Biological control of the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae) by Entomopathogenic fungi and their side effects on natural enemies

Background: The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae) is an insect pest species responsible for damages of citrus fruit quality and tree health. This insect is a vector of bacteria ‘Candidatus Liberibacter’ spp. a putative causal agent of citrus greening disease known as Huanglongbing (HLB), considered one of the most destructive diseases of citrus orchards worldwide. Disease management is mainly based on vector control using pesticides which can affect natural enemies that play an important role in pest control. The entomopathogenic fungi (EPF) Beauveria bassiana (2067 and 2121) and Metarhizium anisopliae (2411) were achieved by applying a suspension of 1 × 107 spores against D. citri nymphs and artificially infected the citrus seedlings under controlled and semi-field conditions. Also, the activity of these EPFs on the coccinellid and lacewing predators was evaluated. The effects of the main chemicals used in citrus plantations on the selected fungi for possible combined use was also investigated. Results: The obtained results showed that under controlled conditions, the percentage of insect mortality produced by EPF varied between 82.8 and 85.9%. Under semi-field conditions, the infection and mortality of D. citri caused by the M. anisopliae 2411 strain was significantly higher than that of B. bassiana 2067, 78.9 and 51%, respectively. Non-significant effect of EPF on the natural enemies of D. citri was observed, suggesting that EPF and predators had compatible effects. Conclusion: This study clearly demonstrated that EPF were able to kill D. citri and can be explored as a promissory biocontrol candidate. Simultaneous use in an integrated pest management program could be possible by applying EPF combined with pesticides

Diversity and virulence of <em>Diaporthe</em> species associated with wood disease symptoms in deciduous fruit trees in Uruguay

Several Diaporthe species are recognized as causal agents of many plant disease symptoms, including twig and branch cankers, dieback, shoot blight, and root and fruit rots. In Uruguay, the proximity between apple, pear and peach orchards offers the possibility to study the presence of different Diaporthe spp. associated with wood cankers across different deciduous fruit trees. Symptomatic twigs and branches of these orchard species were sampled, and isolates of Diaporthe were obtained. Selected isolates were used for cross inoculations in the three hosts. Seven Diaporthe spp. were identified, based on the internal transcribed spacer (ITS) region of rDNA and the translation elongation factor 1-alpha gene (EF1-α) phylogenies. The species were: Diaporthe amygdali, D. foeniculina, D. infecunda, D. eres, D. terebinthifolii, D. oxe and D. phaseolorum, while two isolates Diaporthe sp. 1 and Diaporthe sp. 4 could not be assigned to any species. Diaporthe infecunda, D. eres, D. terebinthifolii, D. phaseolorum and D. oxe on Pyrus communis and D. foeniculina on Malus domestica represent new records in these hosts in Uruguay, while D. oxe isolated from Prunus persica is a new record for this species. Diaporthe eres and D. phaseolorum were the most virulent species, posing the greatest risk due to their wide distribution and virulence in apple and peach trees. Although pear trees showed less symptomatic tissues and were less susceptible than peach and apple trees in the pathogenicity tests, they harboured seven of the species, and therefore should be considered as reservoirs of Diaporthe in Uruguayan orchards. Trees of the three hosts could be considered potential reciprocal sources of pathogenic Diaporthe spp

Diversity and virulence of Diaporthe species associated with wood disease symptoms in deciduous fruit trees in Uruguay

Several Diaporthe species are recognized as causal agents of many plant disease symptoms, including twig and branch cankers, dieback, shoot blight, and root and fruit rots. In Uruguay, the proximity between apple, pear and peach orchards offers the possibility to study the presence of different Diaporthe spp. associated with wood cankers across different deciduous fruit trees. Symptomatic twigs and branches of these orchard species were sampled, and isolates of Diaporthe were obtained. Selected isolates were used for cross inoculations in the three hosts. Seven Diaporthe spp. were identified, based on the internal transcribed spacer (ITS) region of rDNA and the translation elongation factor 1-alpha gene (EF1-α) phylogenies. The species were: Diaporthe amygdali, D. foeniculina, D. infecunda, D. eres, D. terebinthifolii, D. oxe and D. phaseolorum, while two isolates Diaporthe sp. 1 and Diaporthe sp. 4 could not be assigned to any species. Diaporthe infecunda, D. eres, D. terebinthifolii, D. phaseolorum and D. oxe on Pyrus communis and D. foeniculina on Malus domestica represent new records in these hosts in Uruguay, while D. oxe isolated from Prunus persica is a new record for this species. Diaporthe eres and D. phaseolorum were the most virulent species, posing the greatest risk due to their wide distribution and virulence in apple and peach trees. Although pear trees showed less symptomatic tissues and were less susceptible than peach and apple trees in the pathogenicity tests, they harboured seven of the species, and therefore should be considered as reservoirs of Diaporthe in Uruguayan orchards. Trees of the three hosts could be considered potential reciprocal sources of pathogenic Diaporthe spp

In vitro evaluation of sequestering agents for aflatoxins

La presencia de micotoxinas en alimentos es un problema de gran importancia a nivel mundial que provoca serios perjuicios sanitarios y económicos. Para limitar los efectos de las micotoxinas a los animales uno de los métodos más utilizados es la aplicación de secuestrantes. Estos son polímeros inorgánicos u orgánicos que al añadirse a los alimentos forman complejos con las micotoxinas en la luz intestinal disminuyendo así su absorción. Por este motivo se evaluó la eficacia de cuatro secuestrantes, dos alumino silicatos hidratados de calcio y sodio, uno de glucomananos esterificados y otro del tipo multi modular para aflatoxina B1 (AFB1). La capacidad de adsorción fue evaluada in vitro y bajo condiciones de pH similares a las del tracto gastrointestinal de los animales. La concentración de AFB1 fue determinada mediante cromatografía líquida de alta resolución (HPLC). Con la excepción del producto de glucomananos esterificados, el porcentaje de unión de aflatoxina B1 obtenido para los secuestrantes estudiados fue alto (> 76%). Estos resultados sugieren que la mayoría de los secuestrantes utilizados en este estudio son potenciales agentes químicos-biológicos que podrían ser utilizados para disminuir los efectos de las aflatoxinas en animales.The contamination of animal feed with mycotoxins represents a worldwide problem that causes serious diseases in animals and economic losses. One of the most used methods for protecting animals against mycotoxins is the utilization of adsorbents. These are inorganic or organic components that added to foods form complexes with mycotoxins in the gastrointestinal tract thus decreasing its absorption. Four mycotoxin binder products including two hydrated sodium calcium aluminosilicates, one esterified glucomannan and one multi modular were used to determine their efficacity to bind aflatoxin B1. The binding ability for AFB1 was conducted by an in vitro assay, which simulated the pH condition of the gastrointestinal tract of animals. AFB1 contents was determinated by high performance liquid chromatographic (HPLC). With the exception of the esterified glucomannan product, the binding percent of AFB1 was high (> 76%) by the sequestering agents used in the current study. These results suggest that most commercial adsorbent products used in this study are potential chemical - biological agents that might be used to decrease the effects of aflatoxins in animals

Pathogenicity and molecular detection of Uruguayan isolates of Greeneria uvicola and Cadophora luteo-olivacea associated with grapevine trunk diseases

Species from different fungal genera have been indicated as responsible for the development of trunk diseases of grapevines. Greeneria uvicola is responsible for the bitter rot of Vitis vinifera grape bunchesnear harvest, and can also attack other Vitis species. In Uruguay, G. uvicola was isolated from dead arm affected grapevines and as an endophyte from healthy canes. Cadophora luteo-olivacea is a phialophora-likeascomycete with a wide distribution that was isolated from asymptomatic wood tissues in Vitis and Petridisease-affected nursery plants in Uruguay. Pathogenicity of isolates of both species was evaluated on Vitis vinifera cv. Tannat and Cabernet Sauvignon, and rootstocks SO4 and 3309C. Specific primers were developed for the ITS rDNA region for both species. Number of plants showing discoloration, length of discoloration, number of re-isolations and amplifications confirmed the pathogenicity of G. uvicola isolates. Pathogenicityof the isolate of C. luteo-olivacea obtained from symptomatic tissues is discussed. Specific primers can be usedto detect the presence of these fungi in asymptomatic tissues

Selection of Trichoderma strains for biological control of Fusarium nygamai in sorghum (Sorghum bicolor L. Moench)

Uno de los principales problemas que afectan el cultivo de sorgo (Sorghum bicolor) en Uruguay es la enfermedad ocasionada por Fusarium nygamai, responsable de pérdidas en el rendimiento en los cultivos. Además, es capaz de producir micotoxinas como fumonicina, moniliformina y beauvericina, lo que constituye un riesgo para la alimentación animal. El objetivo de este trabajo fue identificar cepas de Trichoderma spp., con potencial de control de F. nygamai en sorgo. Se identificaron dos cepas de Trichoderma asperellum, cinco cepas de Trichoderma atroviride, dos cepas de Trichoderma virens, una cepa de Trichoderma longibrachiatum y dos cepas de Trichoderma sp. aisladas de suelo en plantaciones comerciales de sorgo. Se realizaron cultivos duales y evaluación de metabolitos volátiles in vitro para seleccionar las cepas con la mayor actividad antagonista contra F. nygamai. Las cepas de Trichoderma spp. seleccionadas se evaluaron en ensayos de protección vegetal en plántulas de sorgo inoculadas con F. nygamai. T. asperellum (T6) y T. atroviride (T21) fueron antagonistas efectivos de F. nygamai. Todas las plántulas de sorgo inoculadas con F. nygamai mostraron síntomas de la enfermedad, mientras que el 50% de las plántulas inoculadas con F. nygamai pero tratadas con T. asperellum (T6) permanecieron sanas, recuperando la cepa de los tejidos internos de la raíz, el tallo y las hojas. Estos resultados son promisorios para el desarrollo de una formulación comercial de tratamiento de semillas para el control de F. nygamai en cultivos de sorgo.One of the main problems affecting sorghum (Sorghum bicolor) production in Uruguay is the disease caused by Fusarium nygamai, which is responsible for crop losses and can also produce mycotoxins such as fumonicin, moniliformin and beauvericin. This constitutes a risk for animal feed. The aim of this work was to identify isolates of Trichoderma spp., with F. nygamai control potential in S. bicolor. We identified two strains of Trichoderma asperellum, five strains of Trichoderma atroviride, two strains of Trichoderma virens, one strain of Trichoderma longibrachiatum and two strains of Trichoderma sp. isolated from soils of sorghum commercial plantation. Dual cultures and evaluation of volatile metabolites were performed in vitro to select those strains with the highest antagonistic activity against F. nygamai. S trains of Trichoderma spp. selected were evaluated in plant protection assays in sorghum seedlings inoculated with F. nygamai. Trichoderma asperellum (T6) and T. atroviride (T21) were effective antagonists of F. nygamai. All sorghum seedlings only inoculated with F. nygamai under laboratory conditions evidenced symptoms of disease, while 50% of seedlings inoculated with F. nygamai but treated with T. asperellum (T6) remained healthy. This strain was also recovered from internal tissues of root, stem and leaves. These results are promising for the development of a commercial formulation of seed treatment for the control of F. nygamai in sorghum crops

Selection of Trichoderma strains for biological control of Fusarium nygamai in sorghum (Sorghum bicolor L. Moench)

Uno de los principales problemas que afectan el cultivo de sorgo (Sorghum bicolor) en Uruguay es la enfermedad ocasionada por Fusarium nygamai, responsable de pérdidas en el rendimiento en los cultivos. Además, es capaz de producir micotoxinas como fumonicina, moniliformina y beauvericina, lo que constituye un riesgo para la alimentación animal. El objetivo de este trabajo fue identificar cepas de Trichoderma spp., con potencial de control de F. nygamai en sorgo. Se identificaron dos cepas de Trichoderma asperellum, cinco cepas de Trichoderma atroviride, dos cepas de Trichoderma virens, una cepa de Trichoderma longibrachiatum y dos cepas de Trichoderma sp., aisladas de suelo en plantaciones comerciales de sorgo. Se realizaron cultivos duales y evaluación de metabolitos volátiles in vitro para seleccionar las cepas con la mayor actividad antagonista contra F. nygamai. Las cepas de Trichoderma spp. seleccionadas se evaluaron en ensayos de protección vegetal en plántulas de sorgo inoculadas con F. nygamai. T. asperellum (T6) y T. atroviride (T21) fueron antagonistas efectivos de F. nygamai. Todas las plántulas de sorgo inoculadas con F. nygamai mostraron síntomas de la enfermedad, mientras que el 50 % de las plántulas inoculadas con F. nygamai, pero tratadas con T. asperellum (T6) permanecieron sanas, donde se recuperó la cepa de los tejidos internos de la raíz, el tallo y las hojas. Estos resultados son promisorios para el desarrollo de una formulación comercial de tratamiento de semillas para el control de F. nygamai en cultivos de sorgo.One of the main problems affecting sorghum (Sorghum bicolor) production in Uruguay is the disease caused by Fusarium nygamai, which is responsible for crop losses and can also produce mycotoxins such as fumonicin, moniliformin, and beauvericin. This constitutes a risk for animal feed. The aim of this work was to identify isolates of Trichoderma spp., with F. nygamai control potential in S. bicolor. We identified two strains of Trichoderma asperellum, five strains of Trichoderma atroviride, two strains of Trichoderma virens, one strain of Trichoderma longibrachiatum and two strains of Trichoderma sp., isolated from soils of sorghum commercial plantation. Dual cultures and evaluation of volatile metabolites were performed in vitro to select those strains with the highest antagonistic activity against F. nygamai. The selected s trains of Trichoderma spp. were evaluated in plant protection assays in sorghum seedlings inoculated with F. nygamai. Trichoderma asperellum (T6) and T. atroviride (T21) were effective antagonists of F. nygamai. All sorghum seedlings only inoculated with F. nygamai under laboratory conditions evidenced symptoms of disease, while 50 % of seedlings inoculated with F. nygamai but treated with T. asperellum (T6) remained healthy. This strain was also recovered from internal tissues of root, stem, and leaves. These results are promising for the development of a commercial formulation of seed treatment for the control of F. nygamai in sorghum crops

Diversity and virulence of Diaporthe species associated with wood disease symptoms in deciduous fruit trees in Uruguay

Several Diaporthe species are recognized as causal agents of many plant disease symptoms, including twig and branch cankers, dieback, shoot blight, and root and fruit rots. In Uruguay, the proximity between apple, pear and peach orchards offers the possibility to study the presence of different Diaporthe spp. associated with wood cankers across different deciduous fruit trees. Symptomatic twigs and branches of these orchard species were sampled, and isolates of Diaporthe were obtained. Selected isolates were used for cross inoculations in the three hosts. Seven Diaporthe spp. were identified, based on the internal transcribed spacer (ITS) region of rDNA and the translation elongation factor 1-alpha gene (EF1-a) phylogenies. The species were: Diaporthe amygdali, D. foeniculina, D. infecunda, D. eres, D. terebinthifolii, D. oxe and D. phaseolorum, while two isolates Diaporthe sp. 1 and Diaporthe sp. 4 could not be assigned to any species. Diaporthe infecunda, D. eres, D. terebinthifolii, D. phaseolorum and D. oxe on Pyrus communis and D. foeniculina on Malus domestica represent new records in these hosts in Uruguay, while D. oxe isolated from Prunus persica is a new record for this species. Diaporthe eres and D. phaseolorum were the most virulent species, posing the greatest risk due to their wide distribution and virulence in apple and peach trees. Although pear trees showed less symptomatic tissues and were less susceptible than peach and apple trees in the pathogenicity tests, they harboured seven of the species, and therefore should be considered as reservoirs of Diaporthe in Uruguayan orchards. Trees of the three hosts could be considered potential reciprocal sources of pathogenic Diaporthe spp

Ligninolytic enzymes production by Dichostereum sordulentum cultures in the presence of Eucalyptus bark as a natural laccase stimulator

A strain of a fungal species, i.e., Dichostereum sordulentum, not yet isolated from either Uruguay or decayed Eucalyptus spp. wood, was investigated for its ability of producing extracellular ligninolytic enzymes. To this aim, the strain was grown on a N-rich liquid medium added with either bark or wood Eucalyptus dunnii sawdust. The former additive was more effective than the latter instimulating laccase leading to a production of 4.78 IU mL-1 which was further enhanced by the concomitant presence of 80 ppm CuSO4 (6.56 IU mL-1). The two order of magnitude higher proanthocyanidin content in bark than in wood suggests that this fraction might be responsible for the higher stimulatory effect of the former on laccase production

Composition and characterization of fungal communities from different composted materials

L\u27analyse des communautés de champignons provenant des composts préparés avec différentes matières premières a été menée pour évaluer l\u27abondance et la fréquence des espèces qui pourraient constituer un risque pour les plantes, les animaux ou la santé humaine. Un total de 40 405 × 103 propagules correspondant à 90 espèces a été dénombré dans 30 échantillons de deux composts de composition différente. Douze de ces espèces sont thermo-tolérantes, trois sont thermophiles et les autres sont des espèces mésophiles. Acrodontium crateriforme, est l\u27espèce la plus abondante, présente dans presque la moitié des échantillons de compost préparé principalement à partir de déchets de poils de l\u27industrie du cuir. D\u27autres espèces, Aspergillus spp, Monocillium mucidum, Penicillium spp. Paecilomyces variotii, Candida sp. et Humicola grisea var. thermoidea étaient aussi présentes. Le compost composé de déchets de Ligustrum et d\u27écorces de riz mélangés avec des déjections de poulets est caractérisé par la présence de Aspergillus fumigatus, espèce présente dans presque tous les échantillons, et par Penicillium spp., Fusarium spp., Emericella nidulans, Emericella rugulosa et Humicola fuscoatra. Toutes ces espèces ont été mentionnées dans d\u27autres composts de différentes origines. Plusieurs d\u27entre elles sont importantes dans la biodégradation et d\u27autres sont des antagonistes vis-à-vis des agents pathogènes. Les deux composts peuvent être utilisés séparément ou ensembles pour améliorer la nutrition du sol et participer à la lutte biologique.The analysis of fungal communities of two composts prepared with different raw materials were conducted to evaluate the abundance and frequency of species that could constitute a risk for plant, animal or human health. A total of 40 405 × 103 propagules corresponding to 90 species were found in 30 samples of two composts of different composition. Twelve of the species were thermotolerant, three were thermophilic and the other species were mesophilic. Acrodontium crateriforme present in nearly half of the samples of compost prepared mainly with hair waste from leather industry was the most abundant species. Several other species as Aspergillus spp., Monocillium mucidum, Penicillium spp., Paecilomyces variotii, Candida sp. and Humicola grisea var. thermoidea were present. The community prepared with Ligustrum pruning wastes and rice hull mixed with chicken mess was characterized by Aspergillus fumigatus, present in nearly all samples, and by Penicillium spp., Fusarium spp., Emericella nidulans, Emericella rugulosa and Humicola fuscoatra. All the species are commonly found in composts of different origins. Several are important in biodegradation and in suppressive pathogen abilities. Both composts can be used separately or together to enhance the nutritional and suppressive abilities of soils.</p