LncRNA-HOTAIRM1 promotes aerobic glycolysis and proliferation in osteosarcoma via the miR-664b-3p/Rheb/mTOR pathway.

Osteosarcoma (OS), which is a common and aggressive primary bone malignancy, occurs mainly in children and adolescent. Long noncoding RNAs (lncRNAs) are reported to play a pivotal role in various cancers. Here, we found that the lncRNA HOTAIRM1 is upregulated in OS cells and tissues. A set of functional experiments suggested that HOTAIRM1 knockdown attenuated the proliferation and stimulated the apoptosis of OS cells. A subsequent mechanistic study revealed that HOTAIRM1 functions as a competing endogenous RNA to elevate ras homologue enriched in brain (Rheb) expression by sponging miR-664b-3p. Immediately afterward, upregulated Rheb facilitates proliferation and suppresses apoptosis by promoting the mTOR pathway-mediated Warburg effect in OS. In summary, our findings demonstrated that HOTAIRM1 promotes the proliferation and suppresses the apoptosis of OS cells by enhancing the Warburg effect via the miR-664b-3p/Rheb/mTOR axis. Understanding the underlying mechanisms and targeting the HOTAIRM1/miR-664b-3p/Rheb/mTOR axis are essential for OS clinical treatment.

MicroRNA-324-3p inhibits osteosarcoma progression by suppressing PGAM1-mediated aerobic glycolysis.

Osteosarcoma (OS) is the most common primary malignant neoplasm of the bone. Recent studies have indicated that the inhibitory effects of microRNA (miR)-324-3p could affect the development of numerous cancers. However, its biological roles and underlying mechanisms in OS progression remain unexplored. In this study, miR-324-3p expression was markedly reduced in OS cell lines and tissues. Functionally, miR-324-3p overexpression suppressed OS progression and was involved in the Warburg effect. Mechanistically, miR-324-3p negatively regulated phosphoglycerate mutase 1 (PGAM1) expression by targeting its 3'-UTR. Moreover, high expression of PGAM1 promoted OS progression and aerobic glycolysis, which were associated with inferior overall survival in patients with OS. Notably, the tumor suppressor functions of miR-324-3p were partially recovered by PGAM1 overexpression. In summary, the miR-324-3p/PGAM1 axis plays an important role in regulating OS progression by controlling the Warburg effect. Our results provide mechanistic insights into the function of miR-324-3p in glucose metabolism and subsequently on the progression of OS. Targeting the miR-324-3p/PGAM1 axis could be a promising molecular strategy for the treatment of OS.

Probing the Interaction between Isoflucypram Fungicides and Human Serum Albumin: Multiple Spectroscopic and Molecular Modeling Investigations.

To better understand the potential toxicity risks of isoflucypram in humans, The interaction between isoflucypram and HSA (human serum albumin) was studied through molecular docking, molecular dynamics simulations, ultraviolet-visible absorption, fluorescence, synchronous fluorescence, three-dimensional fluorescence, Fourier transform infrared spectroscopies, and circular dichroism spectroscopies. The interaction details were studied using the molecular docking method and molecular dynamics simulation method. The results revealed that the effect of isoflucypram on human serum albumin was mixed (static and dynamic) quenching. Additionally, we were able to obtain important information on the number of binding sites, binding constants, and binding distance. The interaction between isoflucypram and human serum albumin occurred mainly through hydrogen bonds and van der Waals forces. Spectroscopic results showed that isoflucypram caused conformational changes in HSA (human serum albumin), in which the α-helix was transformed into a ß-turn, ß-sheet, and random coil, causing the HSA structure to loosen. By providing new insights into the mechanism of binding between isoflucypram and human serum albumin, our study has important implications for assessing the potential toxicity risks associated with isoflucypram exposure.

Factors Underlying the Prevalence of Pythium Infection of Corn Seeds Following Seed Treatment Application of Tebuconazole.

Microbial communities are essential for soil health, but fungicide application may have significant effects on their structure. It is difficult to predict whether nontarget pathogens of applied fungicides in the soil will cause crop damage. Tebuconazole is a triazole fungicide that can be used as a seed treatment and, thereby, introduced to the soil. However, seed-applied tebuconazole has a potential risk of causing poor emergence of corn (Zea mays) seedlings. Using soil with a history of poor corn seedling emergence, we demonstrate through TA cloning and isolation that the poor emergence of corn seedlings from tebuconazole-coated corn seeds was primarily because of infection by surviving soil pathogens, specifically Pythium species that are not targeted by tebuconazole, rather than the phytotoxic effects of tebuconazole. Bioassay tests on tebuconazole-amended media showed that tebuconazole can suppress soil fungi while allowing Pythium to grow. Pythium species primarily contributing to the corn seed rot were more pathogenic at cooler temperatures. Furthermore, the nontarget biocontrol agent of Trichoderma spp. was strongly inhibited by tebuconazole. Taken together, the nontarget effects of tebuconazole are likely not significant under favorable plant growing conditions but are considerable because of low-temperature stress.

Primary Mode of Action of the Novel Sulfonamide Fungicide against Botrytis cinerea and Field Control Effect on Tomato Gray Mold.

Botrytis cinerea is considered an important plant pathogen and is responsible for significant crop yield losses. With the frequent application of commercial fungicides, B. cinerea has developed resistance to many frequently used fungicides. Therefore, it is necessary to develop new kinds of fungicides with high activity and new modes of action to solve the increasingly serious problem of resistance. During our screening of fungicide candidates, one novel sulfonamide compound, N-(2-trifluoromethyl-4-chlorphenyl)-2-oxocyclohexyl sulfonamide (L13), has been found to exhibit good fungicidal activity against B. cinerea. In this work, the mode of action of L13 against B. cinerea and the field control effect on tomato gray mold was studied. L13 had good control against B. cinerea resistant to carbendazim, diethofencarb, and iprodione commercial fungicides in the pot culture experiments. SEM and TEM observations revealed that L13 could cause obvious morphological and cytological changes to B. cinerea, including excessive branching, irregular ramification or abnormal configuration, and the decomposition of cell wall and vacuole. L13 induced more significant electrolyte leakage from hyphae than procymidone as a positive control. L13 had only a minor effect on the oxygen consumption of intact mycelia, with 2.15% inhibition at 50 µg/mL. In two locations over 2 years, the field control effect of L13 against tomato gray mold reached 83% at a rate of 450 g ai ha-1, better than the commercial fungicide of iprodione. Moreover, toxicological tests demonstrated the low toxicological effect of L13. This research seeks to provide technical support and theoretical guidance for L13 to become a real commercial fungicide.

Paralogous CYP51 Genes of Colletotrichum spp. Mediate Differential Sensitivity to Sterol Demethylation Inhibitors.

Colletotrichum spp. isolates contain two paralogous CYP51 genes that encode sterol 14-demethylase enzymes; however, their role in sensitivity to demethylation inhibitor (DMI) fungicides is yet to be determined. In this study, each of the two genes from Colletotrichum fioriniae and C. nymphaeae was able to rescue the function of CYP51 in the yeast Saccharomyces cerevisiae, demonstrating their independent function. Deletion of CYP51A led to increased sensitivity to propiconazole, diniconazole, prothioconazole, cyproconazole, epoxiconazole, flutriafol, prochloraz, and difenoconazole in C. fioriniae, and to the same fungicides and tebuconazole in C. nymphaeae, with the exception of prochloraz. Deletion of CYP51B in C. fioriniae and CYP51B in C. nymphaeae made mutants increasingly sensitive to five of nine DMI fungicides tested. The results suggest species-specific, differential binding of DMI fungicides onto the two CYP51 enzymes. Pairing DMIs with different effects on CYP51A and -B deletion mutants resulted in synergistic effects, as determined in mycelial growth inhibition experiments. Deletion mutants showed no fitness penalty in terms of mycelial growth, sporulation, and virulence. Our study elucidates the effect of CYP51A and CYP51B of Colletotrichum spp. on DMI sensitivity, suggesting that using a mixture of DMIs may improve the efficacy for anthracnose management.

First Report of Pythium torulosum Causing Corn Root Rot in Northeastern China.

In October 2017, we collected five soil samples from each of several fields with a history of severe corn (Zea mays) seedling disease in Heilongjiang province of China. Affected seedlings were wilted with severe root rot, and a high incidence of seedling death was observed in the fields. Corn seeds were seeded in the collected soil samples and grown in a growth chamber for 21 days set at the following incubation temperatures: 21℃/7℃ for 6 days, 10℃/3℃ for 4 days, 16℃/7℃ for 5 days, 20℃/20℃ for 6 days (16 h/8 h, light/dark) (Tang et al. 2019). The corn seedlings in the growth chamber showed the same symptoms observed in the field as mentioned above. Corn root rot samples were collected from several symptomatic plants in the growth chamber to isolate the possible pathogen. Symptomatic roots were washed in 0.5% NaOCl for 2 min, rinsed in sterile water and cut into 1-2 mm segments and then plated on corn meal agar amended with pimaricin (5 µg/ml), ampicillin (250 µg/ml), rifampicin (10 µg/ml), pentachloronitrobenzene (50 µg/ml), and benomyl (10 µg/ml) (PARP+B), which is selective for oomycetes (Jeffers and Martin 1986). After 3 days of incubation in the dark at 25℃, colonies were transferred to 10% V8 juice agar and incubated at 25℃ for 2 weeks. Six isolates were identified as Pythium torulosum based on the morphology of sexual and asexual structures following van der Plaats-Niterink's key (van der Plaats-Niterink 1981). On 10% V8 juice agar, the hypha were aseptate and colonies had filamentous sporangia with a dendroid or globose structure. The oogonia were globose or subglobose, laevis, terminal, rarely intercalary, ranging from 12-19 (average 16) µm. Antheridia were mostly sessile or brachypodous, and each oogonium was supplied by 1-2 antheridia cells. Oospores were globose, plerotic, ranging from 9-16 (average 13) µm. For the molecular identification, two molecular targets, the internal transcribed spacer (ITS) region of ribosomal DNA and cytochrome c oxidase subunit II (CoII), were amplified and sequenced using universal primer sets DC6/ITS4 (Cooke et al. 2000) and FM58/FM66 (Villa et al. 2006), respectively for one isolate, "copt". BLAST analyses of a 971 bp ITS segment amplified from copt (GenBank Accession No. MT830918) showed 99.79% identity with a P. torulosum isolate (GenBank Accession No. AY598624.2). For the COⅡ gene of copt, BLAST analyses of a 553 bp segment (GenBank Accession MT843570) showed 98.37% identity with P. torulosum isolate (GenBank Accession No. AB095065.1). Thus, the isolate, copt, was identified as P. torulosum based on morphological characteristics and molecular analysis. To confirm pathogenicity and Koch's postulates, a pathogenicity test was conducted as described by Zhang et al. (2000). Briefly, a 5 mm culture plug from the P. torulosum isolate, copt, was transferred to a 9-cm petri dish containing 20mL 10% V8 juice agar and incubated in the dark at 25℃ for 7 days. The culture was cut into small pieces and mixed with a sterilized soil mix (40% organic peat substrate, 40% perlite, and 20% soil) at a ratio of one petri dish per 100 g soil mix. Ten corn seeds were planted at a depth of 2 cm in a 500-mL pot containing the inoculated soil mix. The control pots were mock inoculated with plain 10% V8 juice agar. Pots were incubated in a greenhouse at temperatures ranging from 21 to 23℃. There were four replications. After 14 days, corn roots brown and rotted were observed, which was similar to those observed in the field and growth chamber. Control plants remained symptomless and healthy. P. torulosum copt was consistently re-isolated from the symptomatic roots. To our knowledge, this is the first report of P. torulosum causing root rot of corn in Northeastern China. Corn is an important crop in Heilongjiang and the occurrence of root rot caused by this pathogen may be a new threat to corn plants. There is a need to develop management measures to control the disease.

First Report of Pythium sylvaticum Causing Corn Root Rot in Northeastern China.

As one of the most planted crops worldwide, corn has continuously increased in importance in China over the last decade. But in recent years, poor stands of corn seedlings have occurred frequently in northeastern China, causing significant economic loss. Mature plants were stunted, the roots were necrotic, and some plants collapsed. We collected soil samples from 5 fields with a history of poor stands of corn seedlings in the Heilongjiang province of China in October 2017. After being planted in the collected soil for 12 days, corn seedlings were uprooted. The pathogen was then isolated as described by Tang et al. (2019). Briefly, the rotted roots were washed in 0.5% NaOCl for 2 min, rinsed in sterile water, and then cut into 1-2 mm segments and placed on cornmeal agar amended with pimaricin (5 µg/ml), ampicillin (250 µg/ml), rifampicin (10 µg/ml), pentachloronitrobenzene (50 µg/ml), and benomyl (10 µg/ml) (PARP+B), which is selective for oomycetes (Jeffers and Martin 1986). After 3 days of incubation in the dark at 25℃, colonies were transferred to 10% V8 juice agar or potato dextrose agar (PDA) and grown for 7 days at 25℃. Based on morphological characteristics, one putative isolate (COPS) was identified as P. sylvaticum (Campbell and Hendrix 1967). On PDA, the culture (COPS) produced creamy white and floccus mycelium. P. sylvaticum (COPS) produced hyphal swellings, but no oogonia or zoospore. Hyphal swellings were globose, terminal, or intercalary, ranging from 12.22-18.55 µm diam. Sequence analysis was performed with the cytochrome c oxidase subunit Ⅱ (COⅡ) gene amplified with primers FM35/FM52 (Martin 2000) and the rDNA ITS amplified with primers DC6/ITS4 (Cooke et al. 2000). For COⅡ gene, BLAST analyses of the 773 bp segments showed 97.93% identity with P. sylvaticum isolate (GenBank Accession No. GU222164.1). For the ITS, BLAST analyses of the 880 bp segments showed 99.89% identity with P. sylvaticum isolate (GenBank Accession No. KY084736.1). Both sequences were submitted to GenBank with accession numbers MK648400 and MK606071 for COⅡ and ITS, respectively. For pathogenicity tests, similar to that described by Ling et al. (2018), four 9-cm petri plates containing 20 mL of 10% V8 juice agar were inoculated with an agar plug (5 mm diam) obtained from a 7-day-old P. sylvaticum culture (COPS) grown on 10% V8 juice agar and then incubated at 25℃ in the dark for 7 days. Nine corn seeds were placed on each plate, after which the plates were filled with 50 g sterilized organic peat substrate. For the controls, seeds were placed on non-inoculated plates of 10% V8 juice agar and filled with 50 g sterilized organic peat substrate. Four replications were inoculated. Plates were maintained in a greenhouse at 23℃. After 14 days, similar symptoms as to those observed in the field were present in the greenhouse, whereas control plants remained symptomless. P. sylvaticum (COPS) was re-isolated from diseased roots as described above, thus confirming Koch's postulates. To our knowledge, this is the first report of P. sylvaticum on corn in China. This pathogen may pose a risk to corn production. The identification of the pathogen will help to develop effective strategies to control the disease.

De novo transcriptome and expression profile analyses of the Asian corn borer (Ostrinia furnacalis) reveals relevant flubendiamide response genes.

BACKGROUND: The Asian corn borer (ACB), Ostrinia furnacalis (Guenée), has become the most damaging insect pest of corn in Asia. However, the lack of genome or transcriptome information heavily hinders our further understanding of ACB in every aspect at a molecular level and on a genome-wide scale. Here, we used the Ion Torrent Personal Genome Machine (PGM) Sequencer to explore the ACB transcriptome and to identify relevant genes in response to flubendiamide, showing high selective activity against ACB. RESULTS: We obtained 35,430 unigenes, with an average length of 716 bp, representing a dramatic expansion of existing cDNA sequences available for ACB. These sequences were annotated with Non-redundant Protein (Nr), Gene Ontology (GO), Clusters of Orthologous Groups (COG) and Kyoto Encyclopedia of Genes and Genomes (KEGG) to better understand their functions. A total of 31 cytochrome P450 monooxygenases (P450s), 27 carboxyl/cholinesterases (CCEs) and 19 glutathione S-transferases (GSTs) were manually curated to construct phylogenetic trees, and 25 unigenes encoding target proteins (acetylcholinesterase, nicotinic acetylcholine receptor, gamma-aminobutyric acid receptor, glutamate-gated chloride channel, voltage-gated sodium channel and ryanodine receptor) were identified. In addition, we compared and validated the differentially expressed unigenes upon flubendiamide treatment, revealing that the genes for detoxification enzymes (P450s and esterase), calcium signaling pathways and muscle control pathways (twitchin and tropomyosin), immunoglobulin (hemolin), chemosensory protein and heat shock protein 70 were significantly overexpressed in response to flubendiamide, while the genes for cuticular protein, protease and oxidoreductase showed much lower expression levels. CONCLUSION: The obtained transcriptome information provides large genomic resources available for further studies of ACB. The differentially expressed gene data will elucidate the molecular mechanisms of ACB in response to the novel diamide insecticide, flubendiamide. In particular, these findings will facilitate the identification of the genes involved in insecticide resistance and the development of new compounds to control the ACB.

Cycloxaprid: A novel cis-nitromethylene neonicotinoid insecticide to control imidacloprid-resistant cotton aphid (Aphis gossypii).

Imidacloprid is a nicotinic acetylcholine receptor (nAChR) agonist with potent insecticidal activity. However, resistance to imidacloprid is a significant threat and has been identified in several pest species. Cycloxaprid with cis-configuration is a novel neonicotinoid insecticide, which shows high activity against imidacloprid-resistant pests. The LC50 of imidacloprid against the resistant Aphis gossypii was 14.33mgL(-1) while it was only 0.70mgL(-1) for the susceptible population, giving a resistance ratio of 20.47. In this imidacloprid-resistant population, a point mutation (R81T) located in the loop D region of the nAChR ß1 subunit was found out. But this point mutation did not decrease the activity of cycloxaprid against A. gossypii. The LC50 of cycloxaprid was 1.05 and 1.36mgL(-1) for the imidacloprid-susceptible and imidacloprid-resistant populations, respectively. In addition, cycloxaprid provided better efficacies against resistant A. gossypii than imidacloprid in the fields. Although cycloxaprid was highly toxic to A. gossypii, it showed high selective activity between A. gossypii and its predominant natural enemies, Harmonia axyridis and Chrysoperla sinica. These results demonstrate that cycloxaprid is a promising insecticide against imidacloprid-resistant A. gossypii and suitable for the integrated pest management.

Structural and functional impacts of neonicotinoids analogues on Apis mellifera's chemosensory protein: Insights from spectroscopic and molecular modeling investigations.

In the intricate web of ecological relationships, pollinators such as the Italian honeybee (Apis mellifera) play a crucial role in maintaining biodiversity and agricultural productivity. This study focuses on the interactions between three neonicotinoid compounds and the honeybee's chemosensory protein 3 (CSP3), a key player in their olfactory system. Employing advanced spectroscopic techniques and molecular modeling, we explore the binding dynamics and conformational changes in CSP3 upon exposure to these pesticides. The research reveals that all three neonicotinoids considerably quench CSP3's fluorescence through a dynamic and static mixing mechanism, indicating a strong binding affinity, predominantly driven by hydrophobic interactions. UV-visible absorption, synchronous fluorescence, and 3D fluorescence spectra support slight changes in the microenvironment around the aromatic amino acids of CSP3. Circular dichroism spectra indicate a reduction in CSP3's α-helix content, suggesting structural alterations. Molecular docking and dynamics simulations further elucidate the binding modes and stability of these interactions, highlighting the role of specific amino acids in CSP3's binding cavity. Findings provide critical insights into molecular mechanisms by which neonicotinoids may impair honeybee chemosensory function, offering implications for designing safer pesticides and understanding the broader ecological impact of these chemicals on pollinator health.

Optimizing UAV spray parameters to improve precise control of tobacco pests at different growth stages.

BACKGROUND: Unmanned aerial vehicles (UAVs) for pesticide application show promising potential in tobacco pest management. However, the impact of flight parameters on spray efficacy requires further investigation. Three field experiments were conducted from the rosette to the maturation stage of tobacco to systematically assess spray efficacy under varying flight heights, speeds, and application volumes. Using a multi-index weight analysis method, optimal operational parameter combinations for different tobacco growth stages were evaluated and compared with backpack electric sprayers. RESULTS: For the rosette stage, the recommended parameter is a flight speed of 5 m s-1, a flight height of 2 m, and a liquid application volume of 30 L hm-2; during the vigorous growth stage, the suggested parameter includes a flight speed of 3 m s-1, a flight height of 2 m, and a liquid application volume of 22.5 L hm-2. In the maturing stage, optimal parameter consists of a flight speed of 3 m s-1, a flight height of 3.5 m, and a liquid application volume of 30 L hm-2. Furthermore, UAV spraying achieves higher droplet deposition on both sides of tobacco leaves compared to traditional electric backpack sprayers. CONCLUSIONS: Adjusting UAV spraying parameters for different tobacco growth stages is crucial. These results can provide the methods for the precise control technology of tobacco pests at different growth stages. © 2024 Society of Chemical Industry.

Effects of Rhizosphere Microorganisms on the Uptake and Translocation of Organic Compounds in Maize Seedlings.

The plant root is a key pathway to absorb insecticides from soil and is colonized by beneficial and pathogenic microbial communities. Our study demonstrated that colonizing roots by nitrogen-fixing bacterium Pseudomonas stutzeri and pathogenic Fusarium graminearum and Pythium ultimum increased the uptake of insecticides into maize roots from soil. An alteration in the permeability of root cells contributed to this increased uptake. For the subsequent root-to-shoot translocation, the relationship between translocation and log P of the compound satisfied a Gaussian distribution. Relatively beneficial P. stutzeri can promote maize seedling growth and increase translocation, whereas Fusarium and Pythium pathogens can retard the seedling growth and reduce the translocation. Furthermore, the relationship between the concentration difference (difference of an insecticide from inoculation treatment to control) and log P also showed a Gaussian distribution. The maximum concentration difference from the Gaussian equation can be applied to assess the capacity of rhizosphere microorganisms to influence translocation.

Seed treatment with chlorantraniliprole and carbaryl mixture for managing fall armyworm on maize: systemic synergism, control efficiency and synergistic mechanism.

BACKGROUND: Fall armyworm (Spodoptera frugiperda) is one of the major invasive pests in China, and has been widely controlled by labor-intensive foliar sprays of agrochemicals in maize (Zea mays L.). RESULTS: Systemic bioassay showed that mixtures of chlorantraniliprole (Chlor) and carbaryl (Carb) had dramatically synergistic effect on toxicity to S. frugiperda. Particularly, a mixture of Chlor with Carb at a mass ratio of 2:1 (MCC) exhibited the highest toxicity to S. frugiperda. Therefore, seed treatment of Chlor mixed with Carb was studied as a simple, accurate, efficient and low-cost control technology. Our results showed that MCC treatment shortened the median lethal time and 90% lethal time to S. frugiperda compared to Chlor- and Carb-alone treatments. Meanwhile, smaller leaf consumption by S. frugiperda was recorded under MCC treatment compared to Chlor- and Carb-alone treatments. In field trial, maize-seed treatment with MCC showed efficacy up to 39 days post-emergence in preventing S. frugiperda foliar damage at a low infestation pressure. Moreover, chemical quantification by ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) showed that Chlor residues were more absorbed and concentrated in maize leaves of MCC treatment, compared to that of Chlor-alone treatment. CONCLUSION: These results suggested that seed treatment with MCC can be applied to increase the control efficacy and reduce the cost of Chlor-alone treatment for controlling S. frugiperda. The present study provided evidence of an enhanced translocation and accumulation of Chlor residues in maize leaves under MCC treatment, which likely contributed to a synergistic effect against S. frugiperda. © 2022 Society of Chemical Industry.

Dynamics of gut microflora across the life cycle of Spodoptera frugiperda and its effects on the feeding and growth of larvae.

BACKGROUND: Spodoptera frugiperda is an important invasive agricultural pest that causes huge economic losses worldwide. Gut microorganisms play a vital role in host feeding, digestion, nutrition, immunity, growth and insecticide resistance. Illumina high-throughput sequencing was used to study the gut microbial community dynamics across the life cycle (egg, 1st to 6th instar larvae, pupae, and male and female adults) of S. frugiperda fed on maize leaves. Furthermore, the gut microbial community and food intake of the 5th instar S. frugiperda larvae were studied after feeding them antibiotics. RESULTS: Enterobacteriaceae and Enterococcaceae dominated the gut during growth and feeding of the larvae. The relative abundance of Enterobacteriaceae was higher in the 4th and 6th instar larvae. With the increase in larval feeding, the relative abundance of Enterococcaceae gradually increased. In addition, principal coordinate analysis and linear discriminant effect size analysis confirmed differences in the structure of gut microbiota at different developmental stages. After antibiotic treatment, the relative abundance of Firmicutes, Proteobacteria and Fusobacteriota decreased. The relative abundance of Enterococcus and Klebsiella decreased significantly. Antibiotic treatment inhibited the gut flora of S. frugiperda, which decreased larval food intake and body weight gain, and prolonged the larval stage. CONCLUSION: The composition of the gut bacterial community plays an important role in the growth, development, and feeding of S. frugiperda. The results have a certain theoretical value for the development of bio-pesticides targeting intestinal flora. © 2022 Society of Chemical Industry.

Controlled-release granules for the delivery of pymetrozine to roots of transplanted rice seedlings with decreased phytotoxicity and enhanced control efficacy against paddy planthoppers.

BACKGROUND: Seedling transplanting is widely used in rice cultivation. Systemic insecticides can be delivered to seedling roots by application through rice seedling boxes before transplanting. The most challenging aspect is to provide long-term control of rice pests and overcome transplanting shock. Precise control of the release rate of insecticide can meet these requirements. Pymetrozine is a promising insecticide used for the control of rice planthoppers resistant to neonicotinoid insecticides. RESULTS: In this study, four controlled-release granular formulations of pymetrozine were prepared based on a mixture of cost-effective and biodegradable kaolin and xanthan gum or a mixture of calcined kaolin and xanthan gum. Fluorescence images showed that different 3D networks were formed in the four granular formulations. The four granular formulations showed different water uptake rates and release rates of pymetrozine in water. Pymetrozine release rate was positively correlated with the water uptake capacity, rather than the water uptake rate of granules. Diffusion was the dominant mechanism for the release of pymetrozine from granules. Pymetrozine was found to reduce the survival of transplanted rice seedlings suffering from transplanting shock. Incorporating pymetrozine in controlled-release granules alleviated this phytotoxicity. The survival rate of rice seedlings in granular pymetrozine treatments ranged 68.8-85.0%, whereas the survival rate was <50% for powdered pymetrozine treatments. Additionally, four prepared granule formulations had a significant control effect on rice planthopper with efficacies ranging from 76.7% to 98.0% 40 days after seedling box treatment. CONCLUSIONS: The granule with an intermediate release rate of pymetrozine was shown to be more suitable for seedling box treatment than field application and traditional liquid spraying for the long-term control of paddy planthoppers. © 2021 Society of Chemical Industry.

Broadcasting of tiny granules by drone to mimic liquid spraying for the control of fall armyworm (Spodoptera frugiperda).

BACKGROUND: The fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith), is an invasive pest. Maize is one of its preferred host plants. The traditional application of granules has been effective for the control of FAW. Nevertheless, the challenge is to develop an application method that is less labor-intensive and also efficient. RESULTS: Tiny granules in the size range of 0.38-0.55 mm were prepared by the centrifugal granulation method for drone application. The in-swath distribution patterns of granules deposited on sticky tapes were similar to the distribution of aqueous droplets through drone spraying. In the range of 1.5-3.5 m, a relatively higher aircraft height of flight can provide a more uniform distribution pattern of deposited granules, but resulted in less deposit of tiny granules in the whorl of maize plants. Similarly, the deposit of granules in the whorl of maize plants significantly decreased when the flight speed increased from 4 to 6 m s-1 . Granules gathered in the whorl accounted for 50.8-58.7% of total granules deposited in the maize canopy. The field experiment demonstrates granular formulations (containing 0.25% chlorantraniliprole + 0.15% emamectin benzoate, or higher concentrations) can provide better and longer duration of FAW control than the aqueous spray formulation at the whorl stage of maize plants. CONCLUSION: Broadcasting of tiny granules by drone can provide better FAW control than liquid spray. The architecture of the maize plant and the downward airstream of the drone create favorable conditions for the deposition of granules in whorls. © 2021 Society of Chemical Industry.

Toxicities of fipronil enantiomers to the honeybee Apis mellifera L. and enantiomeric compositions of fipronil in honey plant flowers.

Fipronil is a chiral phenylpyrazole insecticide that is effective for control of a wide range of agricultural and domestic pests at low application rates. Wide application of fipronil also causes poisoning of some nontarget insects, such as honeybees. In the present study, toxicities of fipronil enantiomers and racemate to the honeybee Apis mellifera L. were determined to examine whether using formulations of single or enriched fipronil enantiomer is a possible option to reduce risks to bees. Contact toxicity tests yielded median lethal doses (LD50) of 3.45, 3.38, and 3.86 ng/bee for the R(-)-enantiomer, S(+)-enantiomer, and racemate, respectively. Analysis of variance indicates that the LD50 values are not statistically different (p = 0.41). Oral toxicities of the R-enantiomer, S-enantiomer, and racemate (nominal median lethal concentration = 0.037, 0.045, 0.053 mg/L, respectively) were also demonstrated to be not statistically different (p = 0.20). In addition, enantiomeric fractions of fipronil in the flowers of three honey plants (Brassica campestris, Cucumis sativus, and Chrysanthemum indicum L.) were examined after treatment with fipronil. It was found that degradation of fipronil in all three plants is not enantioselective. These results indicate that it is unlikely that use of formulations with single or enriched fipronil enantiomer would reduce the risk that fipronil poses to honeybees. Improved fipronil application practices (based on safest timing and bloom conditions) and reduction of overall fipronil usage seem to be more realistic options.

Biocidal radiuses of cycloxaprid, imidacloprid and lambda-cyhalothrin droplets controlling against cotton aphid (Aphis gossypii) using an unmanned aerial vehicle.

BACKGROUND: Unmanned aerial vehicles (UAVs) are a recently advanced aerial spraying technology. However, the median lethal number of droplets (LN50 ) and biocidal radiuses (r50 ) of insecticides droplets sprayed by UAVs are still unknown. Therefore, we evaluated the LN50 and r50 of cycloxaprid, imidacloprid and lambda-cyhalothrin droplets associated with adjuvant controlling against Aphis gossypii. RESULTS: A small UAV and Potter spray tower (PST) were used to generate different size of droplets (Dv0.5 = 185 ± 5 and 43 ± 2 µm). The mortality of A. gossypii showed a droplet density-dependent process. At the concentration of 5 g L-1 , the LN50 of lambda-cyhalothrin, imidacloprid and cycloxaprid droplets sprayed by the UAV were only 49.2, 34.6 and 19.7 droplets cm-2 , respectively, and the r50 were 0.57, 0.68 and 0.90 mm, respectively. The LN50 values were negatively correlated with insecticide concentrations, but the r50 values increased with the increasing concentrations. Although cycloxaprid is less toxic to A. gossypii than lambda-cyhalothrin, cycloxaprid had a larger r50 than lambda-cyhalothrin due to its translocation ability. Furthermore, cycloxaprid had a relatively larger r50 than imidacloprid because it is more toxic to A. gossypii. Moreover, adjuvant silwet DRS-60 can significantly increase the r50 of droplets. CONCLUSION: Our results revealed that the r50 of a droplet was higher than its droplet size at tested concentrations. Smaller droplets generated by the PST had relatively higher insecticidal potential. The median lethal dose (LD50 ) and translocation ability of insecticides and spray adjuvant contributed to their r50 . Therefore, ultra-low-volume spray with UAVs is feasible to control cotton aphids. © 2020 Society of Chemical Industry.

Uptake and translocation of imidacloprid via seed pathway and root pathway during early seedling growth of corn.

BACKGROUND: A systemic seed treatment can be taken up into shoot tissues during early corn seedling growth. However, the pathway that a systemic compound is taken up, either from seed or root uptake to shoot tissues is not fully understood. To study the single contributions of seed pathway and root pathway for the uptake and translocation of imidacloprid seed treatment, two methods were developed: A seed treatment method and a growing media/hydroponic solution delivery method. The seed treatment method employed a live and dead seed separated with plastic wrap to provide a barrier. The growing media/hydroponic solution delivery method quantified the capacity for uptake by seeds and roots. RESULTS: The seed pathway transported 1.9-2.5 times more imidacloprid into shoot tissues when compared to the root pathway at the same dosage rate. The higher amount of imidacloprid taken up and translocated by the seed pathway was attributed to the fact that the corn seeds were in direct contact with high provided concentrations of imidacloprid. However, the root pathway showed 7.9-9.5 times higher capacity for transporting imidacloprid into shoot tissues when compared with the seed pathway. Whenever imidacloprid was taken up by seed or root, amounts of imidacloprid were measured in both tissues of seed and root. CONCLUSION: The seed pathway transported more imidacloprid than the root pathway during early seedling growth since corn seeds were contacted by higher concentrations of imidacloprid. Both seed pathway and root pathway were occurring concurrently during early seedling growth of corn. © 2020 Society of Chemical Industry.