Fumigation Treatment Research Articles

Effect of Ammonia Fumigation Treatment on Wood Color and Chemical Composition

Betula alnoides was used as a test material to study the effect of ammonia fumigation treatment on wood color and chemical composition. The effects of concentration, temperature, and duration of ammonia fumigation on wood color were studied. The properties of the material were studied using contact angle measurements, X-ray diffraction, Fourier-transform infrared spectroscopy, and dynamic thermomechanical analysis. In general, the color difference of the wood increased with the concentration of ammonia used in the fumigation process, treatment temperature, and treatment duration. After ammonia fumigation treatment, the chemical composition of hydroxyl and carboxyl groups in the wood was reduced. We concluded that ammonia fumigation treatment decreased material wettability and dynamic mechanical rigidity and increased the degree of crystallinity in wood.

Combination of precooling with ozone fumigation or low fluctuation of temperature for the quality modifications of postharvest sweet cherries

The ozone fumigation device with the self-circulation function and the low-temperature fluctuation box with precise temperature control were, respectively, designed to study the effect of the combination of vacuum precooling with ozone fumigation or low-temperature fluctuation treatment in the quality modifications of sweet cherries during cold storage. The results showed that all the three treatments had a positive effect on quality maintenance. Although precooling combined with low-temperature fluctuation slightly damaged the fruit after 9 days of storage, the combination of precooling and ozone can better maintain the luster of the fruit and retain the content of total soluble solids, the titratable acid, and anthocyanin during the entire storage period. Meanwhile, it delayed fruit softening, inhibited the accumulation of malondialdehyde and activity of polyphenol oxidase. Additionally, the ultrastructure and cell wall material content indicated that ozone stress could induce shrinkage of stoma and maintain morphology of cell wall and cell structure. Practical applications Sweet cherries are delicious and juicy, but they have quite a short shelf life, limited edible period, and high cost of deep processing. Refrigeration, precooling, and ozone are effective measures to extend the shelf life of fruits and vegetables in the field of postharvest preservation. However, the large flow of personnel in the conventional walk-in cold storage results in low precooling efficiency and significant temperature fluctuations, which make the cherries perishable. In addition, ozone has been evaluated as a promising disinfectant for fresh fruits, which may be used to induce resistance to postharvest decay of fruits and vegetables. Thus, in this study, a combination of precooling with ozone fumigation or low-temperature fluctuation was used to explore the postharvest quality of sweet cherries. All results indicated that vacuum precooling combined with regular ozone fumigation treatment may be a promising technology for the preservation of sweet cherry fruit, which can effectively improve the storage quality.

Effect of interaction between pheromone traps and plant seeds of harmal, Peganum harmala, on lesser date moth, Batrachedra amydraula (Merck), in Basra Province

The lesser date moth, Batrachedra amydraula Merck is one of the most important pests affect date palm fruits, which cause great losses to the yield, whether in quantity or quality. This study was conducted in Basra province / Al-Qurna district to study the effect of harmal plant seeds on the numerical density, percentage and severity of infection caused by lesser date moth on the date palm trees. The results showed that the highest number of lesser date moths’ population density was appeared in the fogging treatment (111.3 / trap), while the lowest was in the fumigation treatment (64.3 / trap). The lowest percentage of infection by lesser date moth was in the aqueous extract treatment of (29.7%), while the highest was in the fumigation treatment (31.4%). In the first period, the treatment of aqueous extract gave the best results, as the percentage of infection was (17.8%). The lowest rate of infection severity was also in the treatment of aqueous extract (2.2 / 5 fruit), while the highest was in the fogging treatment (6.5 / 5 fruit). In the third period, both treatments of fumigation and fogging gave the best results, as the infection severity was (0/5 fruit) compared to the control for the same period of (8.9 / 5 fruit). The treatment of aqueous extract gave the best results in reducing the severity of infection by lesser date moth, while the treatment of fogging gave the best results in reducing the number density of lesser date moth.

Optimal control problem and backward bifurcation on malaria transmission with vector bias

This article aims to apply a mathematical model to investigate the spread of malaria by considering vector bias, saturated treatment, and an optimal control approach. A mathematical analysis of the equilibrium points and an investigation of the basic reproduction number show that if the basic reproduction number (R0) is less than one, the disease-free equilibrium is locally asymptotically stable. Furthermore, the center-manifold theory is applied to analyze the stability of the endemic equilibrium when R0=1. We find that our model performs a backward bifurcation phenomenon when the saturated treatment or vector bias parameter is larger than the threshold. Interestingly, we found that uncontrolled fumigation could increase the chance of the appearance of backward bifurcation. From the sensitivity analysis of R0, we find that the fumigation and vector bias are the most influential parameters for determining the magnitude of R0. Using the Pontryagin maximum principle, the optimal control problem is constructed by treating fumigation and medical treatment parameters as the time-dependent variable. Our numerical results on the optimal control simulation suggest that time-dependent fumigation and medical treatment could suppress the spread of malaria more efficiently at minimum cost.

Preparation and use of trans-2-hexenal microcapsules to preserve ‘Zaosu’ pears

Trans-2-hexenal is a naturally occurring volatile phytochemical with antimicrobial activity. It has not been widely used for the preservation of fruit and vegetables owing to its rapid volatilization. In this study, β-cyclodextrin-trans-2-hexenal microcapsules (β-CTHM) were prepared using the saturated aqueous solution method and their efficacy in preserving pears was evaluated. Results from scanning electron microscopy, thermogravimetric analysis, and Fourier-transform infrared spectroscopy indicated that β-CTHM was successfully prepared with an encapsulation efficiency of 67.52 %. The release of trans-2-hexenal from the microcapsules was dependent on the storage temperature. β-CTHM significantly inhibited the mycelial growth of Alternaria alternata in vitro. Furthermore, β-CTHM at 0.4 g/L fumigation treatment inhibited black rot of ‘Zaosu’ pears, maintained fruit firmness and titratable acidity, and reduced the respiration rate. Our present study suggested that β-CTHM might be used as an alternative to other preservative methods in retaining postharvest fruit quality.

1H-cyclopropabenzene and 1H-cyclopropa[b]naphthalene fumigation downregulates ethylene production and maintains fruit quality of controlled atmosphere stored ‘Granny Smith’ apple

The ‘Granny Smith’ is a commercial apple cultivar in Western Australia and popular in the apple world as well, for its unique green colour and flavour. The effects of two new ethylene antagonists namely 1H-cyclopropabenzene (BC) and 1H-cyclopropa[b]naphthalene (NC), as well as 1-methylcyclopropene (1-MCP) on ethylene production, rates of respiration and fruit quality were investigated in controlled atmosphere (CA) stored ‘Granny Smith’ apple. The apple fruit were fumigated with 1 μM BC (0.09 μL.L−1) or 1 μM NC (0.14 μL.L−1) or 18 μM (1 μL.L−1) 1-MCP for 18 h at room temperature (20 ± 2 °C and 65 ± 5% RH). Following 90 d and 120 d of CA storage (2.5 ± 0.64% O2 and 1.3 ± 0.45% CO2 at 0 ± 1 °C), fumigation treatments with 1-MCP, NC and BC effectively suppressed and delayed climacteric peaks of ethylene and respiration as compared to the control fruit. The 1-MCP treatment was relatively more efficient in reducing the rates of ethylene and respiration climacteric peaks than BC and NC. But all the treatments reduced physiological loss of weight (PLW) (up to 1.38 times) and maintained higher fruit firmness (up to 1.16 times), total phenols (up to 1.53 times) and ascorbic acid (up to 1.15 times), compared to the control, following the CA storage period. Therefore, BC and NC possess the potential to act as ethylene antagonists in CA stored ‘Granny Smith’ apples to retard fruit ripening process and maintain the fruit quality. The effects of different concentrations of BC and NC in antagonising the ethylene action in different cultivars warrants further investigation in CA stored apple fruit.

Effects of ozone fumigation combined with nano-film packaging on the postharvest storage quality and antioxidant capacity of button mushrooms (Agaricus bisporus)

The quality of button mushrooms (Agaricus bisporus) deteriorates rapidly in storage, which seriously affects their commodity value and shelf-life. In this work, preservation using ozone fumigation combined with nano-film packaging was used for the first time to maintain the freshness of A. bisporus. Three key quality attributes, sensory score, browning index, and weight loss rate, were used to select the optimal ozone treatment dosage of A. bisporus. According to the selected optimal ozone fumigation dosage and using untreated mushrooms as controls, comparative freshness was tested in mushrooms treated with ozone fumigation, nano-film packaging, and a combination of ozone fumigation and nano-film packaging. During storage, a series of the quality indicators and antioxidant capacity of A. bisporus were determined. The results showed that the ozone fumigation treatment combined with nano-film packaging effectively delayed the deterioration of sensory quality, weight loss, firmness, peak respiration, and browning, while inhibiting the outbreak of epiphytic microorganisms and the accumulation of reactive oxygen species during the postharvest storage of mushrooms. Hence, the mushrooms maintained good appearance and texture characteristics during storage and retained a higher commercial value. Compared with the control group, ozone fumigation combined with nano-film packaging treatment extended the shelf-life by 8–10 d. Therefore, this treatment can be used as an effective composite freshness-keeping technology in the postharvest storage and distribution of A. bisporus.

Microbial assembly and association network in watermelon rhizosphere after soil fumigation for Fusarium wilt control

Soil fumigation is an effective method to control soil-borne diseases like Fusarium wilt, however the processes and mechanisms driving microbial community reestablishment and pathogen suppression in the rhizosphere after fumigation remain poorly understood. In this study, we examined the dynamics of the rhizosphere microbiome and microbial network associations across different watermelon development stages and plant statuses (i.e. healthy and dead) after soil fumigation and organic fertilizer (OF) application in plastic shelters with Fusarium oxysporum f. sp. niveum (FON) heavily infected. Our results showed that fumigation treatments significantly reduced Fusarium wilt disease incidence and pathogen abundance, meanwhile, decreased soil microbial metabolic activity, fungal biomass and diversity. Bacterial community recovered from fumigation suppression in a short period, while fungal suppression was longer lasting, resulting in decreased fungi to actinomycetes (F/A) and fungi to bacteria (F/B) ratios in PLFA profiles. We further found some bacterial families, such as Actinospicaceae within Actinobacteria, Haliangiaceae, Rhizobiaceae and uncultured Rhodospirillales within Proteobacteria, Sporolactobacillaceae and Limnochordaceae within Firmicutes were greatly enriched after fumigation and might potentially contribute to pathogen suppression. The fumigation treatments significantly reduced microbial network complexity and the percentage of fungal nodes in comparison to un-fumigated control treatment. In contrast, a more complex microbial network was observed in the rhizosphere soil of healthy plants than that in the soil surrounding dead plant roots within fumigation treatments. Furthermore, healthy plant rhizosphere significantly enriched potential beneficial and nitrogen cycle-related bacterial phyla like Gemmatimonadetes, Verrucomicrobia, and Nitrospirae. More interestingly, Fusarium were markedly enriched in the rhizosphere soil of healthy plants and mainly represented by non-FON Fusarium like F. verticillioides and F. solani, implying a potential niche competition between FON and nonpathogenic Fusarium species in the rhizosphere of healthy watermelon. Taken together, our results provide vital information on the reconstruction of microbial communities and potential interactions between plant and its beneficial consortium after fumigation, which is instructive to develop more systematic strategies through targeting both beneficial and pathogen-similar taxa to improve disease control and soil suppression.

Mulberry Protection through Flowering-Stage Essential Oil of Artemisia annua against the Lesser Mulberry Pyralid, Glyphodes pyloalis Walker.

In the present study, the toxicity and physiological disorders of the essential oil isolated from Artemisia annua flowers were assessed against one of the main insect pests of mulberry, Glyphodes pyloalis Walker, announcing one of the safe and effective alternatives to synthetic pesticides. The LC50 (lethal concentration to kill 50% of tested insects) values of the oral and fumigant bioassays of A. annua essential oil were 1.204 % W/V and 3.343 μL/L air, respectively. The A. annua essential oil, rich in camphor, artemisia ketone, β-selinene, pinocarvone, 1,8-cineole, and α-pinene, caused a significant reduction in digestive and detoxifying enzyme activity of G. pyloalis larvae. The contents of protein, glucose, and triglyceride were also reduced in the treated larvae by oral and fumigant treatments. The immune system in treated larvae was weakened after both oral and fumigation applications compared to the control groups. Histological studies on the midgut and ovaries showed that A. annua essential oil caused an obvious change in the distribution of the principal cells of tissues and reduction in yolk spheres in oocytes. Therefore, it is suggested that the essential oil from A. annua flowers, with wide-range bio-effects on G. pyloalis, be used as an available, safe, effective insecticide in the protection of mulberry.

Evaluation of dosimeter tubes for monitoring phosphine fumigations

Within integrated pest management options, fumigation of stored products is one method to help control post-harvest insect infestations in our food and agricultural products. Fumigant gas concentration monitoring is important to confirm that the treatment was adequate to achieve the desired insect control, but monitoring can be relatively expensive and labor intensive. This study evaluated how accurately dosimeter tubes could monitor phosphine fumigation treatments. The dosimeter tube is designed to continuously react with phosphine gas during the fumigation period and yields a measurement in terms of concentration ∗ time product or CT, which can be interpreted as cumulative exposure. Two models of dosimeter tubes were evaluated (high range and low range). The reference method for these trials were wireless phosphine monitoring sensors, which recorded gas concentrations at hourly intervals during an exposure, and from this a CT product was also calculated. Model LPG-1, high-range dosimeter tube, measured within ± 25% of the phosphine monitoring sensors for CT dosages less the 70,000 ppm∗hr. Model LPG-2, low-range tube, tended to significantly over-estimate phosphine CT dosage by 50%–100% of the phosphine monitoring sensor references. Secondly, bioassays of fumigant efficacy were performed using susceptible and resistant adult Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae), lesser grain borers, and Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), red flour beetle, for estimating insect control at the varied fumigation CT treatments. For the susceptible strains, CT dosages ∼5000 ppm∗hr controlled both species. However, the insect control varied from 60% to 100% for resistant adults at CT dosages of ∼20,000 ppm∗hr. The dosimeter tubes function in these ranges of dosages where each insect species are controlled and the dosimeter tube model LPG-1 provides reasonable estimates of the fumigation dosage for a given treatment level.

Fumigating Citrus with Phosphine Does Not Impact Marketability or Eating Quality

To ensure control of arthropod pests, fresh citrus exports from the United States may be subject to postharvest phytosanitary treatment. Treatments, however, can potentially cause a phytotoxic response and damage the fruit. The main purpose of this study was to confirm that phosphine fumigation does not impact either the marketability or eating quality of citrus. Methyl bromide (MB) fumigation and cold treatment (CT) were included in the testing as comparisons. Treatments were conducted as if they were associated with an oceanic voyage of 28 days followed by 1 week at 10°C and then 1 week at 20°C to typify distribution and marketing conditions. Key quality parameters were evaluated, relative to nontreated controls, for each of three “predeparture” phosphine fumigations, an “on arrival” MB fumigation, and a 28-day CT at 1°C. The three phosphine treatments evaluated were 1.5 mg/liter for 12 h or 48 h at 5°C or for 48 h at 12°C. MB was applied at 64 mg/liter for 2 h at 5°C. In the second year, navel oranges were further evaluated using a sequential treatment in which a “predeparture” phosphine fumigation was followed by the “on arrival” MB fumigation. This work is the first to present results comparing phytosanitary treatments over multiple kinds of citrus and indicated that the phosphine treatments did not alter marketability or sensory quality for any of the citrus types. This contrasted with MB fumigation, which was damaging to the peel of all citrus, except Valencia oranges, and harmed grapefruit and mandarin flavor.

Effects of Different Packaging Materials on Storage Quality of Crisp Plum

This experiment uses “Bashan crisp plum” as the material, uses nano-bags and spontaneous modified atmosphere preservation bags for packaging, combined with 1-MCP fumigation treatment, and stores in a cold storage at 1±1.5℃. The physiological and biochemical measurements are measured every 15 days Indicators to discuss the low-temperature storage effects of different packaging materials. The results showed that the use of nano-bags and air-permeability of 3000mL/bag/24h modified atmosphere packaging can reduce fruit rot, delay the yellowing of the peel, better maintain the fruit texture and organic acid content, and better maintain the original fruit.

Peony and licorice decoction fumigation treatment for strephenopodia after stroke: Study protocol for a randomized controlled pilot trial.

Background:As one of the most common functional disabilities in stroke patients with hemiplegia, poststroke strephenopodia (PSS) seriously affects the life quality of patients, and causes mental and emotional disorders. Some studies have suggested that the traditional Chinese medicine fumigation therapy could be an effective intervention method for patients with PSS. This study aims to investigate the biomechanical effect of the classic prescription peony and licorice decoction (PLD) fumigation treatment for PSS.Methods/Design:This study is a multicenter, randomized, placebo-controlled, double blind trial. A total of 190 patients with PSS according to the inclusion criteria will be recruited in 3 centers and randomly distributed to either the intervention group or the control group in a 1:1 ratio. The intervention group will receive PLD fumigation treatment, while the control group will receive placebo fumigation treatment. All patients will receive standardized modern rehabilitation treatment according to the “Chinese Guidelines for Stroke Rehabilitation” (2011 version). The primary outcome measure is medial plantar area (Metatarsal 1+ Metatarsal 2 + Heel Medial) generating from the RSSCAN gait system. The secondary outcome measures contain the scores of clinical scales including Berg Balance Scale, Fugl-Meyer Assessment, Modified Ashworth Scale, Barthel Index, and Stroke-Specific Quality of Life Scale. All assessments will be implemented at baseline, 4 weeks after intervention and at the end of 3 months’ follow-up. Intention-to-treat analysis and per-protocol analysis will be applied in this trial.Discussion:The results of this study are expected to verify the clinical effect of PLD fumigation treatment for strephenopodia after stroke, and to explore the related biomechanical mechanisms by objective evaluation parameter.Trial registration:Chinese Clinical Trial Registry, ChiCTR2000032433. Registered on 28 April 2020. http://www.chictr.org.cn/showprojen.aspx?proj=52644

Vacuum Steam Treatment Effectiveness for Eradication of the Thousand Cankers Disease Vector and Pathogen in Logs From Diseased Walnut Trees

Logs of high-value eastern black walnut (Juglans nigra L.) are commonly exported from the United States for production of veneer and lumber. Veneer logs are not debarked to minimize degradation of wood quality and reduce moisture loss. Thousand cankers disease (TCD) is caused by the walnut twig beetle (Pityophthorus juglandis Blackman) and the fungal pathogen, Geosmithia morbida M. Kolarik, E. Freeland, C. Utley and N. Tisserat sp. nov., which colonize the inner bark of Juglans species. Effective eradication of these organisms by heat or chemical fumigation treatment is required for walnut logs prior to export. Because vacuum steam is an effective and efficient means of heating round wood, its use in eliminating the TCD causal agents was evaluated using Juglans logs (12- to 44-cm small end diameter and 1.7- to 1.9-m length) from TCD-symptomatic trees in Oregon and Washington State. Five replicate trials with three logs per load were conducted in a portable vacuum chamber to test two treatment schedules: 60°C for 60 min and 56°C for 30 min. Complete elimination of P. juglandis and G. morbida was achieved when using a minimum of 56°C at 5-cm targeted depth from bottom of bark furrow into the sapwood and held for 30 min. Treatment cycle time ranged from 298 to 576 min depending on log diameter and initial log temperature. Artificial inoculation of J. nigra trees with G. morbida within the TCD range in Pennsylvania was minimally successful in producing adequately colonized logs for experimental trials.

Fumigant toxicity of some essential oils against Red Flour Beetles, Tribolium castaneum (Herbst) and its safety to mammals.

Fumigant activities for three essential oils; Garlic oil (Allium sativum L); Chili pepper (Capsicum annuum L.) and Nigella (Nigella sativa L.) were assessed at different concentrations against the adult and 20-days old larval stages of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) in the laboratory. The accumulative mortality was observed at different exposure periods (3, 5 and 7 days). The residual effect of garlic oil that was the effective oil, on the treated wheat grains was evaluated with respect to histological changes in the liver, kidney, and stomach of rat fed on this treated wheat. The results showed that the mortality rates of treated stages increased with increasing the time of fumigation treatment. Moreover the highest essential oils toxicity at the Median lethal concentration (LC50) values for exposure periods (3, 5 and 7 days) to fumigation were (126, 53, and 47 mg/L air) for adult stage and were (79, 62, and 41 mg/L air) for larval stage, respectively in the case of Garlic oil treatment. While, the lowest essential oils effective was Nigella oil at the Median lethal concentration (LC50) values for exposure periods (3, 5 and 7 days) to fumigation were (3594, 629, and 335 mg/L air) for adult stage and were (1040, 416, and 227 mg/L air) for larval stage, respectively. The toxicity effect of various essential oils against adults and larvae of T. castaneum at the LC50at 7 days fumigation could be arranged in descending order as follows: Garlic oil, Chili pepper oil, and Nigella oil. The histological changes showed that the organs slightly affected at the fumigation for 3 days. It may be concluded that the garlic essential oil is the good effective fumigant to control T. castaneum in the stored products and it recommended that the fumigation period does not exceed 3 days. The garlic essential oil has the potential for applications in IPM programs for stored-grain pests because of its high volatility and fumigant activity and its safety.

Evaluation of Hydrogen Peroxide Fumigation and Heat Treatment for Standard Emergency Arthropod Inactivation in BSL-3 Insectaries.

Climate change and global movements of people and goods have accelerated the spread of invasive species, including insects that vector infectious diseases, which threaten the health of more than half of the world’s population. Increasing research efforts to control these diseases include the study of vector – pathogen interactions, involving the handling of pathogen-infected vector insects under biosafety level (BSL) 2 and 3 conditions. Like microbiology BSL-3 laboratories, BSL-3 insectaries are usually subjected to fixed-term or emergency room decontamination using recognized methods such as hydrogen peroxide (H2O2) or formaldehyde fumigation. While these procedures have been standardized and approved for the inactivation of diverse pathogens on surfaces, to date, there are no current standards for effective room-wide inactivation of insects in BSL-3 facilities in case of an emergency such as the accidental release of a large number of infected vectors. As H2O2 is often used for standard room decontamination in BSL-3 facilities, we evaluated H2O2 fumigation as a potential standard method for the safe, room-wide deactivation of insects in BSL-3 insectaries in comparison to heat treatment. To account for physiological diversity in vector insect species, six species from three different orders were tested. For the H2O2 fumigation we observed a strong but also varying resilience across all species. Lethal exposure time for the tested dipterans ranged from nine to more than 24 h. Furthermore, the coleopteran, Tribolium castaneum, did not respond to continuous H2O2 exposure for 48 h under standard room decontamination conditions. In contrast, temperatures of 50°C effectively killed all the tested species within 2 to 10 min. The response to lower temperatures (40–48°C) again showed a strong variation between species. In summary, results suggest that H2O2 fumigation, especially in cases where a gas generator is part of the laboratory equipment, may be used for the inactivation of selected species but is not suitable as a general emergency insect inactivation method under normal room decontamination conditions. In contrast, heat treatment at 48 to 50°C has the potential to be developed as an approved standard procedure for the effective inactivation of insects in BSL-3 facilities.

Field Evaluation of a Novel, Granular Soil Fumigant for Controlling Phytophthora ramorum in Field Nursery Soils

Phytophthora ramorum, the causal agent of Sudden Oak Death (SOD) and ramorum blight, infects a wide range of hardwood and nursery ornamental species. Chlamydospores of P. ramorum can survive for extended periods of time in soils. Two studies were conducted, including: 1) a laboratory study to evaluate two liquid disinfectants for controlling P. ramorum chlamydospores, and 2) a field study to evaluate a novel soil fumigation treatment as an alternative to soil steaming or methyl bromide soil fumigation. The liquid disinfectants were ElectroBiocide and Oxidate 2.0. The laboratory study resulted in complete inactivation of the P. ramorum chlamydospores after six minutes of contact time for both the liquid disinfectants The field study evaluated a chlorine dioxide granule formulation that was applied at two rates in a nursery soil. Rhododendron leaf discs were inoculated with P. ramorum, placed in permeable sachets and buried at two soil depths in a research nursery. Soil treatments also included saturated hydrogels (with and without gels) so that soil moisture effects on chlamydospore survival could be estimated. The sachets were recovered 5, 15 and 30 days after the soil treatment. Efficacy of the soil treatments was evaluated by the number of leaf discs showing P. ramorum growth recovered from the sachets. The soil fumigation treatment with highest efficacy occurred when the sachets were buried at the 5 cm soil depth, were treated with hydrogels, at the highest Z-series granule rate (800g/tube), and had a contact time of 30 days. The probability of P. ramorum growth for this soil treatment was 0.18, or 18%, i.e. the probability of that fumigation treatment inactivating the pathogen was 82%. Also, as the soil moisture increased, the efficacy of the fumigation treatments also increased.

Impact of O3 on the phytoremediation effect of Celosia argentea in decontaminating Cd

Elevated atmospheric O3 can inhibit the growth rate of various plants and increase metal content in their tissues owing to the oxidative damage, thereby affecting their phytoremediation efficiency. In this study, a series of O3 fumigation treatments were designed to evaluate the dry weight, Cd content, and transpiration rate responses of Celosia argentea to different levels of O3 (40, 50, 55, 60, 65, and 80 ppb). The dry weight of C. argentea decreased as the atmospheric O3 level increased, and the Cd concentration of the plant leaves increased until the level of O3 reached 60 ppb before decreasing slightly. The variations in the transpiration rate followed a similar trend to the Cd content under different O3 levels. The phytoremediation efficiency of C. argentea increased with O3 fumigation at low (50 ppb) and moderate (55 and 60 ppb) levels, and significantly decreased at the highest level. The regression curves indicated that the plant species treated with 52 ppb of O3 exhibited the highest Cd accumulation capacity. Overall, the phytoremediation effect of C. argentea cultivated in Cd-polluted soil might be improved under the high-O3 conditions. This result might help to choose suitable plants for soil remediation in future atmospheric environment.

Target verification of allyl isothiocyanate on the core subunits of cytochrome c oxidase in Sitophilus zeamais by RNAi

Allyl isothiocyanate (AITC) is a volatile organic compound with a potent insecticidal activity to the stored-grain pest Sitophilus zeamais Motschulsky, which severely damages grain storage and container transport worldwide. Our previous study showed that mitochondrial complex IV was the primary target of AITC in adult Sitophilus zeamais. To further verify the targets of AITC, we employed RNA interference (RNAi) by using double-stranded RNA (dsRNA) to knockdown three core subunits of cytochrome c oxidase (COX)-I, -II and -III in 18-day-old larvae prior to their exposure to AITC to detect susceptibility changes. The susceptibility of dsRNACOX-I and -II injection treatments to AITC significantly increased at 72 h while the mortality reached up to 85.56% and 67.78%, respectively, and dsRNACOX-I and dsRNACOX-II injection showed the same subcellular structural characteristics showing vacuolization and vague mitochondrial cristae and decrease of COX activity during AITC fumigation treatment, suggesting the potential of COX-I and COX-II as the targets of AITC. High mortality reached up to 75.55%, 71.88% and 82.22%, respectively, and the phenotype of larvae turning from milky white to dark brown in the thorax and death eventually was confirmed after dsRNACOX-I, -II and -III injection. COX-I and -II were elucidated as the potential targets of AITC and dsRNACOX-I, -II and -III have the potential to be developed into nucleic acid pesticides for their robust lethal effects and are worth pursuing for improving AITC fumigation activity in Sitophilus zeamais control. © 2020 Society of Chemical Industry.

Scaling recovery of susceptible and resistant stored product insects after short exposures to phosphine by using automated video‐tracking software

Phosphine-susceptible or resistant populations of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) and Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) adults were exposed to 0 (control), 1000 and 3000 ppm of phosphine for 15 or 90 min, to estimate behavioral and mobility responses after exposure to phosphine. Knockdown of the exposed individuals after exposure was recorded visually. The total distance moved and velocity of movement were assessed immediately after exposure to phosphine, 2 or 24 h later using a camera coupled with automated video tracking software (i.e. Ethovision®). For both species tested, the highest percentage of dead adults was noted at the highest concentration (3000 ppm) for both exposure times. For T. castaneum, total distance moved and velocity decreased as the concentration increased for the susceptible population, whereas there was significant variation among individuals in the resistant population. For R. dominica, the distance moved was reduced at the highest concentrations. Individuals of R. dominica moved less than those of T. castaneum and there were significant differences in mobility between susceptible and resistant populations for both species tested. Recovery was much faster in the case of the resistant populations. Changes in movement parameters can be further exploited in assessing the efficacy of different management tactics, such as trapping and sampling. Automated video tracking systems such as Ethovision® can be used to track and record insect behavioral response, providing a more objective measure of insecticide efficacy than visual categorizations. These data shed light on insect mobility and behavioral responses to fumigation treatments in relation to resistance. © 2020 Society of Chemical Industry.