Search Results (30)

Cytoplasmic polyadenylation element-binding proteins (CPEBs) are critical regulators of maternal mRNA translation during oogenesis, yet their roles in insect reproduction remain underexplored. Here, we characterized CmCPEB2, a CPEB homolog in the rice leaf roller Cnaphalocrocis medinalis, a destructive lepidopteran pest insect, and elucidated its role in mating-induced oviposition. The CmCPEB2 protein harbored conserved RNA recognition motifs and a ZZ-type zinc finger domain and was phylogenetically clustered with lepidopteran orthologs. Spatiotemporal expression profiling revealed CmCPEB2 was predominantly expressed in ovaries post-mating, peaking at 12 h with a 6.75-fold increase in transcript levels. Liposome-mediated RNA interference targeting CmCPEB2 resulted in a 52% reduction in transcript abundance, leading to significant defects in ovarian maturation, diminished vitellogenin deposition, and a 36.7% decline in fecundity. The transcriptomic analysis of RNAi-treated ovaries identified 512 differentially expressed genes, with downregulated genes enriched in chorion formation and epithelial cell development. Tissue culture-based hormonal assays demonstrated the juvenile hormone-dependent regulation of CmCPEB2, as JH treatment induced its transcription, while knockdown of the JH-responsive transcription factor CmKr-h1 in the moths suppressed CmCPEB2 expression post-mating. These findings established CmCPEB2 as a juvenile hormone-dependent regulator of mating-induced oviposition that orchestrates vitellogenesis through yolk protein synthesis and ovarian deposition and choriogenesis via transcriptional control of chorion-related genes. This study provides novel evidence of CPEB2-mediated reproductive regulation in Lepidoptera, highlighting its dual role in nutrient allocation and structural eggshell formation during insect oogenesis and oviposition. Full article

The rice leaf folder Cnaphalocrocis medinalis is an important migratory pest in Asia. Although this pest possesses diverse bacterial communities in its gut, functions of these bacteria in modulating host fitness, including development durations, pupal weight, adult longevity, and fecundity, remain unknown. We isolated gut bacteria from field–collected C. medinalis larvae using a culture–dependent method and identified 15 bacterial isolates. Six of the isolates (Klebsiella aerogenes, Klebsiella pneumoniae, Enterobacter ludwigii, Enterobacter asburiae, Pantoea dispersa, and Pantoea ananatis) were newly discovered in C. medinalis. When larvae were orally inoculated with individual bacterial isolates, 15 isolates showed varying degrees of effects on C. medinalis fitness. Importantly, we found that 10 bacterial isolates induced significant larval mortality. Specifically, the inoculation of Pseudomonas mosselii, P. dispersa, Chryseobacterium culicis, P. ananatis, and Myroides odoratus caused high mortality ranging from 40.0% to 56.7%. However, reducing the entire gut bacterial community with antibiotic treatment negatively impacted C. medinalis fitness, while the reinoculation of a bacterial community to antibiotic–treated larvae recovered some of the adverse effects. In particular, control and bacterial community–inoculated C. medinalis laid approximately 37.6% more eggs than antibiotic–treated C. medinalis. This suggests that these bacteria affect their hosts differently when they are together as compared to alone. Our results reveal that C. medinalis harbors gut bacteria capable of both mutualistic and pathogenic interactions, suggesting their potential as biocontrol agents and indicating that targeting the gut bacterial community could be an effective strategy for controlling C. medinalis infestations. Full article

Plant nucleotide-binding leucine-rich repeat immune receptor genes (NLRs) play an important role in plant defenses against pathogens, pathogenic nematodes, and piercing–sucking herbivores. However, little is known about their functions in plant defenses against chewing herbivores. Here, we identified a plasma membrane-localized coiled-coil-type NLR protein, OsPik-2-like, whose transcript levels were induced by the infestation of rice leaf folder (LF, Cnaphalocrocis medinalis) larvae, and by treatment with mechanical wounding. Knocking out OsPik-2-like in rice increased the LF-induced levels of jasmonic acid (JA) and jasmonoyl–isoleucine (JA-Ile), the activity of trypsin protease inhibitors (TrypPIs), and the basal levels of some flavonoids, which in turn decreased the performance of LF larvae. Moreover, knocking out OsPik-2-like reduced plant growth. These findings demonstrate that OsPik-2-like regulates the symbiosis between rice and LF by balancing plant growth and defense. Full article

The rice leaf-roller Cnaphalocrocis medinalis is an important migratory pest of rice. We conducted a study to determine the physiological status of adults trapped by a sex pheromone and floral odor. In the immigrant group, the number of males trapped by the floral odor was greater than the number caught by sex pheromone trapping. The volume of testes was similar in the above two trapping methods but was smaller than in the sweep net method. The ovary developmental grade, mating rate, and number of matings of females caught in floral odor trap were higher than in those caught in the sweep net. In the local breeding group, the number of males trapped by sex pheromones was greater than the number trapped by the floral odor. The volume of testes was smaller in the floral odor trap compared to the pheromone trap group, with the largest in the sweep net group. The ovarian developmental grade, mating rate, and number of matings of females were significantly higher in the floral odor trap group than in the sweep net group. In the emigrant group, the adult olfactory response to the sex pheromone and floral odor was low. The volume of testes was larger in the sweep net group compared to the moths caught by floral odor trapping. The number of eggs laid by female immigrants trapped by the floral odor and sweep net was similar, while the number in the local breeding group was greater in moths caught with the sweep net in comparison with those caught by the floral odor trap. The difference in egg hatchability between the two trapping methods in both immigrants and local breedings was not significant. Full article

The composition of microbiota in the digestive tract gut is essential for insect physiology, homeostasis, and pathogen infection. Little is known about the interactions between microbiota load and oral infection with baculoviruses. CnmeGV is an obligative baculovirus to Cnaphalocrocis medinalis. We investigated the impact of CnmeGV infection on the structure of intestinal microbes of C. medinalis during the initial infection stage. The results revealed that the gut microbiota profiles were dynamically driven by pathogen infection of CnmeGV. The numbers of all the OTU counts were relatively higher at the early and later stages, while the microbial diversity significantly increased early but dropped sharply following the infection. The compositional abundance of domain bacteria Firmicutes developed substantially higher. The significantly enriched and depleted species can be divided into four groups at the species level. Fifteen of these species were ultimately predicted as the biomarkers of CnmeGV infection. CnmeGV infection induces significant enrichment of alterations in functional genes related to metabolism and the immune system, encompassing processes such as carbohydrate, amino acid, cofactor, and vitamin metabolism. Finally, the study may provide an in-depth analysis of the relationship between host microbiota, baculovirus infection, and pest control of C. medinalis. Full article

Three-line hybrid rice is produced by crossing male sterile (A line) rice with a fertility-restorer (R line). Fertile lines (B lines) are also required to maintain A line seed for breeding programs. We used a range of hybrids and their parental lines to assess the frequency and nature of heterosis for resistance to the whitebacked planthopper (Sogatella furcifera), brown planthopper (Nilaparvata lugens) and yellow stemborer (Scirpophaga incertulas). Heterosis is defined as trait improvement above the average of the parental lines as a result of outbreeding. Based on the results from a greenhouse study that challenged hybrids and their parental lines with each herbivore species, we found that susceptibility to planthoppers was associated with one of the eight A lines tested, but resistance was improved by crossing with a relatively resistant restorer. Higher frequencies of heterosis for susceptibility in comparisons between hybrids and their B lines suggest that susceptibility was not related to the cytoplasmic genomes of the associated sterile A lines. Furthermore, because none of the parental lines possessed currently effective resistance genes, improved resistance against planthoppers was probably due to quantitative resistance. In a related field trial, hybrids had generally higher yields than their fertile parents and often produced larger grain; however, they were often more susceptible to stemborers, leaffolders (Cnaphalocrocis medinalis) and other caterpillars (Rivula atimeta). This was largely a consequence of hybrid heterosis for plant biomass and was strongly affected by crop duration. We make a series of recommendations to improve hybrid breeding to reduce the risks of herbivore damage. Full article

Odorant-binding proteins (OBPs) play important roles in the insect olfactory system since they bind external odor molecules to trigger insect olfactory responses. Previous studies have identified some plant-derived volatiles that attract the pervasive insect pest Cnaphalocrocis medinalis (Lepidoptera: Pyralidae), such as phenylacetaldehyde, benzyl acetate, 1-heptanol, and hexanal. To characterize the roles of CmedOBPs in the recognition of these four volatiles, we analyzed the binding abilities of selected CmedOBPs to each of the four compounds, as well as the expression patterns of CmedOBPs in different developmental stages of C. medinalis adult. Antennaes of C. medinalis adults were sensitive to the studied plant volatile combinations. Expression levels of multiple CmedOBPs were significantly increased in the antennae of 2-day-old adults after exposure to volatiles. CmedOBP1, CmedOBP6, CmedPBP1, CmedPBP2, and CmedGOBP2 were significantly up-regulated in the antennae of volatile-stimulated female and male adults when compared to untreated controls. Fluorescence competition assays confirmed that CmedOBP1 could strongly bind 1-heptanol, hexanal, and phenylacetaldehyde; CmedOBP15 strongly bound benzyl acetate and phenylacetaldehyde; and CmedOBP26 could weakly bind 1-heptanol. This study lays a theoretical foundation for further analysis of the mechanisms by which plant volatiles can attract C. medinalis. It also provides a technical basis for the future development of efficient plant volatile attractants of C. medinalis. Full article

Agricultural pests can be effectively controlled using microbes, providing an eco-friendly alternative to available synthetic pesticides. Suitable entomopathogenic bacterial strains were collected from agricultural fields and evaluated for their insecticidal potential against Cnaphalocrocis medinalis. In the four tested entomopathogenic bacteria (W1, Yc1, S1, EB01), the larval mortality ranged from 38 to 74%. Among these isolates, Bacillus subtilis (EB01) induced the highest mortality (74%). In greenhouse conditions, the tests confirm that the results were dosage-dependent: B. subtilis infection considerably delayed the overall development period, reduced pupal conversion, and decreased adult emergence with induced morphological deformities. Larvae fed B. subtilis-treated leaves initiate bacterial infection and broadly damage the midgut tissue, including the epithelial and peritrophic layers. The bacterial growth in the C. medinalis hemolymph considerably increases the activity of enzymes like α and β esterase (85.14 and 44% at 96 h) compared to the control. The isolate B. subtilis-treated diet significantly reduced the larval digestive α and β galactosidase enzyme activity (88.17 and 91.88% at 96 h). Furthermore, germination bioassay with strain EB01 in rice varieties (TN1 and ASD16) significantly increased both varieties’ germination and biomass index. This study shows that the B. subtilis EB01 strain potentially inhibited the biological activity of C. medinalis and improved the rice seeds’ germination index. It can be a potential biocontrol agent in sustainable pest-management strategies. Full article

Chlorantraniliprole is a broad-spectrum insecticide that has been widely used to control pests in rice fields. Limited by its low solubility in both water and organic solvents, the development of highly efficient and environmentally friendly chlorantraniliprole formulations remains challenging. In this study, a low-cost and scalable wet media milling technique was successfully employed to prepare a chlorantraniliprole nanosuspension. The average particle size of the extremely stable nanosuspension was 56 nm. Compared to a commercial suspension concentrate (SC), the nanosuspension exhibited superior dispersibility, as well as superior foliar wetting and retention performances, which further enhanced its bioavailability against Cnaphalocrocis medinalis. The nanosuspension dosage could be reduced by about 40% while maintaining a comparable efficacy to that of the SC. In addition, the chlorantraniliprole nanosuspension showed lower residual properties, a lower toxicity to non-target zebrafish, and a smaller effect on rice quality, which is conducive to improving food safety and the ecological safety of pesticide formulations. In this work, a novel pesticide-reduction strategy is proposed, and theoretical and data-based support is provided for the efficient and safe application of nanopesticides. Full article

Plants and insects are engaged in a tight relationship, with phytophagous insects often utilizing volatile organic substances released by host plants to find food and egg-laying sites. Using plant volatiles as attractants for integrated pest management is vital due to its high efficacy and low environmental toxicity. Using naturally occurring plant volatiles combined with insect olfactory mechanisms to select volatile molecules for screening has proved an effective method for developing plant volatile-based attractant technologies. However, the widespread adoption of this technique is still limited by the lack of a complete understanding of molecular insect olfactory pathways. This paper first describes the nature of plant volatiles and the mechanisms of plant volatile perception by insects. Then, the attraction mechanism of plant volatiles to insects is introduced with the example of Cnaphalocrocis medinalis. Next, the progress of the development and utilization of plant volatiles to manage pests is presented. Finally, the functions played by the olfactory system of insects in recognizing plant volatiles and the application prospects of utilizing volatiles for green pest control are discussed. Understanding the sensing mechanism of insects to plant volatiles and its utilization will be critical for pest management in agriculture. Full article

Cnaphalocrocis medinalis (Lepidoptera: Crambidae) is a migratory insect pest on rice crops. The migratory C. medinalis population in a particular location may be immigrants, local populations, emigrants, or a mix of these. Immigrants are strongly attracted to plant odor. We conducted research to identify the olfactory receptors in a floral scent mixture that is strongly attractive to C. medinalis. Through gene cloning, 12 olfactory receptor (OR) genes were amplified and expressed in Xenopus oocytes in vitro, and three of them were found to be responsive to plant foliar and floral volatiles. These were CmedOR31, a specific receptor for geraniol; CmedOR32, a broad-spectrum OR gene that responded to both foliar and floral odors; and CmedOR1, which strongly responded to 10⁻⁴ M phenylacetaldehyde. The electrophysiological response to phenylacetaldehyde was extremely high, with a current of 3200 ± 86 nA and an extremely high sensitivity. We compared the phylogenetic tree and sequence similarity of CmedOR genes and found that CmedOR1 belonged to a uniquely conserved OR pedigree in the evolution of Glossata species, and the ORs of this pedigree strongly responded to phenylacetaldehyde. The expression of OR1 was significantly higher in the females than in the males. Localization of CmedOR1 in the antennae of C. medinalis by fluorescence in situ hybridization showed that CmedOR1 was expressed in both males and females. CmedOR1 may be an odor receptor used by females to locate food sources. The function of these ORs and their role in pest monitoring were discussed. Full article

The rice leaf folder, Cnaphalocrocis medinalis (Lepidoptera: Pyralidae), is a notorious pest of rice in Asia. The larvae and adults of C. medinalis utilize specialized chemosensory systems to adapt to different environmental odors and physiological behaviors. However, the differences in chemosensory genes between the olfactory organs of these two different developmental stages remain unclear. Here, we conducted a transcriptome analysis of larvae heads, male antennae, and female antennae in C. medinalis and identified 131 putative chemosensory genes, including 32 OBPs (8 novel OBPs), 23 CSPs (2 novel CSPs), 55 ORs (17 novel ORs), 19 IRs (5 novel IRs) and 2 SNMPs. Comparisons between larvae and adults of C. medinalis by transcriptome and RT-qPCR analysis revealed that the number and expression of chemosensory genes in larval heads were less than that of adult antennae. Only 17 chemosensory genes (7 OBPs and 10 CSPs) were specifically or preferentially expressed in the larval heads, while a total of 101 chemosensory genes (21 OBPs, 9 CSPs, 51 ORs, 18 IRs, and 2 SNMPs) were specifically or preferentially expressed in adult antennae. Our study found differences in chemosensory gene expression between larvae and adults, suggesting their specialized functions at different developmental stages of C. medinalis. These results provide a theoretical basis for screening chemosensory genes as potential molecular targets and developing novel management strategies to control C. medinalis. Full article

The rice leaf folder, Cnaphalocrocis medinalis, is a significant migratory pest that restricts rice production in Asia and Africa, and monitoring and early warning measures are the basis for its management. Based on its regional migratory path in China, the pest population dynamics were monitored from 2020 to 2021 using food attractants. In this study, we also used internal reproductive system dissection to determine the adult age and reproductive developmental state. The monitoring results indicated that the trapping dynamics of C. medinalis males using food attractants and sex pheromones were approximately similar. Both trapping methods yielded C. medinalis males of different ages, with an identical age structure for both trap types. Dissection analysis of the reproductive system of females trapped using the food attractants indicated that in 2020, the population of C. medinalis in Liling, Hunan Province, was indigenous, while populations in other monitoring sites mainly comprised migrants from other areas. The ovarian development level of females trapped using food attractants showed a positive correlation with the age of males, and there was also a significant positive correlation between the index of ovarian development of females and the mating time. Furthermore, a dynamic prediction method for fecundity in field populations was established based on the quantity of eggs held by the females. This study provides a new method for the monitoring and early warning of the existence of C. medinalis populations. Full article

As pests are an important factor in reducing crop yields, pest control is an important measure in preventing reductions in crop yields. With the aim of ending the use of chemical pesticides, biological control and genetically modified methods are now considered more reasonable pest control strategies. The bacterium Bacillus thuringiensis (Bt) can produce crystal proteins that have specific toxicity to lepidopteran insects, and so it has been applied as a microbial insecticide in the control of crop pests for several decades. With the development of plant genetic engineering, Bt genes encoding insecticidal crystal protein have been introduced into many crop species for pest control. This article indicates that, after years of experiments and research, Bt transgenic rice is close to becoming a commercial insect-resistant rice, and many studies have shown that transgenic rice has pronounced abilities in the control of pests such as yellow stem borers (Scirpophaga incertulas, YSB), striped stem borers (Chilo suppressalis, SSB), and rice leaf rollers (Cnaphalocrocis medinalis, RLR); moreover, it does not obviously differ from non-transgenic rice in terms of safety. This paper suggests that transgenic Bt rice has application potential and commercial value. Full article

Global warming is posing a threat to animals. As a large group of widely distributed poikilothermal animals, insects are liable to heat stress. How insects deal with heat stress is worth highlighting. Acclimation may improve the heat tolerance of insects, but the underlying mechanism remains vague. In this study, the high temperature of 39 °C was used to select the third instar larvae of the rice leaf folder Cnaphalocrocis medinalis, an important insect pest of rice, for successive generations to establish the heat-acclimated strain (HA39). The molecular mechanism of heat acclimation was explored using this strain. The HA39 larvae showed stronger tolerance to 43 °C than the unacclimated strain (HA27) persistently reared at 27 °C. The HA39 larvae upregulated a glucose dehydrogenase gene, CmGMC10, to decrease the reactive oxygen species (ROS) level and increase the survival rate under heat stress. The HA39 larvae maintained a higher activity of antioxidases than the HA27 when confronted with an exogenous oxidant. Heat acclimation decreased the H₂O₂ level in larvae under heat stress which was associated with the upregulation of CmGMC10. The rice leaf folder larvae may acclimate to global warming via upregulating CmGMC10 to increase the activity of antioxidases and alleviate the oxidative damage of heat stress. Full article