Navegando por Autor "Freitas, Leandro G."
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Item Biological control of infective larvae of Ancylostoma spp. in beach sand(Revista Iberoamericana de Micología, 2013-05-23) Mello, Ingrid Ney Kramer de; Braga, Fabio R.; Monteiro, Thalita S.Avelar; Freitas, Leandro G.; Araujo, Juliana M.; Soares, Filippe E.Freitas; Araújo, Jackson V.Geohelminths are parasites that stand out for their prevalence and wide distribution, depending on the soil for their transmission. The aim of this work was to evaluate the predatory capacity of the fungal isolate of the genus Duddingtonia (CG768) on third stage larvae (L3) of Ancylostoma spp. in beach sand under laboratory conditions. In the assay A five treatment groups and 1 control group were formed. The treatment groups contained 5000, 10,000, 15,000, 20,000 or 25,000 chlamydospores of the fungal isolate and 1000 Ancylostoma spp. L3 in pots containing 30 g of sand. The control group (without fungus) contained only 1000 Ancylostoma spp. L3 and distilled water in pots with 30 g of sand. Evidence of predatory activity was observed at the end of 15 days, where we observed the following percentages of reduction of L3: Group 1 (4.5%); Group 2 (24.5%); Group 3 (59.2%); Group 4 (58.8%); Group 5 (63%). However, difference was noted (p < 0.01) only at concentrations 15,000, 20,000 and 25,000 in relation to control group. In the assay B two groups were formed in Petri dishes of 9 cm in diameter containing agar water 2% medium. In the treated group, each Petri dish contained 500 Ancylostoma spp. L3 and 5 g of sand containing the isolate CG 768 at a concentration of 25,000 chlamydospores/g of sand, and the control group (without fungus) contained only 500 L3. At the end of 7 days the non-predation L3 of Petri dishes using the method of Baermann were recovered. Difference (p < 0.01) between groups on reducing the average number of Ancylostoma spp. L3 (percent reduction of 84%) was observed. The results of this study confirm earlier work on the efficiency of the Duddingtonia genus in the control of Ancylostoma spp. infective larvae.Item Desenvolvimento de Pasteuria penetrans em Meloidogyne spp. parasitando diferentes espécies vegetais(Fitopatologia Brasileira, 2003-05) Rodrigues, Adriana K.; Freitas, Leandro G.; Azevedo, Aristéa A.; Ferraz, SilamarA bactéria Pasteuria penetrans é um parasita obrigatório do nematóide das galhas (Meloidogyne spp.) e produz esporos que persistem por anos no solo. A sua produção por cultivo in vitro ainda é inviável e a produção de inoculo requer o seu cultivo in vivo em nematóides parasitando plantas em vasos. Neste trabalho, buscou-se, por meio do estudo histológico de raízes, averiguar diferenças no desenvolvimento de P. penetrans em Meloidogyne spp. parasitando raízes de tomateiro (Lycopersicon esculentum), maxixe (Cucumis anguria) e camapu (Physalis angulata), e possíveis razões para estas diferenças, como forma e tamanho de células gigantes e das fêmeas do nematóide. O maxixe foi o pior dentre os hospedeiros em teste para a produção de inóculo e apresentou células gigantes anormais. A estrutura das células gigantes assim como o desenvolvimento da bactéria foram semelhantes no camapu e no tomateiro, entretanto o ciclo de vida de P. penetrans foi ligeiramente mais curto no tomateiro.Item Efeito de rizobacterias na adesão de endósporos de Pasteuria penetrans em juvenis do segundo estádio de Meloidogyne javanica(Revista Ceres, 2002-07) Freitas, Leandro G.; Alves, Fábio R.; Costa, Mauro J. N.; Ferraz, Silamarprimeira etapa no parasitismo de Meloidogyne spp. por Pasteuria penetrans é a adesão dos endbsgarvs dessa bacteria cuticula tips nemat6ides, que podgy ser aumentada por fatores biológicos ou fIsicos. Suspens6es de P. penetrans foram concentradas por centrifugação, ressuspendidas e incubadas por cinco dial a 27°C em suspensao aquosacontendo, separadaranente, doffs isolados de ri obactdrias (ALT–'7 e MI--E) antagonistas a M. javanica. Após a incubação, 200 J2 de M. javanica em 1 mL de aqua foram adicionados par tube e centrifugados a 400 G (1.500 rpm), por 20 minutos, pare fazer o contato entre enddsparas e nematbides. ALT7 e MI-+6 diminufram a adesao de enddsporos, quandocomparados água, em 91,5 e 51,6%a (P y 0,05), respectivamente. Elsa redu ao poke ser 4evido a compostos liberados durante o crescimento da rizobacteria no mein, as quaffs podem degrader ou alterar as substãncias responsáveis pelo reconhecimento dos end6sporos pela cuticula dos nematoides.Item Effect of time between soil infestation with Pochonia chlamidosporia and planting on the efficacy of the fungus in managing Meloidogyne javanica(Crop Protection, 2016-12) Podestá, Guilherme S.; Amora, Deisy X.; Maffia, Luiz A.; Nasu, Érica G. C.; Ferraz, Silamar; Freitas, Leandro G.The fungus Pochonia chlamydosporia acts on populations of the root-knot nematode by parasitizing their eggs before they hatch, preventing the release of juveniles. In this study, the effect of the time at which the fungus is applied to soil infested with the nematode, before transplanting tomato and lettuce seedlings, was evaluated. The reduction of symptoms and the nematode population in the host plant was also evaluated, as well as the fluctuation of the fungus population during the studied period. The seedlings were transplanted at 0, 5, 10, 15 or 20 days after incorporation of the inocula of the fungus and the nematode into the soil. The population of P. chlamydosporia, without the presence of plants, increased and reached its maximum 10 days after its incorporation into the soil. At the end of the experiments, the number of colony forming units (CFU) of the fungus in the soil remained high enough to act on the next cycle of crops. For both cultures, the greatest effect on reducing the number of galls and eggs of Meloidogyne javanica was obtained by increasing the contact time of the fungus with the nematode in the soil before transplanting seedlings. In the second run, for both cultures, there was an increase in shoot weight with increasing of incubation time before the transplantation of seedlings.Item Nematode root herbivory in tomato increases leaf defenses and reduces leaf miner oviposition and performance(Journal of Chemical Ecology, 2017-01-13) Arce, Carla C. M.; Machado, Ricardo A. R.; Ribas, Natália S.; Cristaldo, Paulo F.; Ataíde, Lívia M. S.; Pallini, Ângelo; Carmo, Flávia M.; Freitas, Leandro G.; Lima, EraldoThe outcome of plant-mediated interactions among herbivores from several feeding guilds has been studied intensively. However, our understanding on the effects of nematode root herbivory on leaf miner oviposition behavior and performance remain limited. In this study, we evaluated whether Meloidogyne incognita root herbivory affects Tuta absoluta oviposition preference on Solanum lycopersicum plants and the development of the resulting offspring. To investigate the M. incognita-herbivory induced plant systemic responses that might explain the observed biological effects, we measured photosynthetic rates, leaf trypsin protease inhibitor activities, and analyzed the profile of volatiles emitted by the leaves of root-infested and non-infested plants. We found that T. absoluta females avoided laying eggs on the leaves of root-infested plants, and that root infestation negatively affected the pupation process of T. absoluta. These effects were accompanied by a strong suppression of leaf volatile emissions, a decrease in photosynthetic rates, and an increase in the activity of leaf trypsin protease inhibitors. Our study reveals that root attack by nematodes can shape leaf physiology, and thereby increases plant resistance.Item Ovicidal activity of seven Pochonia chlamydosporia fungal isolates on Ascaris suum eggs(Tropical Animal Health and Production, 2010-11-19) Ferreira, Sebastião R.; Araújo, Jackson V.; Braga, Fabio R.; Araujo, Juliana M.; Carvalho, Rogério O.; Silva, André R.; Frassy, Luiza N.; Freitas, Leandro G.The ovicidal effect of the nematophagous fungus Pochonia chlamydosporia on eggs of Ascaris suum was tested under laboratory conditions. A. suum eggs were plated on 2% water–agar with seven fungal isolates (Isol. 5, Isol. 31, Isol. 1, VC1, Isol. 12, Isol. 22 and VC4) and control without fungus. After 5, 7, 10, 14, 15 and 21 days of incubation, approximately 100 eggs were removed from the plates and classified according to the following parameters: type 1, biochemical and physiological effect without morphological damage to the eggshell, type 2, lytic effect with morphological alteration of the eggshell and embryo and type 3, lytic effect with morphological alteration of eggshell and embryo showing hyphal penetration and internal egg colonization. The isolates effectively destroyed A. suum eggs and all types of effects were observed during the experiment. There was no variation in ovicidal capacity (type 3 effect) among the isolates (p > 0.05) throughout the experiment. After 21 days, isolate 5 showed the highest percentages of type 3 effect (58.33%). The results indicated that P. chlamydosporia (Isol. 5, Isol. 31, Isol. 1, VC1, Isol. 12, Isol. 22 and VC4) can destroy A. suum eggs and is, therefore, a potential biological control agent of nematodes.Item Pochonia chlamydosporia var. chlamydosporia (Goddard) Zare & W. Gams for the management of lettuce infected with Meloidogyne javanica (Treub, 1885)(Chilean journal of agricultural research, 2014-12-22) Viggiano, José R.; Freitas, Leandro G.; Lopes, Everaldo A.The application of the nematophagous fungus Pochonia chlamydosporia var. chlamydosporia (Goddard) Zare & W. Gams during seedling production of vegetable crops can be an efficient approach to control root-knot nematode. The aim of this study was to evaluate the effect of treating seedlings and/or soil with bionematicide (wettable powder formulation) based on chlamydospores from isolate Pc-10 on the Meloidogyne javanica (Treub, 1885) control in lettuce (Lactuca sativa L.). Isolate Pc-10 was diluted in water and applied when watering the seedlings (0, 4.5, 9.0, 13.5, and 18.0 g L -1 ) and/or to the potted soil (5000 chlamydospores g -1 ) used for growing lettuce. The soil in each pot was infested with 3000 M. javanica eggs. The number of M. javanica eggs was reduced in lettuce roots when isolate Pc-10 was applied either to seedlings or soil; there was no interaction between application methods. The decrease in the number of eggs was proportional to the increase of isolate Pc-10 applied to seedlings with maximum reduction of 43.5% at the 18 g L -1 dose. When the fungus was applied to the soil, the number of eggs was reduced by 12.3%. Increasing doses of isolate Pc-10 reduced the number of galls up to 21% with the 18 g L -1 dose. Applying bionematicide based on P. chlamydosporia isolate Pc-10 at 18 g L -1 on seedlings controls M. javanica in lettuce.Item Predatory activity of Pochonia chlamydosporia fungus on Toxocara (syn. Neoascaris) vitulorum eggs(Tropical Animal Health and Production, 2009-08-22) Braga, Fabio R.; Ferreira, Sebastião R.; Araújo, Jackson V.; Araujo, Juliana M.; Silva, André R.; Carvalho, Rogério O.; Campos, Artur K.; Freitas, Leandro G.Toxocara (Neoascaris) vitulorum is a gastrointestinal nematode parasite of young ruminants, responsible for high mortality rates in parasitized cattle and buffalo calves. The objective of this work was to compare the predatory capacity under laboratory conditions of four fungal isolates of the nematophagous fungus Pochonia chlamydosporia (VC1, VC4, VC5 and VC12) on T. vitulorum eggs in 2% water-agar (2% WA). T. vitulorum eggs were plated on 2% WA Petri dishes which contained cultured fungal isolates and control plates without fungi. After 10 and 15 days one hundred eggs were removed and classified according to the following parameters: type 1, biochemical and physiological effect without morphological damage to the eggshell, type 2, lytic effect with morphological alteration of the eggshell and embryo and type 3, lytic effect with morphological alteration of eggshell and embryo in addition to hyphal penetration and internal egg colonization. The fungal isolates were effective in the destruction of T. vitulorum eggs presenting the type 3 effect at 10 and 15 days after contact with the fungus. No nematophagous fungi were observed in the control group during the experiment. There was no variation in the predatory capacity of the fungal isolates (P > 0.01) at the intervals of 10 and 15 days. These results indicate that P. chlamydosporia (VC1, VC4, VC5 and VC12) negatively influenced the development of T. vitulorum eggs and can be considered a potential candidate for the biological control of nematodes.Item Screening of Pochonia chlamydosporia brazilian isolates as biocontrol agents of Meloidogyne javanica(Crop Protection, 2012-12) Freitas, Leandro G.; Dallemole-Giaretta, Rosangela; Lopes, Everaldo A.; Pereira, Olinto L.; Zooca, Ronaldo J. F.; Ferraz, SilamarPochonia species can occur in many Meloidogyne-infested soils throughout the world. The objective of this work was to isolate Pochonia species from different Meloidogyne-infested soil locations in Brazil and to screen for potential isolates effective in controlling Meloidogyne javanica under glasshouse conditions. A total of 29 isolates were identified as Pochonia chlamydosporia. Among them, 65.52% were identified as P. chlamydosporia var. chlamydosporia and 34.48% as P. chlamydosporia var. catenulata. For the glasshouse experiments, fungal chlamydospores were incorporated into the soil (5000 g soil^−1) and one tomato seedling was transplanted in 300 mL pot. After one week, each plant was inoculated with 1000 eggs of M. javanica. The isolates 1, 2, 3, 4, 9, 10, 21, 24, 28 (from Brazil) and 64 (from Spain) were the most efficient in reducing the number of eggs of the nematode. These isolates were re-evaluated in another glasshouse experiment, this time the number of eggs was increased (3000), inoculating both eggs and chlamydospores at the same time. After one week of inoculation, a tomato seedling was transplanted in each pot. In this experiment, isolates 64 and 10 were the most efficient in reducing the number of eggs by 72% and 60%, respectively.