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Detecting fraud during online exams using proctoring software comes with substantial privacy challenges. Previous work argues students experience heightened anxiety and have privacy concerns. However, little is known about which specific aspects of online proctoring cause these concerns. This study contributes such insights by using the Contextual Integrity (CI) framework to discover how students (N = 456) rate the acceptability of 1064 proctoring information flows with varying information types, recipients, and transmission principles. We find that the acceptability varies considerably depending on the context. Besides exposing obvious privacy violations, we find that, under certain conditions, students consider it acceptable to share data with teachers - despite their lack of involvement in proctoring. Also, the acceptability of sharing highly sensitive information - which should under no circumstances be shared - sometimes increases. We discuss the implications of these and other findings and provide concrete recommendations for educational institutions using online proctoring.

Banana Fusarium wilt is a major production constraint globally and a significant threat to the livelihoods of millions of people in East and Central Africa (ECA). A proper understanding of the diversity and population dynamics of the causal agent, Fusarium oxysporum f. sp. cubense (Foc), could be useful for the development of sustainable disease management strategies for the pathogen. The current study investigated the diversity of Foc in ECA using vegetative compatibility group (VCG) analysis, PCR-RFLPs of the ribosomal DNA's intergenic spacer region, as well as phylogenetic analysis of the elongation factor-1α gene. Six VCGs (0124, 0125, 0128, 01212, 01220, and 01222), which all belong to one lineage (Foc lineage VI), were widely distributed throughout the region. VCGs 0128 and 01220 are reported for the first time in Burundi, the Democratic Republic of Congo (DRC), Rwanda, Tanzania, and Uganda, while VCG 01212 is reported in the DRC and Rwanda. Isolates that did not belong to any of the known VCGs were identified as Foc lineage VI members by phylogenetic analysis and may represent novel VCGs. CAV 2734, a banana pathogen collected in Rwanda, clustered with nonpathogenic F. oxysporum isolates in lineage VIII. Results from this study will contribute significantly toward the implementation of banana Fusarium wilt disease management practices in the region, such as the restricted movement of infected planting material and the selective planting of resistant banana varieties.

Summary In order to replace particularly biohazardous nematocides, there is a strong drive to finding natural product‐based alternatives with the aim of containing nematode pests in agriculture. The metabolites produced by the fungal endophyte Fusarium oxysporum 162 when cultivated on rice media were isolated and their structures elucidated. Eleven compounds were obtained, of which six were isolated from a Fusarium spp. for the first time. The three most potent nematode‐antagonistic compounds, 4‐hydroxybenzoic acid, indole‐3‐acetic acid (IAA) and gibepyrone D had LC 50 values of 104, 117 and 134 μg ml−1, respectively, after 72 h. IAA is a well‐known phytohormone that plays a role in triggering plant resistance, thus suggesting a dual activity, either directly, by killing or compromising nematodes, or indirectly, by inducing defence mechanisms against pathogens (nematodes) in plants. Such compounds may serve as important leads in the development of novel, environmental friendly, nematocides.

The research demonstrated that Arabidopsis can be used as a model system for studying plant–nematode–endophyte tripartite interactions; thus, opening new possibilities for further characterizing the molecular mechanisms behind these interactions. Arabidopsis has been established as an important model system for studying plant biology and plant–microbe interactions. We show that this plant can also be used for studying the tripartite interactions among plants, the root-knot nematode Meloidogyne incognita and a beneficial endophytic isolate of Fusarium oxysporum, strain Fo162. In various plant species, Fo162 can systemically reduce M. incognita infection development and fecundity. Here it is shown that Fo162 can also colonize A. thaliana roots without causing disease symptoms, thus behaving as a typical endophyte. As observed for other plants, this endophyte could not migrate from the roots into the shoots and leaves. Direct inoculation of the leaves also did not result in colonization of the plant. A significant increase in plant fresh weight, root length and average root diameter was observed, suggesting the promotion of plant growth by the endophyte. The inoculation of A. thaliana with F. oxysporum strain Fo162 also resulted in a significant reduction in the number of M. incognita juveniles infecting the roots and ultimately the number of galls produced. This was also observed in a split-root experiment, in which the endophyte and nematode were spatially separated. The usefulness of Arabidopsis opens new possibilities for further dissecting complex tripartite interactions at the molecular and biochemical level.

Colonization of plants by particular endophytic fungi can provide plants with improved defenses toward nematodes. Evidently, such endophytes can be important in developing more sustainable agricultural practices. The mechanisms playing a role in this quantitative antagonism are poorly understood but most likely multifactorial. This knowledge gap obstructs the progress regarding the development of endophytes or endophyte-derived constituents into biocontrol agents. In part, this may be caused by the fact that endophytic fungi form a rather heterogeneous group. By combining the knowledge of the currently characterized antagonistic endophytic fungi and their effects on nematode behavior and biology with the knowledge of microbial competition and induced plant defenses, the various mechanisms by which this nematode antagonism operates or may operate are discussed. Now that new technologies are becoming available and more accessible, the currently unresolved mechanisms can be studied in greater detail than ever before.

The significance of fungal endophytes in African agriculture, particularly Kenya, has not been well investigated. Therefore, the objective of the present work was isolation, multi-gene phylogenetic characterization and biocontrol assessment of endophytic fungi harbored in tomato roots for nematode infection management. A survey was conducted in five different counties along the central and coastal regions of Kenya to determine the culturable endophytic mycobiota. A total of 76 fungal isolates were obtained and characterized into 40 operational taxonomic units based on the analysis of ITS, β-tubulin and tef1α gene sequence data. Among the fungal isolates recovered, the most prevalent species associated with tomato roots were members of the Fusarium oxysporum and F. solani species complexes. Of the three genes utilized for endophyte characterization, tef1α provided the best resolution. A combination of ITS, β-tubulin and tef1α resulted in a better resolution as compared to single gene analysis. Biotests demonstrated the ability of selected non-pathogenic fungal isolates to successfully reduce nematode penetration and subsequent galling as well as reproduction of the root-knot nematode Meloidogyne incognita. Most Trichoderma asperellum and F. oxysporum species complex isolates reduced root-knot nematode egg densities by 35–46 % as compared to the non-fungal control and other isolates. This study provides first insights into the culturable endophytic mycobiota of tomato roots in Kenya and the potential of some isolates for use against the root-knot nematode M. incognita. The data can serve as a framework for fingerprinting potential beneficial endophytic fungal isolates which are optimized for abiotic and biotic environments and are useful in biocontrol strategies against nematode pests in Kenyan tomato cultivars. This information would therefore provide an alternative or complementary crop protection component.

The mutualistic root-colonizing endophytes Fusarium oxysporum strain Fo162 (Fo162) and Rhizobium etli strain G12 (G12) have been shown to individually induce systemic resistance against the sucking insect Aphis gossypii Glover (Hom., Aphididae). Simultaneous application of both organisms may be a strategy to further increase the systemic defense responses and thus the biocontrol efficacy. The simultaneous inoculation of both endophytes, either in a mixed or in a spatially-separated way, also reduced the aphid population in comparison to untreated squash plants. However, both types of combined treatments did not lead to significant additive biocontrol levels, i.e. further reduction in the aphid population, when compared to individual inoculation. A choice experiment with intact squash plants showed that the aphids favor feeding on endophyte-free plants, indicating that both Fo162 and G12 are able to affect the host plant preference by the aphids. The data illustrate that cocktail type inoculants comprising of different beneficial microorganisms may not always enhance the biocontrol efficacy against insects. Thus, although both Fo162 and G12 are recognized as biocontrol agents, their mutual interactions and their interactions with the host plant have to be taken into account in co-inoculation strategies in biocontrol.

The endophytic fungus Fusarium oxysporum strain Fo162 and the endophytic bacterium Rhizobium etli strain G12 have been shown to enhance plant resistance toward the root-knot nematode Meloidogyne incognita. The individual inoculation of tomato seedlings with these antagonists lead to significant reductions in the number of juveniles that penetrated the root and ultimately the number of galls and egg-masses produced. The present study determined the influence of Fo162 and G12 root colonization on juvenile development inside the root system over time after a synchronized nematode infection. The results showed that 14 and 21 days after nematode inoculation, the development into the third-stage juvenile as well as into the adult-stage was significantly lower in endophyte-treated plants when compared to the untreated control, respectively. In addition, Fo162 and G12 treatment led to a significant reduction in the number of eggs per female 35 days after nematode inoculation. The results demonstrated that both Fo162 and G12 not only reduce M. incognita root penetration, but also reduce their development and reproduction.

The burrowing nematode of banana, Radopholus similis, is difficult, if not impossible, to control effectively. The lack of resistance in commercially acceptable cultivars and the perennial nature of the crop limit management options. Multiplecycle treatment with systemic nematocides is presently the only effective tool available for reducing damage and sustaining yield. Most of these compounds are not toxic to the burrowing nematode, but only inhibit nematode activity for short periods of time. The repetitive application of non-fumigant nematocides has led to an increase in the rapidity of their biodegradation. From environmental, toxicological and consumer viewpoints, this type of pest management is unacceptable. Many attempts have been made to improve the situation with little or no impact to date. Many nematocides have been or are being removed from the market, and new replacement compounds have not been developed. Resistance has never been detected in commercial banana cultivars, and genetically modified cultivars are still unacceptable to a large number of banana consumers. Microbialbased strategies are considered to be a promising alternative approach to nematode management in banana. Progress can only be made if research and crop production systems are streamlined to support new management concepts. The following are discussed: 1) biological enhancement of planting material with fungal endophytes; 2) treatments with multiple nematode antagonists with diverse modes of action; 3) importance of induced systemic resistance in biological control systems; and 4) use of molecular tools to detect effective antagonists. INTRODUCTION There are a large number of effective plant protection technologies available for the management of plant-parasitic nematodes. However, most, if not all, are not adaptable to commercial production systems and less so to subsistence banana and plantain farming. Most people are not aware that Radopholus similis is not controlled by nematocides currently used to secure yield and prevent toppling of the banana plant. Nematocides do not kill nematodes. The majority of systemic nematocides only inhibit movement of R. similis for 2 to 5 weeks. Therefore, nematocides only ensure healthy root growth for a short period. Nematocides are either biodegraded, diluted by rainfall or washed out of the rhizosphere shortly after their application. In addition, microbially enhanced biodegradation of nematocides increases with repeated applications over time (Ou et al., 1994; Karpouzas and Walker, 2000; Pattison et al., 2000; Moens et al., 2004). Microbial degradation also leads to increases in the number of nematocide applications/year, which aggravates the overall situation and disturbs the biological balance in the soil. More importantly, most of the nematocides presently being used are highly toxic to almost all organisms having a nervous system. Most banana crops are grown with nematocides that, for environmental and toxicological reasons, should not be on the market. If R. similis is to be managed without nematocides, new and effective management tools, that actually achieve control without environmental side effects, are needed. Proc. IS on Banana Crop Prot., Sust. Prod.

Abutilon theophrasti Medik., previously found to be rather insensitive to benzoxazinoid containing rye mulch and the allelochemical benzoxazolin-2(3H)-one (BOA), can be associated with the zygomycete Actinomucor elegans, whereby the fungus colonizes the root relatively superficially and mainly in the maturation zone. The fungus mitigates necrosis of the cotyledons when seedlings are incubated with 2 mM BOA, in contrast to those that lack the fungus. In liquid cultures of the fungus, tryptophan was identified. The accumulation of tryptophan is increased in presence of BOA. This amino acid seems to be important in protecting Abutilon against BOA and its derivatives since it suppressed the accumulation of BOA derived, highly toxic 2-aminophen-oxazin-3-one (APO) in the medium and on the root surface during BOA incubations of Abutilon seedlings. Although A. elegans is insensitive to BOA and APO, the fungus is not able to protect the plant against harmful effects of APO, when seedlings are treated with the compound. Abutilon can detoxify BOA via BOA-6-OH glucosylation probably by a cell wall associated glucosyltransferase, but only low amounts of the product accumulate. Low tryptophan concentrations can contribute to a degradation of the toxic intermediate BOA-6-OH by Fenton reactions, whereby the amino acid is oxidized. One of the oxidation products was identified as 4(1H)-quinolinone, which is the core substructure of the quorum sensing molecule 2-heptyl-3-hydroxy-4-quinolone. The mutualistic association of Abutilon theophrasti with Actinomucor elegans is considered as opportunistic and facultative. Such plant-fungus associations depend rather likely on environmental conditions, such as the mode of fertilization.

To explore the feasibility of employing antibodies to obtain disease resistance against plant root pathogens, we have studied the expression of genes encoding antibodies in roots of transgenic plants. A model monoclonal antibody was used that binds to a fungal cutinase. Heavy and light chain cDNAs were amplified by PCR, fused to a signal sequence for secretion and cloned behind CaMV 35S and TR2′ promoters in a single T-DNA. The chimeric genes were cloned both in tandem and in a divergent orientation. The roots of tobacco plants transformed with these constructs produced antibodies that were able to bind antigen in an ELISA. Immunoblotting showed assembly to a full-size antibody. In addition, a F(ab′)2-like fragment was observed, which is probably formed by proteolytic processing. Both antibody species were properly targeted to the apoplast, but the full-size antibody was partially retained by the wall of suspension cells. The construct with divergent promoters showed a better performance than the construct with promoters in tandem. It directed the accumulation of functional antibodies to a maximum of 1.1% of total soluble protein, with half of the plants having levels higher than 0.35%. The high efficiency of this construct probably results from coordinated and balanced expression of light and heavy chain genes, as evidenced by RNA blot hybridization.

Summary There is evidence that the necrotrophic fungal pathogen Botrytis cinerea is exposed to oxidative processes within plant tissues. The pathogen itself also generates active oxygen species and H(2)O(2) as pathogenicity factors. Our aim was to study how the pathogen may defend itself against cellular damage caused by the accumulation of H(2)O(2) and the role of an extracellular catalase in its detoxification during the infection of tomato and bean plants by B. cinerea. Chloronaphthol staining followed by light microscopy showed that H(2)O(2) accumulates in the infection zone in tomato and bean leaves. An extracellular catalase gene (denominated Bccat2) was cloned from B. cinerea. Exposure of mycelium to H(2)O(2) in liquid culture resulted in increased Bccat2 mRNA levels in a concentration-dependent manner. Bccat2 mRNA was detected at early stages of tomato leaf infection, suggesting that B. cinerea experiences oxidative stress. Bccat2-deficient mutants were generated by transformation-mediated gene disruption. Mutants were more sensitive then the wild-type strain to H(2)O(2)in vitro, but they partly compensated for the absence of BcCAT2 by activating other protective mechanisms in the presence of H(2)O(2). Bccat2-deficient mutants did not display a consistent reduction of virulence on bean and tomato leaves. Cerium chloride staining of infected leaf tissue for ultrastructural studies showed that Bccat2-deficient mutants were exposed to H(2)O(2) comparably to the wild-type. The results suggest that B. cinerea is a robust pathogen adapted to growing in hostile oxidizing environments in host tissues.

The non-pathogenic fungus Fusorium oxysporum strain Fo162 can efficiently colonize banana roots and reduce infecting by the burrowing nematode Radopholus similis. It is assumed that the fungus triggers a systemic reaction in the plant, which is affecting the biochemical composition of the root exudates and is thus causing the reduction in nematode colonization. To characterize these shifts, a continuous flow experiment was set up to collect root metabolites on a matrix (XAD-4). Based on HPLC analysis, the extracts, collected from the XAD-4, showed no differences in the composition of the root exudates between plants colonized by the endophyte and the controls. However, the accumulation of several compounds differed significantly. When these extracts were used in a bioassay with Radopholus similis none of the sample-treatment combinations had a significant attracting or repelling effect on the nematodes. This experiment shows that non-pathogenic Fusarium oxysporum strain Fo162 is able to upregulate the synthesis of at least some, so far unidentified compounds released by banana roots under hydroponic conditions. Further studies and optimization of the experimental setup are required to determine whether or not increase in metabolite concentration can affect nematode responses in vitro and ultimately in vivo.

Fenamiphos is a broad spectrum, non-volatile, systemic, organophosphorus nematicide extensively used throughout the world to control plant-parasitic nematodes. The efficacy of this nematicide can decrease in soils where microorganisms accumulate that are capable of rapidly degrading the active ingredient. Among the documented microorganisms to degrade organophosphate compounds, Pseudomonas spp. was frequently identified. However, it still not clear whether or not this bacterial genus is the major responsible one in the biodegradation process. Our objective was to study the roll of Pseudomonas spp. and other soil bacteria on the degradation of fenamiphos in soils with different nematicide application history. In some of these soils fenamiphos metabolizing microorganisms were found, whereas in others not. For example, a soil with 42 fenamiphos applications during 16 years neither contained Pseudomonas spp. nor biodegrading microorganisms. In two different soils, both with 25 fenamiphos applications in 12 years and containing metabolizing microorganisms, only one of them contained Pseudomonas spp., demonstrating that the nematicide was rapidly metabolized by microorganisms other than Pseudomonas spp. Conversely, a control soil, with no previous nematicide application history, contained the highest number of Pseudomonas spp. of all soils analyzed. The number of bacteria of this genus could be increased when compost was added, although this did not alter the lack of the fenamiphos degradation process, even after six weeks and three consecutive nematicide treatments. The Pseudomonas diversity of the non-degrading control soil was composed of P. putida (50%), P. fluorescens (31%), P. syringae (13%) and P. chlororaphis (6%) according to gas chromatography identification. Individual analysis of the Pseudomonas spp. bacteria showed that none were capable of metabolizing fenamiphos in vitro. In conclusion, we demonstrated that Pseudomonas spp. are not intrinsically capable of fenamiphos metabolization. We also found that Pseudomonas spp. may not always accumulate upon fenamiphos treatment and that there are other microorganisms able to metabolize this nematicide.

The biological factors responsible for the microbial breakdown of the organophosphorus nematicide fenamiphos were investigated. Microorganisms responsible for the enhanced degradation of fenamiphos were isolated from soil that had a long application history of this nematicide. Bacteria proved to be the most important group of microbes responsible for the fenamiphos biodegradation process. Seventeen bacterial isolates utilized the pure active ingredient fenamiphos as a carbon source. Sixteen isolates rapidly degraded the active ingredient in Nemacur 5GR. Most of the fenamiphos degrading bacteria were Microbacterium species, although Sinorhizobium, Brevundimonas, Ralstonia and Cupriavidus were also identified. This array of gram positive and gram negative fenamiphos degrading bacteria appeared to be pesticide-specific, since cross-degradation toward fosthiazate, another organophosphorus pesticide used for nematode control, did not occur. It was established that the phylogenetical relationship among nematicide degrading bacteria is closer than that to non-degrading isolates.