Non-chemical Methods Research Articles

Deciphering Molecular Determinants Underlying Penicillium digitatum's Response to Biological and Chemical Antifungal Agents by Tandem Mass Tag (TMT)-Based High-Resolution LC-MS/MS.

Penicillium digitatum is a widespread pathogen responsible for the postharvest decay of citrus, one of the most economically important crops worldwide. Currently, chemical fungicides are still the main strategy to control the green mould disease caused by the fungus. However, the increasing selection and proliferation of fungicide-resistant strains require more efforts to explore new alternatives acting via new or unexplored mechanisms for postharvest disease management. To date, several non-chemical compounds have been investigated for the control of fungal pathogens. In this scenario, understanding the molecular determinants underlying P. digitatum’s response to biological and chemical antifungals may help in the development of safer and more effective non-chemical control methods. In this work, a proteomic approach based on isobaric labelling and a nanoLC tandem mass spectrometry approach was used to investigate molecular changes associated with P. digitatum’s response to treatments with α-sarcin and beetin 27 (BE27), two proteins endowed with antifungal activity. The outcomes of treatments with these biological agents were then compared with those triggered by the commonly used chemical fungicide thiabendazole (TBZ). Our results showed that differentially expressed proteins mainly include cell wall-degrading enzymes, proteins involved in stress response, antioxidant and detoxification mechanisms and metabolic processes such as thiamine biosynthesis. Interestingly, specific modulations in response to protein toxins treatments were observed for a subset of proteins. Deciphering the inhibitory mechanisms of biofungicides and chemical compounds, together with understanding their effects on the fungal physiology, will provide a new direction for improving the efficacy of novel antifungal formulations and developing new control strategies.

Integrirani pristup zaštiti mrkve od dva značajna štetnika – mrkvine muhe i mrkvine cistolike nematode

Carrots are among the top ten vegetable crops in the world, with an annual world production of about 428 million tonnes grown on about 11.5 million hectares. The investment per unit area is not high and with good cultivation techniques yields of up to 50 t/ha can be achieved, together with major economic benefits from winter cultivation. During the growing season, carrots are susceptible to numerous pests. The most important are the carrot root fly (Psila rosae, Fabricius), whose root-feeding fly larvae reside in the soil or plant tissue, and the carrot cyst nematode (Heterodera carotae Jones), which is responsible for the decline of carrots in many countries and requires strict sanitation measures if crops are infected. As insecticides become less available in Europe, the appropriate use of non-chemical methods in integrated pest management (IPM) needs to be emphasised, highlighting the importance of developing new tolerant varieties. This review addresses the approaches to monitor and predict the occurrence of two important carrot pests and the main control measures according to the strategies of IPM.

Microcapsules with slow-release characteristics prepared by soluble small molecular starch fractions through the spray drying method

The utilization of starch in the food and medical industry can be facilitated by using new non-chemical methods to make starch the only wall material to encapsulate microcapsules. In this study, soluble small molecular fraction obtained from corn starch by gelatinization and centrifugation methods and commercial soluble starch were used independently to encapsulate oil under the condition that wall material and core material were 2:1. Molecular weight of these starch fractions was measured firstly. The peak molecular weight of the soluble small molecular fraction of corn starch and commercial soluble starch was 3.537 × 105 Da and 2.720 × 104 Da, respectively. Basic physicochemical characteristics and application characteristics of the microcapsules were then characterized and compared. The soluble small molecular fraction of corn starch encapsulated microcapsule and the commercial soluble starch encapsulated microcapsule had high encapsulation efficiency (higher than 88%), high boiling water solubility (higher than 74%), high rehydration stability (higher than 2 h). Most importantly, the encapsulated oil of these microcapsules could be slowly released under the action of α-amylase and amyloglucosidase. Overall, both the soluble small molecular fraction of corn starch and commercial soluble starch could be used as microcapsule wall materials and might have great application potential in food and medicine.

Susceptibility levels of field populations of Frankliniella occidentalis (Thysanoptera: Thripidae) to seven insecticides in China

The western flower thrips, Frankliniella occidentalis (Pergande), is a widespread and serious agricultural pest. Controlling F. occidentalis is difficult because it rapidly develops resistance to many insecticides. To assess the development status (2016–2018) of insecticide resistance of F. occidentalis and to improve resistance management, we determined the susceptibility levels of field populations in China to seven commonly used insecticides (spinosad, spinetoram, abamectin, emamectin-benzoate, chlorfenapyr, thiamethoxam and β-cypermethrin). The results showed that F. occidentalis developed resistance to spinosad, spinetoram, abamectin, emamectin-benzoate, thiamethoxam and β-cypermethrin, and except for spinetoram and thiamethoxam, the resistance of southern populations to the other four insecticides was higher than that of northern populations. A population from Changping, Beijing, had the highest resistance level and its spinetoram resistance ratio was 16,972 (susceptible reference strain LC50 = 0.001 mg/L). Susceptibility to spinosad and abamectin varied greatly among the populations (LC50 values ranged from 0.006 mg/L to 9.943 mg/L for spinosad and from 1.071 mg/L to 939.410 mg/L for abamectin). The use of non-chemical control methods and IPM should be considered for the sustainable management of F. occidentalis populations.

Surface Coatings and Treatments for Controlled Hydrate Formation: A Mini Review

Gas hydrates (GHs) are known to pose serious flow assurance challenges for the oil and gas industry. Neverthless, over the last few decades, gas hydrates-based technology has been explored for various energy- and environmentally related applications. For both applications, a controlled formation of GHs is desired. Management of hydrate formation by allowing them to form within the pipelines in a controlled form over their complete mitigation is preferred. Moreover, environmental, benign, non-chemical methods to accelerate the rate of hydrate formation are in demand. This review focused on the progress made in the last decade on the use of various surface coatings and treatments to control the hydrate formation at atmospheric pressure and in realistic conditions of high pressure. It can be inferred that both surface chemistry (hydrophobicity/hydrophilicity) and surface morphology play a significant role in deciding the hydrate adhesion on a given surface.

Modelling the Effect and Variability of Integrated Weed Management of Phalaris minor in Rice-Wheat Cropping Systems in Northern India

Phalaris minor Retz. (littleseed canarygrass) is the most problematic and herbicide-resistant weed in the rice-wheat cropping system in India. As such, it poses a severe threat to wheat yield and food security. A number of herbicidal and agronomic practices have been identified for the effective control of P. minor. These include crop rotation, crop establishment methods, herbicide spray technology, sowing time, weed seed harvest and effective herbicide mixtures. A population model of P. minor was built based on the life cycle of the species, herbicide resistance mechanisms and the effects of weed control practices. The model simulated the interactions of these factors and provided the best management recommendations for sustainably controlling this noxious weed species. Model results indicate that integration of chemical and non-chemical control methods was the most effective and sustainable strategy. For example, the integration of a happy seeder (a tractor-mounted mulching and sowing machine) with an effective post-emergence herbicide reduced the probability of weed control failure by 32% compared to the scenario with a rotavator and the same herbicide. Similarly, more conventional crop establishment methods such as a rotavator and conventional tillage could be accompanied by pre- or post-emergence applications of herbicide mixtures. Adoption of good herbicide spray technology and weed seed harvest delayed the onset of resistance evolution by up to four years. Furthermore, effective crop rotation such as the inclusion of sugarcane in place of rice in the summer season reduced the risk of resistance evolution by 31% within the 10 year simulation period. In addition to the scenarios using representative parameter values, the variability of model predictions was investigated based on some field experiments. The model provided a powerful tool for promoting Integrated Weed Management and the sustainable use of herbicides. Pragmatic ways of dealing with uncertainty in model prediction are discussed.

Root Rot Disease Incited by Macrophomina phaseolina in Arid Legumes and their Management: A Review

Macrophomina phaseolina (Tassi) Goid. is a soil- and seed-borne pathogen that causes charcoal rot and various rots and blights of more than 500 crop species. Dry root rot (DRR) also called as charcoal rot which causes yield loss ranged from 25-48 per cent. The pathogen is necrotroph and infects a wide range of crops. It is observed that mycelium of M. phaseolina in cotyledons, plumule and radicle, in the naturally infected seeds of mungbean and cowpea. The disease symptoms are clearly visible from the time of emergence and can be evaluated at various stages of development of the plant. The mechanical plugging of the xylem vessels by microsclerotia, toxin production, enzymatic action and mechanical pressure during penetration lead to disease development. Management of M. phaseolina aim to reduce the number of sclerotia in soil or to minimize the contact of the inoculum and the host. Soil solarization can be a cost-effective method for management of soil borne diseases. Disease suppression by biocontrol agents such as Trichoderma harzianum, T. viride and Bacillus subtilis are the sustained manifestation of interactions among the plant, the pathogen, the biocontrol agent, the microbial community on and around the plant and the physical environment and considerably inhibited growth of M. phaseolina. Essential oils and plant extracts contain a multitude of bioactive substances against fungi, bacteria and nematodes. It has been reported that neem oil, turmeric and garlic was effective against M. phaseolina in in vitro condition. Chemical control is an effective method when seed treatment and foliar spray of carbendazim, topsin M-70, captan, thiram, mancozeb, copper oxychloride against root rot and leaf blight (Macrophomina phaseolina) topsin M-70, captan, thiram, mancozeb, copper oxychloride against root rot (Macrophomina phaseolina). As non-chemical alternative methods can be time-consuming and less effective against soilborne plant pathogens. Chemical control is an effective method of controlling some soilborne diseases in agricultural crops. Varoius workers are reported compatibility of biocontrol agents with fungicides and found that Carbendazim and biocontrol agents Trichoderma viride, T. harizianum were found effective under in vitro and pot condition.

Evaluation of the emergency authorisations granted by Member State Germany for plant protection products containing thiamethoxam

The European Food Safety Authority (EFSA) was requested by the European Commission to provide technical assistance in accordance with Article 53(2) of Regulation (EC) No 1107/2009 to examine the emergency authorisations granted in 2020 by the competent national authority in Germany for plant protection products containing the neonicotinoid active substances (a.s.) clothianidin, imidacloprid, or thiamethoxam for uses on sugar beet which were restricted when all outdoor uses were prohibited in May 2018. EFSA was asked to assess whether the granting of this emergency authorisation and its wide scope was necessary because of danger which cannot be contained by any other reasonable means. In this context, EFSA collected and evaluated the information in relation to the emergency authorisation for thiamethoxam in Germany in line with the EFSA insecticide protocol developed in the framework of a mandate concerning the application of Article 4(7) of Regulation (EC) No 1107/2009. The current technical report summarises the outcome of the evaluation of one crop/pest combination considered in Germany in 2020. The evaluation demonstrated that for the sugar beet/aphids as virus vectors combination no sufficient alternative active substance to thiamethoxam is currently authorised in Germany, in order to provide an alternative mode of action (MoA). The evaluation included an assessment of non-insecticide alternatives for the presented uses. Four non-chemical methods are available, but they are only moderately effective or non-effective.

Evaluation of the emergency authorisations granted by Member State France for plant protection products containing imidacloprid or thiamethoxam

The European Food Safety Authority (EFSA) was requested by the European Commission to provide technical assistance in accordance with Article 53(2) of Regulation (EC) No 1107/2009 to examine the emergency authorisations granted in 2021 by the competent national authority in France for plant protection products containing the neonicotinoid active substances (a.s.) clothianidin, imidacloprid or thiamethoxam for uses on sugar beet which were restricted when all outdoor uses were prohibited in May 2018. EFSA was asked to assess whether the granting of this emergency authorisation and its wide scope was necessary because of danger which cannot be contained by any other reasonable means. In this context, EFSA collected and evaluated the information in relation to the emergency authorisation for imidacloprid and thiamethoxam in France in line with the EFSA insecticide protocol developed in the framework of a mandate concerning the application of Article 4(7) of Regulation (EC) No 1107/2009. The current technical report summarises the outcome of the evaluation of four crop/pest combinations considered in France in 2021.The evaluation demonstrated that for the examined pests (Aphis fabae, Aulacorthum solani, Macrosiphum euphorbiae, Myzus ascalonicus and Myzus persicae) vectors of the quarantine virus BYV (beet yellows virus) no alternative active substance to neonicotinoids is currently authorised in France on sugar beet for seed treatment. Foliar spraying applications against the aphid vectors of BYV can’t be considered as sufficient alternative method to the seed treatment, because they can't control the early proliferation of aphids. The evaluation included an assessment of non-insecticide alternatives for the presented uses. Seven non-chemical methods are available, but they are only moderately effective. For this reason, EFSA concluded when considering the methodology of the EFSA Article 4(7) insecticide protocol, that the emergency authorisations were scientifically supported.

Updated peer review of the pesticide risk assessment of the active substance asulam (variant evaluated asulam-sodium).

The conclusions of EFSA following the peer review of the initial risk assessments carried out by the competent authority of the rapporteur Member State, the United Kingdom (France after Brexit), for the pesticide active substance asulam and the assessment of applications for maximum residue levels (MRLs) are reported. The context of the peer review was that required by Regulation (EC) No 1107/2009 of the European Parliament and of the Council. The conclusions were reached on the basis of the evaluation of the representative use of asulam (variant evaluated asulam‐sodium) as a herbicide on spinach and tulip, hyacinth and lily for bulb production. MRLs were assessed in spinach. The conclusions were updated with regard to the endocrine‐disrupting properties following a mandate received from the European Commission in February 2019. In addition, the peer review also provided considerations on whether exposure to humans and the environment from the representative uses of asulam‐sodium can be considered negligible, taking into account the European Commission's draft guidance on this topic. The reliable endpoints, appropriate for use in regulatory risk assessment and the proposed MRLs, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified. An evaluation of data concerning the necessity of asulam‐sodium as a herbicide to control a serious danger to plant health which cannot be contained by other available means, including non‐chemical methods is also presented.

Combined effects of temperature and population density of Myzus persicae (Hemiptera: Aphididae) on consumption by Harmonia conformis (Coleoptera: Coccinellidae).

The green peach aphid Myzus persicae is a major pest of many crops around the world, causing direct damage and acting as a vector for several viruses. This species has developed resistance to several insecticides, resulting in a greater emphasis on nonchemical methods of control. The aphidophagous ladybird, Harmonia conformis, is one of several species to predate on this pest. H. conformis is native to Australia, but has been exported to New Zealand, the USA and Europe as a biological control agent for horticultural pests and has now become established in several regions. Despite these introductions, the ability of H. conformis to predate on M. persicae has not yet been quantified. To address this knowledge gap, we measured the potential success of this natural enemy and its functional response over a range of temperatures. H. conformis displayed a Type II response over all temperatures assessed. The peak temperature for voracity was 32 °C, with a potential maximum daily predation rate of 204 aphids. Consumption of aphids by H. conformis on canola plants within a glasshouse was less than predicted from the laboratory-generated models. However, consumption increased significantly with increasing density of M. persicae. H. conformis can contribute markedly to aphid suppression and could be incorporated into integrated pest management systems which rely on natural enemies, particularly during spring when temperatures increase above 25 °C. Furthermore, it would also be an ideal candidate for augmentative releases. © 2021 Society of Chemical Industry.

A Simple Approach to Isolate Slow and Fast Cycling Organic Carbon Fractions in Central European Soils—Importance of Dispersion Method

Numerous approaches have been developed to isolate fast and slow cycling soil organic carbon (SOC) pools using physical and chemical fractionation. Most of these methods are complex, expensive, and time consuming and unsuited for high-throughput application, such as for regional scale assessments. For simpler and faster fractionation via particle size the key issue is the dispersion of soil. It is unclear how the initial dispersion of soil affects the turnover rates of isolated fractions. We investigated five commonly used dispersion methods using different intensities: shaking in water, shaking in water with glass beads, ultrasonication at 100 and 450 J ml−1 and sodium hexametaphosphate (Na-HMP). We used soils from long-term field experiments that included a change from C3 to C4 vegetation and adjacent control sites using δ13C isotope ratio mass spectrometry. We evaluated the degree of C3/C4 moieties of the fractions, mass and carbon recovery and reproducibility as well as the time expenditures of the dispersions, sieving and drying techniques to develop an efficient and cheap fractionation method. Our results indicate that ultrasonication as well as H2O treatment with and without glass beads resulted in fractions with different turnover. Moreover, isolation performances depended on soil texture. While the isolation of the fractions using water with and without glass beads was equivalent to ultrasonication in soils with low clay contents, these methods had limited potential for soils with high clay contents. Furthermore, treatment with water alone had less reproducible results than other tested methods. The SOC recovery was comparable and satisfactory amongst non-chemical dispersion methods and reached over 95% for each of these methods. The use of Na-HMP was unsuccessful due to high time expenditures and strong SOC leaching. We propose particle size fractionation combined with ultrasonic dispersion as a fast and highly reliable method to quantify slow and fast cycling SOC pools for a wide range of soil types and textures from agricultural sites in central Europe.

Productivity enhancement of sweet corn (Zea mays) through organic weed management practices

Area under organic cultivation of crops is increasing not only in India but also in Rajasthan as well. Weeds are often recognized as the most serious threat to organic crop production and fear of ineffective weed control is often perceived by farmers as one of the major obstacles to conversion from conventional to organic farming. A two years field experiment was conducted to study the non-chemical methods of weed management in organically grown sweet corn (Zea mays L.) during 2018-19. Among the 12 organic weed management treatments, soil solarization + plastic mulch at sowing resulted in significantly lower weed density, weed dry matter, higher yield attributes and yield over other treatments but at par with stale seed bed preparation + plastic mulch at sowing during both the years. Stale seed bed preparation + plastic mulch at sowing gave highest net returns and benefit-cost ratio of ₹ 62746 and 105201 and 1.62 and 2.35, respectively followed by weedy check, which gave the net returns and benefit: cost ratio of ₹ 16093, 26858 and 0.96 and 2.18, respectively.

Peer review of the pesticide risk assessment of the active substance benthiavalicarb (variant assessed benthiavalicarb‐isopropyl)

The conclusions of the EFSA following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State, Poland, and co‐rapporteur Member State, France, for the pesticide active substance benthiavalicarb (variant assessed benthiavalicarb‐isopropyl) are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012, as amended by Commission Implementing Regulation (EU) No 2018/1659. The conclusions were reached on the basis of the evaluation of the representative use of benthiavalicarb‐isopropyl as a fungicide on potato (field use). The peer review also provided considerations on whether exposure to humans and the environment from the representative uses of benthiavalicarb‐isopropyl can be considered negligible, taking into account the European Commission's draft guidance on this topic. The reliable end points, appropriate for use in regulatory risk assessment, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified. An evaluation of data concerning the necessity of benthiavalicarb‐isopropyl as a fungicide to control a serious danger to plant health which cannot be contained by other available means, including non‐chemical methods, is also presented.

Ecoengineering Solutions for the Impairment of Spreading and Growth of Invasive Spartina patens in Mediterranean Salt Marshes

The invasion of natural communities by non-indigenous species represents one of the most serious threats to biodiversity. Understanding the ecophysiology of invasive species can provide insights into potential physiological handicaps relative to native species. By doing so, we can leverage the development of ecoengineering solutions for the removal of non-indigenous species, preferably using non-chemical methods. Spartina patens is a known invasive species of cordgrass aggressively proliferating in Mediterranean salt marshes, producing impenetrable monospecific stands. As its occurrence is delimited by the upper high tide water level, we hypothesized that S. patens is intolerant to waterlogging. Therefore, we developed a field experiment where strands of S. patens were kept waterlogged over the entire tidal cycle for 30 days. At the end of the experimental period, plants in the trial plots exhibited severe stress symptoms at different physiological levels compared with control plots (no intervention). At the photobiological level, intervened plants exhibited lower efficiency in producing chemical energy from light, whilst at the biochemical level waterlogging impaired the antioxidant system and increased lipid peroxidation products. Furthermore, the application of chlorophyll a pulse amplitude modulated (PAM) fluorometry, a non-invasive technique, allowed us to evaluate the effectiveness of the implemented measures, being the tool that provided the best separation between the control and intervened population. Considering the physiological traits observed here, ecoengineering solutions based on increased waterlogging of S. patens stands, can be a low-cost and efficient measure to reduce the spreading and growth of this invasive species in the Mediterranean and other salt marshes worldwide with little disturbance.

Peer review of the pesticide risk assessment of the active substance clofentezine.

The conclusions of the EFSA following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State, Spain, and co‐rapporteur Member State, the Netherlands, for the pesticide active substance clofentezine and the assessment of applications for maximum residue levels (MRLs) are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012, as amended by Commission Implementing Regulation (EU) No 2018/1659. The conclusions were reached on the basis of the evaluation of the representative use of clofentezine as an acaricide on citrus, pome fruits, strawberry, tomatoes and aubergine. The peer review also provided considerations on whether exposure to humans and the environment from the representative uses of clofentezine can be considered negligible, taking into account the European Commission's draft guidance on this topic. The reliable end points, appropriate for use in regulatory risk assessment, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified. An evaluation of data concerning the necessity of clofentezine as acaricide to control a serious danger to plant health which cannot be contained by other available means, including non‐chemical methods is also presented.

Development of a pest threshold decision support system for minimising damage to winter wheat from wheat bulb fly, Delia coarctata

AbstractWheat bulb fly, Delia coarctata, is an important pest of winter wheat in the UK, causing significant damage of up to 4 t/ha. Accepted population thresholds for D. coarctata are 250 eggs/m2 for crops sown up to the end of October and 100 eggs/m2 for crops sown from November. Fields with populations of D. coarctata that exceed the thresholds are at higher risk of experiencing economically damaging infestations. In the UK, recent withdrawal of insecticides means that only a seed treatment (Signal 300 ES) is available for chemical control of D. coarctata; however, this is only effective for late‐sown crops and accurate estimations of annual population levels are required to ensure a seed treatment is applied if needed. As a result of the lack of postdrilling control strategies, the management of D. coarctata is becoming reliant on nonchemical methods of control. Control strategies that are effective in managing similar stem‐boring pests of wheat include sowing earlier and using higher seed rates to produce crops with greater pest tolerance. In this study, we develop two predictive models that can be used for integrated D. coarctata management. The first is an updated pest level prediction model that predicts D. coarctata populations from meteorological parameters with a predictive accuracy of 70%, a significant improvement on previous prediction models. Our second model predicts the maximum number of shoots for a winter wheat crop that would be expected at the terminal spikelet development stage. This shoot number model uses information about the thermal time from plant emergence to terminal spikelet, leaf phyllochron length, plant population and sowing date to predict the degree of tolerance a crop will have against D. coarctata. The shoot number model was calibrated against data collected from five field experiments and tested against data from four experiments. Model testing demonstrated that the shoot number model has a predictive accuracy of 65.7%. The foundation for a future decision support system using these models for the sustainable management of D. coarcata risk is described. It should be noted that these models represent a stepping‐stone towards a decision support system and that further model validation over a wider geographic range is required.

Effects of steam sterilization on reduction of fungal colony forming units, cannabinoids and terpene levels in medical cannabis inflorescences

Medical cannabis (MC) production is a rapidly expanding industry. Over the past ten years, many additional phytocannabinoids have been discovered and used for different purposes. MC was reported beneficial for the treatment of a variety of clinical conditions such as analgesia, multiple sclerosis, spinal cord injuries, Tourette's syndrome, epilepsy, glaucoma, Parkinson disease and more. Yet, there is still a major lack of research and knowledge related to MC plant diseases, both at the pre- and postharvest stages. Many of the fungi that infect MC, such as Aspergillus and Penicillium spp., are capable of producing mycotoxins that are carcinogenic, or otherwise harmful when consumed, and especially by those patients who suffer from a weakened immune system, causing invasive contamination in humans. Therefore, there are strict limits regarding the permitted levels of fungal colony forming units (CFU) in commercial MC inflorescences. Furthermore, the strict regulation on pesticide appliance application in MC cultivation exacerbates the problem. In order to meet the permitted CFU limit levels, there is a need for pesticide-free postharvest treatments relying on natural non-chemical methods. Thus, a decontamination approach is required that will not damage or significantly alter the chemical composition of the plant product. In this research, a new method for sterilization of MC inflorescences for reduction of fungal contaminantstes was assessed, without affecting the composition of plant secondary metabolites. Inflorescences were exposed to short pulses of steam (10, 15 and 20 s exposure) and CFU levels and plant chemical compositions, pre- and post-treatment, were evaluated. Steam treatments were very effective in reducing fungal colonization to below detection limits. The effect of these treatments on terpene profiles was minor, resulting mainly in the detection of certain terpenes that were not present in the untreated control. Steaming decreased cannabinoid concentrations as the treatment prolonged, although insignificantly. These results indicate that the steam sterilization method at the tested exposure periods was very effective in reducing CFU levels while preserving the initial molecular biochemical composition of the treated inflorescences.

Evaluation of stability and inactivation methods of SARS-CoV-2 in context of laboratory settings

The novel coronavirus SARS-CoV-2 is the causative agent of the acute respiratory disease COVID-19, which has become a global concern due to its rapid spread. Laboratory work with SARS-CoV-2 in a laboratory setting was rated to biosafety level 3 (BSL-3) biocontainment level. However, certain research applications in particular in molecular biology require incomplete denaturation of the proteins, which might cause safety issues handling contaminated samples. In this study, we evaluated lysis buffers that are commonly used in molecular biological laboratories for their ability to inactivate SARS-CoV-2. In addition, viral stability in cell culture media at 4 °C and on display glass and plastic surfaces used in laboratory environment was analyzed. Furthermore, we evaluated chemical and non-chemical inactivation methods including heat inactivation, UV-C light, addition of ethanol, acetone-methanol, and PFA, which might be used as a subsequent inactivation step in the case of insufficient inactivation. We infected susceptible Caco-2 and Vero cells with pre-treated SARS-CoV-2 and determined the tissue culture infection dose 50 (TCID50) using crystal violet staining and microscopy. In addition, lysates of infected cells and virus containing supernatant were subjected to RT-qPCR analysis. We have found that guanidine thiocyanate and most of the tested detergent containing lysis buffers were effective in inactivation of SARS-CoV-2, however, the M-PER lysis buffer containing a proprietary detergent failed to inactivate the virus. In conclusion, careful evaluation of the used inactivation methods is required especially for non-denaturing buffers. Additional inactivation steps might be necessary before removal of lysed viral samples from BSL-3.

Integrating mechanical treatment and biological control to improve field treatment efficiency on invasions

Projecting invasion treatment outcomes and determining controlling efficiency under various management strategies have important implications in field management. Different from herbicide usage that may cause environmental pollution and nontarget effects on native plants, nonchemical (i.e., mechanical) methods, such as mowing and hand weeding, have shown great targeted effectiveness on invasion. However, an interesting and important question that remains unclear is how to reduce the need for repeated applications of mechanical treatments. One possible approach is to integrate mechanical treatments with biological control agents, which can attack and limit invasion spread after being established in the field. We hypothesize that applying mechanical methods to remove invasive plants while establishing biological control agents, then using the established biological control agents to limit future regrowth of invasive plants, will decrease the use of mechanical treatments. To include vegetation dispersal, we developed a spatial modeling framework, using paired logistic equation models of both a resident native plant and an invasive plant, and a biological control agent, to capture the dynamics of native and invasive plants under different treatment scenarios. Specifically, we examined four factors, the initial application location of biological agents, their controlling efficiency, the treatment frequency (how often nonchemical treatment will be applied), and the areal extent of mechanical treatment. We found that explicitly targeted biological control agents showed significantly stronger controlling impacts on invasive plants than did nontargeted agents, whereas a higher treatment frequency could compensate for the drawback of untargeted treatment. Our results also suggested that adding mechanical treatment can further limit invasion spread with the cooperation of established biological control agents, and applying mechanical treatment in a lower frequency, but treating larger areas per time, is a more efficient approach than vice versa. We emphasize that a high biological control efficiency can continuously decrease the requirement of repeated treatment of nonchemical methods and maintain the invasive population at a low level. The model we developed here can be potentially extended and used by field managers on prioritizing controlling efforts to achieve a higher efficiency.