physiological indexes (chlorophyll content, water content, dry matter mass, and soluble protein content), except for leaf thickness, which was reduced. Correlation analysis indicated that the specific rice physical and/or physiological indexes were conducive to the increased infestation behavior preference, extended infestation time, and shortened generation reproduction time of S. furcifera. The results suggested that nitrogen fertilizer triggers bottom-up effects on rice and increases S. furcifera populations. The present study provides an insight into how excess nitrogen fertilization shapes rice–planthopper interactions and the consequent positive effect on S. furcifera infestation.

A rapid multiplex PCR assay for species identification of Asian rice planthoppers (Hemiptera: Delphacidae) and its application to early-instar nymphs in paddy fields.

Rice (Oryza sativa L.) is the main cereal crop in many Asian countries. The Asian rice planthoppers, Nilaparvata lugens (Stål) (brown planthopper), Sogatella furcifera (Horváth) (white-backed planthopper), and Laodelphax striatellus (Fallén) (small brown planthopper) (Hemiptera: Delphacidae), are the most economically important pests of rice. These three rice planthopper species often co-occur in the same paddy field. Traditionally, species identification of individuals of the three rice planthopper species has relied on morphological characters, but accurate discrimination of early-instar nymphs is very difficult, even for expert researchers. In this study, we developed a rapid one-step multiplex PCR assay using conserved and species-specific 5.8S-ITS2 rDNA gene primers for simultaneous identification of individuals of the three rice planthopper species. The multiplex PCR results showed that the three rice planthopper species could be identified accurately based on the length of the resultant amplicon, regardless of the individual developmental stage. Furthermore, we applied this assay for the first accurate quantification of early-instar nymphs of each rice planthopper species in paddy fields. Notably, we found that the species composition of early-instar nymphs cannot be extrapolated from that of adults. Thus, the multiplex PCR assay developed here facilitates detection of each rice planthopper species at the beginning of outbreaks in paddy fields.

Silicon amendment to rice plants reduces the transmission of southern rice black-streaked dwarf virus by Sogatella furcifera.

Plant viruses are transmitted mainly by piercing-sucking herbivores, and viral disease management relies on chemical control of vectors. Southern rice black-streaked dwarf virus (SRBSDV) is transmitted by the white-backed planthopper (WBPH), Sogatella furcifera. This study aimed to evaluate the potential of silicon (Si) amendment for reducing SRBSDV transmission. The settling and ovipositional preferences of WBPH females decreased significantly by 14.6-43.7% for plants treated with either 0.16 g or 0.32 g SiO2 kg-1 soil during SRBSDV acquisition and by 26.2-28.3% for plants treated with 0.32 g SiO2 kg-1 soil during SRBSDV inoculation, compared with controls. Adding either 0.16 or 0.32 g SiO2 kg-1 soil significantly reduced SRBSDV inoculation rate by 31.3% and 45.3%, respectively, and acquisition rate by 25.5% and 66.0%, respectively. Silicification was intensified more in plants treated with 0.32 g SiO2 kg-1 soil than in controls. The nonprobing (np) duration increased, and the phloem sap ingestion (N4-b) duration decreased significantly in the WBPHs feeding on high-rate-Si-supplemented plants compared with control plants during both inoculation and acquisition access. This study showed that Si amendment to rice plants decreased the WBPH settling and ovipositional preference and the SRBSDV acquisition and inoculation rates, thereby reducing SRBSDV transmission. The intensified plant silicification and the altered WBPH feeding behaviors (i.e. prolonged np and shortened N4-b) may explain the reduced SRBSDV transmission in Si-amended plants. © 2021 Society of Chemical Industry.

Effect of weather parameters on the population dynamics of White backed planthopper, Sogatella furcifera (Horvath) in rice

A field experiment on the population dynamics of White backed planthopper (WBPH), Sogatella furcifera (Horvath) carried out during kharif and rabi 2016-17 at Regional Agricultural Research Station, Maruteru, West Godavari District of Andhra Pradesh, India revealed that the incidence of WBPH was observed during 36th SMW (September 3-9). Its activity increased during successive weeks up to 44th SMW with two peaks, first peak at 38th SMW (September 17-23) with population of 46/10 hills and second peak at 42nd SMW (October 15-21) with population of 170/ 10 hills during kharif 2016, while WBPH was first noticed during 7th SMW (February 12-18) and population increased gradually during successive weeks and attained peak number during 13th SMW (March 26-April 1) in rabi 2016-17. Correlation studies revealed that WBPH had significant negative relation with morning relative humidity of current week during kharif 2016. None of the abiotic factors has showed significant relationship with the population of WBPH during rabi 2016-17.

Elucidation of induced host plant resistance to white backed plant hopper (WBPH) in response to zinc application in rice

Aim: The experiment was aimed to study the effects of various Zn formulations towards induced host plant resistance to WBPH in rice. Methodology: Eight zinc treatments comprising basal and foliar applications(at 30 and 45 DAT) of Zn SO4 and Zn-EDTA and their combinations were tested for induced host plant resistance to WBPH (a dreadful sucking insect) in a most sensitive rice variety TN 1. In addition, a treatment without any Zn application served as control. The pot grown plants were kept in the Mylar cages with top end covered by fine mesh muslin cloth and as such maintained till maturity. One adult gravid female insect was released into each cage (at 46DAT) and the insect population build-up was recorded after one month. Soluble protein profiling of leaf samples (at 60DAT) of each treatment was done by SDS-PAGE and data were analyzed for clustering pattern. Results: Altogether, 19 polypeptide bands (14.3-97.4kDa) were revealed. The low molecular weight proteins (14.3-25.1 kDa) were clearly absent in the control. T6(Zn EDTA at basal and foliar) recorded least WBPH build–up and elicited highest number (15) of polypeptide bands including five new bands at 66.0, 37.0, 23.6, 15.8 and 14.3 kDa. Further, 66.0kDa, 37.0 kDa and 14.3 kDa polypeptide bands were commonly shared by T6, T7(ZnSO4 basal+ EDTA foliar) and T8(Zn EDTA basal + ZnSO4) that recorded lower WBPH population and grouped together as compared to rest of the treatments and control. However, 23.6 kDa polypeptide band induced only in T6 and T7 seems to have greater role in manifestation of induced defence mechanism against WBPH in rice. Interpretation: The differentially expressed proteins (as compared to control) revealed in response to Zn application may be considered as biochemical basis of induced resistance for the pest in rice Key words: Induced resistance, Soluble protein profiling, White backed plant hopper, Zinc

Insight into different host range of three planthoppers by transcriptomic and microbiomic analysis.

Brown planthopper (BPH), white-backed planthopper (WBPH) and small brown planthopper (SBPH), are the closely related rice pests that perform differentially on wheat plants. Using fecundity as a fitness measure, we found that SBPH well-adapted on wheat plants, followed by WBPH, while BPH had the worst performance. The transcriptomic responses of SBPH and BPH to wheat plants have been compared previously. To understand the different fitness mechanisms of three planthoppers, this study first investigated the transcriptomic responses of WBPH to rice and wheat plants. Genes involved in detoxification, transportation and proteasome were significantly enriched in WBPH in response to different diets. Moreover, comparative analysis demonstrated that most co-regulated genes in BPH and SBPH showed different expression changes; whereas most co-regulated genes in BPH and WBPH exhibited similar expression changes. Subsequently, this study also investigated the influences of host plants on the bacterial community of three planthoppers. The three planthoppers harboured distant diversity of bacterial communities. However, there was no dramatic change in bacterial diversity or relative abundance in planthoppers colonized on different hosts. This study illustrates generic and species-specific changes of three rice planthoppers in response to different plants, which deepen our understanding towards the host fitness for planthopper species.

Identification of F3H, Major Secondary Metabolite-Related Gene That Confers Resistance against Whitebacked Planthopper through QTL Mapping in Rice.

Whitebacked planthopper (WBPH) is a pest that causes serious damage to rice in Asian countries with a mild climate. WBPH causes severely rice yield losses and grain poor quality each year so needs biological control. Plants resist biotic and abiotic stress using expressing variety genes, such as kinase, phytohormones, transcription factors, and especially secondary metabolites. In this research, quantitative trait locus (QTL) mapping was performed by assigning the WBPH resistance score in the Cheongcheong/Nagdong doubled haploid (CNDH) line in 2018 and 2019. The RM280-RM6909 on chromosome 4 was detected as a duplicate in 2018, 2019, and derived from Cheongcheong. This region includes cell function, kinase, signaling, transcription factors, and secondary metabolites that protect plants from the stress of WBPH. The RM280-RM6909 on chromosome 4 contains candidate genes that are similar to the flavanone 3-hydroxylase (F3H) of rice. The F3H are homologous genes, which play an important role in biosynthesis defending against biotic stress in plants. After WBPH inoculation, the relative expression level of F3H was higher in resistant line than in a susceptible line. The newly identified WBPH resistance gene F3H by QTL mapping can be used for the breeding of rice cultivars that are resistant against WBPH.

Defence response of local rice variety Acuce in Hani terraced fields in Yunnan against the feeding of Sogatella furcifera

[Objective] To study the main defensive response of Acuce, a local rice variety in the Hani terraced fields in Yuanyang, Yunnan under the feeding stress of white-backed planthopper (WBPH), and to clarify its WBPH resistance mechanism. To provide a basis for rice insect-resistant breeding and utilization of insect-resistant germplasm resources. [Method] The contents of nutrient soluble sugar, secondary products malondialdehyde (MDA) and hydrogen peroxide (H 2O 2) in rice plants were determined by colorimetric method at 0, 3, 6, 12, 24, 48, 72 and 96 h after WBPH feeding on Acuce, insect susceptible variety Taichung Native 1 (TN1) and insect resistant variety Rathu Heenati (RHT) in the meantime, the main defense reaction of main protective enzyme activity including peroxidase (POD), phenylalanine ammonia-lyase (PAL) and catalase (CAT) were measured and analyzed. [Result] After WBPH feeding stress 3-96 h, the soluble sugar content of the Acuce increased by 93.19%. The increase rate was significantly lower than TN1(176.23%) ( P<0.05, the same as below), there was no significant difference with RHT(89.16%) ( P>0.05, the same as below). The increase rate of H 2O 2 content was 44.13%, significantly higher than TN1(13.18%) and significantly lower than RHT(83.01%). The content of MDA in the rice plant of Acuce increased, and the mean increase rate was 145.38%, significantly higher than that of TNI(36.84%) and RHT(57.06%). The activities of POD, CAT and PAL were increased after feeding stress. The mean increase rate of POD activity (52.78%) was not significantly different with TN1(52.30%), but was significantly lower than that of RHT(154.53%). The mean increase rate of CAT activity (26.24%) was significantly higher than that of RHT(-9.32%) and TN1(-14.18%). The mean increase rate of PAL activity (3.80%) was significantly higher than that of RHT(-32.01%) and significantly lower than that of TN1(74.03%). [Conclusion] After WBPH feeding, the local rice variety Acuce is more sensitive in nutrients, secondary substances, and major protective enzymes than the insect susceptible variety TN1 and resistant variety RHT, showing a strong defense response. Acuce can be used as the WBPH resistance varieties in the field. 摘要: 【目的】 研究云南元阳哈尼梯山水稻地方品种月亮谷对白背飞虱取食胁迫的主要防御反应,明确月亮谷抗 白背飞虱机制,为水稻抗虫育种及抗虫种质资源利用提供科学依据。 【方法】 以元阳地方水稻品种月亮谷、感虫水稻品 种Taichung Native 1 (TN1) 和抗虫品种Rathu Heenati(RHT)为材料, 采用比色法测定3个水稻品种在白背飞虱取食胁 迫0、3、6、12、24、48、72和96 h后稻株内营养物质可溶性糖、次生产物丙二醛(MDA)和过氧化氢(H 2O)含量及保护酶 过氧化物酶(POD)、苯内'氨酸解氨酶(PAL)和过氧化氢酶(CAT)活性。 【结果】 白背飞虱取食胁迫3~96 h后, 月亮谷稻 株内可溶性糖平均含量增加率为93.19%, 显著小于TN1(176.23%) ( P<0.05,下同), 而与RHT(89.16%)无显著差异( P>0.05,下同)；H 2O 2平均含量增加率为44.13%, 显著高于TN1(13.18%), 而显著低于RHT(83.01%);MDA平均含量增加 率为145.38%, 显著高于TN1 (36.84%)和RHT(57.06%); POD、CAT和PAL活性均增加, 其中POD活性平均增加率 (52.78%)与TN1 (52.30%)无显著差异而显著低于RHT (154.53%), CAT活性平均增加率(26.24%)均显著高于RHT (-9.32%)和TN1(-14.18%), PAL活性平均增加率(3.80%)显著高于RHT(-32.01%)而显著低于TN1(74.03%)。 【结论】 月亮谷受白背飞虱取食胁迫后, 其营养物质、次生产物及主要保护酶活性均较感虫品种TN1和抗虫品种RHT反应敏 感, 表现出强烈的防御反应, 月亮谷可作为抗白背飞虱品种在山间应用。

Screening of Rice Varieties for Resistance to Major Insect Pests

Rice is attacked by several insect pests and of these the stem borers Scirpophaga incertulas (Walker), S. innotata (Walker), Sesamia inferens (Walker), leaf folder Cnaphalocrocis medinalis (Guenee) and plant hoppers viz. brown plant hopper Nilaparvata lugens (Stal), white backed plant hopper, Sogatella furcifera (Horvath) are the most destructive. This study was carried out at the PAU Regional Station, Gurdaspur during kharif seasons of 2017 and 2018 to evaluate performance of varieties viz. PR 121, PR 122, PR 123, PR 124, Pusa 44, PR 126, PR 115, PR 114 and HKR 127 against these pests. The incidence of stem borers, leaf folder and of plant hoppers/ hill were observed at 40, 60, 80 and 100 days after transplanting. It was observed that rice varieties PR 126, PR 115 were the least preferred whereas Pusa 44 was found highly preferred by these major insect pests.

Plant-Mediated Horizontal Transmission of Asaia Between White-Backed Planthoppers, Sogatella furcifera.

Asaia is a bacterial symbiont of sugar-feeding insects that has been shown to be vertically transmitted by maternal transmission and paternal transmission mechanism, and to be horizontally transmitted via co-feeding artificial diet and venereal routes. Here, the first case of plant-mediated horizontal transmission of Asaia between white-backed planthoppers (WBPH), Sogatella furcifera, was reported. In Asaia-infected WBPH, Asaia was detected mostly in salivary glands and to a less extent in stylets. The rice leaf sheaths fed by Asaia-infected WBPH for 12 h were all positive with Asaia, where Asaia persisted for at least 30 d but was localized in the feeding sites only. When confined to Asaia-infected leaf sheaths for 7 d at the sites pre-infested by the Asaia-infected WBPH, all Asaia-free WBPH became infected with Asaia and the acquired Asaia could be vertically transmitted to their offspring. Phylogenetic analysis confirmed an identical Asaia strain in the Asaia-infected donor WBPH, the Asaia-infected leaf sheaths, and the newly infected recipient WBPH. Our findings provide direct evidence for the first time that rice plant can mediate horizontal transmission of Asaia between WBPH, which may contribute to the spread of Asaia in the field WBPH populations.

Efficacy of Entomopathogenic Fungi Alone and in Combination with Buprofezin Against Sogatella Furcifera (Horváth) on Rice

The whitebacked planthopper, Sogatella furcifera Horvath (Homoptera: Delphacidae), is a serious pest of rice crop in Pakistan. In the current study the efficacy of entomopathogenic fungi Beauveria bassiana, Metarhizium anisopliae and Akanthomyces lecanii was evaluated against whitebacked planthopper (WBPH) under laboratory and field conditions. There were two concentrations of entomopathogenic fungi (EPF, 1 × 109 CFU/mL and 1 × 108 CFU/mL) used in the bioassays. Combination of EPF with the insecticide buprofezin at low dose rates (0.001 mg/mL and 0.006 mg/mL) was also evaluated. Results showed that mortality of the pest ranged from 50–80% when EPF was used alone. Mortality of WBPH was 53–90% when buprofezin was combined with EPF. B. bassiana and M. anisopliae were more effective than A. Lecanii. In field trials, EPF were applied at the rate of 2.5 × 1012 CFU/ha and buprofezin at the rate of 78 g/ha. Relative efficacies of EPF ranged from 40.54–59.17% when only using EPF after 21 days of the first application. Relative efficacy climbed to 71.62% and 70.20% when buprofezin was combined with B. bassiana and M. anisopliae, respectively, after 14 days of the first spray. The results revealed that EPF has the potential to control the population of WBPH. Additionally, their efficacy can be further enhanced by combining them with buprofezin even at low dose rates.

Migration of Sogatella furcifera between the Greater Mekong Subregion and northern China revealed by mtDNA and SNP

BackgroundThe white-backed planthopper (WBPH), Sogatella furcifera (Horváth) (Hemiptera, Delphacidae), is a migratory pest of rice in Asia. Shandong Province, in northern China, is located on the migration pathway of WBPH between southern and northeast China. The potential sources of WBPH in northern China are poorly understood. We studied the sources of WBPH in Shandong Province by determining the population genetic structure of WBPH in 18 sites distributed in Shandong and in six regions of the Greater Mekong Subregion (GMS). We used mitochondrial gene and single-nucleotide polymorphism (SNP) markers for analysis.ResultsAll of the WBPH populations studied in the seven regions had low genetic diversity. Pairwise FST values based on mtDNA ranged from − 0.061 to 0.285, while FST based on SNP data ranged from − 0.007 to 0.009. These two molecular markers revealed that 4.40% (mtDNA) and 0.19% (SNP) genetic variation could be explained by the interpopulation variation, while the rest came from intrapopulation variation. The populations in the seven geographic regions comprised four hypothetical genetic clusters (K = 4) not associated with geographic location. Eighty-four of 129 individuals distributed across the given area were designated as recent migrants or of admixed ancestry. Although the substantial migration presented, a weak but significant correlation between genetic and geographic distances was found (r = 0.083, P = 0.004).ConclusionThe Greater Mekong Subregion was the main genetic source of WBPH in Shandong, while other source populations may also exist. The genetic structure of WBPH is shaped by both migration and geographic barriers. These results help clarify the migration route and the source of WBPH in northern China.

Chromosomal-level genomes of three rice planthoppers provide new insights into sex chromosome evolution.

The brown planthopper Nilaparvata lugens, white-backed planthopper Sogatella furcifera, and small brown planthopper Laodelphax striatellus are three major insect pests of rice. They are genetically close; however, they differ in several ecological traits such as host range, migration capacity, and in their sex chromosomes. Though the draft genome of these three planthoppers have been previously released, the quality of genome assemblies need to be improved. The absence of chromosome-level genome resources has hindered in-depth research of these three species. Here, we performed a de novo genome assembly for N.lugens to increase its genome assembly quality with PacBio and Illumina platforms, increasing the contig N50 to 589.46Kb. Then, with the new N.lugens genome and previously reported S. furcifera and L.striatellus genome assemblies, we generated chromosome-level scaffold assemblies of these three planthopper species using HiC scaffolding technique. The scaffold N50s significantly increased to 77.63Mb, 43.36Mb and 29.24Mb for N.lugens, S.furcifera and L.striatellus, respectively. To identify sex chromosomes of these three planthopper species, we carried out genome re-sequencing of males and females and successfully determined the X and Y chromosomes for N.lugens, and X chromosome for S.furcifera and L.striatellus. The gene content of the sex chromosomes showed high diversity among these three planthoppers suggesting the rapid evolution of sex-linked genes, and all chromosomes showed high synteny. The chromosome-level genome assemblies of three planthoppers would provide a valuable resource for a broad range of future research in molecular ecology, and subsequently benefits development of modern pest control strategies.

Antimicrobial Activity of Chrysoeriol 7 and Chochlioquinone 9, White-Backed Planthopper-Resistant Compounds, Against Rice Pathogenic Strains.

Simple SummaryThis study is an important contribution to the development of biopesticide materials for controlling major pathogens in rice. Chrysoeriol 7 and cochlioquinone 9, which repel the white-backed planthopper, were extracted from rice and their antimicrobial activity was investigated. The results show they are effective in limiting the growth of pathogens of the genera Fusarium, Cladosporium and Pythium. This shows that they have great potential as an alternative to chemical pesticides and is also thought to be helpful in development of eco-friendly agriculture.As environmental damage caused by chemical pesticides appears worldwide, eco-friendly agriculture is increasing, and finding eco-friendly pesticide materials has become very important. Chrysoeriol and cochlioquinone, two flavonoids, act as an antibacterial and antioxidant, and increase the resistance of rice to the white-backed planthopper (WBPH). In this experiment, chrysoeriol 7 (C7) and cochlioquinone 9 (C9) were extracted from rice inoculated with the WBPH using MeOH, and cultivars with high extraction efficiency were selected. In addition, the antimicrobial activity of C7 and C9 against various pathogens causing disease in rice was tested. The results show that C7 has antifungal activity against Fusarium graminearum and Pythium graminicola, and C9 show antifungal activity against Cladosporium herbarum, Cladosporium cladosporioides, Gibberella zeae, Fusarium graminearum and Pythium graminicola. When both substances were treated at a concentration of 1000 ppm, they showed high inhibition rates of 62.3% and 36.2% against P. graminicola, respectively. After that, a phylogenetic tree was created to clarify the relationship between the microorganisms whose growth was inhibited and divided into three groups. This result can contribute to the study of biopesticide materials that can control pests and pathogens.

Changes in Transcriptome and Gene Expression in Sogatella furcifera (Hemiptera: Delphacidae) in Response to Cycloxaprid.

The white-backed planthopper, Sogatella furcifera (Horváth), causes substantial damage to crops by direct feeding or virus transmission, especially southern rice black-streaked dwarf virus, which poses a serious threat to rice production. Cycloxaprid, a novel cis-nitromethylene neonicotinoid insecticide, has high efficacy against rice planthoppers, including imidacloprid-resistant populations. However, information about the influence of cycloxaprid on S. furcifera (Hemiptera: Delphacidae) at the molecular level is limited. Here, by de novo transcriptome sequencing and assembly, we constructed two transcriptomes of S. furcifera and profiled the changes in gene expression in response to cycloxaprid at the transcription level. We identified 157,906,456 nucleotides and 131,601 unigenes using the Illumina technology from cycloxaprid-treated and untreated S. furcifera. In total, 38,534 unigenes matched known proteins in at least one database, accounting for 29.28% of the total unigenes. The number of coding DNA sequences was 28,546 and that of amino acid sequences in the coding region was 22,299. In total, 15,868 simple sequence repeats (SSRs) were identified. The trinucleotide repeats accounted for 45.1% (7,157) of the total SSRs and (AAG/CTT)n were the most frequent motif. There were 359 differentially expressed genes that might have been induced by cycloxaprid. There were 131 upregulated and 228 downregulated genes. Twenty-two unigenes might be involved in resistance against cycloxaprid, such as cytochrome P450, glutathione S-transferase (GST), acid phosphatase (ACP), and cadherin. Our study provides vital information on cycloxaprid-induced resistance mechanisms, which will be useful to analyze the molecular mechanisms of cycloxaprid resistance and may lead to the development of novel strategies to manage S. furcifera.

Bioefficacy of crude polyherbal formulations against hoppers (Insecta: Hemiptera) of rice

Bio-efficacy of two crude polyherbal formulations against Nephotettix virescens- the Green Leafhopper (GLH) and Sogatella furcifera, the White-backed plant hopper (WBPH), major sucking insect pests of paddy was carried out at farmer’s field of North Gujarat Zone (GJ-4), Gandhinagar, Gujarat during Kharif 2018. The aqueous and oil-based crude formulations were tested at two different concentrations each, in comparison with chemical, botanical and untreated control. Both the crude formulations were effective in the management of green leafhopper and white backed plant hopper in a dose-dependent manner, however, the aqueous formulation was more efficacious as compared to the oil-based formulation. These herbal formulations are an eco-friendly, cost-effective and safe alternative to chemical control measures for the management of paddy pests and can easily be incorporated in the integrated pest management (IPM) programs for the control of sucking pests in Paddy.

Field evaluation of novel insecticides against brown planthopper (Nilaparvata lugens) and white backed planthopper (Sogatella furcifera) in rice

A field experiment was conducted to evaluate the bioefficacy of novel insecticides against brown planthopper [Nilaparvatha lugens (Stal)] (BPH) and white backed planthopper [Sogatella furcifera (Hoverth)] (WBPH) on rice. The results revealed that field application of triflumezopyrim 10 SC @ 235 ml per ha was found superior and registered 1.88 and 1.26 hoppers per hill against BPH and WBPH followed bypymetrozine 50 WG @ 300g per ha with 2.12 and 1.26 hoppers of BPH and WBPH per hill, respectively. The response of these insecticides was also observed on the yield attributes, with highest grain yield of 55.58 q/ha in triflumezopyrim 10 SC @ 235 ml per ha followed by pymetrozine 50 WG @ 300 g per ha (53.79 q/ ha).