Field Evidence Research Articles

Hydrogeomorphology of asymmetric meandering channels: experiments and field evidence

Hydrogeomorphology of asymmetric meandering channels: experiments and field evidence

Application of a temporal decorrelation model using Sentinel-1 SAR data to Detect volcanic ash deposits related to the 2020 Taal volcano eruption

Volcanic ash deposits affect buildings, vegetation, and population. After a volcanic eruption, it is critical to detect the areas affected by ash deposits to achieve an advisable management of the emergency. Optical sensors have been widely used to carry out this task, but they are limited by solar illumination and weather conditions. As an alternative, Synthetic Aperture Radar (SAR) data are not affected by those limitations. Recently, a Temporal Decorrelation Model (TDM) that uses SAR data was proposed for detecting and mapping ash deposits, but it has only been applied to L-band data. Today there is available a huge quantity of C-band data acquired by the Sentinel-1 constellation. In this study we applied the TDM to Sentinel-1 data in order to assess its performance for detecting volcanic ash deposits after an eruption. We selected the eruption of Taal volcano in The Philippines on January 12, 2020, as our case study. We computed more than 4000 interferometric pairs from a dataset of 93 images acquired before, during, and after the eruption. Our results show that TDM can be applied to C-band data, despite the higher temporal decorrelation suffered by them. Our final probability map is consistent with the field evidence reported by the Philippines Institute of Volcanology and Seismology (PHILVOLCS) and the isopachs map reported in the literature. This new application provides a novel framework for the coherence exploitation of C-Band data. Also, this approach could be applied to detection and monitoring of other natural disasters.

Field evidences of fluorescent dissolved organic matter (FDOM) as potential fingerprints for agricultural and urban sources in river environment.

Field evidences of the fluorescence differences between agricultural and urban river reaches are still lack. In this study, the middle reaches of Danhe River (DH) and Mihe River (MH) in Shouguang, China, were designed as agricultural and urban river reaches, respectively, to compare the the fluorescence differences in disparate river reaches using excitation-emission matrix coupled with parallel factor analysis (EEM-PARAFAC). Three fluorescence components were identified. C1 (Ex/Em=230,255,295 nm/420 nm) was categorized as humic-like fluorophores, C2 (Ex/Em=230,275 nm/330 nm) was recognized as tryptophan-like substances, and C3 (Ex/Em=215 nm/290 nm) was noted as tyrosine-like and phenylalanine-like compounds. The results showed that the FDOM posed significant differences between agricultural and urban river reaches (P < 0.001). The monitoring sites in DH were rich in C2 (1.90 ± 0.62 Raman Unit (RU), mean ± standard deviation), and the monitoring sites in MH were rich in C3 (1.32 ± 0.51 RU). Redundancy analysis revealed that C2 could be regarded as a fluorescence indicator of agricultural sewage in river environment, while C3 was recognized as a fluorescence indicator of domestic sewage in river environment. In conclusion, this study provided field evidences of FDOM as potential fingerprints for agricultural and urban sources in river environment.

Late Mississippian-Pennsylvanian extensional deformation along the SW Gondwana margin: Insight from the San Rafael Basin, western Argentina

The retro-arc San Rafael Basin (34° SL) records a long-term history of its varied filling. This is the reason why it has been approached by several studies from many disciplines. However, its origin has been a controversial issue until now. There exists an agreement about its development during the latest Mississippian-Early Pennsylvanian ages, coetaneous with the sedimentation of the El Imperial Formation. The generation of this basin took place afterward the Chanic Orogeny and before the San Rafael orogeny. Although there is consensus about an extensional setting controlled the basin's inception, no crustal deformation corroborates this tectonic regime. This contribution is a first attempt to present geological and structural field evidence supported by preliminary kinematic analysis. From these new field observations, an NNE-SSW extensional deformation coetaneous to the deposition of the lower Member of the El Imperial Formation was recognized in the area near the confluence of the Atuel river and Aisol stream. Consequently, our data are following the previous hypothesis of an extensional origin for the San Rafael retro-arc basin.

All in one: single‐season multi‐clutching in an ephemeral pool‐breeding frog that is otherwise virtually semelparous

AbstractThe sandpaper frog, Lechriodus fletcheri, is a temperate anuran that has previously been shown to be virtually semelparous, with adults overwhelmingly reproducing in a single year of life. Yet, this species almost exclusively oviposits in highly ephemeral pools where there is a high chance of total reproductive failure due to hydroperiods often being unpredictable and too short for their offspring to reach metamorphosis. We sought to understand how L. fletcheri copes reproductively in such a risky breeding environment in the absence of a classical iteroparous life history. We investigated aspects of reproduction in wild and laboratory‐reared individuals to determine whether females are capable of intra‐seasonal multi‐clutching and/or clutch partitioning, and males of fertilizing multiple clutches. Direct field evidence was obtained that males participated in multiple mating events within season, while indirect evidence of this ability in females was obtained based on laboratory‐held individuals that produced an additional batch of mature oocytes weeks after an initial release of eggs. Our findings suggest that both males and females likely have the capacity to participate in multiple reproductive events within season and, while most adults may not reproduce more than once, that they are abbreviate iteroparous rather than truly semelparous. Our findings provide evidence that short‐lived anurans may exploit alternative bet‐hedging strategies that mimic the fitness benefits of multi‐year iteroparity.

The Development of Interactive E-Book-Based Teaching Materials for Senior High School Students

This study aimed to develop interactive e-book-based teaching materials for Madrasah Aliyah students in class X to support independent learning and to assess the levels of validity and practicability of their use. The growth of students' learning is positively impacted by the creation of teaching materials that are appropriate for their circumstances and ages, especially those that encourage independent learning. Field evidence indicates that students must build their knowledge outside the classroom to learn effectively, as suggested by the constructivist theory. This research employed the research and development method with the ADDIE (Analysis, Design, Development, Implementation, and Evaluation) model. The data were collected through questionnaires and observations and then analyzed using descriptive statistical techniques. The product of this research was an interactive e-book assisted by a Heyzine Flipbook with al-tahiyyat wa al-ta’aruf materials that could be accessed online via smartphones, tablets, and laptops. Based on the validation conducted by media experts, material specialists, and Arabic linguists, the validity of this product was rated as legitimate and worth testing with a feasibility score of 4.42, which was good, and an average eligibility percentage of 88%. Responses from 40 students and five Arabic teachers, who had a very positive response rate of 91%, were used to determine the practical value of use. Based on these results, the interactive e-book-based teaching materials assisted by the Heyzine Flipbook al-tahiyyat wa al-ta’aruf materials for Madrasah Aliyah students were valid and practical for use.

Exploring the Magnetic Field Geometry in NGC 891 with SOFIA/HAWC+

Stratospheric Observatory For Infrared Astronomy/High-resolution Airborne Wideband Camera-plus 154 μm Far-Infrared polarimetry observations of the well-studied edge-on galaxy NGC 891 are analyzed and compared to simple disk models with ordered (planar) and turbulent magnetic fields. The overall low magnitude and the narrow dispersion of fractional polarization observed in the disk require significant turbulence and a large number of turbulent decorrelation cells along the line of sight through the plane. Higher surface brightness regions along the major axis to either side of the nucleus show a further reduction in polarization and are consistent with a view tangent to a spiral feature in our disk models. The nucleus also has a similar low polarization, and this is inconsistent with our model spiral galaxy where the ordered magnetic field component would be nearly perpendicular to the line of sight through the nucleus on an edge-on view. A model with a barred spiral morphology with a magnetic field geometry derived from radio synchrotron observations of face-on barred spirals fits the data much better. There is clear evidence for a vertical field extending into the halo from one location in the disk coincident with a polarization null point seen in near-infrared polarimetry, probably due to a blowout caused by star formation. Although our observations were capable of detecting a vertical magnetic field geometry elsewhere in the halo, no clear signature was found. A reduced polarization due to a mix of planar and vertical fields in the dusty regions of the halo best explains our observations, but unusually significant turbulence cannot be ruled out.

Proposing a novel geo-structural model for Torbat-e- Jam-Fariman plain (Northeast of Iran), based on Geomorphic indices calculation, conjugating the field evidences

Proposing a novel geo-structural model for Torbat-e- Jam-Fariman plain (Northeast of Iran), based on Geomorphic indices calculation, conjugating the field evidences

Socioemotional competencies and behaviour management at school: An exploratory socio-educational intervention

Socioemotional competencies are based on self-knowledge, self-regulation, social awareness, relational skills and responsible decision-making, presenting a close relationship with the efficient management of behaviours in the classroom. In collaboration with 3 schools in the interior of Portugal, an exploratory socio-educational intervention project was developed over a period of 3 months, with the purpose of promoting the socioemotional competencies of 41 primary school children, as a basis for building classroom behaviour management strategies that would facilitate the teachers’ educational action. The intervention involved a process based on collaborative work between teachers, psychologists and educologists, having been able to produce 8 activities that promote socioemotional competencies. Ethnographic procedures, namely, the use of participant observation, field notes and informal interviews, were used to produce scientifically valid and socially useful knowledge. The results show that each activity works on more than one socioemotional skill. The data allowed to outline 6 efficient strategies to manage classroom behaviour. This exploratory project, besides contributing to enriching the educational project of these schools, proved to be a production of knowledge capable of contributing to filling the gap in terms of guidelines for socioemotional education in Portugal based on field evidence.

Improving the Quality of In-Kind Donations: A Field Experiment

Problem definition: Although in-kind donations contribute to charity’s triple bottom line (i.e., generating additional revenue for the charity, contributing to social welfare, and reducing environmental waste through rechanneling used items), inappropriate material donations impose additional costs to sort, process, or discard them. Minimizing the amount of undesired in-kind donations, however, is a challenge given charities’ sensitive relationship with their donors. This paper examines the effectiveness of behavioral interventions on improving the quality of in-kind donations gifted by individuals. Methodology/results: We conducted a field experiment to implement interventions motivated by two well-established behavioral mechanisms: information disclosure and social norm. We studied the reaction of 763 donors who were scheduled to make an in-kind donation at a local charity between October 31 and November 11, 2020. Our results show that using the social norm intervention effectively improved the quality of in-kind donations, whereas information disclosure, which is commonly used in practice as the industry standard intervention, was ineffective. We also conducted two postexperiment analyses. First, we collected additional data on 1,301 in-kind donations whose donors had received the social norm intervention during February 2021. Results show that the impact of the social norm intervention is stable over different time periods. Second, we studied the spillover effect of these interventions for a period of 12 months and did not find a negative long-term impact on in-kind donations. Managerial implications: A conservative estimation shows that implementing the social norm intervention reduced the junk donations received by 50% without having a negative spillover effect on donors’ in-kind donations or imposing any direct operating cost. Consequently, this field evidence provides an effective, cost-efficient, and scalable solution for charities to address the quality problem of in-kind donations. In addition, our results challenge the industry conventional practice of incorporating information disclosure in their communications with donors. Funding: This work was supported by Virginia G. Piper Charitable Trust [Grant 2020 Initiative].

Impact of short-term discontinuation of ivermectin-based chemoprevention on onchocerciasis transmission in endemic settings with long history of mass drug administration.

The control of onchocerciasis currently relies on annual distribution of single dose ivermectin. Because ivermectin has minimal effects on the adult parasite, mass drug administration (MDA) campaigns against onchocerciasis require at least 15 years of annual uninterrupted ivermectin distribution. Mathematical models have predicted that short-term disruption of MDA (as was seen during COVID-19) could impacted the microfilaridermia prevalence depending on the pre-control endemicity and the histories of treatment, requiring corrective measures (such as biannual MDA) to mitigate the effect on onchocerciasis elimination. Field evidence supporting this prediction, however, has yet to be gathered. This study aimed to assess the impact of ~2 years disruption of MDA on onchocerciasis transmission indicators. A cross-sectional survey was carried out in 2021 in seven villages of Bafia and Ndikinimeki, two health districts located in the Centre Region, Cameroon, where MDA has been ongoing for two decades, but interrupted in 2020 as a response to the COVID-19 pandemic. Volunteers aged 5 years and above were enrolled for clinical and parasitological examinations for onchocerciasis. Data were compared with pre-COVID-19 prevalence and intensity of infection from the same communities to measure changes over time. A total of 504 volunteers (50.3% males), aged 5-99 years (Median: 38; IQR: 15-54) was enrolled in the two health districts. The overall prevalence of microfilaridermia in 2021 was similar in Ndikinimeki health district (12.4%; 95% CI: 9.7-15.6) and Bafia health district (15.1%; 95% CI: 11.1-19.8) (p-value = 0.16). Microfilaridermia prevalences were either similar between 2018 and 2021 in the communities of Ndikinimeki health district (19.3% vs 12.8% (p = 0.057) for Kiboum 1; and 23.7% vs 21.4% (p = 0.814) for Kiboum 2), or higher in 2019 compared to 2021 in the communities of Bafia health district (33.3% vs 20.0% (p = 0.035) for Biatsota). The mean microfilarial densities in these communities dropped from 5.89 (95% CI: 4.77-7.28) mf/ss to 2.4 (95% CI: 1.68-3.45) mf/ss (p-value < 0.0001), and from 4.81 (95% CI: 2.77-8.31) mf/ss to 4.13 (95% CI: 2.49-6.86) mf/ss (p-value < 0.02) in Bafia and Ndikinimeki health districts, respectively. Community Microfilarial Load (CMFL) dropped from 1.08-1.33 mf/ss in 2019 to 0.052-0.288 mf/ss in 2021 in Bafia health district while remaining stable in the Ndikinimeki health district. The continued decline in prevalence and CMFL observed ~2 years after MDA disruption is consistent with mathematical predictions (ONCHOSIM) and shows that additional efforts and resources are not needed to mitigate the effects of short-term MDA disruption in highly endemic settings prior to intervention with long treatment histories.

Mud‐rich low‐density turbidites in structurally‐controlled intraslope mini‐basin: The influence of flow containment on depositional processes and sedimentation patterns (Szczawa, Oligocene, Polish Outer Carpathians)

ABSTRACTThis study demonstrates the effectiveness of sedimentological–statistical multivariate analysis of one‐dimensional‐section in the unravelling depositional processes and sedimentation patterns recorded in a contained and partially ponded succession. Turbidite deposition of a 100 m thick mud‐rich Oligocene‐age sequence at Szczawa, the Polish Outer Carpathians, was primarily controlled by topographic confinement and magnitude of incoming flows. Only the largest turbidite flows were subjected to the true flow ponding, while in smaller volume flows the silty/sandy part behaved as unconfined flow and only muddy suspension cloud developed a ponded character. True ponding of low‐density turbidity currents is interpreted for sandstones that show sedimentary structures attesting to flow reflections and combined‐flow processes, and are associated with abnormally thick co‐genetic mudstones, which in turn results in low sandstone‐to‐mudstone ratio, irrespective of turbidite bed thickness. These features testify to pronounced interaction of flows with confining topography. Tractional structures associated with a considerable proportion of fines, namely banded structure and heterolithic bedding, are interpreted as produced during transitional (turbulent to laminar) flow phase in the condition of mud‐rich turbidite flow confinement. These structures are also considered here as indicators of proximity to source area and location on the slope. The co‐occurrence of banded sandstones, hybrid event megabeds and an olistostrome resulted from flows‐trapping, confined basin geometry, which precluded downslope propagation and further transformation of large‐volume flows. Therefore, a structurally‐controlled contained intraslope mini‐basin is proposed here as the most likely depositional setting. This work provides robust field and statistical evidence for ponding processes of low‐density turbidity currents in a structurally‐controlled mini‐basin. The results of this study are consistent with experimental data and recent field studies on ponded turbidites. Therefore, the Szczawa succession may serve as a new reference example of containment processes of low‐density turbidity currents and represents a valuable depositional model for intraslope turbidite succession.

Soil pH change induced by smelting activities affects secondary carbonate production and long-term Cd activity in subsoils

Cadmium (Cd) is a typical element with contamination risk caused by anthropogenic sources. Cd is known to associate with Fe (hydr)oxides in pH-neutral to slightly acidic soils. However, field evidence on the effects of high pH on the long-term migration and redistribution of Cd in the soil is lacking. In this study, a comprehensive investigation of Cd, Pb, and Zn distribution in soils was performed at a Pb–Zn smelter site to unravel the pH control of long-term Cd activity in soils contaminated by non-ferrous metal smelting. Atmospheric deposition caused widespread contamination of the surface soil. In contrast, the discharge of heavy metals and alkaline waste liquid from two separate pollutant sources inside the smelter resulted in severe pollution migrating from the deeper layers up to a depth of 10 m. Elemental analysis showed that the Cd/Zn ratio in soil increased as the pH value increased, indicating that Cd was progressively decoupled from Zn and accumulated in the solid phase. Chemical extraction, SEM-EDS mapping, and micro-FTIR mapping analysis of soil particles revealed that most of the Cd were correlated with calcite, which formed as a secondary mineral at a higher pH. The production of secondary carbonate as a geochemical barrier enhanced the natural attenuation of Cd, which provides a reference for remediating Cd pollution. Overall, the results provide information for studying the transport and accumulation of heavy metals in deep soil layers. On the other hand, as carbonate is an unstable sink compared to other carriers, this mechanism should be considered in future studies on health and ecological risk assessment criteria for heavy metal pollutants in alkaline environments.

MPM-based mechanism and runout analysis of a compound reactivated landslide

Understanding the entire process of hydraulic-related landslide reactivations is crucial for risk assessment, which includes initiation and runout evolves from a small-deformation in the pre-failure stage to large-deformation after failure, with complex interactions between the materials in solid and liquid phases. This paper reproduces the entire process of a reactivated landslide using Material Point Method (MPM). The accuracy of MPM is validated in comparison to Limit Equilibrium Method (LEM) and Finite Element Method (FEM). The effects of antecedent rainfall and pre-existing groundwater on landslide runout and the deposits morphology are discussed. Results show that the antecedent rainwater rises the groundwater level and saturates the front edge of slope where the initial failure occurred. Three computed spatio-temporal distributions of pore water pressure show good agreement and match well with field evidence. The kinematic characteristics show that the landslide has different moving features with different microtopography, which reveals retrogressive failure in front and middle part of slope initially and compound retro- and pro-gressive failures occur at the rear edge. The results of unsaturated two-phase MPM are in better agreement with the measured morphology than full-saturated MPM. The antecedent rainfall and the pre-existing groundwater are the main contributing factors to the landslide runout.

Evaluating the Protectiveness of a Bioavailability-Based Environmental Quality Standard for the Protection of Aquatic Communities from Zinc Toxicity Based on Field Evidence.

Environmental quality standards (EQS) are typically derived from the results of laboratory studies on single species. There is always uncertainty surrounding the protectiveness of an EQS when applied to real ecosystems containing a multitude of chemical and physical stressors. Quantile regression was used with field biological data on invertebrates in United Kingdom waters to identify taxa that are responsive to bioavailable zinc exposures. A threshold based on the total abundance of eight responsive taxa is used as an indicator of the overall ecosystem sensitivity. The inclusion of some responsive but insensitive taxa in this ecological metric could bias the results toward a higher threshold. The least responsive species were progressively removed from the collective ecological metric, basing the analysis on a progressively smaller number of the more responsive species. Quantile regression analysis at the 95th quantile for the three most responsive taxa resulted in a 10% effect concentration of 14.8 µg L-1 bioavailable zinc, suggesting that the EQS of 10.9 µg L-1 bioavailable zinc is sufficiently protective of sensitive members of the invertebrate community. There is a compromise between the robustness of the analysis and the sensitivity of the subcommunity that it is based on. Analyses based on fewer taxa provide a more sensitive result. This approach assessed real ecosystem data and evaluated the uncertainty associated with the protectiveness of the EQS for zinc. The zinc EQS is sufficiently protective of sensitive members of benthic macroinvertebrate communities under real environmental conditions, including a mix of multiple substances. Environ Toxicol Chem 2023;42:1010-1021. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Financial reporting and disclosure practices in China

We study financial reporting and disclosure practices in China using survey methods similar to prior studies of U.S. firms (i.e., Graham et al., 2005; Dichev et al., 2013). Comparing earnings features, motives to manage and smooth earnings, and voluntary disclosure practices between the two countries, we reveal three major differences. First, Chinese firms exhibit a stronger preference for predictive, relative to verifiable, attributes of earnings that can signal stable firm performance to their stakeholders. Second, smooth earnings are desired by various stakeholders and can be achieved through coordination among connected stakeholders, which is conceptually different from earnings management. Third, Chinese firms consider public disclosure as less relevant in the reduction of the cost of capital. In addition, Chinese firms do not have a bias towards conservative reporting. We explain and reconcile these differences as resulting from some unique institutional features of China. Our study provides novel field evidence that contributes to, expands, and directly corroborates existing empirical studies.

Kaolinite Effects on Injectivity Impairment: Field Evidence and Laboratory Results

Summary Clay interaction with fluids is a well-known phenomenon that depends on formation mineralogy. This paper focuses on the impact of kaolinite clay dispersion on well injectivity impairment. It is based on field evidence from more than 50 injectors, and it is supported by a huge set of laboratory tests. All analyzed wells showed an initial injectivity lower than the theoretical potential, estimated on the basis of reservoir quality and drawdown mobilities (DDMs). This impairment occurs before connecting wells to the injection network; therefore, injected water quality and network conditions do not take part in the damage. Consequently, the impairment mechanism seems to be correlated to the interaction between the formation and drilling fluids. A set of laboratory experiments was planned on cuttings collected in two recently drilled wells. Different intervals were selected in the reservoir sandstones, representative of the facies where injected water is most likely to flow. Samples were first mineralogically characterized by different laboratory techniques: Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction, and cation exchange capacity. Then, swelling and recovery tests were performed using different fluids: mud (field formulation), mud filtrate, and water (varying pH and salinity). Results were correlated with petrophysical analysis, mercury injection tests on cores, and major injectivity impairments observed on the analyzed wells. Analyzed samples showed the presence of kaolinite that may affect the formation permeability by filling porosity and pore throats (diagenetic effect). Moreover, in case of interaction with fluids, kaolinite can lead to an additional permeability reduction by disaggregation and dispersion phenomena. Laboratory tests showed a clear trend: The higher the kaolinite content is in the selected intervals, the higher the observed disaggregation will be, especially when the samples interact with mud filtrate and water. It was observed that mud formulation is effective, allowing to preserve disaggregation, but only below a threshold of kaolinite content. Field experience proved that the only effective remedial actions to restore the well injectivity potential are fracturing jobs, allowing bypass of the near-wellbore damaged zone.

New Insight into Mechanisms of Cardiovascular Diseases: An Integrative Analysis Approach to Identify TheranoMiRNAs.

MiRNAs regulate both physiological and pathological heart functions. Altered expression of miRNAs is associated with cardiovascular diseases (CVDs), making miRNAs attractive therapeutic strategies for the diagnosis and treatment of heart diseases. A recent publication defined, for the first time, the term theranoMiRNA, meaning the miRNAs that may be used both for diagnosis and treatment. The use of in silico tools may be considered fundamental for these purposes, clarifying several molecular aspects, suggesting future directions for in vivo studies. This study aims to explore different bioinformatic tools in order to clarify miRNA interactions with candidate genes, demonstrating the need to use a computational approach when establishing the most probable associations between miRNAs and target genes. This study focused on the functions of miR-133a-3p, miR-21-5p, miR-499a-5p, miR-1-3p, and miR-126-3p, providing an up-to-date overview, and suggests future lines of research in the identification of theranoMiRNAs related to CVDs. Based on the results of the present study, we elucidated the molecular mechanisms that could be linked between miRNAs and CVDs, confirming that these miRNAs play an active role in the genesis and development of heart damage. Given that CVDs are the leading cause of death in the world, the identification of theranoMiRNAs is crucial, hence the need for a definition of in vivo studies in order to obtain further evidence in this challenging field of research.

How to Conduct a Photovoice Systematic Review: Lessons Learned and Recommendations

Photovoice distinguishes itself from other qualitative research methods for its visual features and participant empowerment. As a powerful tool for community-based participatory research and health promotion programs, researchers and practitioners are paying more attention to this method in recent years. Accordingly, some photovoice systematic reviews have been published and more are underway to synthesize evidence in various research fields. However, due to the exploratory nature of the photovoice method, broad research questions for photo taking, flexible steps in photo discussion and analysis, and lack of standardized qualitative review guidelines, it could be challenging to conduct a photovoice systematic review. The purpose of this paper is to provide an overview of the photovoice method, debrief the process of a previous review, summarize lessons learned, and provide suggestions to facilitate future photovoice systematic reviews. This paper may also be of benefit to researchers who intend to apply photovoice to their research topics, or plan to conduct other types of photovoice literature reviews (e.g., scoping reviews).

Characterization of Soybean, Tomato, and Nicandra physalodes as Sources of Inoculum of Tomato Severe Rugose Virus to Tomato Crops.

Tomato severe rugose virus (ToSRV) is one of Brazil's main begomoviruses infecting tomatoes (Solanum lycopersicum). Recent studies indicate that soybean (Glycine max) crops harboring the whitefly Bemisia tabaci MEAM1 may have epidemiological significance by acting as an asymptomatic amplifier host for the virus. In this study, we gathered experimental greenhouse and field evidence of the role of soybeans in the epidemiology of the disease caused by ToSRV. Tomato and Nicandra physalodes, known as good sources of inoculum of this begomovirus, were used as references. The infection rates of soybean, tomato, and N. physalodes with ToSRV in greenhouse no-choice transmission tests with B. tabaci MEAM1 were 50%, 71.4%, and 64.2%, respectively. The transmission efficiencies of ToSRV to tomato when B. tabaci MEAM1 acquired the virus in ToSRV-infected soybean, tomato, and N. physalodes were 43%, 33%, and 20%, respectively. Leaves of ToSRV-infected soybean, tomato, and N. physalodes used as sources of inoculum had similar virus titers. In the host preference assay, viruliferous whiteflies preferred to land on tomato than soybean and N. physalodes, whereas aviruliferous whiteflies landed indistinctly on these plants. Under experimental field conditions, the transmission efficiency of ToSRV to tomato was higher when tomato was used as a source of inoculum, followed by N. physalodes and soybean. Considering that soybean is extensively cultivated in several Brazilian states that also grow tomatoes, it can serve as an efficient asymptomatic source of inoculum and support the recent hypothesis that it can also play, under certain conditions, a relevant role as an amplifier host in the epidemiology of the disease caused by ToSRV.