Fungicide Chlorothalonil Research Articles

Selective extraction of fungicides from fruit samples with defective UiO-66 as solid-phase microextraction fiber coating

A defective UiO-66 with rich defect sites was synthesized by a modulator-induced defect formation approach and used as the solid-phase microextraction (SPME) fiber coating material. The extraction experimental results showed that the defective UiO-66 coating can selectively extract the fungicides chlorothalonil, vinclozolin, dimethachlon, procymidone and iprodione with a high adsorption capability. The superior adsorption capability can be attributed to hydrophobic, Lewis acid-base and hydrogen bonding interactions. After optimization, a SPME with the defective UiO-66 as the fiber coating combined with GC–MS detection was established for the sensitive and selective determination of the five fungicides in fruit samples. Under the optimized experimental conditions, the quantitative linear response was in the range of 0.83–300 ng g−1, with the coefficients of determination in the range from 0.9970 to 0.9986 and the limits of detection between 0.25 and 9.0 ng g−1 for the analytes. The method was successfully applied for the determination of the fungicides in different fruit samples. Satisfactory method recoveries (82.7%-117.7%) and good precisions with the relative standard deviations being from 3.2% to 12% were achieved.

Effects of fungicide chlorothalonil on freshwater plankton communities: a microcosm study.

Direct and indirect effects of the fungicide chlorothalonil on aquatic plankton community structure were investigated by exposing plankton to chlorothalonil concentrations of 0.010, 0.025, 0.100, 0.250 and 1.000mg/L over 20days in 18 microcosms (glass tanks having 8 L of pond water). Each treatment was executed in three replicates. Total phytoplankton and zooplankton abundance and chlorophyll-a concentrations in microcosms were measured 5, 10 and 20days after pesticide exposure. Plankton community and taxa response to pesticide concentrations were analyzed using the similarity of percentages procedure (SIMPER) and one-way ANOVA test. The results of the study indicated that highest concentration levels of chlorothalonil exposure had a significant impact on phytoplankton and zooplankton taxa. Phytoplankton taxa Amphora sp. and Staurastrum sp. and zooplankton taxa Moina sp. and copepod Nauplius were highly sensitive to chlorothalonil exposure. Phytoplankton taxa Mougeotia sp. increased with increased chlorothalonil (0.1-1.0mg/L) concentrations, and zooplankton taxa of Aeolosoma sp. showed no significant reduction of individuals in response to pesticide exposure. Results showed that pesticide residues have a direct and rapid impact on phytoplankton and zooplankton community structure. Changes in diversity and species composition induced by pesticides indicate the importance of considering indirect effects of pesticides on the ecological food chain in the aquatic environment.

Design and synthesis of novel benzoxazole/chromene-phthalide scaffolds hybrids as potential natural products-based fungicide

Phthalide, benzoxazole, and chromene are important heterocyclic skeletons with extensive biological activities. In order to develop novel potential antifungal agents, twenty-two benzoxazole/chromene-containing phthalide derivatives were prepared, and their fungicidal activity against nine common plants pathogenic fungi were evaluated in vitro. The EC50 values indicated that compound Z-4b displayed superior antifungal activity against P. oryzae (11.0 μg/mL), F. solani (8.5 μg/mL), P. capsici (27.8 μg/mL), V. mali (3.1 μg/mL) and A. brassicae (4.3 μg/mL) strains, which was more potent than the two commercialized fungicides hymexazol and chlorothalonil. In addition, the structure-activity relationship analysis demonstrated that the combination site of oxazolamide with phthalide has an important effect on antifungal activity. This research offers a potential compound for the development of novel agricultural fungicides.

High-intensity ultrasonication impact on the chlorothalonil fungicide and its reduction pathway in spinach juice

Among different novel technologies, sonochemistry is a sustainable emerging technology for food processing, preservation, and pesticide removal. The study aimed to probe the impact of high-intensity ultrasonication on chlorothalonil fungicide degradation, reduction pathway, and bioactive availability of spinach juice. The chlorothalonil fungicide-immersed spinach juice was treated with sonication at 360 W, 480 W, and 600 W, 40 kHz, for 30 and 40 min at 30 ± 1 °C. The highest reduction of chlorothalonil fungicide residues was observed at 40 min sonication at 600 W. HPLC-MS (high-performance liquid chromatography-mass spectroscopy) analysis revealed the degradation pathway of chlorothalonil and the formation of m-phthalonitrile, 3-cyno-2,4,5,6-tetrachlorobenamide, 4-dichloroisophthalonitrile, trichloroisophtalonitrile, 4-hydoxychlorothalonil, and 2,3,4,6-tetrachlorochlorobenzonitrile as degradation products. High-intensity sonication treatments also significantly increased the bioavailability of phenolic, chlorophyll, and anthocyanins and the antioxidant activity of spinach juice. Our results proposed that sonication technology has excellent potential in degrading pesticides through free radical reactions formation and pyrolysis. Considering future perspectives, ultrasonication could be employed industrially to reduce pesticide residues from agricultural products and enhance the quality of spinach juice.

Efficacy of Botanical Mixture and Fungicides to Combat Sigatoka Disease in Banana Cultivation

Black Sigatoka disease caused by Mycosphaerella fijiensis seriously threatens banana cultivation worldwide. This infirmity is controlled by the recurrent application of synthetic fungicides, which leads to several adverse effects. Plant extracts with antifungal potential have long been investigated as they contain secondary bioactive compounds for protecting crops from microbial infection. This study compared the antifungal activities of both botanical mixtures and recommended fungicides to control Black Sigatoka in banana. Laboratory and field studies were conducted to assess the antifungal activity of the botanical mix prepared from eight different herbal plant parts against M. fijiensis, with two recommended fungicides as the positive control. In vitro results showed that the radial growth of the fungus was significantly impaired (P<0.05.) by the addition of the botanical mixture, fungicides, and combination of the botanical mixture (BM) and fungicides in the PDA media. Mycosphaerella fijiensis differed in their reaction to the BM and fungicides, and combination of BM and fungicides, but on the whole, growth inhibition increased with the concentration. In field experiments, all the treatments reduced the disease incidence significantly compared to the unsprayed control, where the disease severity index (DSI) increased from 43.88 to 67.77 within 28 days. After the first spray, the botanical mixture and fungicides (Chlorothalonil and Carbendazim) reduced the disease severity index to 39.7, 41.19, and 44.44, respectively. Fungicides and combinations of Chlorothalonil + BM and Carbendazim + BM showed the lowest DSI, 34.07 and 35.83, respectively. The results show that combining the synthetic and botanical mixture is more effective for controlling the disease. The study reveals the possibility of utilizing a botanical mixture as an integrated approach to manage Black Sigatoka disease more efficiently and in an eco-friendly manner.

Pesticide Prioritization by Potential Biological Effects in Tributaries of the Laurentian Great Lakes.

Watersheds of the Great Lakes Basin (USA/Canada) are highly modified and impacted by human activities including pesticide use. Despite labeling restrictions intended to minimize risks to nontarget organisms, concerns remain that environmental exposures to pesticides may be occurring at levels negatively impacting nontarget organisms. We used a combination of organismal-level toxicity estimates (in vivo aquatic life benchmarks) and data from high-throughput screening (HTS) assays (in vitro benchmarks) to prioritize pesticides and sites of concern in streams at 16 tributaries to the Great Lakes Basin. In vivo or in vitro benchmark values were exceeded at 15 sites, 10 of which had exceedances throughout the year. Pesticides had the greatest potential biological impact at the site with the greatest proportion of agricultural land use in its basin (the Maumee River, Toledo, OH, USA), with 72 parent compounds or transformation products being detected, 47 of which exceeded at least one benchmark value. Our risk-based screening approach identified multiple pesticide parent compounds of concern in tributaries of the Great Lakes; these compounds included: eight herbicides (metolachlor, acetochlor, 2,4-dichlorophenoxyacetic acid, diuron, atrazine, alachlor, triclopyr, and simazine), three fungicides (chlorothalonil, propiconazole, and carbendazim), and four insecticides (diazinon, fipronil, imidacloprid, and clothianidin). We present methods for reducing the volume and complexity of potential biological effects data that result from combining contaminant surveillance with HTS (in vitro) and traditional (in vivo) toxicity estimates. Environ Toxicol Chem 2023;42:367-384. Published 2022. This article is a U.S. Government work and is in the public domain in the USA. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Cost effective management of early blight disease of potato (Solanum tuberosum) caused by Alternaria solani

Early blight disease of potato (Solanum tuberosum L.) caused by Alternaria solani (Ellis and Martin), is one of the most important fungal disease throughout the potato growing areas. Field experiments were conducted during winter (rabi) season, 2018–19 and 2019–20 at Vegetable Research Centre, Govind Ballabh Pant University of Agriculture and Technology, Pantnagar, Uttarakhand for evaluating fungicides against early blight of potato. All the fungicides (mancozeb, hexaconazole, difenoconazole and chlorothalonil) were evaluated in vitro using poison food technique as well as field conditions. In vitro study revealed that chlorothalonil 75% wp gave the best results and showed 18.0 mm, 17.67 mm, 16.33 mm, 12.33 mm and 8.33 mm mycelial growth of Alternaria solani @25 ppm, 50 ppm, 100 ppm, 150 ppm and 200 ppm concentration at 7 days after inoculation. In field condition, chlorothalonil 75% WP @0.2% applied as foliar sprays at 10 days interval resulted the lowest disease severity i.e. 22.50% with highest tuber yield (317.90 q/ha). The findings regarding the economics of the potato cultivation clearly revealed that the treatment chlorothalonil @0.2% gave the highest benefit cost ratio i.e. 2.96. The early blight disease of potato may be controlled by applying chlorothalonil at a concentration of 0.25 three times at a 10-day interval, which increased production and provided extra benefits to farmers.

Reduced Degradation of the Herbicide 4-Chloro-2-Methylphenoxyacetic Acid (MCPA) in Soil Induced by the Fungicide Mixture Mancozeb, Metalaxyl-M, and Chlorothalonil Used in Tank Mixtures and Spray Series

Pesticides are extensively used in agriculture to prevent infestation of crops, control plant-associated diseases and pests, and increase crop productivity. With regards to typical agricultural practice, tank mixing of two or more plant protection products or the subsequent applications of herbicides, fungicides, and insecticides are common application strategies to improve pest control. Our study provides evidence that the fungicide mixture consisting of mancozeb, metalaxyl-M, and chlorothalonil, each applied according to their recommended field rates, retarded the degradation of the phenoxy herbicide 4-chloro-2-methylphenoxyacetic acid (MPCA) in soil. MCPA dissipation times were between 1.6 and 1.9 days without and 2.5–3.5 days with co-applied fungicides. Furthermore, the proportions of extractable residues, non-extractable residues, mineralization, volatile organic compounds, and MPCA metabolism were altered by the fungicide mixture, i.e., considerably lower amounts of the main transformation product of MCPA, 4-chloro-2-methylphenol, were formed. The effects induced by the fungicides persisted throughout the experiment. Our results demonstrate that the current situation of considering individual active substances in the authorization process for plant protection products could lead to a discrepancy in the exposure assessment for humans and the environment. For specifically these cases, this calls into question whether the legally required level of protection is provided.

Discovery of Hyrtinadine A and Its Derivatives as Novel Antiviral and Anti-Phytopathogenic-Fungus Agents

Plant diseases caused by viruses and fungi have a serious impact on the quality and yield of crops, endangering food security. The use of new, green, and efficient pesticides is an important strategy to increase crop output and deal with the food crisis. Ideally, the best pesticide innovation strategy is to find and use active compounds from natural products. Here, we took the marine natural product hyrtinadine A as the lead compound, and designed, synthesized, and systematically investigated a series of its derivatives for their antiviral and antifungal activities. Compound 8a was found to have excellent antiviral activity against the tobacco mosaic virus (TMV) (inactivation inhibitory effect of 55%/500 μg/mL and 19%/100 μg/mL, curative inhibitory effect of 52%/500 μg/mL and 22%/100 μg/mL, and protection inhibitory effect of 57%/500 μg/mL and 26%/100 μg/mL) and emerged as a novel antiviral candidate. These compound derivatives displayed broad-spectrum fungicidal activities against 14 kinds of phytopathogenic fungi at 50 μg/mL and the antifungal activities of compounds 5c, 5g, 6a, and 6e against Rhizoctonia cerealis are higher than that of the commercial fungicide chlorothalonil. Therefore, this study could lay a foundation for the application of hyrtinadine A derivatives in plant protection.

Disinfection procedure for stem cuttings and in vitro production of axillary buds for the Persian lime sanitation

The research work covered the in vitro establishment of Persian lime nodal segments using a twig disinfection protocol, and their culture on Murashige and Skoog (MS) culture media supplemented with antibiotics (Estrepto-Ler® and Rifampicin) and fungicide (Chlorothalonil). The axillary buds production was performed cultured the nodal segments without contamination signs on MS culture media enriched with two cytokinins (6-BAP and Kinetin) at different concentrations. Results showed that 52 % of the nodal segments did not show signs of in vitro contamination when the twig submerged in 20% chlorine for 15 min during disinfection process and nodal segments were grown in MS culture medium supplemented with 2 mg L-1 of Rifampicin and fungicide Chlorothalonil. Interestingly, MS culture medium enriched with 6-BAP (0.5 mg L-1) + Kinetin (0.5 mg L-1) turned out to be the best combination to achieve that 78 % of nodal segments promoted 1 to 2 axillary buds.

Exposure assessment for pesticide residues in agricultural products consumed in the Republic of Korea during 2016-2020.

Pesticide residues in food comprise compounds such as insecticides, fungicides, herbicides, miticides, and plant activators. The insecticides diazinon (O, O-diethyl O-2-isopropyl-6-methylpyrimidin-4-yl phosphorothioate) and malathion (O, O-dimethyl dithiophosphate of diethyl-mercaptosuccinate) are classified as probably carcinogenic (Group 2A) and the fungicides chlorothalonil (2,4,5,6-tetrachloro-1,3-benzenedicarbonitrile) and hexachlorobenzene (pentachlophenyl chloride) as possibly carcinogenic to humans (Group 2B) by the International Agency for Research on Cancer under the World Health Organization. In this study, gas chromatographic and gas chromatography-tandem mass spectrometric analyses were used to determine the concentrations of pesticide residues in agricultural products and assess the effects of chronic human exposure to pesticide residues through the consumption of agricultural products during 2018-2020. Food consumption data were obtained from the Korea National Health and Nutrition Examination Survey of 2016-2018. The chronic exposures determined using mean consumption data for the whole population and mean concentrations of the pesticide residues were 5.15E-11 to 2.08E-05 [lower bound (LB)] and 2.41E-07 to 4.69E-05 mg/kg bw/day [upper bound (UB)], corresponding to 0.00012-2.16% of the hazard index (HA). Exposures to pesticide residues, calculated using the 95th percentile of the consumption data, were 0-8.76E-05 (LB) and 9.26E-07 to 1.56E-04 mg/kg bw/day (UB), corresponding to 0.00045-9.41% of the HA. Based on the result of current exposure assessment, it could be considered that the pesticide residues in agricultural products are properly controlled by the regulatory authorities.

Discovery of Novel Quinazoline-2-Aminothiazole Hybrids Containing a 4-Piperidinylamide Linker as Potential Fungicides against the Phytopathogenic Fungus Rhizoctonia solani.

A total of 29 novel quinazoline-2-aminothiazole hybrids containing a 4-piperidinylamide linker were designed, synthesized, and evaluated for their anti-microbial properties against phytopathogenic fungi and bacteria of agricultural importance. The anti-fungal assays indicated that some of the target compounds exhibited excellent inhibitory effects in vitro against Rhizoctonia solani. For example, 11 compounds within this series (including 4a, 4g, 4h, 4j, 4o, 4s, 4t, 4u, 4v, 4y, and 4b') were found to possess EC50 values (effective concentration for 50% activity) ranging from 0.42 to 2.05 μg/mL against this pathogen. In particular, compound 4y with a 2-chloro-6-fluorophenyl substituent displayed a potent anti-R. solani efficacy with EC50 = 0.42 μg/mL, nearly threefold more effective than the commercialized fungicide Chlorothalonil (EC50 = 1.20 μg/mL) and also slightly superior to the other fungicide Carbendazim (EC50 = 0.53 μg/mL). Moreover, compound 4y could efficiently inhibit the growth of R. solani in vivo on the potted rice plants, displaying an impressive protection efficacy of 82.3% at 200 μg/mL, better than those of the fungicides Carbendazim (69.8%) and Chlorothalonil (48.9%). Finally, the mechanistic studies showed that compound 4y exerted its anti-fungal effects by altering the mycelial morphology, increasing the cell membrane permeability, and destroying the cell membrane integrity. On the other hand, some compounds demonstrated good anti-bacterial effects in vitro against Xanthomonas oryzae pv. oryzae (Xoo). Overall, the presented results implied that 4-piperidinylamide-bridged quinazoline-2-aminothiazole hybrids held the promise of acting as lead compounds for developing more efficient fungicides to control R. solani.

Fungicides have transgenerational effects on Rhopalosiphum padi but not their endosymbionts.

While several agricultural fungicides are known to directly affect invertebrate pests, including aphids, the mechanisms involved are often unknown. One hypothesis is that fungicides with antibacterial activity suppress bacterial endosymbionts present in aphids which are important for aphid survival. Endosymbiont-related effects are expected to be transgenerational, given that these bacteria are maternally inherited. Here, we test for these associations using three fungicides (chlorothalonil, pyraclostrobin and trifloxystrobin) against the bird cherry-oat aphid, Rhopalosiphum padi, using a microinjected strain that carried both the primary endosymbiont Buchnera and the secondary endosymbiont Rickettsiella. We show that the fungicide chlorothalonil did not cause an immediate effect on aphid survival, whereas both strobilurin fungicides (pyraclostrobin and trifloxystrobin) decreased survival after 48 h exposure. However, chlorothalonil substantially reduced the lifespan and fecundity of the F1 generation. Trifloxystrobin also reduced the lifespan and fecundity of F1 offspring, however, pyraclostrobin did not affect these traits. None of the fungicides consistently altered the density of Buchnera or Rickettsiella in whole aphids. Our results suggest fungicides have sublethal impacts on R. padi that are not fully realized until the generation after exposure, and these sublethal impacts are not associated with the density of endosymbionts harbored by R. padi. However, we cannot rule out other effects of fungicides on endosymbionts that might influence fitness, like changes in their tissue distribution. We discuss these results within the context of fungicidal effects on aphid suppression across generations and point to potential field applications. © 2022 Society of Chemical Industry.

Assessing availability of European plant protection product data: an example evaluating basic area treated.

Besides the benefits of plant protection products (PPPs) for agricultural production, there is an increasing acknowledgement of the associated potential environmental risks. Here, we examine the feasibility of summarizing the extent of PPP usage at the country level, using Ireland as a case study, as well as at the European level. We used the area over which PPPs are applied (basic area) as an example variable that is relevant to initially assess the geographic extent of environmental risk. In Irish agricultural systems, which are primarily grass-based, herbicides fluroxypyr and glyphosate are the most widely applied active substances (ASs) in terms of basic area, followed by the fungicides chlorothalonil and prothioconazole that are closely associated with arable crops. Although all EU countries are subject to Regulation (EC) No 1185/2009, which sets the obligation of PPP usage data reporting at the national level, we only found usable data that met our criteria for Estonia, Germany, Finland, and Spain (4 of 30 countries reviewed). Overall, the most widely applied fungicide and herbicide in terms of basic area were prothioconazole (20%, 7% and 5% of national cultivated areas of Germany, Estonia and Ireland) and glyphosate (11%, 8% and 5% of national cultivated areas of Spain, Estonia and Ireland) respectively, although evaluations using application frequency may result in the observation of different trends. Several recommendations are proposed to tackle current data gaps and deficiencies in accessibility and usability of pesticide usage data across the EU in order to better inform environmental risk assessment and promote evidence-based policymaking.

Antifungal Activities of Pure and ZnO-Encapsulated Essential Oil of Zataria multiflora on Alternaria solani as the Pathogenic Agent of Tomato Early Blight Disease.

The utilization of plant essential oils (EOs) and nanomaterials due to their safety compared with synthetic chemicals has been considered in the management of plant diseases. In this study, the inhibitory effects of Zataria multiflora, Nepeta haussknechtii, Artemisia sieberi, and Citrus aurantifolia EOs in pure and Zinc Oxide (ZnO) nanocapsulated formulations were evaluated on the mycelial growth of Alternaria solani to find a suitable alternative for synthetic chemicals. The crystal structure and morphological properties of the fabricated nanomaterials were assessed via X-ray diffraction (XRD) and scanning electron microscope (SEM) analyses. The textural features of the prepared nanoparticles were investigated with Brunauer–Emmett–Teller (BET) analysis, and the presence of elements in the samples was studied with energy-dispersive X-ray (EDX) technique. The mycelial growth inhibitory (MGI) was performed in the laboratory by mixing with potato dextrose agar (PDA) medium at concentrations of 100, 300, 600, 1,000, 1,500, and 2,000 ppm. Based on the results, major differences were monitored between different concentrations. At the highest studied concentration, the inhibition of Z. multiflora EO was 100%, which was 43.20, 42.37, and 21.19% for N. haussknechtii, A. sieberi, and C. aurantifolia, respectively, and the inhibition of their nanocapsules was 100, 51.32, 55.23, and 26.58%, respectively. In the greenhouse study, Z. multiflora EO and its nanocapsule (ZnO-ZmEO) were compared with the ZnO and chlorothalonil fungicide based on the highest inhibitory of Z. multiflora in vitro. The highest antifungal effect was related to the ZnO-ZmEO by 53.33%. Therefore, the ZnO-ZmEO formulation can be recommended as a biofungicide for managing and controlling tomato early blight disease after further research.

Fungicides and bees: a review of exposure and risk.

Fungicides account for more than 35% of the global pesticide market and their use is predicted to increase in the future. While fungicides are commonly applied during bloom when bees are likely foraging on crops, whether real-world exposure to these chemicals - alone or in combination with other stressors - constitutes a threat to the health of bees is still the subject of great uncertainty. The first step in estimating the risks of exposure to fungicides for bees is to understand how and to what extent bees are exposed to these active ingredients. Here we review the current knowledge that exists about exposure to fungicides that bees experience in the field, and link quantitative data on exposure to acute and chronic risk of lethal endpoints for honey bees (Apis mellifera). From the 702 publications we screened, 76 studies contained quantitative data on residue detections in honey bee matrices, and a further 47 provided qualitative information about exposure for a range of bee taxa through various routes. We compiled data for 90 fungicides and metabolites that have been detected in honey, beebread, pollen, beeswax, and the bodies of honey bees. The risks posed to honey bees by fungicide residues was estimated through the EPA Risk Quotient (RQ) approach. Based on residue concentrations detected in honey and pollen/beebread, none of the reported fungicides exceeded the levels of concern (LOC) set by regulatory agencies for acute risk, while 3 and 12 fungicides exceeded the European Food Safety Authority (EFSA) chronic LOC for honey bees and wild bees, respectively. When considering exposure to all bees, fungicides of most concern include many broad-spectrum systemic fungicides, as well as the widely used broad-spectrum contact fungicide chlorothalonil. In addition to providing a detailed overview of the frequency and extent of fungicide residue detections in the bee environment, we identified important research gaps and suggest future directions to move towards a more comprehensive understanding and mitigation of the risks of exposure to fungicides for bees, including synergistic risks of co-exposure to fungicides and other pesticides or pathogens.

Virulence of native isolates of entomopathogenic fungi (Hypocreales) against the “sweetpotato whitefly” Bemisia tabaci (Hemiptera: Aleyrodidae), including the effects of temperature and fungicides

Hypocrella, Moelleriella and related species in the Hypocreales (Ascomycota, Sordariomycetes) cause epizootics of whiteflies and scale insects in nature. However, studies on their host specificity, virulence, infection cycles, optimal development under laboratory conditions, and compatibility with other control methods, are unexplored for most species. Under laboratory conditions, the virulence of several isolates of field-collected hypocrealean fungi (Hypocrella, Moelleriella, Regiocrella, and Verticillium) was determined on Bemisia tabaci eggs and 4th instar nymphs. In addition to virulence, the effect of temperature and two commercial fungicides on growth rates and germination of the isolates was evaluated. None of the isolates infected the eggs, while M. libera, M. ochracea, and M. turbinata caused high nymphal mortality. Moelleriella libera was the most virulent isolate. At all temperatures, M. libera, Regiocrella sp. (P17H20), and Verticillium cf. pseudohemipterigenum had the highest germination and growth rates. The optimal growth temperature depended on the isolate, but at 23 °C and 25 °C, the probability of spore germination was higher for most isolates. Finally, the fungicides azoxystrobin and chlorothalonil inhibited growth rates and conidial germination at 24 and 48 h of exposure. This research produces vital knowledge on the virulence and infection cycles of poorly studied native species of entomopathogenic fungi. In addition, the results provide information on the optimal temperature for development in laboratory conditions and susceptibility to fungicides, which could contribute to future biological control strategies.

Modeling Pesticide Effects on Multiple Threatened and Endangered Cyprinid Fish Species: The Role of Life-History Traits and Ecology

Mechanistic models are invaluable in ecological risk assessment (ERA) because they facilitate extrapolation of organism-level effects to population-level effects while accounting for species life history, ecology, and vulnerability. In this work, we developed a model framework to compare the potential effects of the fungicide chlorothalonil across four listed species of cyprinid fish and explore species-specific traits of importance at the population level. The model is an agent-based model based on the dynamic energy budget theory. Toxicokinetic-toxicodynamic sub-models were used for representing direct effects, whereas indirect effects were described by decreasing food availability. Exposure profiles were constructed based on hydroxychlorothalonil, given the relatively short half-life of parent chlorothalonil. Different exposure magnification factors were required to achieve a comparable population decrease across species. In particular, those species producing fewer eggs and with shorter lifespans appeared to be more vulnerable. Moreover, sequentially adding effect sub-models resulted in different outcomes depending on the interplay of life-history traits and density-dependent compensation effects. We conclude by stressing the importance of using models in ERA to account for species-specific characteristics and ecology, especially when dealing with listed species and in accordance with the necessity of reducing animal testing.

Design and synthesis of novel 2,2-dimethylchromene derivatives as potential antifungal agents.

In order to find novel environment-friendly and effective antifungal agents, four series of 2,2-dimethyl-2H-chromene derivatives were designed, synthesized and characterized by spectroscopic analysis. The antifungal activities of all the target compounds against nine phytopathogenic fungi were evaluated in vitro. Preliminary results indicated that most of the target compounds exhibited obvious antifungal activity at the concentration of 50μg/mL. Among them, compound 4j displayed more promising antifungal potency against Fusarium solani, Pyricularia oryzae, Alternaria brassicae, Valsa mali and Alternaria alternata strains than the two commercially available fungicides chlorothalonil and hymexazol, with the corresponding EC50 values of 6.3, 7.7, 7.1, 7.5, 4.0μg/mL, respectively. Moreover, the cell experiments results suggested that the target compounds had low cytotoxicity to the PC12 cell. This research will provide theoretical basis for the future application of 2,2-dimethyl-2H-chromenes as botanical fungicides in agriculture. Four series of novel, potent and low-toxicity 2,2-dimethyl-2H-chromene derivatives were designed and synthesized as agricultural antifungal agents. The in vitro antifungal experiments showed that compound 4j exhibited higher antifungal efficacy against five strains than the two commercially-available fungicides chlorothalonil and hymexazol.

Synthesis, Antifungal Activity and 3D-QSAR Study of Novel Anisaldehyde-Derived Amide-Thiourea Compounds.

Succinate dehydrogenase (SDH) is an important target enzyme for designing agricultural chemical fungicides. In order to explore novel natural product-based antifungal agents, twenty-one unreported anisaldehyde-derived amide-thiourea compounds were designed and synthesized using the principle of active splicing, and structurally confirmed by 1 H-NMR, 13 C-NMR, ESI-MS, FT-IR, and element analysis. In vitro antifungal activity of the target compounds was evaluated by the agar dilution method. The results showed that some target compounds exhibited better or comparable antifungal activity than that of the commercial fungicide chlorothalonil, in which compounds 5c, 5o, and 5r displayed excellent antifungal activity of 92.6 %, 92.6 % and 99.1 % against P. piricola, respectively, better than that of the positive control. In addition, 3D-QSAR analysis was carried out by the CoMFA method to reveal the relationship between the structures of the target compounds and their inhibitory activities. The simulative binding mode of the target compounds and SDH was also studied by molecular docking.