Striped Stem Borer Chilo Suppressalis Research Articles

Efficacy of different control methods of the rice striped stem borer Chilo suppressalis (Lepidoptera: Grambidae) under water stress conditions in paddy fields

Efficacy of different control methods of the rice striped stem borer Chilo suppressalis (Lepidoptera: Grambidae) under water stress conditions in paddy fields

Efficacy of the new insecticide thiocyclam hydrogen oxalate in the control of rice striped stem borer Chilo suppressalis (Lepidoptera: Grambidae) under field conditions

Efficacy of the new insecticide thiocyclam hydrogen oxalate in the control of rice striped stem borer Chilo suppressalis (Lepidoptera: Grambidae) under field conditions

Moth sex pheromones affect interspecific competition among sympatric species and possibly population distribution by modulating pre-mating behavior.

Premating behaviors mediated by pheromones play pivotal roles in animal mating choices. In natural populations of the striped stem borer Chilo suppressalis and the rice leaf roller Cnaphalocrocis medinalis in the rice field habitat, we discovered that Z11-16:Ald, a major component of the C. suppressalis pheromone, modulated the premating behavior of C. medinalis. Z11-16:Ald evoked a strong olfactory response in male antennae and strongly inhibited the sex pheromone trapping of male C. medinalis in the field. The functions of three C. medinalis sex pheromone receptor genes (CmedPR1-3) were verified through heterologous expression in Xenopus oocytes. CmedPR1 responded to Z11-18:OH and Z11-18:Ald, as well as the interspecific pheromone compound Z11-16:Ac of sympatric species; CmedPR2 responded to Z13-18:OH and Z13-18:Ald, as well as the sex pheromone compounds Z11-16:Ald and Z9-16:Ald of sympatric species; and CmedPR3 responded to Z11-18:OH and Z13-18:OH, as well as the interspecific pheromones Z11-16:OH, Z9-16:Ald, Z11-16:Ac, and Z11-16:Ald of sympatric species. Thus, CmedPR2 and CmedPR3 share the ligand Z11-16:Ald, which is not a component of the C. medinalis sex pheromone. Therefore, the sex pheromones of interspecific species affected the input of neural signals by stimulating the sex pheromone receptors on the antennae of male C. medinalis moths, thereby inhibiting the olfactory responses of the male moths to the sex pheromones. Our results demonstrate chemical communication among sympatric species in the rice field habitat, the recognition of intra- and interspecific sex pheromones by olfactory receptors, and how insect premating behaviors are modulated to possibly affect resource partitioning.

Downregulation of the CsABCC2 gene is associated with Cry1C resistance in the striped stem borer Chilo suppressalis

Chilo suppressalis is a major target pest of transgenic rice expressing the Bacillus thuringiensis (Bt) Cry1C toxin in China. The evolution of resistance of this pest is a major threat to Bt rice. Since Bt functions by binding to receptors in the midgut (MG) of target insects, identification of Bt functional receptors in C. suppressalis is crucial for evaluating potential resistance mechanisms and developing effective management strategies. ATP-binding cassette (ABC) transporters have been vastly reported to interact with Cry1A toxins, as receptors and their mutations cause insect Bt resistance. However, the role of ABC transporters in Cry1C resistance to C. suppressalis remains unknown. Here, we measured CsABCC2 expression in C. suppressalis Cry1C-resistant (Cry1C-R) and Cry1C-susceptible strains (selected in the laboratory) via quantitative real-time PCR (qRT-PCR); the transcript level of CsABCC2 in the Cry1C-R strain was significantly lower than that in the Cry1C-susceptible strain. Furthermore, silencing CsABCC2 in C. suppressalis via RNA interference (RNAi) significantly decreased Cry1C susceptibility. Overall, CsABCC2 participates in Cry1C mode of action, and reduced expression of CsABCC2 is functionally associated with Cry1C resistance in C. suppressalis.

Trans-kingdom expression of an insect endogenous microRNA in rice enhances resistance to striped stem borer Chilo suppressalis.

The striped stem borer (SSB), Chilo suppressalis Walker, is a major pest of rice worldwide. Breeding of transgenic rice expressing Bacillus thuringiensis (Bt) toxins is a powerful strategy to control SSB. However, pests may evolve certain resistance to Bt toxins in transgenic plants. Hence, new controlling strategies must be continuously developed. We successfully generated SSB-resistant rice (csu-53) expressing the artificial microRNA (amiRNA) of SSB endogenous miRNA (csu-novel-miR53) through the RNAi-based technology. Feeding assays demonstrated that csu-53 rice inhibited larval growth, delayed pupation time, and reduced pupal weight and eclosion rate of SSB larva. In a 10-day feeding experiment, the miRNA mimic of csu-novel-miR53 also suppressed larval growth and more importantly increased larval mortality. Transcriptome analysis identified 28 differentially expressed unigenes (DEGs) in the midgut between SSB larvae fed on csu-53 rice and the wild type. One DEG (DN90065_c0_g12) validated by qRT-PCR had a predicted target site of csu-novel-miR53. In addition, in vitro double-stranded RNA synthesis and further feeding assay proved that DN90065_c0_g12 is most likely the target of csu-novel-miR53. amiRNA-mediated strategy can be applied to the development of insect-resistant crops, and the novel amiRNA csu-novel-miR53 of SSB has important application potential in developing SSB resistant rice. © 2021 Society of Chemical Industry.

Nitrogen Supply Alters Rice Defense Against the Striped Stem Borer Chilo suppressalis.

Plant nutrition status is closely associated with plant defense against insect herbivores. However, the way nitrogen supply regulates rice anti-herbivore is not clear. This study investigated the effects of low (LN, 0.3 mM) and high (HN, 3 mM) nitrate levels on rice resistance against the striped stem borer Chilo suppressalis (SSB), one of the major destructive rice pests. Seven-day-old rice seedlings were cultured with different nitrate levels for 30 days and then inoculated with third instars of SSB. LN significantly enhanced rice anti-herbivore defense and lowered the total nitrogen content in the plants, but increased the content of free amino acids after SSB infestation. Additionally, LN significantly increased the accumulation of phenolic acids and flavonoids, especially lignin, resulting in enhanced constitutive defense in SSB-infested plants. SSB feeding led to a rapid accumulation of secondary metabolites. HN application led to the accumulation of metabolites derived from cinnamic acid, p-coumaric acid, p-coumaric CoA, feruloyl CoA, and apigenin, while LN led to the accumulation of metabolites derived from 3-dehydroquinic acid, phenylalanine, acetyl CoA, and aspartic acid. Collectively, our finding suggests that nitrogen deficiency enhances rice anti-herbivore defense via constitutive defense by the accumulation of phenolic acids and flavonoids.

Gut microbial communities associated with phenotypically divergent populations of the striped stem borer Chilo suppressalis (Walker, 1863)

Chilo suppressalis (Walker, 1863) is a serious stem borer of rice and water-oat plants, and has phenotypically diverged into rice and water-oat populations. Insect gut microbiota plays an important role in the host life and understanding the dynamics of this complicated ecosystem may improve its biological control. The effect of diet and gut compartments on the gut microflora of divergent populations of C. suppressalis is not fully clear. Herein, we characterized the gut microbiota of C. suppressalis populations fed on two hosts (i.e., water-oats fruit pulps and rice seedlings), by sequencing the V3–V4 hypervariable region of the 16S rRNA gene using the Illumina MiSeq platform. Gut bacterial communities showed variation in relative abundance among C. suppressalis populations fed on water-oats fruit pulps or rice seedlings. Proteobacteria and Firmicutes became the predominant phyla, and Enterobacteriaceae, Enterococcaceae and Halomonadaceae were the predominant family in all C. suppressalis populations. The highest bacteria diversity was found in the midgut of the rice population fed on water-oat fruit pulps. Bacterial communities in the midgut were more diverse than those in the hindgut. The bacterial genera distribution showed great differences due to diet types and gut compartments among populations. Our results demonstrated that the host plants tested had a considerable impact on gut bacterial composition of C. suppressalis populations. Additionly, the unique gut morphology and physiological conditions (viz., oxygen content, enzymes) also contributed to variation in microbiomes. In conclusion, our study provided an important insight into investigation of insect-bacteria symbioses, and biocontrol of this species and other related lepidopterans.

Expressing OsMPK4 Impairs Plant Growth but Enhances the Resistance of Rice to the Striped Stem Borer Chilo suppressalis.

Mitogen-activated protein kinases (MPKs) play a central role not only in plant growth and development, but also in plant responses to abiotic and biotic stresses, including pathogens. Yet, their role in herbivore-induced plant defenses and their underlying mechanisms remain largely unknown. Here, we cloned a rice MPK gene, OsMPK4, whose expression was induced by mechanical wounding, infestation of the striped stem borer (SSB) Chilo suppressalis, and treatment with jasmonic acid (JA), but not by treatment with salicylic acid (SA). The overexpression of OsMPK4 (oe-MPK4) enhanced constitutive and/or SSB-induced levels of JA, jasmonoyl-l-isoleucine (JA-Ile), ethylene (ET), and SA, as well as the activity of elicited trypsin proteinase inhibitors (TrypPIs), and reduced SSB performance. On the other hand, compared to wild-type plants, oe-MPK4 lines in the greenhouse showed growth retardation. These findings suggest that OsMPK4, by regulating JA-, ET-, and SA-mediated signaling pathways, functions as a positive regulator of rice resistance to the SSB and a negative regulator of rice growth.

Electrophysiological responses of the rice striped stem borer Chilo suppressalis to volatiles of the trap plant vetiver grass (Vetiveria zizanioides L.)

Vetiver grass (Vetiveria zizanioides L.) was previously found to effectively attract female adults of Chilo suppressalis (Walker), an important pest of rice. To determine the volatile compounds involved in this attraction, electroantennography (EAG) responses to seven synthetic volatiles released from vetiver plants were examined. Our results indicated that the responses of C. suppressalis adult antennae to the different compounds varied widely. The compounds elicited strong EAG responses in female antennae were subsequently selected for further EAG response tests, namely, caryophyllene, β-ocimene, linalool and α-pinene. EAG responses to a combination of these four compounds did not differ significantly from the individual compounds. However, pair combination tests indicated that 0.01 μg μL−1 linalool and 50 μg μL−1 α-pinene, 50 μg μL−1 caryophyllene and 0.01 μg μL−1 linalool, 0.01 μg μL−1 β-ocimene and 0.01 μg μL−1 linalool, and 0.01 μg μL−1 β-ocimene and 50 μg μL−1 caryophyllene elicited significantly greater EAG responses in 3-day female moths compared to the 1-day female. These compound combinations and the corresponding ratios are probably playing an important role in attracting female adults of C. suppressalis to the vetiver grass.

A Simple and Efficient Method for Improving Pupation and Eclosion Rates of Striped Stem Borer,Chilo suppressalisWalker (Lepidoptera: Crambidae)

ABSTRACT: The striped stem borer Chilo suppressalis (Lepidoptera: Crambidae) is an important generalist feeder on gramineous crops and is difficult to control. To develop sound IPM programs, efficient methods for improving pupation and eclosion rates are desirable. Novel pupation substrates based on plastic wraps and towels were developed. The pupation rate, pupal mortality rate and eclosion rate were calculated to evaluate the performance of pupal C. suppressalis under different pupation substrates (i.e., bibulous paper, corrugated paper, paper scroll). Larvae pupated on the new substrates (i.e., plastic wraps covered with towels) showed the best performance among the substrates. These results indicated that pupal C. suppressalis adapted well to the new substrates, and the substrates could serve as a viable alternative to traditional chartaceous substrates for pupation. In addition, the substrates are time-saving, recyclable, contamination-free, and can maintain a relatively suitable humidity. The succes...

Two general odorant binding proteins display high bindings to both host plant volatiles and sex pheromones in a pyralid moth Chilo suppressalis (Lepidoptera: Pyralidae)

Odorant sensitivity and selectivity play a crucial role in insects for finding host plants, mates and oviposition sites. General odorant binding proteins (GOBPs) are thought to be involved in the detection of general odorants released by foods and host plants. However, recent studies suggest GOBPs may also play some role in detection of sex pheromones. In the present study with the rice striped stem borer Chilo suppressalis (Walker) real time quantitative PCR (qPCR) measurements showed that both GOBP genes were specifically expressed in the antennae of both sexes, proposing their important roles in olfaction. To examine their specific functions, binding affinities to three sex pheromones and 35 plant volatiles were measured using fluorescence competitive binding assays. As a result, both GOBPs showed very strong binding affinities (Ki=0.33–1.50μM) to all three sex pheromone components (Z11–16:Ald, Z9–16:Ald and Z13–18:Ald). In addition, GOBP1 and GOBP2 displayed high binding affinities (Ki<10μM) to two volatiles (farnesol and oleic acid) and five volatiles (+)-cedrol, farnesol, myrcene, β-ionone and linoleic acid), respectively; GOBP1 and GOBP2 also displayed moderate binding affinities (Ki=10–20μM) to two and one compounds, respectively. Furthermore, electroantennogram (EAG) measurements indicated that except oleic acid and myrcene, all volatiles of high binding affinity could elicit significant EAG response in moths of one or both sexes. Our study suggests that two CsupGOBPs tune to different array of plant volatiles, and also play roles in perception of the female sex pheromones, providing insights in to the mechanisms of olfaction in C. suppressalis.

Water-oats harbors two strains of the striped stem borer Chilo suppressalis (Lepidoptera: Crambidae) with temporal divergence in mating behavior

The striped stem borer, Chilo suppressalis Walker, is a widespread insect pest in China, which feeds both on rice (Oryza sativa L.) and water-oats (Zizania latifolia Griseb.). The populations collected from rice (rice population, CSR) and water-oats (water-oats population, CSW) were observed for mating behavior. Results showed that the mating rhythm of CSR in scotophase was unimodal distribution, while that of CSW was bimodal distribution. The first mating peak of CSW occurred about 3.5 h after the onset of scotophase, which overlapped well with the single mating peak of CSR. The second mating peak of CSW occurred about 5.5 h after the onset of scotophase. The descendant populations from those three mating peaks were also observed for mating behavior, and the temporal patterns were found to be hereditable. In the second generation, mating rate was abnormally low in crossings between females of the first mating peak and males of the second mating peak. Pupae weight differed significantly between CSR and CSW in the first generation but did not in the second generation reared with the same food in laboratory. Our results indicated population collected from water-oats is mixed population, containing indigenous water-oats feeders and temporary residences from rice field. It was discussed that water-oats acts as a refuge crop to delay the resistance development to pesticides and Bt (Bacillus thuringiensis) rice.

OsWRKY53, a versatile switch in regulating herbivore-induced defense responses in rice

ABSTRACTWRKY proteins, which belong to a large family of plant-specific transcription factors, play important roles in plant defenses against pathogens and herbivores by regulating defense-related signaling pathways. Recently, a rice WRKY transcription factor OsWRKY53 has been reported to function as a negative feedback modulator of OsMPK3/OsMPK6 and thereby to control the size of the investment a rice plant makes to defend against a chewing herbivore, the striped stem borer Chilo suppressalis. We investigated the performance of a piecing-sucking herbivore, the brown planthopper (BPH) Nilaparvata lugens, on transgenic plants that silence or overexpress OsWRKY53, and found that OsWRKY53 activates rice defenses against BPH by activating an H2O2 burst and suppressing ethylene biosynthesis. These findings suggest that OsWRKY53 functions not only as a regulator of plants' investment in specific defenses, but also as a switch to initiate new defenses against other stresses, highlighting the versatility and importance of OsWRKY53 in herbivore-induced plant defenses.

Efficient generation of marker-free transgenic rice plants using an improved transposon-mediated transgene reintegration strategy.

Marker-free transgenic plants can be developed through transposon-mediated transgene reintegration, which allows intact transgene insertion with defined boundaries and requires only a few primary transformants. In this study, we improved the selection strategy and validated that the maize (Zea mays) Activator/Dissociation (Ds) transposable element can be routinely used to generate marker-free transgenic plants. A Ds-based gene of interest was linked to green fluorescent protein in transfer DNA (T-DNA), and a green fluorescent protein-aided counterselection against T-DNA was used together with polymerase chain reaction (PCR)-based positive selection for the gene of interest to screen marker-free progeny. To test the efficacy of this strategy, we cloned the Bacillus thuringiensis (Bt) δ-endotoxin gene into the Ds elements and transformed transposon vectors into rice (Oryza sativa) cultivars via Agrobacterium tumefaciens. PCR assays of the transposon empty donor site exhibited transposition in somatic cells in 60.5% to 100% of the rice transformants. Marker-free (T-DNA-free) transgenic rice plants derived from unlinked germinal transposition were obtained from the T1 generation of 26.1% of the primary transformants. Individual marker-free transgenic rice lines were subjected to thermal asymmetric interlaced-PCR to determine Ds(Bt) reintegration positions, reverse transcription-PCR and enzyme-linked immunosorbent assay to detect Bt expression levels, and bioassays to confirm resistance against the striped stem borer Chilo suppressalis. Overall, we efficiently generated marker-free transgenic plants with optimized transgene insertion and expression. The transposon-mediated marker-free platform established in this study can be used in rice and possibly in other important crops.

Creation of Bt rice expressing a fusion protein of Cry1Ac and Cry1I-like using a green tissue-specific promoter.

The insecticidal genes from Bacillus thuringiensis Berliner (Bt) have long been successfully used for development of insect-resistant rice. However, commercial planting of Bt rice has been delayed by the concern over food safety, although no scientific evidence is ever found to justify the concern. To address this safety concern, we developed a transgenic insect-resistant rice line using a green tissue promoter to minimize the Bt protein expression in the rice seeds. The Bt protein expressed in the rice was a fusion protein of two different Bt toxins, Cry1Ac and Cry1I-like protein. The fusion of the two toxins may be helpful to delay the development of insect resistance to Bt rice. Laboratory and field bioassays demonstrated that the transgenic rice plants created by this study were highly active against the rice leaf folder Cnaphalocrocis medinalis (Guenée) and the striped stem borer Chilo suppressalis (Walker). Western analysis indicated that the fusion protein was specifically expressed in green tissues but not in seeds. Therefore, the transgenic rice created in this study should be useful to mitigate the food safety concern and to delay the development of insect resistance.

The broad‐leaf herbicide 2,4‐dichlorophenoxyacetic acid turns rice into a living trap for a major insect pest and a parasitic wasp

Synthetic chemical elicitors of plant defense have been touted as a powerful means for sustainable crop protection. Yet, they have never been successfully applied to control insect pests in the field. We developed a high-throughput chemical genetics screening system based on a herbivore-induced linalool synthase promoter fused to a β-glucuronidase (GUS) reporter construct to test synthetic compounds for their potential to induce rice defenses. We identified 2,4-dichlorophenoxyacetic acid (2,4-D), an auxin homolog and widely used herbicide in monocotyledonous crops, as a potent elicitor of rice defenses. Low doses of 2,4-D induced a strong defensive reaction upstream of the jasmonic acid and ethylene pathways, resulting in a marked increase in trypsin proteinase inhibitor activity and volatile production. Induced plants were more resistant to the striped stem borer Chilo suppressalis, but became highly attractive to the brown planthopper Nilaparvata lugens and its main egg parasitoid Anagrus nilaparvatae. In a field experiment, 2,4-D application turned rice plants into living traps for N. lugens by attracting parasitoids. Our findings demonstrate the potential of auxin homologs as defensive signals and show the potential of the herbicide to turn rice into a selective catch crop for an economically important pest.

Do rice water weevils and rice stem borers compete when sharing a host plant?

The rice water weevil (RWW) Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae) is an invasive insect pest of rice Oryza sativa L. in China. Little is known about the interactions of this weevil with indigenous herbivores. In the present study, adult feeding and population density of the weevil, injury level of striped stem borer Chilo suppressalis (Walker) (Lepidoptera: Pyralidae) and pink stem borer Sesamia inferens (Walker) (Lepidoptera: Noctuidae) to rice, as well as growth status of their host plants were surveyed in a rice field located in Southeastern Zhejiang, China, in 2004 with the objective to discover interspecific interactions on the rice. At tillering stage, both adult feeding of the weevil and injury of the stem borers tended to occur on larger tillers (bearing 5 leaves) compared with small tillers (bearing 2~4 leaves), but the insects showed no evident competition with each other. At booting stage, the stem borers caused more withering/dead hearts and the weevil reached a higher density on the plants which had more productive tillers and larger root system; the number of weevils per tiller correlated negatively with the percentage of withering/dead hearts of plants in a hill. These observations indicate that interspecific interactions exist between the rice water weevil and the rice stem borers with negative relations occurring at booting or earlier developmental stages of rice.

Expression of Cry1Ac protein in cry1Ac/CpTI transgenic rice and its resistance in different developmental stages to Chilo suppressalis

AbstractThe expression patterns of Cry1Ac protein and the resistance to striped stem borer Chilo suppressalis (Walker) of cry1Ac/CpTI transgenic rice (Oryza sativa L.) were investigated by ELISA and laboratory bioassay. ELISA results showed that Cry1Ac protein could be detected in all organs during the development process of cry1Ac/CpTI transgenic rice. The content of Cry1Ac protein varied markedly in different tissues at different stages: it was higher in the earlier stage than in the later stage. The highest level of Cry1Ac protein in terminal leaves of the main stem was found at the jointing stage. Thereafter, it decreased at the booting stage, and a gradual reduction to the lowest level was recorded from the flowering to the filling stage, before a slight increase was shown at the maturing stage. In addition, higher concentrations of this protein were detected in the main stem at the seedling, jointing and flowering stages than at other stages. Relatively lower levels of Cry1Ac protein were found in seeds. The results from laboratory bioassay showed high resistance of terminal leaves of the main stem in all developmental stages to C. suppressalis larvae. Corrected mortality values of C. suppressalis at 4 days after feeding on the detached leaves of cry1Ac/CpTI transgenic rice reached 90% before the filling stage and decreased to nearly 60% after the filling stage. Interestingly, results of whole plant bioassay coincided with those obtained in the detached leaf bioassay. The tendency of larval morality in the detached leaf bioassay and whole plant bioassay was consistent with that of Cry1Ac protein content in the different growing periods and organs.

Interactions between the striped stem borer Chilo suppressalis (Walk.) (Lep., Pyralidae) larvae and rice plants in response to nitrogen fertilization

A screenhouse experiment was conducted to examine the damage and compensation in rice plants when injured by the striped stem borer, Chilo suppressalis (Walker), larvae at tillering stage, as well as larval survival and development of the insect at different nitrogen (N) fertilization levels. Potted plants were fertilized at late seedling stage at the rates 0, 200, 400, 600 and 800 mgN/pot, respectively. More deadheads were caused as fertilization increased. Plants compensated well for injury at the fertilization concentrations of 200 and 400 mgN/pot by producing new tillers, but such compensation did not take place at 600 and 800 mgN/pot. Two weeks after infestation, the highest number of remaining healthy tillers was found in plants fertilized at 400 mgN/pot. Larval survival varied little among the treatments 200 to 800 mgN/pot. Larval weight attainment and/or developmental rate increased with increasing fertilization level from 200 to 600 mgN/pot, but both declined rapidly as fertilization reached 800 mgN/pot, indicating the great dependence of plant suitability on N fertilization levels. Conclusively, both the compensation response of rice plants and their suitability for C. suppressalis larvae could be significantly affected by N fertilization levels.

Relationship Between Levels of Resistance to the Striped Stemborer Chilo suppressalis (Walker) (Lepidoptera: Pyralidae) and Rice Grain Yield Losses

Six commercial IR rice cultivars with varying levels of resistance to the striped stemborer, Chilo suppressalis (Walker), in the vegetative stage were evaluated to determine their response when infested with different levels of C. suppressalis larvae in the vegetative and reproductive stages. Resistant cultivars had the least deadhearts and whiteheads. Grain yields at five larvae per plant in the vegetative stage were reduced 66% in susceptible, 50% in moderately resistant, and 13% in resistant cultivars. Following infestation in the reproductive stage, grain yield reduction with five larvae per plant was 47% for susceptible, 14% for moderately resistant, and 15% for resistant cultivars. In both plant growth stages, percentage unfilled grains was highest in the susceptible cultivars. Considering a 10% yield loss as an action threshold, one egg mass per m2 for susceptible and two egg masses per m2 for resistant varieties is suggested.