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Biological control with a fungus called Beauveria bassiana
No full textSeveral commercial biological products are based on fungal microorganisms that are antagonistic of insects and fungal pathogens causing severe damage of agricultural plants.
Beauveria bassiana is the most wide-spread entomopathogenic fungus, component of several commercial products. This fungus parasitizes a wide range of noxious pests for agricultural plants such as the greenhouse whitefly (T. vaporariorum), different aphid species (Aphis fabae, Macrosiphum euphorbiae, Chaetosiphon fragaefolii), thrips (Frankliniella occidentalis and Thrips tabaci) and spider mites (Tetranychus urticae). When spores of B. bassiana come in contact with the skin of a susceptible insect, they penetrate its body, grow inside and kill the insect within few days. Finally, a white mould comes out from the cadaver and produces new spores that can colonize others hosts.
Beauveria bassiana based products have not a preharvest interval (PHI), any harmful effects on human or animal health, on groundwater or they have not any unacceptable influence on the environment. Furthermore, no effects of B. bassiana on bees (Apis mellifera) or other pollinators have been observed and the fact that bee vectoring is used to apply this strain would indicate a low risk to bees and other pollinators, making B. bassiana a useful tool in pests management strategies
Compatibility of Beauveria bassiana with fungicides in vitro and on zucchini plants infested with Trialeurodes vaporariorum
No full textThe effect of fungicides on the entomopathogenic fungus Beauveria bassiana strain ATCC 74040 (Naturalis®) was evaluated in vitro and in vivo. The formulated fungicides Cantus® (boscalid), Frupica (mepanipyrim), Galben (benalaxyl), Melody® Compact (iprovalicarb + Cu oxychloride), Oracle⢠(fenamidone + Cu), Prosper® 300 CS (spiroxamine), Signum® (boscalid + pyraclostrobin), Switch® (cyprodinil + fludioxonil) and Talendo® (proquinazid) were tested on fungal colony growth from 10 field dose (10FD) to 10â4 FD. Each product mixed with Naturalis at FD was also tested against Trialeurodes vaporariorum on zucchini plants. Fungal colony growth was not affected by Cantus, Galben, Melody Compact, Oracle and Talendo at FD, while Frupica and Prosper 300 CS reduced colony growth by 9.7% and 6.9%, respectively. All these products did not inhibit the activity of B. bassiana on whiteflies at FD. On the contrary, Signum and Switch significantly inhibited colony growth at all doses and reduced the entomopathogenic activity on whiteflies when applied in mixture with B. bassiana. The toxic effect of both fungicides on B. bassiana persisted for 10 days after treatments, with a 91.2% reduction in nymph mortality in comparison to control for Signum and 87.4% for Switch. The mode of action of their active ingredients, boscalid, pyraclostrobin, cyprodinil and fludioxonil, individually and in mixture (boscalid + pyraclostrobin and cyprodinil + fludioxonil), was studied on fungal colony growth, spore germination, germ tube elongation and spore survival from 10FD to 10â2 FD. All these parameters were reduced by the four active ingredients at all doses, pyraclostrobin and fludioxonil completely inhibited spore germination, fludioxonil alone and in mixture with cyprodinil also inhibited completely spore survival
Activity of seaweed and cyanobacteria water extracts against Podosphaera xanthii on zucchini
Full text linkThe purpose of this research was to study the effects of water extracts of algae belonging to the phylum Rodophyta, Heterokontophya, Chlorophyta and of Cyanobacteria against Podosphaera xanthii on zucchini (Cucurbita pepo) cotyledons. Each extract was sprayed on the upper surface of cotyledons at the concentration of 0.5 %, then cotyledons were inoculated with six 10-µl drops of a spore suspension of the pathogen (1×106 spores/ml), and incubated on water agar in Petri dishes. Depending on the species, the extracts showed inhibition, stimulation or no effect on the disease severity caused by P. xanthii and on the pathogen sporulation density. Extracts of Corallina sp., Halopithys sp., Sargassum sp. and Anabaena sp. showed significant inhibitory effect on both parameters. This study suggests that seaweed and cyanobacteria water extracts applied on zucchini cotyledons may be considered in further experiments on plants as a useful preventative tool for the disease management in sustainable agriculture
Prospecting algae and cyanobacteria as bioprotectans for plant disease control
No full textThe European Directive 2009/128 on sustainable use of pesticides promotes the use of alternative approaches
to synthetic products for plant disease control to reduce human, animals and environmental risks. Among
alternatives, natural products based on cyanobacteria and algae are gaining attention. Our studies demonstrated
that application of water extracts from Anabaena minutissima, Ecklonia maxima and Jania adhaerens
controlled powdery mildew caused by Podosphaera xanthii on cucumber detached cotyledons and seedlings
and induced the expression of PR genes related to plant-induced resistance. In addition, tomato seed treatment
with the same extracts increased germination, seedling dry weight, calibre, and reduced root rot caused by
Rhizoctonia solani on tomato plants. Seed treatment also increased chitinase activity and lignin compound
contents in tomato seedlings. A deeper investigation on the possible bioactive compounds of A. minutissima,
E. maxima and J. adhaerens, revealed the antifungal activity of polysaccharides against Botrytis cinerea, agent
of grey mould, in vitro and in vivo on strawberry fruits. Latest research pointed out that application of
phycobiliproteins from A. minutissima, Arthrospira platensis and Hydropuntia cornea on tomato fruits before
B. cinerea challenge reduced grey mould disease. In particular, FT-IR and FT-Raman spectroscopies have
shown that phycobiliproteins from A. minutissima preserved cutin and pectine structures of tomato fruit from
B. cinerea infection. In conclusion, our research demonstrate the potentialities of algae and cyanobacteria as a
bioprotectans for plant disease control
Activity of polysaccharides extracted from Ecklonia sp. and Jania sp. against Botrytis cinerea
No full textAntifungal activity of Ecklonia sp. and Jania sp. polysaccharides against Botrytis cinerea
No full textSeaweeds are a source of macro and microelements, amino acids, vitamins,
polysaccharides and hormones, such as auxins, auxin-like compounds and cytokinins
(Craigie, 2011). Seaweeds extracts (SE) have long been used in agriculture as soil amendment
for their beneficial properties on plants, because they stimulate both plant growth and
production (Crouch & van Staden, 1992; Arthur et. al., 2003). They also increase fruit weight,
fresh dry mass of root, leaf area, yield per plant, the chlorophyll content and minerals
(Sivasankari et al., 2006; Rayorath et al., 2008; Roussos et al., 2009). It has also been shown
that SE may help the plants to counteract abiotic and biotic stresses. Among abiotic stresses,
Ashraf & Foolad (2007) demonstrated that SE are involved in overcoming plant stress
conditions such as drought and salinaty. Several studies have shown antibiotic, antiviral and
antifungal activities of SE against a number of plant pathogens such as Penicillium spp. and
Fusarium oxysporum (Khallil et al., 2015) and Aspergillus sp. (Kosanić et al., 2015).
Seaweeds extracts are also rich in several bioactive compounds, such as polysaccharides that
are well known to be elicitors of plant defence responses. Simultaneously to the growing
consumption of agricultural products, such as strawberry, there was an increase in the use of
chemical fertilizers to improve plant yield, and of synthetic pesticides to control fungal plant
pathogens. The continuous use of chemicals during the years has affected human and animal
health and the ecosystem.
Strawberry is one of the most consumed berries and its high nutritional value and
composition have stimulated its consumption increase. A number of fungal pathogens can
affect strawberry plants such as Colletotrichum spp., and several species of the soil borne
pathogens, such as Rhizoctonia, Fusarium and Pythium causing the so-called black root rot
complex (Manici et al., 2005). Among these pathogens, Botrytis cinerea, the agent of grey
mold, cause several losses especially during shelf life. Alternative approaches to chemical
treatments are necessary to preserve the quality of strawberries during the shelf life in order to
protect health safety and limit the development of the fungus.
In this study, the antifungal activity of cationic polysaccharides extracted from two
macroalgae, Ecklonia sp. (Ochrophyta) and Jania sp. (Rhodophyta) was investigated against
B. cinerea in vitro and in vivo on strawberry. Polysaccharides were extracted by selective
precipitation with 2% (w/v) N-Cetylpyridinium bromide monohydrate (Cetavlon) (Diaz et al.,
2011). In the in vitro assay, fungal colony portions were treated for 6 hours by immersion in
three polysaccharides aqueous concentrations, 1.65, 0.82 and 0.41 mg/ml for Ecklonia sp. and
0.18, 0.09 and 0.045 mg/ml for Jania sp. The treated colony portions were inoculated in
agarized medium and daily growth was measured for a week. Ecklonia sp. polysaccharides at
0.18 mg/ml and 0.09 mg/ml significantly inhibited B. cinerea growth by 21.0% and 22.8%,
respectively, two days after treatment. Jania sp. polysaccharides did never inhibit fungal colony growth. For in vivo experiments, strawberry ripe fruits cv. Cristal were immerged
before or after harvesting in polysaccharide aqueous solutions of Ecklonia sp. at the
concentrations of 0.82 and 0.41 mg/ml, and of Jania sp., at 0.09 and 0.045 mg/ml. A spore
suspension of B. cinerea (1 × 105
spores/ml) was inoculated by spraying fruits 24 hours after
treatment. Disease symptoms over the total area inoculated of fruit were evaluated as
percentage of infected area. The pre-harvest treatment with Jania sp. showed to reduce
disease symptoms by 100% at 0.09 mg/ml and by 50% at 0.045 mg/ml and with Ecklonia sp.
by 16.7% (0.82 mg/ml) and 11.11% (0.41 mg/ml). Post-harvest treatment did never inhibit
disease symptoms. This study showed that SE could be considered for further investigation in
control strategy against B. cinere
TOMATO SEED PRIMING WITH WATER-SOLUBLE POLYSACCHARIDES FROM JANIA ADHAERENS PROMOTES PLANT GROWTH AND INCREASES PLANT RESISTANCE TO SOILBORNE PATHOGENS
No full textMarine macroalgae are a source of natural bioactive compounds, such as polysaccharides, that deserve exploitation in the field of plant disease management. Moreover, current European regulations require that priority should be given to alternative products than synthetic pesticides. In agriculture, algae have been mostly used for their beneficial properties on plant development. In this study, we showed that tomato seed biopriming with water-soluble polysaccharides (WSPs) from the alga Jania adhaerens protects seedlings and adult plants from the soilborne pathogens Fusarium oxysporum f.sp. lycopersici, Pythium ultimum and Rhizoctonia solani artificially inoculated in a growing substrate.
First, WSPs were characterized by FT-IR spectroscopy and seedling emergence, disease severity, and expression of genes related to phenylpropanoid, chlorogenic acid, SAR and ISR pathways, and chitinase and β-1,3 glucanase activities were investigated after seed priming. WSPs FT-IR spectra showed typical bands assigned to alduronic acids and glycosidic linkage formation in polysaccharides. Depending on the WSPs dose, seed treatment enhanced seedling emergence, reduced disease severity and increased plant growth. Moreover, HQT, HCT, PAL, PR1 and PR2 genes were significantly upregulated together with β-1,3 glucanase activity. These results show that algal WSPs have the potential for being considered as natural compounds for soilborne pathogens control in sustainable agriculture
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Inhibitory activity of aqueous extracts from Anabaena minutissima, Ecklonia maxima and Jania adhaerens on the cucumber powdery mildew pathogen in vitro and in vivo
Full text linkAqueous extracts from Anabaena minutissima BEA 0300B (ANA), Ecklonia maxima (ECK) and Jania adhaerens (JAN) were evaluated for their antifungal effect against powdery mildew disease caused by Podosphaera xanthii on cucumber detached cotyledons and seedlings. All the extracts were sprayed on detached cotyledons at 2.5, 5.0 and 10.0 mg dry biomass mL−1 water and those of ANA and JAN at 5.0 and 10.0 mg mL−1 on seedlings before pathogen challenge (106 spores mL−1). ANA and JAN at 5.0 and 10.0 mg mL−1 reduced infected area and fungal sporulation on both detached cotyledons and seedlings. ANA and JAN at 5.0 and 10.0 mg mL−1 were also evaluated for their elicitation of seedling defence responses, 1, 2 and 3 days before P. xanthii inoculation. Treatments reduced disease symptoms depending on extract, concentration and application time. Both extracts differentially induced the expression of PR genes, which may have concurred to pathogen control. At all times, ANA mainly induced AePR3 and PR1 genes, at 5.0 and 10.0 mg mL−1, respectively, while JAN mainly induced AePR3 and PR4 at 5.0 mg mL−1. This suggests that both ANA and JAN activated the expression of genes within the jasmonic acid and salicylic acid pathway. Proteins, phycobiliproteins, chlorophylls, carotenoids and antioxidant activities determined in the extracts could be involved in the antifungal effect or induction of plant systemic resistance. These results demonstrate that aqueous extracts from algae and cyanobacteria may be considered for further studies as a bio-based strategy for sustainable disease management
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