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Preparation of epichlorohydrin modified corn starch biochar and its adsorption performance on imidacloprid from water
LI Zifen, YANG Longxiang, JU Chao, etc
Abstract： Imidacloprid is a commonly used neonicotinoid pesticide. Imidacloprid widely exists in aqueous environment due to its usage, high water solubility, and long half-life. This poses a potential threat to the ecological safety and human health. Biochar is a solid product obtained from biomass pyrolysis. It has the characteristics of wide source, low energy consumption, easy regeneration, and environmental friendliness, etc, and has been widely concerned in the field of adsorption. In this study, epichlorohydrin modified corn starch biochar (ECSB) was prepared by crosslinking epichlorohydrin with corn starch as raw material. Scanning electron microscopy etc was applied to characterize the structure of ECSB, study the adsorption behavior of ECSB towards imidacloprid, and investigate the adsorption mechanism. The results showed that ECSB had abundant pore structure, with the specific surface area of 285 m2/g and pore volume of 0.162 cm3/g, which were 46.5 and 31.4 times higher than those of unmodified corn starch biochar (CSB), respectively. The maximum adsorption capacity of ECSB for imidacloprid was 70.9 mg/g, which was 112 times higher than that of CSB. Adsorption of imidacloprid by ECSB was in accordance with the quasi-second-order kinetic and Langmuir isothermal model, and was an endothermic, entropy-increasing, and spontaneous process. The presumable adsorption mechanism was mainly attributed to the pore-filling action. Moreover, the adsorption capacity of ECSB still reached 96.6% of the original one after five regenerations using a co-processing technology of ultrasound cavitation and reagent extraction. This study can provide research ideas and theoretical basis for the treatment of environmental imidacloprid wastewater and the development and application of corn starch. [Review Details]
Determination of thiamethoxam residues in cucumber, Brassica chinensis and water by chemiluminescence enzyme immunoassay
GUO Zhihui, SONG Tianwei, QIAN Lei, etc
Abstract： In order to establish a sensitive and rapid detection method of the residues of thiamethoxam in cucumber, Brassica chinensis and water samples, the chemiluminescence enzyme immunoassay (CLEIA) of thiamethoxam residues was studied. A CLEIA method was developed by optimizing the working concentration of antigen and antibody, the type of blocker, methanol content, Na+ concentration and pH value in the analyzing system. Under the optimal conditions, the linear range of the method was 0.125-12.5 ng/mL, the limit of quantification (LOQ) was 0.125 ng/mL, and the IC50 was 1.01 ng/mL. The cross-reaction rates of the seven analogues of thiamethoxam were all lower than 0.3%, which indicated that the CLEIA method had good specificity. The recovery study in cucumber, Brassica chinensis and pond water showed that the recovery range was 86%-108%, and the relative standard deviation (RSD) was 2.6%-9.1%, which was consistent with the analysis results of ultra-high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Using the established method, the residues of thiamethoxam in market samples of cucumber, Brassica chinensis and pond water samples was detected, and the results showed that the residues of thiamethoxam in the three kinds of samples were lower than the detection limit. This study showed that the established CLEIA method was highly sensitive, environmental friendly, the sample preparation was simple, and it can be used in the detection of thiamethoxam residues in cucumber, Brassica chinensis and water samples. [Review Details]
Study on anti-leaching and mildew resistance of bamboo treated with immobilized thymol catalyzed by laccase
WANG Hui, MENG Yao, ZHANG Qiaoling, etc
Abstract： In this paper, the natural antibacterial agent thymol was used as a mildew inhibitor for bamboo, which was immobilized in bamboo by laccase. The mildew resistance of the treated bamboo against Aspergillus niger, Trichoderma virens and Penicillium citrinum was tested, respectively. The laccase-catalyzed fixation effect was evaluated by volatility of thymol, the mildew resistance after leaching treatment and the changes of water contact angle. Scanning electron microscopy (SEM) was used to study the micro-morphology of the treated bamboo, and further Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) were employed to explore the chemical bond changes during the laccase-catalyzed process. The results show that, compared with the bamboo treated by thymol alone, the bamboo treated by laccase catalysis exhibited a good inhibitory effect on A. niger, T. virens and P. citrinum before and after the leaching treatment, the mildew-proof efficiency was above 80%, and the mildew-proof performance of the bamboo treated both with thymol and laccase after the leaching treatment was better than that treated with thymol alone. The volatility of thymol was significantly reduced from 17.03% to 6.75%. The water contact angle increase significantly from 35° to 97°, which was contributing to the mildew resistance of treated bamboo. The enzymatic immobilization did not significantly change the micro-morphology of bamboo, but a large number of flaky substances appeared on the surface of bamboo cell wall, which was considered as aggregates of thymol molecules grafted onto the surface of bamboo. The FT-IR and XPS results shown new formed chemical bonds between thymol and bamboo lignin were the key factor for immobilization of thymol. This study realized the green fixation of natural antibacterial agent through the catalysis of laccase, reducing its volatilization and leaching, and the mildew resistance of treated bamboo was prolonged. The results of this study provide a new idea for green mildew prevention of bamboo, which can achieve safe and long-lasting protection of bamboo. [Review Details]
Effects of natenpac, a functional analogue of abscisic acid on the growth and yield of rice
LI Jingru, LI Chuanyan, WANG Tao, etc
Abstract： The cross-talk of plant hormones plays a synergistic role in the growth and development of crops. In order to explore the application prospects of the functional analogue of abscisic acid—natenpac in rice, this paper studied the effects of seed soaking with 1000 times solution of 0.03% natenpac aqueous solution (AS), and spraying 2% natenpac + IBA wettable powder (WP) dilution seven days before transplanting rice seedlings on the growth, development and yield of rice, through four kinds of different treatment modes "seed soaking + direct seeding" "seed soaking + transplanting" "seed soaking + spraying + transplanting" and "spraying + transplanting". The 0.03% S-ABA AS and 2% S-ABA + IBA (0.2 : 1.8, m/m, a.i) WP dilutions were used as the drug control, and water used as blank control, respectively. The effect of natenpac on rice growth and development and yield was assessed by investigating seed germination potential, germination rate, tiller number, number of spikes, seed-setting rate, 1000-grain weight and yield for determining the best treatment pattern for yield increase. The results showed that seed soaking with 1000 times solution of 0.03% natenpac AS could increase the germination rate of rice seeds by 3.3%, which was 1% higher than 0.03% S-ABA AS. In terms of rice yield increase, each treatment mode has a significant impact on the yield increase. In terms of increasing yield alone, the "spraying + transplanting" treatment mode has the best yield increase effect. Spraying 1000 times solution of 2% natenpac + IBA WP seven days before transplanting can achieve a 21.7% increase in rice yield. From the perspective of both improving rice quality and increasing rice yield, the "soaking + transplanting" treatment mode has the best effect. It is appropriate to seed soaking with 1000 times solution of 0.03% natenpac AS and then raise seedlings for transplanting, which not only ensures the quality of rice but also increases yield by 9.7%. This study clarifies the best treatment mode for improving rice quality and yield, and provides a sufficient basis for the application of natenpac in rice production. [Review Details]
Resistance status of Alopecurus aequalis to commonly used ACCase inhibitors in some rice-wheat rotation areas of Anhui Province and screening of mixed formula of post-emergence herbicides
XU Jincheng, WANG Hui, XING Yucheng, etc
Abstract： In order to clarify the resistance status of Alopecurus aequalis to acetyl-CoA carboxylase (ACCase)-inhibiting herbicides, 30 populations of A. aequalis were collected from rice-wheat rotation fields in Anhui Province and determined by whole plant bioassay of resistance levels to three ACCase herbicides, including fenoxaprop-P-ethyl, clodinafop-propargyl and pinoxaden. Seven kinds of post-emergence herbicides such as tralkoxydim and pyroxsulam were selected for the boi-activity test to highly resistant population AHCZ-2. Five herbicides mixed with isoproturon were employed for the field efficacy evaluation. The results showed that among 30 tested populations, 26 populations were highly resistant to fenoxaprop-P-ethyl, accounting for 86.67% of the total tested populations. The GR50 value (active ingredients, the same as below) was 230.93-1755.54 g/hm2, and resistance index (RI) was 12.58-95.66. Twenty-one populations were highly resistant to clodinafop-propargyl, accounting for 70% of the total tested populations. The GR50 value was 147.18-1213.44 g/hm2, and RI was 11.93-98.36. The 19 populations were highly resistant to pyraclostrobin, accounting for 63.33% of the total tested. The GR50 value ranged from 107.63 to 614.18 g/hm2, and RI ranged from 12.21 to 69.69. The resistance of A. aequalis populations collected from the same area to three kinds of ACCases inhibitors was similar. Among the 7 kinds of post-emergence herbicides tested, the activity to highly resistant A. aequalis population AHCZ-2 was higher in tralkoxydim and chlortoluron with GR90 of 468.74 g/hm2 and 1495.85 g/hm2, followed by cypyrafluone-isoproturon with the GR90 of 1035.62 g/hm2. The activity of isoproturon, pyroxsulam, mesosulfuron-methyl and flucarbazone-Na was low. The field screening results showed that recommended high dose mesosulfuron-methyl (15.75 g/hm2), pyroxsulam (15 g/hm2) and chlortoluron (2250 g/hm2) mixed with isoproturon at 1500 g/hm2 had the best control efficacy on A. aequalis. The plant control efficacy was between 91.18% and 94.05%, and the fresh weight control efficacy was between 92.40% and 95.68%, the yield increased by 25.04%-35.08%. Cypyrafluone-isoproturon at 937.5 g/hm2 was the next with 90.78% control efficacy of fresh weight and yield increase of 22.78%. The results can provide reference for chemical control of rice-wheat field resistance A. aequalis. [Review Details]
Study on usage reduction of glyphosate mixed with a novel protoporphyrinogen oxidase inhibitor-X18002
WANG Junwei, HUANG Xiaohui, YANG Randi, etc
Abstract： In order to reduce the usage of glyphosate, delay the growth of glyphosate-resistant weeds, and expand the weed control spectrum of glyphosate, the effect of temperature, light and simulated rainfall on herbicidal activity, and the absorption and conductivity of glyphosate and X18002[compound name was ethyl 3-(2-chloro-5-(3,5-dimethyl-2,6-dioxo-4-thioxo-1,3,5-triazinan-1-yl)-4-fluorophenyl)-5-methyl-4,5-dihydroisoxazole-5-carboxylate] were studied by indoor bioassays. Mixture proportion screening tests and tank-mix field trials were carried out after investigating the difference between glyphosate and X18002 and the necessity of a mixture. The result showed that the fresh-weight inhibition rate of X18002 (37.50 g a.i/hm2) and glyphosate (600.0 g a.i/hm2) against Portulaca oleracea L. and Eleusine indica (L.) Gaertn. under high (30-35 ℃) and medium (20-25 ℃) temperatures were 83.48%-100.0%, significantly higher than those under the low temperature (10-15 ℃). The herbicidal activity was significantly reduced under low temperature. The fresh-weight inhibition rates of X18002 (37.50 g a.i/hm2) were 16.03%-95.46% and 2.24%-85.04%, significantly increased with the increase of illuminance within the range of 0-22000 lx. X18002 was proved to be light-demanding herbicide, while glyphosate was proved to be a light-independent herbicide. X18002 had stable herbicide activity with no significant decrease of fresh-weight inhibition rate between simulated rainfall after 0.5 h of application, which was 100.0% and 81.76%-87.62% to P. oleracea and E. indica, and unsimulated rainfall with a dose of 37.50 g a.i/hm2. Glyphosate had a weak rainfastness with a significant decrease in inhibition rate when simulated rainfall within 0.5-8 h of application compared to unsimulated rainfall with a dose of 600.0 g a.i/hm2. The absorption and conductivity tests showed that both two compounds could be absorbed by the root, stem, and leaf of Abutilon theophrasti Medic.. Compared to X18002, which only had acropetal translocation capability, glyphosate had the ability of acropetal and basipetal translocation. The proportions of mixture which showed the synergistic effect on Erigeron canadensis L., E. indica and Cyperus iria L. were 1 : 10 and 1 : 20. The result of the field trials showed that total control effect of X18002 + glyphosate tank-mix at 45.0 + 450.0 g a.i./hm2 dosage on Alternanthera philoxeroides (Mart.) Griseb., E. canadensis, Digitaria sanguinalis (L.) Scop. and C. iria were better than or equivalent to glyphosate at 1200.0 g a.i./hm2 treatment. The usage of glyphosate could reduce to 750.0 g a.i./hm2. Meanwhile, X18002 + glyphosate tank-mix at 45.0 + 450.0 g a.i./hm2 treatment had a faster action than glyphosate and a longer lasting effective period than X18002. [Review Details]
Effects of a novel 2,6-difluorobenzoylurea compound on the bioactivity and chitin synthesis of Spodoptera frugiperda
CHEN Jinpeng, XIE Jia, ZHAO Ke, etc
Abstract： In this paper, structural modification of benzoylurea compound NK-17, which has been reported to have excellent insecticidal activity, resulted in the compound (E)-N-((4-((tert-butoxyimino)methyl)phenyl)(methyl)carbamoyl)-2,6-difluoro benzamide (hereinafter referred to as HN-21 )to improve its solubility in organic solvents. The leaf film method was used to determine the bioactivity of lufenuron and HN-21 against the second instar larvae of Spodoptera frugiperda, and their effects on the chitin synthesis process were also analyzed. The results showed that the median lethal concentration (LC50) of HN-21 for 72 h was 0.681 mg/L, significantly lower than that of the positive control lufenuron (10.052 mg/L), and all the abnormal larvae died during molting. Compared to the control group, the expression of chitin synthesis pathway genes (sfTRE1, sfTRE2, sfGFAT, sfUAP, sfCHS1) decreased significantly after 24 h of lufenuron treatment at the concentration of 10.052 mg/L, earlier than HN-21 treatment at the concentration of 0.681 mg/L, but there was no significant difference between the two groups after 48 h treatment. These results can provide a theoretical basis for the development and utilization of benzoylurea compounds. [Review Details]
Research progress on the molecular targets of herbicides
TANG Ting, CHEN Dongyu, ZHANG Ziye, etc
Abstract： Herbicides account for more than half of global pesticide applications. The long-term and massive use of herbicides led to the emergence of resistant weeds against the existing herbicides. Thus, it is very urgent to discover new molecular targets or new mechanisms of action of herbicides. In this view, the research progresses on the types, biochemical functions and three-dimensional structures of existing herbicide molecular targets, as well as representative commercialized herbicides in recent decades were summarized. An outlook on the current status of herbicide molecular target discovery as well as new technologies were provided. This review may provide some guidance for the discovery of herbicide molecular targets and the development of green herbicides. [Review Details]
Pests are the main risk factors threatening the growth and development of crops and product quality. Effective control of pests is an important part to ensure the stable production of crops. Traditionally, chemical pesticides have been effective in pest control, but chemical pesticides themselves have also posed a significant risk of persistent damage to non-target organisms and the ecological environment. Pest green control is an inevitable requirement of sustainable agricultural development. Among them, protein-type biological materials with insecticidal function are a hot spot in the innovative research and development and application of pest green control because of their high safety and use in mass production of insecticides and even transgenic insect-resistant crops. For example, the protein-type biological materials with insecticidal function such as Bt toxin, lectin, venom, defensin and protease inhibitor, have been intensively studied and widely applied in pest control. In addition, in recent years, some new insecticidal proteins including insecticidal antibodies and corresponding innovative technologies, have been emerging and developing rapidly. In this paper, the potential innovative research and development and application of protein-type biological materials with insecticidal function are prospected, of which on the basis of systematically reviewing the current research and development and application status of them, and combining the original research results and experience of the author's team in the targeting design of insecticidal antibodies. The aims to provide the latest literature and technical reference for the green control of agricultural pests.
Based on the recently reported structure of highly active mesoionic nAChR modulators, 30 novel benzopyrazole compounds were designed and synthesized through scaffold hopping. Their structures were confirmed by 1H NMR, 13C NMR and HRMS. Insecticidal activity assays revealed compounds A1 , A7 , A13 and A19 showed about 50% mortality against Aphis craccivora at the concentration of 500 mg/L, although still less active than lead compound 1 . Preliminary analysis suggests similar binding modes for mesoionic and non-mesoionic structures., and the differences in their physicochemical properties and electrostatic potential surface between A1 and compound 1 may be the main reason for the lower activities of the target compounds than that of compound 1 .
To improve the utilization rate of pesticides and reduce the economic losses and environmental hazards caused by pesticide loss, the self-assembly layer of poly (octadecylsiloxane) (PODS) was prepared by hydrolysis, self-assembly and polycondensation of octadecyltrichlorosilane (OTS) on the surface of rapeseed meal (RSM) with octadecyltrichlorosilane (OTS) and p-aminoazobenzene (AAB) as modifiers. At the same time, AAB with photoisomerism was attached to RSM surface to synthesize RSM-PODS/AAB pesticide carrier with photoresponsiveness. Its structure and composition were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), UV-Vis spectroscopy and contact angle measurement device. The results showed that the loading rate of modified RSM was 21.4% higher than that of original RSM, and the cumulative release rate of pinoxaden was 83% in 72 h in the dark. The cumulative release rate of RSM-PODS/AAB was 95% after UV-Vis irradiation for 4 h and 92% after sunlight irradiation for 6 h. The application results showed that RSM-PODS/AAB loaded with pesticides had good UV-Vis and sunlight controlled release performance. The light responsive lipophilic pesticide carrier could effectively control the drug release behavior through UV-Vis and sunlight response.
Natural product-derived botanical insecticides have the advantages of strong target specificity, easy degradation, pesticide residue free and no pollution to the environment compared to the traditional chemical insecticides. They meet the development requirements of green agriculture and are one of the important research and development fields of insecticides. In this paper, the current status of the research and development of botanical natural product insecticides as lead compounds for structural modification since 2015 were reviewed. Finally, the trends of future development, current challenges and the subsequent research strategy of botanical insecticides were analyzed and prospected.
To quantitatively evaluate the chemotaxis of the second-stage juveniles (J2s) of Meloidogyne incongnita, an experimental method using stereomicroscope camera and ImageJ grayscale statistics method to detect the chemotaxis of J2s by analyzing the movement trajectory of the root-knot nematode in Pluronic F-127 gel was established, and verified the reliability of the method with 10 reported compounds to induce chemotaxis. In addition, the method was used to determine the chemotaxis of 40 compounds against M. incongnita. The results showed that 22 compounds had attractive activity and 11 compounds had repellent activity at the concentration of 10 μg/mL, with p-anisidine and phloroglucinol being the most attractive and repellent to nematodes, respectively. Further studies showed that p-anisidine exhibited attraction activity at low concentrations and repellent activity against J2s of M. incongnita at high concentrations, while the repellent activity of phloroglucinol increased with higher concentrations. This study provides a reliable method for rapid and quantitative evaluation of the chemotaxis of compounds against M. incongnita and for the discovery of highly active root-knot nematode repellents.
In order to explore the chemical fruit thinning system suitable for different apple varieties, naphthalene acetic acid (NAA), 6-benzylaminopurine (6-BA) as fruit thinning agents, dioctyl sulfosuccinate sodium salt (AOT) and dioctyl sulfosuccinate sodium salt + methyl oleate (AOT + MO) as tank-mix adjuvants were applied to two apple cultivars, "Yueguan" and "Longfeng". Physicochemical property determination experiments of different assistant systems were carried out to observe their impact, spreading and permeation behaviors on the surface of apple peels. Fruit quality after treatment was determined by spraying different assistant systems in combination with different concentrations of fruit removers at young fruit stage and counting inflorescence fruit set rate, flower fruit set rate, single double fruit rate, for different treatments. The results showed that adding 0.1% AOT (m/m) or 0.3% (AOT + MO) (m/m) adjuvants significantly reduced the dynamic surface tension of the solution and the contact angle at the target interface. This reduced or inhibited the splash and bounce behavior of the droplets on the peel, while promoting deposition, spreading and penetration behavior of the droplets. The fruit thinning agent 6-BA + NAA, NAA system has a certain thinning effect on "Longfeng" apple. The addition of AOT and (AOT + MO) adjuvants can significantly improve the thinning effect of the fruit thinning agent on "Longfeng" apple. Among them, 40 mg/L NAA AS + 0.1% AOT (m/m) treatment shown no difference with artificial thinning, significantly improving the fruit quality, which is better than artificial thinning; the fruit thinning agent water dispersion oil suspension agent 6-BA + NAA has a certain thinning effect on "Yueguan" apple. The addition of AOT and (AOT + MO) adjuvants can significantly improve the thinning effect of the fruit thinning agent on "Yueguan" apple. Among them, 150 mg/L 6-BA + 12.5 mg/L NAA OD + 0.3% (AOT + MO) (m/m) treatment matched artificial thinning, and significantly improved the fruit quality over artificial thinning.
With the implementation of pesticide reduction, plant-derived pesticides have received more and more attention because of their low toxicity and low residue. Limonene is a natural monocyclic terpene widely present in citrus essential oils, which has diverse biological activities, and has potential and application prospect in agricultural disease, pest and weed control. The research progress of limonene and its essential oil in the agricultural fields of insecticidal, acaricidal, phytocidal and antifungal activity in recent years, and the mechanism of its biological activities were briefly reviewed and summarized in this paper. Meanwhile, the registration of limonene formulations in China and the research progress and application of limonene nano-formulations against agricultural diseases and pests were introduced, and the future development trend and research direction of this field were prospected, which will provide the scientific basis for the application of limonene in pesticide reduction and agricultural disease, pest and weed control.
In order to clarify the field sampling methods suitable for pesticide residue testing under the application mode of plant protection unmanned aerial spray system (UAS), this study explored the four sampling methods, Z-shaped method, checkerboard method, diagonal method, and '米'-shaped method, under optimal application conditions, and the density distribution of droplets under different sampling points, and evaluated the uncertainty introduced by the sampling methods. The results show that the optimal operating parameters of T30 plant protection UAS are: flight speed of 3 m/s, flight altitude of 2 m from crop canopy, and working distance of 5 m. The spray deposition content at the periphery of the spray operation area of the plant protection UAS has a great influence on the change of the average spray deposition content in the region, and the residual samples should be collected as much as possible to avoid collecting from the periphery of the application operation area. In order to increase the uniformity and representativeness of field sample collection in the application mode of plant protection UAS, it is recommended that the number of sampling points should be set at 18 or more, and the diagonal method, checkerboard method and Z-shaped method can be selected.
A rapid method was established for the detection of acetamiprid, imidacloprid and carbofuran in three typically high residue vegetables, including celery, leek and cowpea, using magnetic solid-phase extraction and portable ion trap mass spectrometer. The main extraction conditions were optimized and the suitable procedures were as follows: The vegetable samples were extracted by 20 mL water, and the target pesticides in the extracted solution was then adsorbed by 30 mg magnetic solid-phase absorbents using the ultrasonic extraction for 15 min. After the magnetic separation, the adsorbed pesticides were desorbed with 4 mL of acetonitrile with 0.1% (V/V) formic acid by ultrasonic extraction for 3 min. Method validation indicated that all the three pesticides showed good linearity in the range of 0.01-0.25 mg/L, except that it was 0.05-0.5 mg/L for imidacloprid in leek sample. The limits of detection were 0.001-0.035 mg/L, and the limits of quantitation were 0.02-0.05 mg/kg. The spiked recoveries ranged from 50% to 71% with the RSDs of 4.2% to 22% at the spiked levels of 0.02, 0.05 and 0.2 mg/kg. The presented method displayed good qualitative/semi quantitative ability, and could be used for simultaneous and rapid on-site detection of multiple pesticide residues in vegetables.
To discovery novel acaricides based on natural products, twenty-six piperine derivatives containing 1,3,4-oxadiazoles ( 8a – 8z ) were designed and synthesized using piperine as a lead compound. Their structures were well characterized by 1H NMR (13C NMR), IR and HRMS. The steric configuration of compound 8g was confirmed by single crystal X-ray diffraction analysis. Their acaricidal activities were tested against female adults of Tetranychus cinnabarinus Boisduval by slide-dipping method. Compounds 8m (LC50: 0.41 mg/mL), 8r (LC50: 0.36 mg/mL) and 8u (LC50: 0.32 mg/mL) showed potent acaricidal activities which were 38.1, 43.4 and 48.9 folds of that of its precursor piperine (LC50: 15.64 mg/mL). Moreover, compound 8u also showed good control effects on T. cinnabarinus in the greenhouse, and its control efficiency was 61.8% on the 5th day after treatment at 0.3 mg/mL. The SARs analysis showed that introduction of 1,3,4-oxadiazoles on the C2 position of piperine was beneficial to the acaricidal activity, and the acaricidal activity was also related with the substituents on the phenyl of 1,3,4-oxadiazoles.
Black pepper (Piper nigrum L.) is an important tropical cash crop in China and suffers huge economic losses every year due to foot rot disease. In order to clarify the pathogen in black pepper main producing area and screen potential fungicides for disease control. Seven strains were isolated from Wanning City of Hainan Province and identified by morphological characteristics and ITS sequence specificity. The laboratory toxicities of 20 fungicides, registered for the control of oomycete diseases, were determined by the mycelial growth rate method. Results showed that all three strains isolated from black pepper foot rot disease samples, were Phytophthora capsici. Among the 20 tested oomycete fungicides, pyraclostrobin, fluazinam, thiram, dimethomorph, cyazofamid, and metalaxyl showed the highest activity in suppressing the mycelial growth of three P. capsici isolates (EC50<1 μg/mL), followed by oxine-copper, chlorothalonil, mancozeb, zineb, copper hydroxide (1 μg/mL<EC50<10 μg/mL), and then cuprous oxide, copper oxychloride, azoxystrobin, carvacrol, cymoxanil, berberine (10 μg/mL<EC50<50 μg/mL). Chitosan and fosetyl-aluminium exhibited the lowest inhibition activity (EC50>300 μg/mL). This study would help further the understanding and management of tropical P. capsici diseases.
In recent years, strawberry tan-brown leaf spot disease caused by Pilidium lythri is a serious new disease that has occurred in China. Between 2015 and 2017, a total of 90 symptomatic samples were collected from Changping District, Beijing City; Zhucheng County, Shandong Province; and Loudi City, Hunan Province in China, with 30 samples from each district. Twenty-six fungal isolates were identified as P. lythri based on morphology, molecular biology, and phylogenetic analyses. This is the first report of P. lythri caused strawberry tan-brown spot in Shandong and Hunan Provinces in China. At present, there are no registered fungicides in China for controlling tan-brown spot disease on strawberry caused by P. lythri. In this study, the susceptibility of 26 isolates to eight commonly used fungicides and novel fungicide SYP-14288 were determined in vitro. The result shows that SYP-14288 has the strongest inhibitory activity on the mycelial growth of 26 isolates of P. lythri, with an average EC50 value of (0.33 ± 0.06) μg/mL, can be used as an effective fungicide for the control of strawberry tan-brown leaf spot disease. The average EC50 values were from 3.92 μg/mL to 72.58 μg/mL for epoxiconazole, difenoconazole, prochloraz, tebuconazole, chlorothalonil, and myclobutanil. Among them, azoxystrobin had lower toxicity, and mancozeb had the lowest inhibitory activity. The results of this study can provide an important reference for the rational use of fungicides to control strawberry tan-brown spot disease.
The photodegradation behavior of the mixture of chlorothalonil and profenofos in water was investigated under high pressure mercury lamp (HPML). The results showed that the half-life of chlorothalonil at 3 μmol/L was 122.46 min under the HPML irradiation, and the half-lives of chlorothalonil were 64.54, 38.25 and 33.05 min in the presence of 1, 2 and 3 equivalent of profenofos. The half-lives of 3, 6, and 9 μmol/L profenofos were 87.85, 86.11 and 87.63 min, while they were 85.57, 83.51 and 84.32 min in the presence of chlorothalonil, respectively. This indicates that profenofos promoted the photodegradation of chlorothalonil in water and the promotion effect was increased as the concentration of profenofos increased. Chlorothalonil did not affect the photodegradation of profenofos. The main photodegradation product of chlorothalonil was 4-hydroxyl chlorothalonil with and without profennofos. Five photodegradation products of profenofos were detected, namely, 4-bromo-2-chlorophenyl hydrogen phosphate ethyl ester, O-(4-bromo-2-chlorophenyl)-O-ethyl-S-hydrogen phosphate, O-(2-chlorophenyl)-O-ethyl-S-propyl phosphorothioate, (2-chloro-4-hydroxyphenyl)-O-Ethyl-S-propyl phosphorothioate, and 2-chloro-4-bromophenol. Profenofos promoted the degradation of chlotothalonil via the generation of more hydroxyl radicals. This study provides important theoretical support for the evaluation of the environmental ecotoxicity of combined pollution of chlorothalonil and profenofos.
Thrips hawaiiensis (Morgan) is one of the main pests on bananas and mainly harms the flower buds. Traditional application methods of pesticides were ineffective for this kind of thrips, and in recent years, the insects have developed resistance to imidacloprid and other commonly used insecticides, resulting in pesticide residue problems on banana fruits. In this study, the control efficacy of broflanilide, afidopyropen, sulfoxaflor, flonicamid and imidaclothiz against T. hawaiiensis were determined by bud injection of the pesticide formulations in the early stage of bud development of banana, and the residue behavior was analyzed for broflanilide and imidaclothiz, which both showed high control efficacy. Results showed that broflanilide and imidaclothiz had control efficiencies of 84.7% and 82.1% after bud injection at the early stage of budding with 5% broflanilide suspension concentrate at 1000-fold dilution and 40% imidaclothiz water dispersible granules at 5000-fold dilution, respectively. The half-lives of broflanilide and imidaclothiz on bananas were 8.1 d and 8.0 d, respectivery and the final residues were below the LOQ (0.005 mg/kg) in whole fruit of bananas. Therefore, broflanilide and imidaclothiz were recommended to be used on banana by bud injection method to control T. hawaiiensis.
The heat resistance of the spore directly affects the production efficiency and cost of the dry powder of technical concentrate for Bacillus biocontrol bacteria. In order to develop the techniques to enhance the spore heat resistance of B. amyloliquefaciens PHODG36, a mutant strain BBW-11 of B. amyloliquefaciens PHODG36 with enhanced spore heat resistance was obtained by heat-treated mutagenesis and variable temperature mutagenesis. The spore survival rate of BBW-11 increased by more than 55.0%, while no significant difference in terms of colony morphology, biofilm formation, growth dynamics and antifungal activity compared to the wild-type strain PHODG36. The appropriate protective agent and treating conditions of BBW-11 were determined by orthogonal tests, and the technology to enhance the spore heat resistance of strain PHODG36 was established such as ‘the heat resistant mutant strain BBW-11 + 0.5% sucrose + 55 ℃ temperature treating for 0.5 h’, the spore survival rate was 2.3 times higher than that of the untreated mutant strain BBW-11 and 2.8 times higher than that of the wild-type strain PHODG36. In conclusion, the technique to enhance the spore heat resistance of strain PHODG36 was established in this study, which provides a technical support for the optimization of the spray drying process of the dry powder.
Herbicides account for more than half of global pesticide applications. The long-term and massive use of herbicides led to the emergence of resistant weeds against the existing herbicides. Thus, it is very urgent to discover new molecular targets or new mechanisms of action of herbicides. In this view, the research progresses on the types, biochemical functions and three-dimensional structures of existing herbicide molecular targets, as well as representative commercialized herbicides in recent decades were summarized. An outlook on the current status of herbicide molecular target discovery as well as new technologies were provided. This review may provide some guidance for the discovery of herbicide molecular targets and the development of green herbicides.
Pests, diseases and weeds are detrimental to grain production; and the overuse of chemical pesticides has led to increasingly serious problems such as pesticide residues and environmental pollution. As one of the main types of biological pesticides, microbial pesticides have been developing rapidly in recent years due to their low residues and low toxicity to humans and animals. This paper summarizes the progress of microbial pesticides, fungicides and herbicides in the screening of biocontrol strains, product creation and application in our country, additionally, suggestions and prospects are made for the development of microbial pesticides which aims to provide reference for industry-related units and practitioners.
In this paper, the research on the discovery, synthesis, biological activities, mechanism of action, non-target toxicity and derivatives of hinokitiol was reviewed. Hinokitiol is a kind of plant secondary metabolite with antimicrobial, insecticidal, anti-inflammatory, anticancer and other biological activities. It can be synthsized from readily available raw materials in industry and has significant development value. The seven-membered ring and carbonyl group of hinokitiol are essential groups for its bioactivity, and the structure-activity relationship suggests that the modification of hydroxyl group position may be one of the important ways to discover the highly active hinokitiol derivatives. However, the action characters, non-target toxicity and structural stability of hinokitiol are still unclear, which greatly limits the application of hinokitiol.
As a class of broad-spectrum insecticides, pyrethroids have been widely used in agriculture, forestry and health fields, and are frequently detected in aquatic environments in various regions. Meanwhile, pyrethroids are easy to be accumulated in aquatic organisms and cause high toxicity. Pyrethroids are highly hydrophobic compounds, and their environmental risks are often overestimated if their total concentrations in environmental media are analyzed using conventional chemical analysis methods. In recent 20 years, bioavailability has been widely used in environmental risk assessment of hydrophobic organic pollutants. Passive sampling technology as a sampling technology in which the analytes spontaneously transmitted from the sampling medium to the sampler. The free dissolved concentrations of pyrethroids determined by passive sampling technology can reflect their bioavailability more accurately than the total concentrations. In this paper, the latest research progress in the evaluation of the bioavailability of pyrethroids in aquatic environments using passive sampling techniques was reviewed. Firstly, the principle of passive sampling technology for evaluating the bioavailability of pyrethroids in aquatic environments was briefly summarized. Then, the basic performances and application characteristics of the commonly used passive samplers were discussed. Meanwhile, the application of passive sampling technology in the residue monitoring, aquatic organism toxicity evaluation, and residue accumulation prediction of pyrethroid in water were introduced in detail. Finally, the future development direction of this technology in China was prospected.
In this paper, structural modification of benzoylurea compound NK-17, which has been reported to have excellent insecticidal activity, resulted in the compound (E)-N-((4-((tert-butoxyimino)methyl)phenyl)(methyl)carbamoyl)-2,6-difluoro benzamide (hereinafter referred to as HN-21 )to improve its solubility in organic solvents. The leaf film method was used to determine the bioactivity of lufenuron and HN-21 against the second instar larvae of Spodoptera frugiperda, and their effects on the chitin synthesis process were also analyzed. The results showed that the median lethal concentration (LC50) of HN-21 for 72 h was 0.681 mg/L, significantly lower than that of the positive control lufenuron (10.052 mg/L), and all the abnormal larvae died during molting. Compared to the control group, the expression of chitin synthesis pathway genes (sfTRE1, sfTRE2, sfGFAT, sfUAP, sfCHS1) decreased significantly after 24 h of lufenuron treatment at the concentration of 10.052 mg/L, earlier than HN-21 treatment at the concentration of 0.681 mg/L, but there was no significant difference between the two groups after 48 h treatment. These results can provide a theoretical basis for the development and utilization of benzoylurea compounds.
Amino-pesticide conjugates enable to improve the systemic conductivity of parent ingredients, increase utilization efficiency, and decrease the waste that was caused by the unreached target and thus pollution to the environment. In this study, four target compounds were designed and synthesized using the natural product Rhein as the leading compound and β-aminobutyric acid (BABA) as the directing group, and their antifungal activities against the six plant pathogens, effects on enzymatic activities of the phenylalanine ammonialyase (PAL) and peroxidase (POD) of wheat leaves, which were treated by the compounds, and their phloem translocation in Ricinus seedling were measured. The results showed that compound 4b (concentration at 0.5 mmol/L) had not only an inhibition effect on the Rhizoctonia solani Kühn (the inhibition rate of mycelial growth was 53.5%), but also an inducible resistance (duration was nearly 7 d), and phloem translocation (sap concentration was 15.1 µmol/L). This study provides a new idea for developing systemic and inducible fungicides.
In order to reduce the usage of glyphosate, delay the growth of glyphosate-resistant weeds, and expand the weed control spectrum of glyphosate, the effect of temperature, light and simulated rainfall on herbicidal activity, and the absorption and conductivity of glyphosate and X18002[compound name was ethyl 3-(2-chloro-5-(3,5-dimethyl-2,6-dioxo-4-thioxo-1,3,5-triazinan-1-yl)-4-fluorophenyl)-5-methyl-4,5-dihydroisoxazole-5-carboxylate] were studied by indoor bioassays. Mixture proportion screening tests and tank-mix field trials were carried out after investigating the difference between glyphosate and X18002 and the necessity of a mixture. The result showed that the fresh-weight inhibition rate of X18002 (37.50 g a.i/hm2) and glyphosate (600.0 g a.i/hm2) against Portulaca oleracea L. and Eleusine indica (L.) Gaertn. under high (30-35 ℃) and medium (20-25 ℃) temperatures were 83.48%-100.0%, significantly higher than those under the low temperature (10-15 ℃). The herbicidal activity was significantly reduced under low temperature. The fresh-weight inhibition rates of X18002 (37.50 g a.i/hm2) were 16.03%-95.46% and 2.24%-85.04%, significantly increased with the increase of illuminance within the range of 0-22000 lx. X18002 was proved to be light-demanding herbicide, while glyphosate was proved to be a light-independent herbicide. X18002 had stable herbicide activity with no significant decrease of fresh-weight inhibition rate between simulated rainfall after 0.5 h of application, which was 100.0% and 81.76%-87.62% to P. oleracea and E. indica, and unsimulated rainfall with a dose of 37.50 g a.i/hm2. Glyphosate had a weak rainfastness with a significant decrease in inhibition rate when simulated rainfall within 0.5-8 h of application compared to unsimulated rainfall with a dose of 600.0 g a.i/hm2. The absorption and conductivity tests showed that both two compounds could be absorbed by the root, stem, and leaf of Abutilon theophrasti Medic.. Compared to X18002, which only had acropetal translocation capability, glyphosate had the ability of acropetal and basipetal translocation. The proportions of mixture which showed the synergistic effect on Erigeron canadensis L., E. indica and Cyperus iria L. were 1 : 10 and 1 : 20. The result of the field trials showed that total control effect of X18002 + glyphosate tank-mix at 45.0 + 450.0 g a.i./hm2 dosage on Alternanthera philoxeroides (Mart.) Griseb., E. canadensis, Digitaria sanguinalis (L.) Scop. and C. iria were better than or equivalent to glyphosate at 1200.0 g a.i./hm2 treatment. The usage of glyphosate could reduce to 750.0 g a.i./hm2. Meanwhile, X18002 + glyphosate tank-mix at 45.0 + 450.0 g a.i./hm2 treatment had a faster action than glyphosate and a longer lasting effective period than X18002.
In order to clarify the resistance status of Alopecurus aequalis to acetyl-CoA carboxylase (ACCase)-inhibiting herbicides, 30 populations of A. aequalis were collected from rice-wheat rotation fields in Anhui Province and determined by whole plant bioassay of resistance levels to three ACCase herbicides, including fenoxaprop-P-ethyl, clodinafop-propargyl and pinoxaden. Seven kinds of post-emergence herbicides such as tralkoxydim and pyroxsulam were selected for the boi-activity test to highly resistant population AHCZ-2. Five herbicides mixed with isoproturon were employed for the field efficacy evaluation. The results showed that among 30 tested populations, 26 populations were highly resistant to fenoxaprop-P-ethyl, accounting for 86.67% of the total tested populations. The GR50 value (active ingredients, the same as below) was 230.93-1755.54 g/hm2, and resistance index (RI) was 12.58-95.66. Twenty-one populations were highly resistant to clodinafop-propargyl, accounting for 70% of the total tested populations. The GR50 value was 147.18-1213.44 g/hm2, and RI was 11.93-98.36. The 19 populations were highly resistant to pyraclostrobin, accounting for 63.33% of the total tested. The GR50 value ranged from 107.63 to 614.18 g/hm2, and RI ranged from 12.21 to 69.69. The resistance of A. aequalis populations collected from the same area to three kinds of ACCases inhibitors was similar. Among the 7 kinds of post-emergence herbicides tested, the activity to highly resistant A. aequalis population AHCZ-2 was higher in tralkoxydim and chlortoluron with GR90 of 468.74 g/hm2 and 1495.85 g/hm2, followed by cypyrafluone-isoproturon with the GR90 of 1035.62 g/hm2. The activity of isoproturon, pyroxsulam, mesosulfuron-methyl and flucarbazone-Na was low. The field screening results showed that recommended high dose mesosulfuron-methyl (15.75 g/hm2), pyroxsulam (15 g/hm2) and chlortoluron (2250 g/hm2) mixed with isoproturon at 1500 g/hm2 had the best control efficacy on A. aequalis. The plant control efficacy was between 91.18% and 94.05%, and the fresh weight control efficacy was between 92.40% and 95.68%, the yield increased by 25.04%-35.08%. Cypyrafluone-isoproturon at 937.5 g/hm2 was the next with 90.78% control efficacy of fresh weight and yield increase of 22.78%. The results can provide reference for chemical control of rice-wheat field resistance A. aequalis.
In order to determine the best application conditions of fenpyrazone in corn fields, the effects of temperature, light intensity, interval time of rainfall after herbicide application and weed leaf stage on the herbicidal activity of fenpyrazone against barnyard grass Echinochloa crus-galli were studied using whole-plant dose-response experiments in greenhouse. At the temperature of 15-35 ℃, the efficacy of fenpyrazone was increased with the increase in temperature. At the temperature of 20-35 ℃, the efficacy of fenpyrazone tended to be stable, and the GR50 value for barnyard grass was between 2.8-7.6 g/hm2. With the increase in light intensity, the inhibition rate of the fresh weight of barnyard grass by fenpyrazone increased significantly from 41.19% to 90.84%. Fenpyrazone showed strong tolerance to rain erosion and could quickly penetrate the leaf tissues. And there was no significant correlation between its herbicidal activity and the interval time when the rainfall interval after treatment was more than 1 h, with the GR50 value of 1.7-2.4 g/hm2 for barnyard grass. The weed leaf stage significantly affected the efficacy of fenpyrazone against barnyard grass. The barnyard grass at 1- to 4-leaf stage was the most sensitive, with the GR50 value of <1.0 g/hm2. In conclusion, to maximize the efficacy of fenpyrazone, it should be applied when the weather is sunny, the temperature is higher than 20 ℃ and the targeted weed of barnyard grass is at the 1- to 4-leaf stage. The herbicide needs to be reapplied in case of rainy weather within 1 h after the application. The results provide a scientific basis for further promoting and applying fenpyrazone in corn fields.
Corm rot is the most serious disease on saffron, a Chinese medical herb belonging to "New Zhe Ba Wei". The sensitivity of 82 isolates of the pathogenic Fusarium oxysporum to a novel sterol demethylase inhibitor (DMI) mefentrifluconazole was determined using the mycelial growth rate method and the effects of mefentrifluconazole on the growth, sporulation, spore germination, and cell membrane permeability of F. oxysporum were investigated. The most and least sensitive strains in the population were used to determine the biological activity of mefentrifluconazole against F. oxysporum and the protective and curative efficacy were determined. The results showed that the EC50 values of mefentrifluconazole inhibiting mycelial growth of F. oxysporum ranged from 0.182 μg/mL to 2.491 μg/mL, and the average EC50 value was (0.838 ± 0.438) μg/mL. The sensitivity frequency distribution conforms to normal distribution. Mefentrifluconazole significantly decreased mycelial growth and sporulation of F. oxysporum. The conductivity test of mycelia demonstrated that mefentrifluconazole damaged cell membrane of F. oxysporum resulting in electrolyte leakage. In addition, the protective efficacy of mefentrifluconazole against saffron corm rot was superior to the curative efficacy. These results provide a theoretical basis for the effective control of saffron corm rot in production.
Tobacco target spot is a fungal disease on tobacco. In this paper, the mycelial growth rate method was used for the potential evaluation of dimetachlone to Rhizoctonia solani, and the effect of dimetachlone on the microbes of tobacco leaves after different periods of application was studied with Illumina high-throughput sequencing technology as well. Results showed that dimetachlone had strong inhibitory activity against the mycelial growth of R. solani with an EC50 value of 1.20 μg/mL and a complete inhibition of mycelial growth at 6.47 μg/mL. Within 0-18 days of treatment with 4200 g/hm2 dimetachlone 40% WP, there were significant differences in microbial community structure between healthy and diseased tobacco leaves. The phyllosphere fungi in both healthy and diseased tobacco were all distributed in Thanatephorus, Alternaria, and Fusarium, the phyllosphere bacteria in tobacco leaves were Pseudomonas, Staphylococcus, and Sphingomonas. Three days after application, the relative abundance of Thanatephorus in healthy and diseased tobacco leaves decreased 12.41% and 51.62%, the relative abundance of Alternaria increased 0.54% and 0.42%, the relative abundance of Pseudomonas decreased 13.48% and 19.17%, respectively. Nine days after application, the relative abundance of Thanatephorus in healthy and diseased tobacco leaves decreased 1.38% and 47.42%, the relative abundance of Alternaria decreased 0.36% and 0.18%, the relative abundance of Pseudomonas decreased 2.73% and 2.73%, respectively. Eighteen days after application, the relative abundance of Thanatephorus in healthy and diseased tobacco leaves decreased 26.74% and 39.03%, the relative abundance of Alternaria increased 26.02% and 2.70%, the relative abundance of Pseudomonas increased 6.56% and 16.02%, respectively. The application of dimetachlone 40% WP in the field significantly suppressed the relative abundance of Thanatephorus genus in healthy and diseased tissues within 3 d, but the effect on disease tissues was greater than that on healthy leaves; it also caused changes in the structure of interleaf bacterial flora, but the effect on diseased leaves was less than that on healthy tobacco leaves. The results of the study revealed the differences in the phyllosphere microorganism communities between healthy and diseased interleaf tissues after the application of dimetachlone from a microscopic perspective, providing a scientific basis for the application of dimetachlone.
Tobacco bacterial wilt caused by Ralstonia solanacearum is one of the important diseases in tobacco production, which seriously affects the yield and quality of tobacco leaves. In order to screen out efficient chemical agents for controlling tobacco bacterial wilt, the inhibitory activity of zhongshengmycin, oxytetracycline, benziothiazolinone, kasugamycin and chlorobromoisocyanuric acid on R. solanacearum was determined by plate colony counting method. The Biolog GEN III Microplate was used to investigate the carbon metabolism and chemical susceptibility of R. solanacearum under the stress of the above five chemicals. The results showed that R. solanacearum was restrained by all the five chemicals, and their antibacterial activity from strong to weak was zhongshengmycin > oxytetracycline > benziothiazolinone > kasugamycin > chlorobromoisocyanuric acid with EC50 values of 0.24, 0.74, 2.84, 7.95 and 273.99 mg/L, respectively. The Biolog GEN III carbon metabolism showed that all the 71 carbon sources such as monosaccharides and amino acids in the Biolog GEN III Microplate could be metabolized by R. solanacearum. However, under chemical stress, the metabolism of carbon sources by R. solanacearum was inhibited to varying degrees, with amino acids, hexoic acids, carboxylic acids, esters and fatty acid carbohydrates being the most significantly inhibited. As the concentration of the tested chemicals increased, R. solanacearum reduced the metabolic intensity of 65, 18, 60, and 7 carbon sources in the Biolog GEN III Microplate under 6 mg/L of zhongshengmycin, 8 mg/L of oxytetracycline, 30 mg/L of kasugamycin and 5738 mg/L of chlorbromoisocyanuric acid stress, and increased 6, 53, 10, and 60 carbon sources, respectively. Under the stress of 8 mg/L benziothiazolinone, the metabolic intensity of 71 carbon sources of R. solanacearum decreased. In addition, the susceptibility of R. solanacearum to 23 chemicals in the Biolog GEN III Microplate differed at different concentrations of the five chemicals stress and without chemical treatment, with greater sensitivity to low pH and less sensitivity to low concentrations of NaCl. This study can provide a reference for the selection and efficient utilization of chemical control agents to tobacco bacterial wilt.
To clarify the insecticidal activity and field efficacy of seven insecticides （IRAC 28 group: chlorantraniliprole, cyantraniliprole, tetrachlorantraniliprole, tetraniliprole and thiotraniliprole, IRAC 30 group: broflanilide and isocycloseram）on lepidopterous pests, the bioactivity assays against Plutella xylostella, Spodoptera exigua, Helicoverpa armigera and Chilo suppressalis were performed by immersion method, and the field trials were conducted to evaluate the control efficacy on P. xylostella and S. exigua. The bioassay showed that the toxicities of isocycloseram against P. xylostella, S. exigua and C. suppressalis were the highest, with LC50 values of 0.0040, 0.0521 and 0.0078 mg/L, respectively. Followed by broflanilide, the LC50 values were 0.0198, 0.0584 and 0.0339 mg/L, respectively. The LC50 values of the other five insecticides against P. xylostella, S. exigua and C. suppressalis were 0.0212-0.1378 mg/L, 0.2577-0.8080 mg/L and 0.2886-1.2277 mg/L, respectively. The toxicity of thiotraniliprole against H. armigera was an highest with the LC50 value of 0.0218 mg/L, which was significantly higher than that of the other 6 insecticides (LC50 values were 0.0694-0.2747 mg/L). The field trials for controlling P. xylostella showed that the control efficacy of IRAC 30 group insecticides at a dose of 30 a.i. g/hm2 was 95.60%-96.68% at 7 d after treatment, significantly higher than that of IRAC 28 group insecticides at the dose of 30 a.i. g/hm2 and 60 a.i. g/hm2 (49.07%-81.77% and 57.47%-85.90%). The control efficacy of thiotraniliprole, cyantraniliprole and tetrachlorantraniliprole was over 80% at the dose of 60 a.i. g/hm2, which was higher than that of chlorantraniliprole (57.47%). The control efficacy of broflanilide against S. exigua was 96.45% after 7 d treatment at a dose of 22.5 a.i. g/hm2, which was higher than that of the other six insecticides at a dose of 22.5 and 45 a.i. g/hm2 (62.34%-86.75% and 68.06%-85.56%). Chlorantraniliprole showed the weakest effect on S. exigua (62.34%). The research showed that the seven insecticides tested had high activity against four lepidopterous pests, but variations of control effect existed under field trials. Field populations of P. xylostella and S. exigua were likely to have developed different levels of resistance to insecticides in IRAC 28 group. Corresponding resistance management strategies need to be launched timely and the development and application of insecticides in IRAC 30 group need to be accelerated.
The cross-talk of plant hormones plays a synergistic role in the growth and development of crops. In order to explore the application prospects of the functional analogue of abscisic acid—natenpac in rice, this paper studied the effects of seed soaking with 1000 times solution of 0.03% natenpac aqueous solution (AS), and spraying 2% natenpac + IBA wettable powder (WP) dilution seven days before transplanting rice seedlings on the growth, development and yield of rice, through four kinds of different treatment modes "seed soaking + direct seeding" "seed soaking + transplanting" "seed soaking + spraying + transplanting" and "spraying + transplanting". The 0.03% S-ABA AS and 2% S-ABA + IBA (0.2 : 1.8, m/m, a.i) WP dilutions were used as the drug control, and water used as blank control, respectively. The effect of natenpac on rice growth and development and yield was assessed by investigating seed germination potential, germination rate, tiller number, number of spikes, seed-setting rate, 1000-grain weight and yield for determining the best treatment pattern for yield increase. The results showed that seed soaking with 1000 times solution of 0.03% natenpac AS could increase the germination rate of rice seeds by 3.3%, which was 1% higher than 0.03% S-ABA AS. In terms of rice yield increase, each treatment mode has a significant impact on the yield increase. In terms of increasing yield alone, the "spraying + transplanting" treatment mode has the best yield increase effect. Spraying 1000 times solution of 2% natenpac + IBA WP seven days before transplanting can achieve a 21.7% increase in rice yield. From the perspective of both improving rice quality and increasing rice yield, the "soaking + transplanting" treatment mode has the best effect. It is appropriate to seed soaking with 1000 times solution of 0.03% natenpac AS and then raise seedlings for transplanting, which not only ensures the quality of rice but also increases yield by 9.7%. This study clarifies the best treatment mode for improving rice quality and yield, and provides a sufficient basis for the application of natenpac in rice production.
In this paper, the natural antibacterial agent thymol was used as a mildew inhibitor for bamboo, which was immobilized in bamboo by laccase. The mildew resistance of the treated bamboo against Aspergillus niger, Trichoderma virens and Penicillium citrinum was tested, respectively. The laccase-catalyzed fixation effect was evaluated by volatility of thymol, the mildew resistance after leaching treatment and the changes of water contact angle. Scanning electron microscopy (SEM) was used to study the micro-morphology of the treated bamboo, and further Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) were employed to explore the chemical bond changes during the laccase-catalyzed process. The results show that, compared with the bamboo treated by thymol alone, the bamboo treated by laccase catalysis exhibited a good inhibitory effect on A. niger, T. virens and P. citrinum before and after the leaching treatment, the mildew-proof efficiency was above 80%, and the mildew-proof performance of the bamboo treated both with thymol and laccase after the leaching treatment was better than that treated with thymol alone. The volatility of thymol was significantly reduced from 17.03% to 6.75%. The water contact angle increase significantly from 35° to 97°, which was contributing to the mildew resistance of treated bamboo. The enzymatic immobilization did not significantly change the micro-morphology of bamboo, but a large number of flaky substances appeared on the surface of bamboo cell wall, which was considered as aggregates of thymol molecules grafted onto the surface of bamboo. The FT-IR and XPS results shown new formed chemical bonds between thymol and bamboo lignin were the key factor for immobilization of thymol. This study realized the green fixation of natural antibacterial agent through the catalysis of laccase, reducing its volatilization and leaching, and the mildew resistance of treated bamboo was prolonged. The results of this study provide a new idea for green mildew prevention of bamboo, which can achieve safe and long-lasting protection of bamboo.
In order to establish a sensitive and rapid detection method of the residues of thiamethoxam in cucumber, Brassica chinensis and water samples, the chemiluminescence enzyme immunoassay (CLEIA) of thiamethoxam residues was studied. A CLEIA method was developed by optimizing the working concentration of antigen and antibody, the type of blocker, methanol content, Na+ concentration and pH value in the analyzing system. Under the optimal conditions, the linear range of the method was 0.125-12.5 ng/mL, the limit of quantification (LOQ) was 0.125 ng/mL, and the IC50 was 1.01 ng/mL. The cross-reaction rates of the seven analogues of thiamethoxam were all lower than 0.3%, which indicated that the CLEIA method had good specificity. The recovery study in cucumber, Brassica chinensis and pond water showed that the recovery range was 86%-108%, and the relative standard deviation (RSD) was 2.6%-9.1%, which was consistent with the analysis results of ultra-high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Using the established method, the residues of thiamethoxam in market samples of cucumber, Brassica chinensis and pond water samples was detected, and the results showed that the residues of thiamethoxam in the three kinds of samples were lower than the detection limit. This study showed that the established CLEIA method was highly sensitive, environmental friendly, the sample preparation was simple, and it can be used in the detection of thiamethoxam residues in cucumber, Brassica chinensis and water samples.
An analytical method for the determination of 41 pesticide residues in crucian carp and bottom sediment was established using modified QuEChERS sample preparation and gas chromatography-tandem mass spectrometry (GC-MS/MS). The crucian carp samples were extracted by acetonitrile and ethyl acetate (V:V = 1:1) and cleaned-up with 600 mg Alumina-B. The bottom sediment samples were extracted by ethyl acetate and cleaned-up with 600 mg Florisil and 150 mg Graphitized carbon black. The pesticide residues were analyzed by GC-MS/MS. A HP-5MS column was used for the separation, and the electron ionization (EI) was employed using dynamic multiple reaction monitoring (dMRM) mode for the detection. The matrix-matched external standard calibration curves were used for quantitative analysis. The method validation results indicated that in crucian carp, the instrumental limits of detection (LOD) for 41 pesticides were 0.05-2.5 μg/L, and the limits of quantification (LOQ) were 0.1-5.0 μg/kg for the method. The linear correlation coefficients (r) of the calibration curves were 0.9960-0.9999. The average recoveries at three spiked levels (LOQ, 2LOQ and 10LOQ) were 73%-116% (n = 6) with relative standard deviations (RSDs) of 0.65%-13%. In aquaculture sediment, the instrumental LODs for 41 pesticides were 0.05-2.5 μg/L, and the LOQs were 0.1-5.0 μg/kg for the method. r of the calibration curves were 0.9964-1.000. The average recoveries at three spiked levels (LOQ, 2LOQ and 10LOQ) were 73%-104% (n = 6) with RSDs of 0.051%-10%. The method was rapid, sensitive and accurate, and has a good application prospect in the detection of amides, triazines, phenyl pyrazoles, organochlorine and organophosphorus pesticide residues in crucian carp and bottom sediment.
To evaluate the residue risk and safety of pydiflumetofen in tomato, an analytical method based on ultra-high performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS) was developed, and the dissipation and residues of pydiflumetofen under different planting modes were investigated. Moreover, the dietary risk assessment was conducted based on the dietary consumption and residue datas. The results showed that the linearity was acceptable in the range of 0.010-2.0 mg/L with r > 0.99. At the spiking levels of 0.010, 0.10, 0.50 and 1.0 mg/kg, the average recoveries ranged from 92% to 108% with the relative standard deviations (RSDs) of 2.9%-8.1%, and the limit of quantification was 0.010 mg/kg. The residue dissipation of pydiflumetofen in tomato in Beijing, Hainan and Shandong were in accordance with the first-order kinetic equation, and the half-lives were 11.4, 11.4 and 7.1 d, respectively. The final residues at the pre-harvest interval of 5 days were lower than the maximum residue limits (MRL) in the United States, Japan and Codex Alimentarius Commission (CAC). The short-term dietary exposure risks to children aged 1-6 and to the general population in China were 1.8%-2.8% and 0.6%-1.0%, respectively, which were all lower than 100% and indicated that there were no un-acceptable dietary exposure risk to different populations. The results provide scientific suggestions for the rational use and establishment of the MRL of pydiflumetofen on tomato in China.
Imidacloprid is a commonly used neonicotinoid pesticide. Imidacloprid widely exists in aqueous environment due to its usage, high water solubility, and long half-life. This poses a potential threat to the ecological safety and human health. Biochar is a solid product obtained from biomass pyrolysis. It has the characteristics of wide source, low energy consumption, easy regeneration, and environmental friendliness, etc, and has been widely concerned in the field of adsorption. In this study, epichlorohydrin modified corn starch biochar (ECSB) was prepared by crosslinking epichlorohydrin with corn starch as raw material. Scanning electron microscopy etc was applied to characterize the structure of ECSB, study the adsorption behavior of ECSB towards imidacloprid, and investigate the adsorption mechanism. The results showed that ECSB had abundant pore structure, with the specific surface area of 285 m2/g and pore volume of 0.162 cm3/g, which were 46.5 and 31.4 times higher than those of unmodified corn starch biochar (CSB), respectively. The maximum adsorption capacity of ECSB for imidacloprid was 70.9 mg/g, which was 112 times higher than that of CSB. Adsorption of imidacloprid by ECSB was in accordance with the quasi-second-order kinetic and Langmuir isothermal model, and was an endothermic, entropy-increasing, and spontaneous process. The presumable adsorption mechanism was mainly attributed to the pore-filling action. Moreover, the adsorption capacity of ECSB still reached 96.6% of the original one after five regenerations using a co-processing technology of ultrasound cavitation and reagent extraction. This study can provide research ideas and theoretical basis for the treatment of environmental imidacloprid wastewater and the development and application of corn starch.
Sclerotinia stem rot is a destructive disease caused by the fungus Sclerotinia sclerotiorum, and it occurs in oilseed rape and many other broadleaf crops. The chemical control with fungicides is usually applied in fields. As a kind of succinate dehydrogenase inhibitors (SDHIs), bixafen showed higher efficiency in inhibiting mycelial growth. To establish the baseline sensitivity of S. sclerotiorum to bixafen in Henan Province, 119 isolates of S. sclerotiorum were obtained from diseased stems of oilseed rape collected from fields in different geographical regions in Henan Province, China, in 2015 and 2016, and their sensitivity to bixafen was determined based on mycelial growth rate method. The results showed that the 50% inhibition of mycelial growth (EC50) values of S. sclerotiorum ranged from 0.0417 to 0.4732 µg/mL with an average EC50 value (mean ± SD) of (0.1968 ± 0.1053) µg/mL. The frequency distribution range curve was narrow and unimodal, and the average EC50 value obtained can be used as the baseline sensitivity of S. sclerotiorum to bixafen in Henan Province. In order to determine whether bixafen can be mixed with other fungicides with different modes of action, the EC50 values of S. sclerotiorum to bixafen, carbendazim, fludioxonil, prothioconazole, dimetachlone, metconazole, and their mixtures were determined based on mycelial growth rate method. The results showed that the EC50 values for bixafen, carbendazim, fludioxonil, prothioconazole, dimetachlone and metconazole were 0.1256, 0.1122, 0.0229, 0.0651, 0.8057, and 0.0278 µg/mL, respectively. For fungicide mixtures of bixafen and carbendazim, fludioxonil, prothioconazole, dimetachlone or metconazole (1 : 1, 1 : 3, 1 : 5, 3 : 1 and 5 : 1, V/V), the synergistic ratio (SR) ranges from 0.54 to 3.57, which indicates additive or synergistic inhibition. These results suggested that bixafen could be used alternately or in combination with carbendazim, fludioxonil, prothioconazole, dimetachlone and metconazole to prevent and delay the development of resistance in S. sclerotiorum. These results provide important and scientific information for the control of sclerotinia stem rot and for monitoring the sensitivity of S. sclerotiorum to bixafen in Henan Province.
To determine the control efficacy of the mixture of salicylic acid and prochloraz on anthracnose of Camellia oleifera, the efficacy tests were conducted both in the lab and in the field. In the lab, leaves detached from seedlings of C. oleifera were inoculated with Colletotrichum gloeosporioides for bioassays. The field plot assays were employed for the verification of control efficacy. Lab tests showed the control efficacy of 150 mg/L salicylic acid mixed with 200 mg/L prochloraz (C2) was significantly higher than that of 200 mg/L prochloraz (P2), and the mixture presented a synergistic effect. The synergic ratio of the C2 treatment was 1.42 at ten days after the second spray. Twenty days after the second spray, the control efficacy of the C2 treatment was maintained at 57.26%, significantly higher than that of the P2 treatment at 27.49%. Twenty-eight days after the second spray in the field trial, the control efficacy of C2 treatment was 72.86%, while the efficacy in P2 treatment was only 46.54%, consistent with the observation in the lab. The results demonstrated that the mixture of salicylic acid and prochloraz enhances the control efficacy and prolongs the effective duration of prochloraz against anthracnose of C. oleifera. Thus, the application of the mixtures will reduce the use frequency and concentration of prochloraz and achieve the purpose of reducing pesticide use and increasing efficiency.
In order to clarify the resistance status and resistance mechanism of the field population of the small brown planthopper (SBPH), Laodelphax striatellus, to commonly used insecticides, we monitored the resistance level of SBPH collected from Yizheng and Yancheng in Jiangsu Province, Changxing in Zhejiang Province and Lujiang in Anhui Province, to eight insecticides during 2021 to 2022 using rice seedling dipping method. The synergistic effects of three detoxification enzyme inhibitors, piperonyl butoxide (PBO), diethylmaleate (DEM), and triphenyl phosphate (TPP), to buprofezin on the control of SBPH were measured. The results showed that four regions populations of SBPH have developed medium to high level resistance to buprofezin (RR = 61.5-148.8), and moderate level resistance to chlorpyrifos (RR = 14.9-28.3). Furthermore, the four regions SBPH populations exhibited sensitive or low-level resistance to nitenpyram (RR = 0.7-9.9), thiamethoxam (RR = 1.6-8.3), dinotefuran (RR = 2.9-10.0) and sulfoxaflor (RR = 2.5-8.7). In addition, all field populations of SBPH were susceptible to pymetrozine (RR = 1.0-5.0) and triflumezopyrim (RR = 0.5-2.3). PBO, TPP, and DEM displayed no synergism effect on the sensitivity of SBPH to buprofezin, which indicated that these three detoxifying enzymes might play little role in the buprofezin resistance. The results of this study provided a scientific basis for the resistance management and field control of SBPH.
Journal Introduction
Superintendent：Ministry of Education of the People's Republic of China
Sponsor：China Agricultural University
Editor-in-Chief：ZHOU Zhiqiang
Deputy Editor-in-Chief：PAN Canping
Address：College of Science Room 340, China Agricultural University, No. 2, Yuanmingyuan West Road, Haidian, Beijing, China.
Postal Code：100193
Tel：86-010-62733003
E-mail：nyxuebao@263.net
ISSN：1008-7303
CN：11-3995/S
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