The Jinggangmycin-induced Mthl2 gene regulates the development and stress resistance in Nilaparvata lugens Stål (Hemiptera: Delphacidae).

Methuselah (Mth) belongs to the GPCR family B, which regulates various biological processes and stress responses. The previous transcriptome data showed jinggangmycin (JGM)-induced Mthl2 expression. However, its detailed functional role remained unclear in brown planthopper, Nilaparvata lugens Stål. In adult N. lugens, the Mthl2 gene showed dominant expressions, notably in ovaries and fat body tissues. The 3rd instar nymphs treated with JGM increased starvation, oxidative stress, and high temperature (34 °C) tolerance of the adults. On the contrary, under dsMthl2 treatment, completely opposite phenotypes were observed. The lipid synthesis genes (DGAT1and PNPLA3) of both females and males treated with JGM in the nymphal stage were observed with high expressions, while the lipolysis of the Lipase 3 gene was observed with low expressions. The JGM increased triglyceride (TG) content, fat body droplet size, and the number of fat body droplets. The same treatment also increased the Glutathione S-transferase (GST), catalase (CAT), and superoxide dismutase (SOD) activities. An increase in the heat shock protein (HSP70 and HSP90) expression levels was also observed under JGM treatment but not dsMthl2. The current study demonstrated the influential role of the Mthl genes, particularly the Mthl2 gene, in modulating the growth and development and stress-responsiveness in N. lugens. Thus, providing a platform for future applied research programs controlling N. lugens population in rice fields.

Adenosine Monophosphate-Activated Protein Kinase (AMPK) Phosphorylation Is Required for 20-Hydroxyecdysone Regulates Ecdysis in Apolygus lucorum.

The plant mirid bug Apolygus lucorum is an omnivorous pest that can cause considerable economic damage. The steroid hormone 20-hydroxyecdysone (20E) is mainly responsible for molting and metamorphosis. The adenosine monophosphate-activated protein kinase (AMPK) is an intracellular energy sensor regulated by 20E, and its activity is regulated allosterically through phosphorylation. It is unknown whether the 20E-regulated insect's molting and gene expression depends on the AMPK phosphorylation. Herein, we cloned the full-length cDNA of the AlAMPK gene in A. lucorum. AlAMPK mRNA was detected at all developmental stages, whereas the dominant expression was in the midgut and, to a lesser extent, in the epidermis and fat body. Treatment with 20E and AMPK activator 5-aminoimidazole-4-carboxamide-1-ß-d-ribofuranoside (AlCAR) or only AlCAR resulted in activation of AlAMPK phosphorylation levels in the fat body, probed with an antibody directed against AMPK phosphorylated at Thr172, enhancing AlAMPK expression, whereas no phosphorylation occurred with compound C. Compared to compound C, 20E and/or AlCAR increased the molting rate, the fifth instar nymphal weight and shortened the development time of A. lucorum in vitro by inducing the expression of EcR-A, EcR-B, USP, and E75-A. Similarly, the knockdown of AlAMPK by RNAi reduced the molting rate of nymphs, the weight of fifth-instar nymphs and blocked the developmental time and the expression of 20E-related genes. Moreover, as observed by TEM, the thickness of the epidermis of the mirid was significantly increased in 20E and/or AlCAR treatments, molting spaces began to form between the cuticle and epidermal cells, and the molting progress of the mirid was significantly improved. These composite data indicated that AlAMPK, as a phosphorylated form in the 20E pathway, plays an important role in hormonal signaling and, in short, regulating insect molting and metamorphosis by switching its phosphorylation status.

The Phosphoserine Phosphatase Alters the Free Amino Acid Compositions and Fecundity in Cyrtorhinus lividipennis Reuter.

The mirid bug Cyrtorhinus lividipennis (Reuter) is an important predator that consumes eggs and young nymphs of the brown planthopper Nilaparvata lugens as a primary food source and thus becomes an important member of the rice ecosystem. We identified and characterized the ClPSP gene in C. lividipennis encoding the phosphoserine phosphatase enzyme. The ClPSP has an open reading frame (ORF) of 957 bp encoding a protein with a length of 294bp and it possesses a haloacid dehalogenase-like (HAD) hydrolase, phosphoserine phosphatase, eukaryotic-like (HAD_PSP_eu) conserved domain. Furthermore, the in silico analysis of the ClPSP gene unveiled its distinct characteristics and it serves as a key player in the modulation of amino acids. The ClPSP showed expression in all developmental stages, with higher expression observed in the ovary and fat body. Silencing the ClPSP by RNA interference (RNAi) significantly decreased PSP enzyme activity and expression compared to dsGFP at two days after emergence (2DAE). The dsPSP treatment altered free hemolymph amino acid compositions, resulting in a significant reduction of serine (Ser) and Arginine (Arg) proportions and a significant increase of Threonine (Thr), Cystine (Cys), and Tyrosine (Tyr) in the C. lividipennis female at 2 DAE. Additionally, a hindered total protein concentration in the ovary and fat body, and reduced vitellogenin (Vg) expression, body weight, and number of laid eggs, were also observed. The same treatment also prolonged the preoviposition period and hindered ovarian development. Our data, for the first time, demonstrated the influential role of the PSP gene in modulating the fecundity of C. lividipennis and provide a platform for future insect pest control programs using the PSP gene in modulating fecundity.

Octopamine signaling is involved in the female postmating state in Nilaparvata lugens Stål (Hemiptera: Delphacidae).

Mating triggers physiological and behavioral changes in female insects. In many species, females experience postmating behavioral and physiological changes that define a post-mated state. These changes are comprised of several conditions, including long-term refractoriness to re-mating and increased production and laying of eggs. Here, we report that mating led to several changes in brown planthopper (BPH) females, including increased octopamine (OA), cAMP concentrations, and activities of several enzymes. Mating also led to changes in the expression of several genes acting in female physiology, including those in the cAMP/PKA signal transduction pathway. OA injections into virgin females led to similar changes. RNAi silencing of the gene encoding tyramine ß-hydroxylase, involved in the final step in OA synthesis, led to decreased expression of these genes, and reduced the cAMP/PKA signaling. At the whole-organism level, the RNAi treatments led to reduced fecundity, body weights, and longevity. RNAi silencing of genes acting in OA signaling led to truncated ovarian development, egg maturation, and ovarian vitellogenin (Vg) uptake. The impact of these decreases is also registered at the population level, seen as decreased population growth. We infer that OA signaling modulates the postmating state in female BPH and possibly other hemipterans.

Pesticide-Induced Planthopper Population Resurgence in Rice Cropping Systems.

Planthoppers are serious rice pests in Asia. Their population resurgence was first reported in the early 1960s, caused mainly by insecticides that indiscriminately killed beneficial arthropods and target pests. The subsequent resurgence involved two mechanisms, the loss of beneficial insects and insecticide-enhanced planthopper reproduction. In this review, we identify two forms of resurgence, acute and chronic. Acute resurgence is caused by traditional insecticides with rapid resurgence in the F1 generation. Chronic resurgence follows application of modern pesticides, including fungicides and herbicides, with low natural enemy toxicity, coupled with stimulated planthopper reproduction. The chemical-driven syndrome of changes leads to later resurgence in the F2 or later generations. Chronic resurgence poses new threats to global rice production. We review findings on the physiological and molecular mechanisms of chronic planthopper resurgence and suggest research directions that may help manage these new threats.

Silencing of triazophos-induced Hexokinase-1-like reduces fecundity in Nilaparvata lugens (Stål) (Hemiptera: Delphacidae).

Hexokinase is a rate-limiting enzyme that plays pivotal roles in glucose homeostasis and energy metabolism via glucose (Glc) phosphorylation and Glc signaling mediation. Previous investigations have revealed the modulatory role of Hexokinase (Hex) genes involved in proper glucose regulation during insect diapause and embryo development, whereas whether it functions in insect fecundity remains largely unknown. We aimed to explore the relationship between Triazophos (TZP)-induced Hex-1 and fecundity of female Nilaparvata lugens. In this study, Hex-1 expression were characterized at different developmental stages and in various tissues of N. lugens, with the highest expression registered in brain tissues and 5th instar nymph. The present findings indicated that TZP + dsHex-1 silencing significantly reduced protein synthesis, including the fat body and ovarian protein content of female adults. Meanwhile, the glycometabolism with respect to the soluble sugar, trehalose and glucose content in female adults were strikingly influenced as a result of Hex-1 knockdown. The relative transcript level of Hex-1, vitellogenin (NlVg) and vitellogenin receptor (NlVgR) considerably decreased in TZP + dsHex-1 treated females compared to TZP and TZP + dsGFP-treated groups. More importantly, TZP + dsHex-1 silencing led to reduced number of eggs laid and vitellogenin (Vg) accumulation as well as retarded ovary development compared with TZP-treated and TZP + dsGFP-treated groups. Taken together, it is proposed that Hex-1 implicates in N. lugens fecundity by exerting profound effects on glycometabolism, protein sythesis and NlVg expression.

Two Fungicides Alter Reproduction of the Small Brown Planthopper Laodelphax striatellus by Influencing Gene and Protein Expression.

Aside from their intended actions, fungicides can drive pest insect outbreaks due to virtually continuous use and pest evolution. Small brown planthopper (SBPH), Laodelphax striatellus, outbreaks occurred recently in many provinces in China, with devastating rice losses. Because exposure to the fungicide jinggangmycin (JGM) increased reproduction of the brown plant hopper, Nilaparvata lugens, via its influence on fatty acid synthase, we posed the hypothesis that JGM and carbendazim (CBM) influence SBPH reproduction via their influence on enzymes involved in other aspects of lipid metabolism. Exposure to the fungicide CBM stimulated SBPH reproduction (egg-laying up by 78%) and to another fungicide, JGM, led to decreased egg-laying (down by 47.3%). These inverse effects are mediated by down-regulated expression of l-3-hydroxyacyl-coenzyme A dehydrogenase (LCHAD) in JGM-treated females and up-regulated expression of hydroxysteroid dehydrogenase-like protein 2-like (HSD) in CBM-treated females. RNAi knockdown of, separately, LCHAD and HSD led to reduced egg-laying (down by 52% for dsLCHAD and by 73% for dsHSD). dsLCHAD, dsHSD, and JGM treatments also led to severely reduced ovarian development in experimental SBPH, with shorted and thinned valvula and lack of egg cells in ovaries. Valvula of CBM-treated females enlarged, with banana-shaped eggs in ovaries. These data strongly support our hypothesis.

Long chain fatty acid coenzyme A ligase (FACL) regulates triazophos-induced stimulation of reproduction in the small brown planthopper (SBPH), Laodelphax striatellus (Fallen).

The small brown planthopper (SBPH), Laodelphax striatellus (Fallen) is a major pest insect of rice, wheat, and maize in China and other countries. SBPH not only damage rice plants through sucking plant sap, but also transmits rice virus diseases, for example, striped virus disease (RSV), black streaked dwarf, and maize rough disease virus. Therefore, understanding of pesticide-induced stimulation of reproduction in SBPH is of great significance for the pest management. Our previous study discovered that triazophos (TZP) increased reproduction of SBPH. But the molecular mechanisms are unclear. Here, by using proteomic analysis, we screened and cloned the gene of long chain fatty acid coenzyme A ligase (FACL), and silenced FACL to examine influences of TZP on reproduction and glycerin content in SBPH females. In TZP-treated females vs control females, there were 41 differential proteins in 18 pathways related to reproduction, of which 8 were up-regulated and 33 were down-regulated. TZP + dsFACL eliminated TZP-induced stimulation of reproduction of SBPH females (↓about 73.92%) and decreased glycerin content and body weight (↓about 19.93% and 13.62%). TZP + dsFACL treatment led to reduced expression of FACL (↓about 61.88%). FACL is a key gene of TZP-induced increase of reproduction of SBPH.

Silencing pyruvate kinase (NlPYK) leads to reduced fecundity in brown planthoppers, Nilaparvata lugens (Stål) (Hemiptera: Delphacidae).

Pyruvate kinase (PYK) operates in the glycolytic pathway, responsible for regulating the balance between glycolysis and gluconeogenesis. The previous work indicates PYK acts in development of Drosophila embryos and in embryonic muscle growth, from which it may be inferred that PYK acts in insect fecundity. More to the point, as a central enzyme in the glycolytic pathway, PYK acts in many energy-spending functions in most organisms. On the background findings that triazophos (TZP) stimulates fecundity via increase activities of several genes in brown planthoppers, Nilaparvata lugens, we investigated the combined influence of TZP and silencing a N. lugens PYK (NlPYK) on reproduction-linked biological performance parameters. Here, we report that TZP+dsNlPYK treatments led to reduced (by 26%) ovarian, but not fat body, protein content relative to controls. Ovarian (35%) and fat body (54%) soluble sugar contents were reduced. TZP+dsNlPYK treatments also led to reduced (by about 24%) fecundity, expressed as numbers of eggs laid. These data show directly that NlPYK acts in insect fecundity, probably via increases in glucose metabolism.

Jinggangmycin-suppressed reproduction in the small brown planthopper (SBPH), Laodelphax striatellus (Fallen), is mediated by glucose dehydrogenase (GDH).

The small brown planthopper (SBPH), Laodelphax striatellus (Fallen), is a serious pest insect of rice, wheat, and maize in China. SBPH not only sucks plant sap but also transmits plant disease viruses, causing serious damage. These viruses include rice striped virus disease (RSV disease), black streaked dwarf, and maize rough disease virus. SBPH outbreaks are related to the overuse of pesticides in China. Some pesticides, such as triazophos, stimulate the reproduction of SBPH, but an antibiotic fungicide jinggangmycin (JGM) suppresses its reproduction. However, mechanisms of decreased reproduction of SBPH induced by JGM remain unclear. The present findings show that JGM suppressed reproduction of SBPH (↓approximately 35.7%) and resulted in the down-regulated expression of glucose dehydrogenase (GDH). GDH-silenced control females (control+dsGDH) show that the number of eggs laid was reduced by 48.6% compared to control females. Biochemical tests show that the total lipid and fatty acid contents in JGM-treated and control+dsGDH females decreased significantly. Thus, we propose that the suppression of reproduction in SBPH induced by JGM is mediated by GDH via metabolic pathways.

Silencing of ACO decreases reproduction and energy metabolism in triazophos-treated female brown plant hoppers, Nilaparvata lugens Stål (Hemiptera: Delphacidae).

The brown plant hopper (BPH), Nilaparvata lugens Stål (Hemiptera: Delphacidae), is a major pest affecting rice in Asia, and outbreaks of this pest are closely linked to pesticide-induced stimulation of reproduction. Therefore, the BPH is a classic example of a resurgent pest. However, the effects of different genes on the regulation of pesticide-induced reproductive stimulation in the BPH are unclear. In this study, the regulatory effects of acyl-coenzyme A oxidase (ACO) on the reproduction and biochemistry of the BPH were investigated with gene silencing. The number of eggs laid per female by triazophos (TZP)+dsACO BPH females was significantly lower than those of TZP-treated (without ACO silencing) or TZP+GFP females (negative control), with the number of eggs decreasing by 30.8% (from 529.5 to 366.3) and 32.0% (from 540.5 to 366.3), respectively. The preoviposition period, oviposition period, and longevity of the TZP-treated females were also influenced by dsACO treatment. Additionally, the amounts of crude fat, protein, and some fatty acids (oleic acid, palmitic acid, linoleic acid, stearic acid, and myristoleic acid) in TZP+dsACO females were significantly lower than in TZP-treated females. Thus, ACO is one of the key genes regulating the TZP-induced stimulation of reproduction in BPH females.

The effects of triazophos applied to transgenic Bt rice on the nutritional indexes, Nlvg expression, and population growth of Nilaparvata lugens Stål under elevated CO2.

The brown planthopper, Nilaparvata lugens (Stål) (Hemiptera: Delphacidae), is a typical pest in which population resurgence can be induced by insecticides. Warmer global temperatures, associated with anthropogenic climate change, are likely to have marked ecological effects on terrestrial ecosystems. However, the effects of elevated CO2 (eCO2) concentrations on the resurgence of N. lugens that have been treated with pesticides used for transgenic Bt rice cultivation are not fully understood. The present study investigated changes in the protein content, soluble sugar content, free amino acid level, vitellogenin (Nlvg) mRNA expression, and the population growth of N. lugens on transgenic Bt rice (TT51) following triazaophos foliar spray under conditions of eCO2. The results showed that the protein content in the fat bodies and ovaries of N. lugens adult females in TT51 treated with 40 ppm triazophos under eCO2 was significantly higher than under ambient CO2 (aCO2) and was also higher than that in females feeding on the non-transgenic parent (MH63) under aCO2 at different days after emergence (DAEs). The soluble sugar content and free amino level of adult females in TT51 treated with 40 ppm triazophos under eCO2 was significantly higher than under aCO2 and was also higher than in MH63 under aCO2 at 1 and 3 DAE. The Nlvg mRNA expression level of N. lugens adult females in TT51 treated with 40 ppm triazophos under eCO2 was significantly higher than under aCO2 and was also higher than in MH63 under aCO2 at 1 and 3 DAE. The population number of N. lugens in TT51 treated with 40 ppm triazophos under eCO2 was significantly higher than under aCO2 and was also higher than in MH63 under aCO2. The present findings provide important information for integrated pest management with transgenic varieties and a better understanding of the resurgence mechanism of N. lugens under eCO2.

Effects of two pesticides, TZP and JGM, on reproduction of three planthopper species, Nilaparvata lugens Stål, Sogatella furcifera Horvath, and Laodelphax striatella Fallén.

Three planthopper species, the brown planthopper (BPH), Nilaparvata lugens Stål, the white-backed planthopper (WBPH), Sogatella furcifera Horvath, and the small brown planthopper (SBPH), Laodelphax striatella Fallén, often co-occur in rice grown regions of China. The present investigation examined effects of two pesticides, triazophos (TZP) and jinggangmycin (JGM) (a fungicide), on reproduction of BPH, WBPH, and SBPH. The results showed that TZP stimulated the fecundity of the three planthopper species. Interestingly, JGM stimulated the fecundity of BPH but suppressed the fecundity of WBPH. In addition, TZP and JGM had a significant effect on the preoviposition period (PVD), the oviposition period (OPD), and the longevity of adult females (LAF) of BPH and WBPH. Based on these findings, to avoid resurgence occurrence of planthoppers, we suggest that the application of TZP should be banned in rice fields, that JGM should be used to control rice sheath blight at the early growth stages of rice (with WBPH occurrence and without BPH occurrence).

Comparisons of topical and spray applications of two pesticides, triazophos and jinggangmycin, on the protein content in the ovaries and fat bodies of the brown planthopper Nilaparvata lugens Stål (Hemiptera:Delphacidae).

The pesticide-induced stimulation of reproduction in pests is one of the most important mechanisms of pest resurgence. There have been numerous reports on the insecticide-induced stimulation of reproduction. However, the relationship between pesticide application method and pest resurgence (stimulation of reproduction) has received little attention. Here, we studied the effect of two treatment methods, triazophos (TZP) and jinggangmycin (JGM), on the protein content in the ovaries and fat bodies of the brown planthopper (BPH) Nilaparvata lugens Stål. The results showed that pesticide treatment methods significantly affected the protein content in the ovaries and fat bodies of BPH. In addition, grand means (means of main effect) of the protein content at 2 and 3 days after emergence (2 and 3 DAE) for foliar sprays was significantly higher than that observed after topical treatments, which increased by 23.9% (from 1.42 to 1.76) and 8.82% (from 4.42 to 4.81), respectively. No significant differences on the protein content in the ovaries and fat bodies for the JGM topical treatment were observed compared with controls. However, the protein content for JGM foliar sprays was significantly higher than that for the controls. The protein contents in both topical and spray treatments of TZP were significantly higher than those of the controls. Ovarian protein is mainly yolk protein. There is a positive correlation between ovarian protein content and the number of eggs laid. These findings show that foliar spray of the pesticides promotes the resurgence of BPH. Therefore, the foliar spray of some pesticides, such as JGM, should be avoided for the control of pests, which is the sideeffects of the fungicide on non-target insect pests' occurrence.

Gene cloning, protein expression, and enzymatic characterization of a double-stranded RNA degrading enzyme in Apolygus lucorum.

RNA interference (RNAi) is a powerful tool that post-transcriptionally silences target genes in eukaryotic cells. However, silencing efficacy varies greatly among different insect species. Recently, we met with little success when attempting to knock down genes in the mirid bug Apolygus lucorum via dsRNA injection. The disappearance of double-stranded RNA (dsRNA) could be a potential factor that restricts RNAi efficiency. Here, we found that dsRNA can be degraded in midgut fluids, and a dsRNase of A. lucorum (AldsRNase) was identified and characterized. Sequence alignment indicated that its 6 key amino acid residues and the Mg2+ -binding site were similar to those of other insects' dsRNases. The signal peptide and endonuclease non-specific domain shared high sequence identity with the brown-winged green stinkbug Plautia stali dsRNase. AldsRNase showed high salivary gland and midgut expression and was continuously expressed through the whole life cycle, with peaks at the 4th instar ecdysis in the whole body. The purified AldsRNase protein obtained by heterologously expressed can rapidly degrade dsRNA. When comparing the substrate specificity of AldsRNase, 3 specific substrates (dsRNA, small interfering RNA, and dsDNA) were all degraded, and the most efficient degradation is dsRNA. Subsequently, immunofluorescence revealed that AldsRNase was expressed in the cytoplasm of midgut cells. Through cloning and functional study of AldsRNase, the enzyme activity and substrate specificity of the recombinant protein, as well as the subcellular localization of nuclease, the reason for the disappearance of dsRNA was explained, which was useful in improving RNAi efficiency in A. lucorum and related species.

Molecular basis for insecticide-enhanced thermotolerance in the brown planthopper Nilaparvata lugens Stål (Hemiptera:Delphacidae).

Climate change is likely to have marked ecological effects on terrestrial ecosystems, including the activities of insect pests. Most attention has focused on the increasing geographical ranges of pests; however, if extrinsic factors enhance their thermotolerance, populations may express increased voltinism and longer daily and annual activity periods. These changes in pest populations have the potential for severe consequences, including increased crop losses and decreased food security at the global level. The brown planthopper (BPH) Nilaparvata lugens Stål (Hemiptera: Delphacidae) is a serious pest of rice crops in temperate and tropical regions of Asia. It is often present in rice microclimates at temperatures close to its maximum thermotolerance. Recent BPH outbreaks in tropical Asia are considered to be associated with excess use of pesticides and increasing temperature. This study tested whether exposure to sublethal concentrations of triazophos (tzp), an insecticide widely used in Asian rice production, enhances thermotolerance of BPH. Tzp exposure (40 ppm at 40 °C) significantly decreased mortality (from 94% in controls to 50% at 48 h post-treatment) and increased lethal mean time (LT50 ) of adults by 17.2 h. To investigate the underlying molecular mechanism of this tzp-enhanced thermotolerance, we selected Hsp70 and Arginine kinase (Argk) for detailed study. Transcripts encoding both proteins in third-instar nymphs and brachypterous adult females were up-regulated, compared with controls, after exposure to tzp. RNAi silencing of both genes demonstrated that Hsp70 and Argk are essential for survival and tzp-increased thermotolerance. We propose that tzp induces thermotolerance in BPHs by increasing the expression of genes that act in cell protection mechanisms. The significance of our proposal relates to the importance of understanding the influence of sublethal concentrations of insecticides on pest biology. In addition to its influence on thermotolerance, tzp also enhances BPH reproduction. We infer that exposure to a pesticide stressor can produce cross-tolerance, that is, increased tolerance to one stressor also increases tolerance to other stressors, including temperature. Aside from needing a better understanding of these effects in nature and in other pest/cropping systems, we suggest that pest management programmes can be improved with better understanding of the influences of stressors, including increased environmental temperatures and sublethal concentrations of insecticides, on pest biology.

Effects of nitrogen fertilizer and magnesium manipulation on the Cnaphalocrocis medinalis (Lepidoptera: Pyralidae).

The rice leaffolder, Cnaphalocrocis medinalis Guenee (Lepidoptera: Pyralidae), is a rice pest that is prone to outbreaks when high levels of nitrogen (N) fertilizer are applied to rice. The larvae feed by scraping the mesophyll cells of leaves, which are mainly composed of chloroplasts containing significant levels of elemental magnesium (Mg). To determine the cause of N fertilizer-induced rice leaffolder outbreaks and the effects of Mg and Mg uptake on the rice leaffolder, the changes in the life history traits and biochemistry of C. medinalis larvae feeding on rice leaves treated with different Mg and N concentrations were investigated in this study. The results showed that foliar treatment using different Mg concentrations under hydroponic culture conditions significantly decreased the developmental duration (days) (DD) of the larvae and pupae but did not influence the pupation rate or adult emergence rate. The number of eggs laid by adult females and the protein content and total sugar content in the larvae and pupae significantly increased with increasing Mg concentrations. Under soil culture conditions, the DD for the larvae and number of eggs laid by adult females significantly increased with increasing nitrogen fertilizer levels, but the applied fertilizer did not influence the DD in the pupae, pupation rate, or adult emergence rate. In contrast, the DD for adults decreased with increased fertilizer levels. In hydroponic culture, Mg in the culture solution and Mg foliar sprays significantly increased the Mg content in rice leaves. In soil cultures, the use of N fertilizer and Mg foliar spray did not significantly increase the leaf Mg content, except at a concentration of 12.5 g/L, indicating that the leaf Mg content may be related to the root uptake of Mg.

The superoxide dismutase (SOD) genes family mediates the response of Nilaparvata lugens to jinggangmycin and sugar.

Introduction: Brown planthopper (BPH), Nilaparvata lugens Stål (Hemiptera: Delphacidae), is a major rice pest causing significant damage to rice throughout the world. Intensive pesticide usage often causes resistance in these seasonal pests, mainly through the modulation of antioxidant machinery. The superoxide dismutase (SOD) gene family is known for regulating BPH response to pesticides. Methods: In the present study, we identified eight NlSOD genes from the NCBI using the BLASTP program. The bioinformatics analysis includes a phylogenetic tree, conserved domain, motifs, gene ontology (GO) analysis, Kyoto encyclopedia of genes and genomes (KEGG) pathways, and protein-protein interaction, highlighting the distinctive functional elements of NlSOD genes. Results and discussion: Additionally, the NlSOD genes showed expression in all developmental stages of BPH. Under three sugars (glucose, sucrose, and trehalose) treatment, the respective upregulation of NlSOD8, NlSOD6, and NlSOD2 was noted. The NlSOD1 induced significantly under jinggamycin (JGM) deduced its potential as a key regulator of BPH response to the pesticide. Our study has provided detailed knowledge of the NlSOD gene family in-silico analysis and the defensive response to insecticide and high sugar of BPH. We hope the results of this research will help to shed light on the resistance of BPH towards insecticide toxicity and high sugar and help to control it more efficiently.

The Homeodomain-Leucine Zipper Genes Family Regulates the Jinggangmycin Mediated Immune Response of Oryza sativa to Nilaparvata lugens, and Laodelphax striatellus.

The homeodomain-leucine zipper (HDZIP) is an important transcription factor family, instrumental not only in growth but in finetuning plant responses to environmental adversaries. Despite the plethora of literature available, the role of HDZIP genes under chewing and sucking insects remains elusive. Herein, we identified 40 OsHDZIP genes from the rice genome database. The evolutionary relationship, gene structure, conserved motifs, and chemical properties highlight the key aspects of OsHDZIP genes in rice. The OsHDZIP family is divided into a further four subfamilies (i.e., HDZIP I, HDZIP II, HDZIP III, and HDZIP IV). Moreover, the protein-protein interaction and Gene Ontology (GO) analysis showed that OsHDZIP genes regulate plant growth and response to various environmental stimuli. Various microRNA (miRNA) families targeted HDZIP III subfamily genes. The microarray data analysis showed that OsHDZIP was expressed in almost all tested tissues. Additionally, the differential expression patterns of the OsHDZIP genes were found under salinity stress and hormonal treatments, whereas under brown planthopper (BPH), striped stem borer (SSB), and rice leaf folder (RLF), only OsHDZIP3, OsHDZIP4, OsHDZIP40, OsHDZIP10, and OsHDZIP20 displayed expression. The qRT-PCR analysis further validated the expression of OsHDZIP20, OsHDZIP40, and OsHDZIP10 under BPH, small brown planthopper (SBPH) infestations, and jinggangmycin (JGM) spraying applications. Our results provide detailed knowledge of the OsHDZIP gene family resistance in rice plants and will facilitate the development of stress-resilient cultivars, particularly against chewing and sucking insect pests.