Modified Composite Biodegradable Mulch for Crop Growth and Sustainable Agriculture.

Using biodegradable films as a substitute for conventional polyolefin films has emerged as a crucial technology to combat agricultural white pollution. To address the shortcomings in the tensile strength, water vapor barrier properties, and degradation period of PBAT-based biodegradable films, this investigation aimed to create a composite film that could improve the diverse properties of PBAT films. To achieve this, a PBAT/PLA-PPC-PTLA ternary blend system was introduced in the study. The system effectively fused PBAT with PLA and PPC, as evidenced by electron microscopy tests showing no apparent defects on the surface and cross-section of the blended film. The developed ternary blend system resulted in a 58.62% improvement in tensile strength, a 70.33% enhancement in water vapor barrier properties, and a 30-day extension of the functional period compared to pure PBAT biodegradable films. Field experiments on corn crops demonstrated that the modified biodegradable film is more suitable for agricultural production, as it improved thermal insulation and moisture retention, leading to a 5.45% increase in corn yield, approaching the yield of traditional polyolefin films.

Identification and characterization of Prx5 and Prx6 in Chilo suppressalis in response to environmental stress.

The antioxidant proteins, peroxiredoxins (Prxs), function to protect insects from reactive oxygen species-induced toxicity. In this study, two Prx genes, CsPrx5, and CsPrx6, were cloned and characterized from the paddy field pest, Chilo suppressalis, containing open reading frames of 570 and 672 bp encoding 189 and 223 amino acid polypeptides, respectively. Then, we investigated the influence of various stresses on their expression levels using quantitative real-time PCR (qRT-PCR). The results showed expression of CsPrx5 and CsPrx6 in all developmental stages, with eggs having the highest level. CsPrx5 and CsPrx6 showed higher expression in the epidermis and fat body, and CsPrx6 also showed higher expression in midgut, fat body, and epidermis. Increasing concentrations of insecticides (chlorantraniliprole and spinetoram) and hydrogen peroxide (H2 O2 ) increased the expression levels of CsPrx5 and CsPrx6. In addition, the expression levels of CsPrx5 and CsPrx6 were almost markedly upregulated in larvae under temperature stress or fed by vetiver. Thus, CsPrx5 and CsPrx6 upregulation might increase the C. suppressalis defense response by reducing the impact of environmental stress, providing a better understanding of the relationship between environmental stresses and insect defense systems.

Processing Properties and Potency of Bacillus thuringiensis Cry Toxins in the Rice Leaffolder Cnaphalocrocis medinalis (Guenée).

Different Cry toxins derived from Bacillus thuringiensis (Bt) possess different insecticidal spectra, whereas insects show variations in their susceptibilities to different Cry toxins. Degradation of Cry toxins by insect midgut extracts was involved in the action of toxins. In this study, we explored the processing patterns of different Cry toxins in Cnaphalocrocis medinalis (Lepidoptera: Crambidae) midgut extracts and evaluated the impact of Cry toxins degradation on their potency against C. medinalis to better understand the function of midgut extracts in the action of different Cry toxins. The results indicated that Cry1Ac, Cry1Aa, and Cry1C toxins could be degraded by C. medinalis midgut extracts, and degradation of Cry toxins by midgut extracts differed among time or concentration effects. Bioassays demonstrated that the toxicity of Cry1Ac, Cry1Aa, and Cry1C toxins decreased after digestion by midgut extracts of C. medinalis. Our findings in this study suggested that midgut extracts play an important role in the action of Cry toxins against C. medinalis, and the degradation of Cry toxins by C. medinalis midgut extracts could reduce their toxicities to C. medinalis. They will provide insights into the action of Cry toxins and the application of Cry toxins in C. medinalis management in paddy fields.

Tenacissoside G alleviated osteoarthritis through the NF-κB pathway both in vitro and in vivo.

BACKGROUND: Osteoarthritis (OA) is a degenerative joint disease characterized by the destruction of articular cartilage. Tenacissoside G is a flavonoid isolated from the dry roots of Marsdenia tenacissima (Roxb) and has been shown to have anti-inflammatory effects. However, there is no report on the protective effects of Tenacissoside G on OA. OBJECTIVES: To identify the effects and mechanism of Tenacissoside G on OA. METHODS: In vitro, primary mouse chondrocytes were induced with IL-1ß to establish OA model. mRNA expression of MMP-13, MMP-3, TNF-α, IL-6 and iNOS, was detected by PCR. Protein expression of Collagen-II, MMP-13, p65, p-p65, and IκBα was detected by Western blot. Collagen-II in chondrocytes was also detected by immunofluorescence. In vivo, we established DMM OA mice model. The preventive effect of Tenacissoside G on OA was observed by micro-CT and histological analysis. RESULTS: In vitro, Tenacissoside G significantly inhibited the expression of iNOS, TNF-α, IL-6, MMP-3, MMP-13 and the degradation of collagen-II, Tenacissoside G also significantly suppressed NF-κB activation in chondrocytes by IL-1ß-stimulated. In vivo, we demonstrated Tenacissoside G can decrease articular cartilage damage and reduce OARSI score. CONCLUSION: These results suggest that Tenacissoside G may serve as a potential drug for the prevention and treatment of OA.

Sublethal effects of chlorantraniliprole on growth, biochemical and molecular parameters in two chironomids, Chironomus kiiensis and Chironomus javanus.

Pesticide residues have serious environmental impacts on rice-based ecosystems. In rice fields, Chironomus kiiensis and Chironomus javanus provide alternative food sources to predatory natural enemies of rice insect pests, especially when pests are low. Chlorantraniliprole is a substitute for older classes of insecticides and has been used extensively to control rice pests. To determine the ecological risks of chlorantraniliprole in rice fields, we evaluated its toxic effects on certain growth, biochemical and molecular parameters in these two chironomids. The toxicity tests were performed by exposing third-instar larvae to a range of concentrations of chlorantraniliprole. LC50 values at 24 h, 48 h, and 10 days showed that chlorantraniliprole was more toxic to C. javanus than to C. kiiensis. Chlorantraniliprole significantly prolonged the larval growth duration, inhibited pupation and emergence, and decreased egg numbers of C. kiiensis and C. javanus at sublethal dosages (LC10 = 1.50 mg/L and LC25 = 3.00 mg/L for C. kiiensis; LC10 = 0.25 mg/L and LC25 = 0.50 mg/L for C. javanus). Sublethal exposure to chlorantraniliprole significantly decreased the activity of the detoxification enzymes carboxylesterase (CarE) and glutathione S-transferases (GSTs) in both C. kiiensis and C. javanus. Sublethal exposure to chlorantraniliprole also markedly inhibited the activity of the antioxidant enzyme peroxidase (POD) in C. kiiensis and POD and catalase (CAT) in C. javanus. Expression levels of 12 genes revealed that detoxification and antioxidant abilities were affected by sublethal exposures to chlorantraniliprole. There were significant changes in the expression levels of seven genes (CarE6, CYP9AU1, CYP6FV2, GSTo1, GSTs1, GSTd2, and POD) in C. kiiensis and ten genes (CarE6, CYP9AU1, CYP6FV2, GSTo1, GSTs1, GSTd2, GSTu1, GSTu2, CAT, and POD) in C. javanus. These results provide a comprehensive overview of the differences in chlorantraniliprole toxicity to chironomids, indicating that C. javanus is more susceptible and suitable as an indicator for ecological risk assessment in rice ecosystems.

Shoot rot of Zizania latifolia and the first record of its pathogen Pantoea ananatis in China.

The aquatic grass Zizania latifolia grows symbiotically with the fungus Ustilago esculenta producing swollen structures called Jiaobai, widely cultivated in China. A new disease of Z. latifolia was found in Zhejiang Province, China. Initial lesions appeared on the leaf sheaths or sometimes on the leaves near the leaf sheaths. The lesions extended along the axis of the leaf shoots and formed long brown to dark brown streaks from the leaf sheath to the leaf, causing sheath rot and death of entire leaves on young plants. The pathogen was isolated and identified as the bacterium Pantoea ananatis, based on 16S ribosomal RNA (rRNA) gene sequencing, multilocus sequence analysis (atpD (ß-subunit of ATP synthase F1), gyrB (DNA gyrase subunit B), infB (translation initiation factor 2), and rpoB (ß|-subunit of RNA polymerase) genes), and pathogenicity tests. Ultrastructural observations using scanning electron microscopy revealed that the bacterial cells colonized the vascular tissues in leaf sheaths, forming biofilms on the inner surface of vessel walls, and extended between vessel elements via the perforated plates. To achieve efficient detection and diagnosis of P. ananatis, species-specific primer pairs were designed and validated by testing closely related and unrelated species and diseased tissues of Z. latifolia. This is the first report of bacterial sheath rot disease of Z. latifolia caused by P. ananatis in China.

Detection of disease in Cucurbita maxima Duch. ex Lam. caused by a mixed infection of Zucchini yellow mosaic virus, Watermelon mosaic virus, and Cucumber mosaic virus in Southeast China using a novel small RNA sequencing method.

The genus Cucurbita comprises many popular vegetable and ornamental plants, including pumpkins, squashes, and gourds, that are highly valued in China as well as in many other countries. During a survey conducted in Zhejiang province, Southeast China in 2016, severe symptoms of viral infection were observed on Cucurbita maxima Duch. ex Lam. Diseased plants showed symptoms such as stunting, mosaicking, Shoe string, blistering, yellowing, leaf deformation, and fruit distortion. Approximately, 50% of Cucurbita crops produced in Jinhua were diseased, causing an estimated yield loss of 35%. In this study, we developed a method using all known virus genomes from the NCBI database as a reference to map small RNAs to develop a diagnostic tool that could be used to diagnose virus diseases of C. maxima. 25 leaf samples from different symptomatic plants and 25 leaf samples from non-symptomatic plants were collected from the experimental field of Jihua National Agricultural Technology Garden for pathogen identification. Small RNAs from each set of three symptomatic and non-symptomatic samples were extracted and sequenced by Illumina sequencing. Twenty-four different viruses were detected in total. However, the majority of the small RNAs were from Zucchini yellow mosaic virus (ZYMV), Watermelon mosaic virus (WMV), and Cucumber mosaic virus (CMV). Mixed infections of these three viruses were diagnosed in leaf samples from diseased plants and confirmed by reverse transcription PCR (RT-PCR) using primers specific to these three viruses. Crude sap extract from symptomatic leaf samples was mechanically inoculated back into healthy C. maxima plants growing under greenhouse conditions. Inoculated plants developed the same disease symptoms as those observed in the diseased plants and a mixed infection of ZYMV, WMV, and CMV was detected again by RT-PCR, thus fulfilling Koch's postulates. The diagnostic method developed in this study involves fewer bioinformatics processes than other diagnostic methods, does not require complex settings for bioinformatics parameters, provides a high level of sensitivity to rapidly diagnose plant samples with symptoms of virus diseases and can be performed cheaply. This method therefore has the potential to be widely applied as a diagnostic tool for viruses that have genome information in the NCBI database.

Assessing the effects of Cry1C rice and Cry2A rice to Pseudogonatopus flavifemur, a parasitoid of rice planthoppers.

Transgenic rice producing insecticidal proteins from Bacillus thuringiensis (Bt) could help protect the plants from damage by lepidopteran pests. However, one concern is the potential of Bt rice to harm non-target natural enemies, which play a vital role in pest control. In the present study, the potential effects of Cry1C rice and Cry2A rice on different life-table parameters and population dynamics of Pseudogonatopus flavifemur, a parasitoid of rice planthoppers, were evaluated under laboratory and field condition. The exposure of P. flavifemur to plant-produced Bt proteins was also analyzed. Results indicated that direct feeding on rice plants was the main exposure pathway of P. flavifemur to the Cry1C and Cry2A proteins. No significant difference on the development, survival, longevity, fecundity, and prey consumption of P. flavifemur was detected over two generations between the Bt and non-Bt rice treatments. Furthermore, the population dynamics of P. flavifemur were not affected by Cry1C rice and Cry2A rice. In conclusion, the tested Cry1C rice and Cry2A rice do not appear to harm the parasitoid P. flavifemur.

Effects of Transgenic Rice Infected with SRBSDV on Bt expression and the Ecological Fitness of Non-vector Brown Planthopper Nilaparvata lugens.

The susceptibility of rice lines, T1C-19, T2A-1, and MH63 to SRBSDV infection are similar and the contents of cry protein in T2A-1 and T1C-19 do not change significantly. The survival rates of BPH nymphs feeding on SRBSDV-infected T1C-19, Bt T2A-1, or MH63 rice plants were not significantly different. The developmental stages of female BPH fed on T1C-19 plants infected with SRBSDV were significantly shorter than those fed on uninfected rice, while the males showed no significant difference. The duration of BPH feeding on SRBSDV-infected T2A-1 and MH63 also showed no significant difference in comparison with the respective control groups. Longevities of BPH adults feeding on SRBSDV-infected T1C-19, T2A-1 or MH63 were also not significant. However, the longevity of male adult BPH feeding on un-infected MH63 was significantly reduced in comparison with that of adult males feeding on un-infected T1C-19 and T2A-1 rice. In addition, the different rice lines and the rice plants infected and uninfected with SRBSDV did not significantly affect the sex ratio, female body weight, longevity, fecundity, or egg hatchability of BPH. In general, transgenic Bt rice infected with SRBSDV had little effect on the ecological adaptability of BPH.

Infection of rice plants by rice black streaked dwarf virus improves an egg parasitoid, Anagrus nilaparvatae (Hymenoptera: Mymaridae), of rice planthoppers.

The effects of rice plants infected by rice black streaked dwarf virus (RBSDV) on the host preference, duration of immature stages, sex ratio, and adult longevity and parasitic capacity of an egg parasitoid, Anagrus nilaparvatae Pang et Wang, of rice brown planthopper, Nilaparvata lugens Stål, were evaluated. Tests of response to plant volatiles using an olfactometer showed that A. nilaparvatae preferred rice plants harboring rice brown planthopper eggs over plants free of rice brown planthopper eggs. However, both the response to plant volatiles and the host selectivity test showed no significant differences in host preference between RBSDV-infected plants and healthy plants when both contained rice brown planthopper eggs. The developmental duration at immature stage of the male A. nilaparvatae in rice brown planthopper eggs on RBSDV-infected rice plants was significantly prolonged, and the parasitic capacity of rice brown planthopper eggs was significantly increased in comparison with the A. nilaparvatae parasite in rice brown planthopper eggs on healthy rice plants. There were no significant differences between RBSDV-infected rice plants and healthy rice plants in other ecological fitness parameters, including the developmental duration of female adults, female percentage, and adult longevity of A. nilaparvatae.

Virus-mediated chemical changes in rice plants impact the relationship between non-vector planthopper Nilaparvata lugens Stål and its egg parasitoid Anagrus nilaparvatae Pang et Wang.

In order to clarify the impacts of southern rice black-streaked dwarf virus (SRBSDV) infection on rice plants, rice planthoppers and natural enemies, differences in nutrients and volatile secondary metabolites between infected and healthy rice plants were examined. Furthermore, the impacts of virus-mediated changes in plants on the population growth of non-vector brown planthopper (BPH), Nilaparvata lugens, and the selectivity and parasitic capability of planthopper egg parasitoid Anagrus nilaparvatae were studied. The results showed that rice plants had no significant changes in amino acid and soluble sugar contents after SRBSDV infection, and SRBSDV-infected plants had no significant effect on population growth of non-vector BPH. A. nilaparvatae preferred BPH eggs both in infected and healthy rice plants, and tended to parasitize eggs on infected plants, but it had no significant preference for infected plants or healthy plants. GC-MS analysis showed that tridecylic aldehyde occurred only in rice plants infected with SRBSDV, whereas octanal, undecane, methyl salicylate and hexadecane occurred only in healthy rice plants. However, in tests of behavioral responses to these five volatile substances using a Y-tube olfactometer, A. nilaparvatae did not show obvious selectivity between single volatile substances at different concentrations and liquid paraffin in the control group. The parasitic capability of A. nilaparvatae did not differ between SRBSDV-infected plants and healthy plant seedlings. The results suggested that SRBSDV-infected plants have no significant impacts on the non-vector planthopper and its egg parasitoid, A. nilaparvatae.

[Effects of plant viruses on vector and non-vector herbivorous arthropods and their natural enemies: a mini review].

Plant viruses transmitted by arthropods, as an important biotic factor, may not only directly affect the yield and quality of host plants, and development, physiological characteristics and ecological performances of their vector arthropods, but also directly or indirectly affect the non-vector herbivorous arthropods and their natural enemies in the same ecosystem, thereby causing influences to the whole agro-ecosystem. This paper reviewed the progress on the effects of plant viruses on herbivorous arthropods, including vector and non-vector, and their natural enemies, and on their ecological mechanisms to provide a reference for optimizing the management of vector and non-vector arthropod populations and sustainable control of plant viruses in agro-ecosystem.

Southern rice black-streaked dwarf virus (SRBSDV) directly affects the feeding and reproduction behavior of its vector, Sogatella furcifera (Horváth) (Hemiptera: Delphacidae).

BACKGROUND: Southern rice black-streaked dwarf virus (SRBSDV) is a recently discovered member of the genus Fijivirus and it is transmitted by the rice whitebacked planthopper (WBPH), Sogatella furcifera (Horváth). It was found that SRBSDV infected vectors might contribute negatively to the WBPH population, although the longer nymphal period might benefit viral acquisition, transmission and increase infection rate. The interaction between SRBSDV and its vector need to be further explored to gain better understanding of the dispersal of WBPH and the spread of virus disease, in particular the feeding and reproduction behavior of viruliferous WBPH. METHODS: Newly hatched nymphs of WBPH were fed on healthy rice plant after feeding on SRBSDV-infected rice plants for 2 h, and newly emerged adults were numbered and tested. Feeding behaviors of WBPH adults were monitored electronically within a Faraday cage using a Giga-4 DC EPG amplifier. The newly emerged adults were paired, and the fecundity and egg hatchability were investigated. WBPH was molecularly identified for SRBSDV when they dead. According to the identification results, data on viruliferous and non-viruliferous WBPH were collected and analyzed. RESULTS: Feeding behavior of viruliferous WBPH was different from those of non-viruliferous WBPH. Frequency of phloem sap ingestion of viruliferous WBPH increased significantly, however the total feeding duration did not increase markedly. When both WBPH parents were infected with SRBSDV, their fecundity and hatchability of the eggs produced were significant lower than those of normal WBPH parents. However, if only one of the parents was viruliferous, fecundity and egg hatchability were only slightly affected. CONCLUSIONS: Viruliferous WBPH fed on the phloem more frequently than non-viruliferous WBPH and can thus contribute to virus transmission. When both vector parents are viruliferous fecundity and hatchability of the eggs were significantly reduced. However when only one of the parents WBPH was viruliferous, there were no significant effects.

Influence of rice black streaked dwarf virus on the ecological fitness of non-vector planthopper Nilaparvata lugens (Hemiptera: Delphacidae).

Rice black streak dwarf virus (RBSDV) is transmitted by the small brown planthopper (SBPH), Laodelphax striatellus (Fallen). Non-vector rice brown planthopper (BPH), Nilaparvata lugens (Stål), shares the same host rice plants with SBPH in paddy fields. The changes in nutritional composition of rice plants infected by RBSDV and the ecological fitness of BPH feeding on the infected plants were studied under both artificial climate chamber and field conditions. Contents of 16 detected amino acids and soluble sugar in RBSDV infected rice plants were higher than those in the healthy ones. On the diseased plants BPH had significantly higher nymphal survival rates, nymphal duration of the males, weight of the female adults, as well as egg hatchability compared to BPH being fed on healthy plants. However, there was no obvious difference in female nymph duration, longevity and fecundity. Defense enzymes (superoxidase dismutase, SOD and catalase, CAT) and detoxifying enzymes (carboxylesterase, CAE and glutathione S-transferase, GST) in BPH adults fed on diseased plants had markedly higher activities. The results indicate rice plants infected by RBSDV improved the ecological fitness of the brown planthopper, a serious pest but not a transmitter of the RBSDV virus.