Confrontation Test Research Articles

Antifungal mechanisms and characteristics of Pseudomonas fluorescens: Promoting peanut growth and combating Fusarium oxysporum-induced root rot

Continuous cropping of peanuts presents significant challenges to sustainable production due to soil-borne diseases like root rot caused by Fusarium species. In this study, field inoculation experiments treatments and in vitro agar plate confrontation tests were conducted, including non-inoculated controls (CK), inoculation with Pseudomonas fluorescens (PF), Fusarium oxysporum (FO), and co-inoculation with both (PF + FO). The aim was to explore the antifungal mechanisms of Pseudomonas fluorescens in mitigating root rot and enhancing peanut yield. The results indicated that PF and PF + FO significantly enhanced peanut root activity, as well as superoxide dismutase, catalase, and glutathione S-transferase activities, while simultaneously decreasing the accumulation of reactive oxygen species and malondialdehyde contents, compared to FO treatment. Additionally, PF treatment notably increased lignin content through enhanced phenylalanine ammonia lyase, cinnamate 3-hydroxylase, and peroxidase activity compared to CK and FO treatment. Moreover, PF treatment resulted in longer roots and a higher average diameter and surface area, potentially due to increased endogenous levels of auxin and zeatin riboside, coupled with decreased abscisic acid content. PF treatment significantly elevated chlorophyll content and the maximum photochemical efficiency of PSII in the light-adapted state, the actual photochemical efficiency and the proportion of PSII reaction centers open, leading to improved photosynthetic performance. Confrontation culture assays revealed PF's notable inhibitory effects on Fusarium oxysporum growth, subsequently reducing rot disease incidence in the field. Ultimately, PF treatment led to increased peanut yield by enhancing plant numbers and pod weight compared to FO treatment, indicating its potential in mitigating Fusarium oxysporum-induced root rot disease under continuous cropping systems.

Plant, bacteria and fungi crosstalk: Direct and indirect biocontrol mechanisms of sugarcane rhizoplane Pseudomonas species against Fusarium wilt

In order to identify an effective rhizoplane Pseudomonas species to combat sugarcane wilt pathogen (Fusarium sacchari), twenty Pseudomonas isolates were obtained from the sugarcane rhizoplane of different genotypes. The three-tier confrontation (direct, indirect and remote) tests revealed antagonistic activity of the bacteria, bacterial non-volatile and volatile compounds. In dual culture assay, SRP19 (46.30%) and SRP20 (39.30%) have shown the highest inhibition against F. sacchari. 16S-23S rDNA sequencing identified them as Pseudomonas chlororaphis subsp. aurantiaca (SRP19) and Pseudomonas aeruginosa (SRP20). Exploration of biocontrol mechanisms revealed the potential roles for IAA production, extracellular enzyme secretion (proteases, cellulases and chitinases), HCN synthesis, siderophore production, pyocyanin or fluorescein production and phosphate solubilization. The molecular analysis revealed the presence of genes (phz, prnD, phlD and pltC) involved in the biosynthesis of antimicrobial peptides like phenazines, pyrrolnitrin, 2,4-diacetyl phloroglucinol and pyoleuteorin, involved in suppressing Fusarium. The antagonistic activity was further confirmed under greenhouse conditions by sett treatment with potential antagonistic isolates, which increased germination and reduced the pre-emergent mortality by 60% and post-emergent seedling mortality by 76% in SRP19 treated pots. The study revealed that the isolate Pseudomonas chlororaphis subsp. aurantiaca strain SRP19 can act as PGPR with both plant growth promoting and pathogen suppressing activity that can be used as an effective biocontrol agent against Fusarium wilt of sugarcane.

MutL Significantly Regulates the Formation of Biofilms in Bacillus amyloliquefaciens YT1

The purpose of this study is to discover and excavate more key factors and signaling pathways that regulate the formation intensity of biofilms and to fully reveal the possible models affecting biofilm formation. By using gene homologous recombination and bioinformatics technology, a MutL protein-directed deletion mutant strain was successfully constructed. The growth status of the mutant strain was observed, and it was confirmed that, except for the change in cell morphology, there were no significant differences in growth and reproduction between the mutant strain and the wild-type strain. By using the induced biofilm formation technique, the significant decrease in biofilm formation in the MutL mutant strain was successfully verified. The plate confrontation test confirmed that the inhibitory ability of the mutant strain against rice blast fungus was not significantly different from that of the WT strain. The colonization ability of the mutant strain on rice stems was tested, and it was confirmed that the colonization ability of the mutant strain was significantly lower than that of the WT strain. In terms of the prevention and control effect of rice blast disease, the mutant strain showed a significant decrease. By using transcriptomic big data, the gene and pathway expression differences between the mutant strain and the WT strain during biofilm formation were analyzed. The analysis revealed no significant correlation with the previously reported spo0A and tapA-sipW-tasA pathways. The key factor capB of the polyglutamic acid signaling pathway, which affects the formation of the biological model, was found to have a significant decrease in expression. A mechanical hypothesis was proposed: MutL may participate in regulating the formation intensity of Bacillus biofilms by regulating the formation of glutamic acid to polyglutamic acid.

Are Users Good Assessors of Social Dominance in Domestic Horses?

Horse users and caretakers must be aware of the risks of mixing social groups. The current study investigated whether eight equine practitioners can assess the social dominance rank of 20 horses. The horses' feeding time and agonistic/aggressive and submissive behaviours were observed during the feed confrontation test, and the dominance index (DI) was calculated. Kendal's W, Spearman correlations and factor analysis were applied to test the raters' agreement, the relationship between dominance ranks and the behavioural variables, and to determine the clustered behaviours. The agreement between all raters in the classification of dominance order ranged from moderate to perfect. The ranking by every rater was strongly and negatively correlated with the time of eating in feed confrontation tests and with the DI, evidencing shorter feeding times for more submissive horses. The withdrawal of the horse when threatened was the behavioural variable that was most often correlated with raters' ranking. The current study confirmed the abilities of practitioners to categorise the horses under their care according to their social interactions. Additionally, rolling when denied access to feed was proposed as frustration-releasing (redirected) behaviour.

Microbial-Based Biofungicides Mitigate the Damage Caused by Fusarium oxysporum f. sp. cubense Race 1 and Improve the Physiological Performance in Banana.

Fusarium wilt of banana (FWB) is the most limiting disease in this crop. The phytosanitary emergency caused by FWB since 2019 in Colombia has required the development of ecofriendly control methods. The aim of this study was to test the effectiveness of microbial-based biofungicides against FWB caused by Fusarium oxysporum f. sp. cubense race 1 (Foc R1) and correlate such effect with plant physiological parameters. Five Trichoderma (T1 to T4 and T9) and four Bacillus (T5 to T8)-based biofungicides were evaluated in pot experiments. In vitro, dual confrontation tests were also carried out to test whether the in vitro effects on Foc growth were consistent with the in vivo effects. While Trichoderma-based T3, T4, and T9, and Bacillus-based T8, significantly reduced the growth of Foc R1 in vitro, Trichoderma-based T1, T3, T4, and T9 temporarily reduced the Foc population in the soil. However, the incidence progress of FWB was significantly reduced by Bacterial-based T7 (74% efficacy) and Trichoderma-based T2 (50% efficacy). The molecular analysis showed that T7 prevented the inner tissue colonization by Foc R1 in 80% of inoculated plants. The T2, T4, T7, and T9 treatments mitigated the negative effects caused by Foc R1 on plant physiology and growth. Our data allowed us to identify three promising treatments to control FWB, reducing the progress of the disease, delaying the colonization of inner tissue, and mitigating physiological damages. Further studies should be addressed to determine the modes of action of the biocontrol agents against Foc and validate the utilization in the field.

Trichoderma carraovejensis: a new species from vineyard ecosystem with biocontrol abilities against grapevine trunk disease pathogens and ecological adaptation.

Trichoderma strains used in vineyards for the control of grapevine trunk diseases (GTDs) present a promising alternative to chemical products. Therefore, the isolation and characterization of new indigenous Trichoderma strains for these purposes is a valuable strategy to favor the adaptation of these strains to the environment, thus improving their efficacy in the field. In this research, a new Trichoderma species, Trichoderma carraovejensis, isolated from vineyards in Ribera de Duero (Spain) area, has been identified and phylogenetically analyzed using 20 housekeeping genes isolated from the genome of 24 Trichoderma species. A morphological description and comparison of the new species has also been carried out. In order to corroborate the potential of T. carraovejensis as a biological control agent (BCA), confrontation tests against pathogenic fungi, causing various GTDs, have been performed in the laboratory. The compatibility of T. carraovejensis with different pesticides and biostimulants has also been assessed. This new Trichoderma species demonstrates the ability to control pathogens such as Diplodia seriata, as well as high compatibility with powdered sulfur-based pesticides. In conclusion, the autochthonous species T. carraovejensis can be an effective alternative to complement the currently used strategies for the control of wood diseases in its region of origin.

Insights into the biocontrol and plant growth promotion functions of Bacillus altitudinis strain KRS010 against Verticillium dahliae

BackgroundVerticillium wilt, caused by the fungus Verticillium dahliae, is a soil-borne vascular fungal disease, which has caused great losses to cotton yield and quality worldwide. The strain KRS010 was isolated from the seed of Verticillium wilt-resistant Gossypium hirsutum cultivar “Zhongzhimian No. 2.”ResultsThe strain KRS010 has a broad-spectrum antifungal activity to various pathogenic fungi as Verticillium dahliae, Botrytis cinerea, Fusarium spp., Colletotrichum spp., and Magnaporthe oryzae, of which the inhibition rate of V. dahliae mycelial growth was 73.97% and 84.39% respectively through confrontation test and volatile organic compounds (VOCs) treatments. The strain was identified as Bacillus altitudinis by phylogenetic analysis based on complete genome sequences, and the strain physio-biochemical characteristics were detected, including growth-promoting ability and active enzymes. Moreover, the control efficiency of KRS010 against Verticillium wilt of cotton was 93.59%. After treatment with KRS010 culture, the biomass of V. dahliae was reduced. The biomass of V. dahliae in the control group (Vd991 alone) was 30.76-folds higher than that in the treatment group (KRS010+Vd991). From a molecular biological aspect, KRS010 could trigger plant immunity by inducing systemic resistance (ISR) activated by salicylic acid (SA) and jasmonic acid (JA) signaling pathways. Its extracellular metabolites and VOCs inhibited the melanin biosynthesis of V. dahliae. In addition, KRS010 had been characterized as the ability to promote plant growth.ConclusionsThis study indicated that B. altitudinis KRS010 is a beneficial microbe with a potential for controlling Verticillium wilt of cotton, as well as promoting plant growth.

Bio-Inspired Intelligent Swarm Confrontation Algorithm for a Complex Urban Scenario

This paper considers the confrontation problem for two tank swarms of equal size and capability in a complex urban scenario. Based on the Unity platform (2022.3.20f1c1), the confrontation scenario is constructed featuring multiple crossing roads. Through the analysis of a substantial amount of biological data and wildlife videos regarding animal behavioral strategies during confrontations for hunting or food competition, two strategies are been utilized to design a novel bio-inspired intelligent swarm confrontation algorithm. The first one is the “fire concentration” strategy, which assigns a target for each tank in a way that the isolated opponent will be preferentially attacked with concentrated firepower. The second one is the “back and forth maneuver” strategy, which makes the tank tactically retreat after firing in order to avoid being hit when the shell is reloading. Two state-of-the-art swarm confrontation algorithms, namely the reinforcement learning algorithm and the assign nearest algorithm, are chosen as the opponents for the bio-inspired swarm confrontation algorithm proposed in this paper. Data of comprehensive confrontation tests show that the bio-inspired swarm confrontation algorithm has significant advantages over its opponents from the aspects of both win rate and efficiency. Moreover, we discuss how vital algorithm parameters would influence the performance indices.

Study on the use of Imazalil to continuous cropping obstacle of Ganoderma lucidum caused by Xylogone ganodermophthora

BackgroundThe Xylogone ganodermophthora is a pathogenic bacterium that poses a significant challenge to the continuous cultivation of the Ganoderma lucidum fungus. This study aims to identify and investigate specific agents for the effective prevention and control of X. ganodermophthora, establishing a theoretical foundation for overcoming this persistent challenge in G. lucidum cultivation.ResultsUsing different G. lucidum soil as materials to study the presence of X. ganodermophthora in the soil. Additionally, the plate confrontation test was employed to investigate the impact of X. ganodermophthora on G. lucidum growth. The impact of physical factors and antibacterial agents on pathogenic bacteria was successfully carried out, with a further exploration of the effectiveness of field control. PCR amplification experiment and sequencing analysis verified that X. ganodermophthora existed in G. lucidum continuous cropping obstacle soil. This pathogenic bacteria has a significant inhibitory effect on the growth of G. lucidum, with an inhibition rate of up to 52.23%. High temperature, low temperature, light and other physical factors have no obvious inhibitory effect on this pathogen. Further investigation revealed that specific drugs, such as low concentrations (10 μL/mL) of Acticide DB20 and Imazalil, could effectively inhibit X. ganodermophthora growth in G. lucidum. Among them, Imazalil has a notable inhibitory effect on the growth of X. ganodermophthora.ConclusionsIndoor toxicity test and field control results showed that Imazalil could effectively control the growth of pathogen X. ganodermophthora in G. lucidum continuous cropping obstacle, and promote the growth of G. lucidum.Graphical

In vitro antagonist activity of cedar Trichoderma species against three cedarwood lignivorous fungi

Cedarwood lignivorous fungi cause significant damage to cedar groves. In Morocco, the losses of cedar wood are estimated at more than 30% due to these fungi, which cause two primary diseases known as M'jej and Saboune. In this study, we are interested in the isolation and molecular identification of parasitic fungi and trichoderma species in the cedar groves of Tazekka National Park and Azrou forest, as well as the biological control of these lignivorous fungi by Trichoderma species. The molecular characterization identified three phytopathogenic fungi: Paecilomyces maximus, Pleurostoma richardsiae, and Alternaria tenuissima. Under in vitro conditions, Trichoderma species (Trichoderma lixii, Trichoderma simmonsii, and Trichoderma viridescens) were more effective. They significantly inhibited the mycelial growth of the studied pathogens through the production of volatile metabolites and mycoparasitic capacity. A maximum percentage exceeding 73 % was recorded. In addition, the direct confrontation tests showed a great capacity of Trichoderma isolates to colonize the medium in competition with the pathogenic fungi, with colonization percentages that reached 81.25 %. In general, Trichoderma agents significantly inhibited the growth of pathogens through various inhibition mechanisms, including colonization of the space, mycoparasitism, or the production of volatile or diffusible metabolites. An in-vivo study is recommended to take advantage of this ecological biocontrol solution.

Sensitivity and Specificity of Qualitative Visual Field Tests for Screening Visual Hemifield Deficits in Right-Brain-Damaged Stroke Patients.

A timely detection of visual hemifield deficits (VHFDs; hemianopias or quadrantanopias) is critical for both the diagnosis and treatment of stroke patients. The present study determined the sensitivity and specificity of four qualitative visual field tests, including face description, confrontation tests (finger wiggle), and kinetic boundary perimetry, to screen large and dense VHFDs in right-brain-damaged (RBD) stroke patients. Previously, the accuracy of qualitative visual field tests was examined in unselected samples of patients with heterogeneous aetiology, in which stroke patients represented a very small fraction. Building upon existing tests, we introduced some procedural ameliorations (incl. a novel procedure for kinetic boundary perimetry) and provided a scoresheet to facilitate the grading. The qualitative visual field tests' outcome of 67 consecutive RBD stroke patients was compared with the standard automated perimetry (SAP; i.e., reference standard) outcome to calculate sensitivity and specificity, as well as positive and negative predictive values (PPV and NPV), both for each individual test and their combinations. The face description test scored the lowest sensitivity and NPV, while the kinetic boundary perimetry scored the highest. No test returned false positives. Combining the monocular static finger wiggle test (by quadrants) and the kinetic boundary perimetry returned the highest sensitivity and specificity, in line with previous studies, but with higher accuracy (100% sensitivity and specificity). These findings indicate that the combination of these two tests is a valid approach with RBD stroke patients, prompting referral for a formal visual field examination, and representing a quick, easy-to-perform, and inexpensive tool for improving their care and prognosis.

Challenges in Diagnosing Functional Visual Loss and Malingering: a Case Report

Abstract
 Introduction : Functional Visual Loss (FVL) is decreased visual acuity and/or altered visual fields without any associated organic pathology and is considered within the spectrum of malingering. It manifests as either simulating an ophthalmic disease or denying ophthalmic disease. Thorough history-taking and careful examination of the patient are essential in reaching the diagnosis.
 Case Illustration : A 17-year-old female came with complaints of a spinning headache, sudden and painless blurry vision in both eyes, double vision, and a history of syncope for the last two days. Ophthalmology examination revealed UCVA was 0.5/60 for both eyes with inconsistent answers from the patient. The confrontation test, light reflex, funduscopy, Humphrey visual test, OCT, and MRI were normal. Malingering was suspected and a psychiatric consultation was made. The patient was found to be a victim of bullying and had a history of visual hallucinations. The patient was then diagnosed with severe depression with psychotic signs.
 Discussion : 
 Conclusion : FVL can be suspected when there is inconsistency in the results of some clinical basic tests. Despite the association between FVL and psychological problems like depression is complicated, this condition may occur in a bidirectional relationship in which depression leads to disability or contrarily. In conclusion, diagnosing visual problems in malingering patients can be challenging. Subjective and objective tests are needed to help practitioners confirm the malingering state of the patient. Practitioners also should be aware of the underlying risk of psychological problems among persons reporting visual function loss.

Post Stroke, Is Perimetry Necessary? A Case Report

Abstract
 Introduction : Stroke are generally associated with peripheral visual field loss. Three out of four stroke patients report some form of disability, one of which is visual impairment. Approximately 16% of these patients have a homonymous visual field defect poststroke. These vision problems can lead to difficulty carrying out a lot of daily tasks and activities, such as driving. This report tries to define the diagnostic flow to determine the exact type and lesion.
 Case Illustration : Male, 61 years old, came to Universitas Sumatera Utara Hospital with visual field loss in both eyes. Two months ago, he was diagnosed with ischemic stroke and treated with Aspirin 80 mg, with no limbs disability right now. He also had hypertension and treated with Amlodipine 10 mg. VOD: 6/60 with BCVA S-2.00 6/7,5, VOS: 6/60 with BCVA S-2.00 6/7.5. With confrontation test and perimetry, defect was found in medial visual field OD and lateral visual field OS. Hess screen and Amsler Grid was normal. Head CT-Scan was performed with multiple infarcts, mainly in right occipital lobe. The patient was diagnosed with Incomplete Hemianopia, Left Congruous Homonymous Hemianopia with Macular Sparing, and treated with Citicholine 1000 mg once daily.
 Discussion
 Conclusion : In stroke patients with homonymous visual field loss, visual field testing with detailed evaluation of visual field defect can determine the lesion location, and neuro-radiological imaging was necessary to assess visual pathway. It’s important for educate the patients, diagnostic and prevent the stroke recurrent.

In vitro characterization of a Bacillus velezensis isolate as an antagonist of grapevine trunk disease pathogens

AbstractOne of the major and yet unsolved threats for viticulture is the group of vascular fungal infections, the so-called grapevine trunk diseases. Besides their latent nature and the enormous number of associated pathogens, their control is also hampered by the lack of effective fungicides, directing growing attention toward the use of biocontrol agents. In the present study the isolation, identification, and characterization of a bacterial strain are presented, showing biocontrol potential against some main causal agents of grapevine trunk diseases. The strain was isolated from the wood of an asymptomatic grapevine and selected for the fungicidal activity against the pathogen Phaeomoniella chlamydospora. According to 16S rDNA, gyrA, and gyrB sequences, the isolate belongs to Bacillus velezensis species. Confrontation tests with the bacterium or with its fermentation broth further revealed growth inhibition and fungicide activity against Botryosphaeria dothidea, Eutypa lata and Diaporthe ampelina pathogens. Fractionation of the bacterial culture filtrate suggests that the antifungal agents secreted by the B. velezenzis isolate are mainly lipoproteins. Phytotoxicity tests were also carried out with the isolate, showing no harmful effects on grapevine foliar disks.

ISOLATION AND IDENTIFICATION OF BROAD-SPECTRUM ANTAGONIST BACTERIA AGAINST PATHOGENIC FUNGI OF MAIZE CROP

Fungal diseases may cause significant damage to crops worldwide, generating yield losses, poor grain quality, and health risks to humans and animals. Biological control using antagonistic bacteria offers innovative solutions for sustainable management aiming at plant protection. However, beneficial plant-microorganism interactions are particular, and few antagonists with broad-spectrum activity have been reported. In this work, two bacteria isolated from sorghum seeds were identified by partial sequencing of the 16S rRNA gene and tested in vitro for their capacity to control six important pathogenic fungi of maize: Fusarium verticillioides, Macrophomina phaseolina, Stenocarpella sp., Fusarium graminearum, Colletotrichum graminicola, and Bipolaris sp. The molecular identification revealed that the bacterial isolates belong to the genera Bacillus (strain LIS05) and Paenibacillus (strain LIS04). Both bacterial isolates inhibited the growth of all six phytopathogens by at least 49%. The isolate LIS05 showed the most significant antagonistic potential against the fungal pathogens tested, at an average of 73% inhibition. The highest antagonist activity (86.1% inhibition) was observed in the confrontation test between the isolate LIS05 and C. graminicola. In addition to the mycelial growth inhibition, the isolate LIS04 blocked the production of dark pigments by Bipolaris sp. This study showed that LIS05 and LIS04 are promising alternatives for developing integrated management strategies to control fungal diseases in maize and sorghum.

5-Aminolevulinic acid against strawberry Fusarium wilt: Bidirectional regulation of biocontrol agents and pathogens

Strawberry Fusarium wilt (SFW) is a systematic soil-borne disease caused by Fusarium oxysporum f. sp. fragaria (Fof), which infects the vascular bundles, blocking water and nutrient transport from roots to the aboveground. It is a severe pathogen which spreads rapidly and destroys strawberry production. Finding a way to control this disease is of great scientific value and practical importance. In this study, three fungi were isolated from the vascular tissues of sick strawberries in the field. After DNA sequencing, they were identified as Fof, Aspergillus fumigatus and Trichoderma harzianum, respectively, among which the first two are pathogens and the third is a probiotic. All fungi were controlled by thiophanate-methyl (TM), a commercial fungicide. On PDA medium, 20 mg·L−1 5-aminolevulinic acid (ALA), a natural non-protein amino acid, promoted T. harzianum proliferation, but inhibited Fof and A. fumigatus. In confrontation test, the growth of Fof or A. fumigatus was inhibited by T. harzianum and exogenous ALA promoted T. harzianum growth but significantly inhibited the pathogen growth. When three species of fungi were separately or combinedly inoculated on healthy strawberry plants, T. harzianum promoted plant growth and development while Fof or A. fumigatus caused growth retardation, where Fof directly caused leaf yellowing and plant wilting. When the plants inoculated with different fungus were treated with ALA, the results turned out that ALA alleviated SFW symptoms by bidirectionally promoting T. harzianum proliferation and inhibiting Fof and A. fumigatus. Thus, ALA might be used in comprehensively controlling SFW in strawberry industry.

Efficacy of Streptomyces melanosporofaciens strain X216 at controlling clubroot disease on oilseed rape.

Oilseed rape (Brassica napus L.) is highly susceptible to infection from the soilborne pathogen Plasmodiophora brassicae Woronin that causes clubroot disease and deleteriously affects production throughout the world. In this study, biological control resources were explored by isolating 237 strains of bacteria from fields of oilseed rape using the gradient dilution coating method. A strain with strong antagonistic ability was screened using a plate confrontation test and designated X216. It was identified as Streptomyces melanosporofaciens owing to its morphological characteristics and 16S rRNA gene sequence. This study also examined the lethality of strain X216 to the resting spores of P. brassicae, its influence on infection in root hairs, and its ability to control clubroot on oilseed rape. The corrected lethality rate on resting spores after strain X216 had been used for 14 days was 56.59% ± 1.97%, which was significantly higher than the use of 75% of the fungicides chlorothalonil WP and 20% Fluazinam SC. Significantly fewer root hairs were infected after this treatment. A pot test showed that X216 was 62.14% effective at controlling the disease, which was not significantly different from that of the fungicide 100 g L-1 cyazofamid SC diluted 1,000-fold but significantly higher than those of 75% chlorothalonil and 50% carbendazim WP. Strain X216 controlled 43.16% of the incidence of clubroot in the field, which could significantly reduce the disease index of oilseed rape clubroot. Therefore, strain X216 is promising to study for the biological control of oilseed rape clubroot.

Biocontrol potential of inflorescence rot of date palm caused by <i>Mauginiella scaettae</i> in the Biskra region (Algeria)

Date palm inflorescence rot (known as Khamedj disease) caused by Mauginiella scaettae is a serious problem in most date palm-growing areas of the world, and it causes considerable yield loss. The extensive use of fungicides has resulted in the emergence of fungicide-resistant pathogens, and concerns have been raised over the residual effects on the environment and human health. In this regard, biocontrol agents have been proposed as an alternative to standard fungicides. The aim of our study was to evaluate the biocontrol agent Aspergillus niger against the pathogen M. scaettae. In vitro confrontation tests between M. scaettae and A. niger showed that, after 10 days of incubation, the Petri dish was almost completely covered by the antagonist A. niger, while the pathogen M. scaettae occupied only 0.61±0.015 cm of diameter, which corresponds to a considerable inhibition of the mycelial growth (85.33%). Microscopic observations showed an abundant sporulation of A. niger around the colony of M. scaettae and marked a very important mycoparasitic power. In conclusion, the use of biological control agents is cost-effective, easy to use, and environmentally friendly for the control of Khamedj disease.

Improving the success of reinforcement programs: effects of a two-week confinement in a field enclosure on the anti-predator behaviour of captive-bred European hamsters.

Captive breeding programs are an important pillar in biodiversity conservation, aiming to prevent the extinction of threatened species. However, the establishment of self-sustaining populations in the wild through the release of captive-bred animals is often hampered by a high mortality upon release. In this study, we investigated how a 2-week confinement period within a large field enclosure affected the anti-predator behaviour of 'naive' captive-bred hamsters and how potential modifications persisted over time. During three consecutive tests, hamsters were confronted with a moving predator model (a red fox mount, Vulpes vulpes) and their behaviour was filmed. After the initial round of confrontation with the predator model, one group of hamsters (field group) was released into a field enclosure protected from predators, while the other group (control) remained in their individual laboratory cages. After 2 weeks, hamsters from the field group were recaptured and individuals of both groups underwent a second confrontation test. A total of 1 month after their return from the field enclosure, field hamsters were subjected to a last confrontation test. Video analysis, investigating four behavioural variables, revealed that field hamsters significantly modified their behavioural response following the 2 weeks confinement in the enclosure, while this was not the case for control hamsters. In addition, most behavioural modifications in field hamsters persisted over 1 month, while others started to revert. We suggest that an appropriate pre-release period inside a field enclosure will enable naive (captive-bred) hamsters to develop an adequate anti-predator behaviour that will increase their immediate survival probability upon release into the wild. We believe that such measure will be of great importance for hamster conservation programs.

In vitro antagonism of Trichoderma against Rhizoctonia solani

Trichoderma spp., is a highly efficient antagonist of root pathogens, such as Rhizoctonia solani, which causes loss in many crops. The aim of this research was to evaluate in vitro the antagonistic capacity of T. viride, T. koningii, T. harzianum and Trichoderma spp. isolates against R. solani from a potato crop. In confrontation tests, all Trichoderma isolates were classified as antagonists class 2 according to Bell scale, where T. harzianum and T. koningii showed more than 60% inhibition of the radial growth of R. solani at 120 h. In the interaction between T. harzianum and Trichoderma spp. with R. solani, as mycoparasitism strategy, vacuolization, lysis, coiling, and penetration were demonstrated, the last two were present in all Trichoderma isolates evaluated.