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Pochonia chlamydosporia is a soil-dwelling fungus and biological control agent of nematodes, active ingredient in commercial bionematicides. The fungus is also endophytically associated with the roots of several plant species, promoting their growth and inducing systemic resistance. In this study, different pathways and tomato defense metabolites were studied to identify mechanisms induced by P. chlamydosporia that contribute to the control of Meloidogyne javanica, at early and late developmental stages. Some defense responses activated by the fungus appeared related to the nematode life cycle. Among the evaluated biochemical analysis, root colonization of P. chlamydosporia showed an increase in the concentration of phenolic compounds, such as chlorogenic acid. In addition, the expression of some host plant genes was also modified. The interaction of the fungus with roots parasitized by M. javanica resulted in the highest expression of Phenylalanine Ammonia-Lyase (PAL), Chalcone synthase (LECHS 2), and Protease Inhibitor (PI1) genes at 24 days post-inoculation. At the second sampling time (44 days), there was an increase in the expression of the Respiratory Burst Oxidase Homolog (RBOH) gene. Fungus reduced the expression of the ACC-oxidase and Pathogenesis-Related Proteins 1 (PR-1) genes in roots. Moreover, P. chlamydosporia inoculation changed metabolites and phytohormone profiles of the gall formed by M. javanica. Plant defense response appeared to involve the jasmonic acid and phytosphingosine cascades. With this analysis, it was possible to propose new molecular mechanisms induced by the fungus that contribute to the control of M. javanica.

Summary Pratylenchus brachyurus is considered one of the most important plant pathogens of soybean and corn in Brazil, mainly found in areas where no-tillage is practised. Nematophagous fungi are used as an alternative for chemical nematicides in the management of nematodes that affect these crops in Brazil. This study evaluated the fungi Pochonia chlamydosporia, Trichoderma sp. and Duddingtonia flagrans for the biocontrol of P. brachyurus in soybean and corn. The first and second experiments were carried out using soybean, and five isolates of P. chlamydosporia (Pc-3, Pc-4, Pc-10, Pc-35 and Pc-49), one of Trichoderma sp. (T-10), an isolate of D. flagrans (AC001) and a mix (MIX) of all the isolates. In the third experiment using corn, three isolates of P. chlamydosporia (Pc-3, Pc-10 and Pc-35) and one isolate of Trichoderma sp. (T-10) were compared. In the first experiment, the isolates Pc-3, Pc-10, Pc-35 and T-10 reduced the total population of P. brachyurus up to 43.7% when compared with the control treatment. In the second experiment, the isolates Pc-10, T-10 and the MIX reduced the total population of P. brachyurus up to 58.7% when compared with the control. In the third experiment, the isolates reduced the total population of P. brachyurus in corn when compared with the control treatment, except for D. flagrans, which was not able to control P. brachyurus in any experiment. The P. chlamydosporia (Pc-3, Pc-10, Pc-35) and Trichoderma sp. (T-10) isolates were shown to be promising for the control of P. brachyurus in soybean and corn.

One of the major challenges for biological control candidates is the ability to survive after contact with chemical pesticides, which are regularly used in the conventional agriculture. The use of a biological tool does not eliminate the need for less sustainable practices to protect the crops in the field. Therefore, this study evaluated the compatibility of the fungus Pochonia chlamydosporia with pesticides commonly used in cotton and soybean crops. The tests were performed in vitro and in the greenhouse. For the in vitro test, the isolate Pc - 10 of P. chlamydosporia was transferred to Petri dishes containing potato-dextrose-agar medium and agricultural pesticides in different concentrations. The evaluations of the growth were performed by measuring the diameter (cm) of the colonies. To evaluate the compatibility of P. chlamydosporia with the pesticides in soil, a greenhouse experiment was conducted with cotton and soybean seeds treated with a combination of the fungus and each pesticide separately. Seeds treated only with P. chlamydosporia were also prepared. Each pot soil was infested with 3000 eggs of Meloidogyne incognita race 3 for cotton, and 3000 eggs of M. incognita race 2 for soybean. Each pot received one seed of cotton or soybean pretreated with one pesticide and P. chlamydosporia. For the positive control treatment, each seed was only treated with P. chlamydosporia. A non-treated seed per pot was used in the negative control. In the in vitro tests, the fungus P. chlamydosporia was sensitive to all agrochemicals used. However, in the greenhouse experiments, the fungus could survive, colonize the roots and the soil, and consequently reduces the M. incognita populations. This study demonstrates the feasibility of the combined use of fungicides, insecticides and nematicides with P. chlamydosporia without compromising the activity of the biological agent.

The production of volatile organic compounds (VOCs) acting against plant-parasitic nematodes has been characterized in different fungi; however, the role of VOCs emitted by Pochonia chlamydosporia in its trophic interaction with Meloidogyne incognita is still unknown. The aim of this study was to determine the effects of VOCs emitted by P. chlamydosporia strain Pc-10 on different stages (eggs, juveniles and female) of the M. incognita life cycle. Exposure of M. incognita eggs to VOCs released by Pc-10 resulted in a reduction up to 88 % in the nematode egg hatching, when compared to the control treatments. The VOCs emitted by Pc-10 also attracted M. incognita second-stage juveniles (J2). Through gas chromatography-mass spectrometry (GC-MS), three molecules were identified from the volatiles of the strain Pc-10, with 1,4-dimethoxybenzene being the major compound. In tests performed in vitro, 1,4-dimethoxybenzene at a concentration of 1050 μg mL-1 inhibited M. incognita egg hatching by up to 78.7 % compared to the control (0 μg mL-1) and attracted M. incognita J2 in all concentrations evaluated (1, 10, 100, 1000, and 10000 μg mL-1). The 1,4-dimethoxybenzene also showed fumigant and non-fumigant nematicidal activity against M. incognita. This compound presented lethal concentration for 50 % (LC50) of M. incognita J2 ranged from 132 to 136 μg mL-1. Fumigation with 1,4-dimethoxybenzene (100 mg) reduced egg hatching by up to 89 % and killed up to 86 % of M. incognita J2 compared to the control (0 μg mL-1). In vivo, the VOCs produced by Pc-10, 1,4-dimethoxybenzene, and the combination of both (Pc-10 + 1,4-dimethoxybenzene) attracted the M. incognita J2, compared to the respective controls. To the best of our knowledge, this is the first report on the attraction of M. incognita J2 and the toxicity to eggs and J2 by VOCs from P. chlamydosporia in which 1,4-dimethoxybenzene is the main toxin and attractant.

The treatment of seeds with biological control agents is one of the most convenient methods of introducing microorganisms into the root environment. Pochonia chlamydosporia is a promising biological control agent of plant-parasitic nematodes and a good root colonizer. Seed treatment with this fungus would make its application viable for soybean and grain crops. Therefore, the aim of the present work was to evaluate the influence of soil texture under the development of P. chlamydosporia applied as a seed dressing to control Meloidogyne incognita in soybean greenhouse. Soybean seeds treated with P. chlamydosporia were sown in PVC (55 cm × 10 cm) tubes containing clayey or sandy soil infested with M. incognita eggs. Sixty days after sowing, the tubes were sectioned into four parts (0.0–12.5, 12.5–25.0, 25.0–37.5, and 37.5–50.0 cm of length) to evaluate the percolation and multiplication of P. chlamydosporia at four different soil depths. The development of P. chlamydosporia in the absence of the nematode was also evaluated. It was possible to verify soil colonization by P. chlamydosporia throughout the profile of both soils tested. The fungus was able to percolate in the soil up to at least 50 cm depth and was efficient in controlling M. incognita in both sandy and clayey soils; however, in the sandy soil, the fungus presented greater colonization and percolation, which may explain why it is more efficient in controlling the nematode when applied in sandy soil.

Some nematophagous fungi control nematodes and are also able to compensate the damage they cause in plant roots. However, the effects of these fungi on plant growth promotion are still underexplored. Here, we evaluated if some nematophagus fungi (Pochonia chlamydosporia and Duddingtonia flagrans) may increase nutrient bioavailability and promote plant growth. A growth chamber assay and a greenhouse study (both without nematodes) were carried out to assess the effects of the fungi on growth and phosphorus uptake by tomato plants. The use of P. chlamydosporia and D. flagrans substantially increased growth and the uptake of nutrients by tomato plants (mainly phosphorus – up to 70% in the best treatments). We conclude that P. chlamydosporia and D. flagrans are potentially useful not just for nematode control but also for promoting plant growth and for increasing nutrient use efficiency.

Several plants are used as cover crops in the no-tillage system in order to improve the physical, chemical and biological characteristics of the soil. The fungus Pochonia chlamydosporia (Goddard) Zare and Gams 2001, a biological control agent of plant parasitic nematodes (PPNs), is capable of promoting plant growth and adding it to the cover crop can increase the biomass of these plants and reduce the population level of nematodes in the soil. The objective of this work was to evaluate the ability of P. chlamydosporia to colonize soil and roots of the cover crops Pennisetum glaucum (L.) R. Br. (ADR 300, ADR 500 and ADRG 9050 cultivars), Urochloa ruziziensis (R. Germ. & Evrard) Crins, Crotalaria spectabilis Roth and Stylosanthes sp. and to promote the growth of these plants. P. chlamydosporia colonized the root systems of all the evaluated cover crops. Chlamydospores, conidia and hyphae were easily observed within the cells of plant roots. P. chlamydosporia increased the height of the shoots of all plants, except U. ruziziensis. The fungus also increased the total weight of the dry plant of cultivars ADR 300 and ADR 500 of P. glaucum, U. ruziziensis and C. spectabilis in 29, 17, 16 and 30%, respectively. The root volume of P. glaucum (ADR 300), U. ruziziensis and C. spectabilis were also increased in 66, 88 and 64%, respectively, in the presence of P. chlamydosporia. Higher numbers of colony forming units (CFU) of P. chlamydosporia g−1 of soil were detected in the presence of cultivars ADR 300 and ADR 500 of P. glaucum at the 12.5 cm soil depths (12.5, 25.0, 37.5 and 50.0 cm), highlighting the 12.5 cm depth with 10,684 CFU of P. chlamydosporia g−1 of soil. This is the first report of the colonization of cover crops roots by P. chlamydosporia and its resulting plant growth promotion effect, as well as the formation of chlamydospores of P. chlamydosporia inside their root cells. The application of P. chlamydosporia in the cover crop increases the biomass of crops that will be used as green manure and guarantee a greater establishment of the fungus in the area, consequently reducing even more the populations of PPNs in the soil.

The use of beneficial microorganisms in agricultural production systems has been growing due to the worldwide demand for more sustainable crops. Biological control has thus gained prominence in the management of plant parasitic nematodes, as the result of the efficiency in reducing their population densities, improving plant development. The objectives of this study were to evaluate the association of the nematophagous fungi Duddingtonia flagrans and Pochonia chlamydosporia to reduce the population of Meloidogyne javanica in soybean, and to check if D. flagrans promotes the acquisition of nutrients in soybean. The plant-parasitic nematode biocontrol experiment was carried out twice, at 20 and 27 °C. In the nutrient acquisition test, plants grown in soil infested by D. flagrans and/or Bradyrhizobium japonicum were compared with plants grown in soil without the application of these organisms. All treatments with fungi resulted in reductions in the numbers of eggs and galls per g of root, when compared to the control. A compatible association between D. flagrans and P. chlamydosporia was verified in the experiment. For the nutrition test, the fungus, combined or not with B. japonicum, promoted an increase in the nutrient content in the soybean roots. In this study, we found that D. flagrans may be associated with other microorganisms to control nematodes and to promote the acquisition of nutrients.

Nematophagous fungi, such as Monacrosporium thaumasium (NF34), have a high potential to produce enzymatic pool containing protease with nematicidal activity. Thus, the aim of this study was to optimize the conditions that affect this pool production by the fungus M. thaumasium on solid medium and its nematicidal effect on Meloidogyne javanica eggs. With the optimization assays, there was a significant increase in enzyme production, allowing a 30% reduction in larvae (p

The fungus Pochonia chlamydosporia (Pc) has been increasingly used to control plant-parasitic nematodes. This fungus also increases the uptake of nutrients by plants. However, the mechanisms by which Pc modifies the soil nutrient supply and, or the capacity of plants to acquire nutrients are not fully understood. In this research we investigated possible mechanisms that explain how Pc increases phosphorus uptake by plants. We tested the hypothesis that Pc produces phosphatases, which are enzymes that promote depolymerization of organic phosphate compounds. We further investigated if the known effect of Pc on inorganic phosphate (IP) solubilization could be credited to the release of organic acids and, if so, which organic acids are secreted by the fungus. Three isolates of the fungus (Pc-10, Pc-40, and Pc-46) were used in the study. We found that Pc can produce acid (Pc-10 = 0.0209 U/ml, Pc-40 = 0.0282 U/ml, Pc-46 = 0.0094 U/ml) and alkaline phosphatases (Pc-10 = 0.0490 U/ml, Pc-40 = 0.0000, Pc-46 = 0.0306 U/ml). All isolates were able to solubilize IP. The isolate Pc-10 solubilized higher amounts of phosphate (47.5 mg/l) compared to Pc-40 (37.9 mg/l) and Pc-46 (36.6 mg/l). We also identified three organic acids (acetic, citric, and propionic acid) produced by Pc-10. To our knowledge, this is the first report of Pc producing phosphatases and organic acids.

Pleurotus eryngii is one of the most cultivated and consumed mushroom species in North Africa, Europe and Asia. Fungi from Pleurotus genus have demonstrated nematophagous activities, however most of the literature reports are focused on Pleurotus ostreatus. The aim of this work was to evaluate P. eryngii action on Panagrellus sp. and to evaluate the effect of this fungus culture extract on Meloidogyne javanica eggs. P. eryngii fungus and its extract significantly reduced (p < 0.01) the number of intact Panagrellus sp. larvae after 24 h treatment in 60% and 90%, respectively. This effect is not related to enzymatic activity, but to the presence of other metabolites. M. javanica eggs, when treated with P. eryngii extract, showed a 53% reduction (p < 0.01) in the number of intact eggs. The M. javanica intact eggs reduction is attributed to enzymatic activity, once the extract showed proteolytic and chitinolytic activities of, respectively, 32.74 and 3.57 U/mL. P. eryngii fungus has predatory activity against Panagrellus sp. larvae due to toxins production and negatively affects M. javanica eggs and juveniles development due to chitinases and proteases production, evidencing this fungus potential to be used in biological control.

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

A persistência do vírus da lagarta-da-soja AgMNPV, produzido de forma bruta (maceração de lagartas) e liofilizada (produto comercial), foi avaliada após a aplicação em plantas de soja seguida de diferentes regimes pluviométricos (0; 10; 20; 30mm) na intensidade de 30mm.hora-1. Essas precipitações foram simuladas com microaspersores, em casa-de-vegetação. Após a simulação, a soja foi oferecida às lagartas zero, três, seis e nove dias após a aplicação (DAP). As plantas, durante esse período, foram mantidas em casa-de-vegetação, protegidas da chuva. O experimento foi conduzido em delineamento inteiramente casualizado em condições controladas (UR 70±10%, 25±2°C, fotofase de 14h), em esquema fatorial 4 (intensidades de precipitações pluviométricas) x 2 (formulações de vírus, bruta e liofilizada) com quatro repetições, com 30 lagartas cada. Os resultados comprovam que precipitações até 30mm, em 60 minutos, não reduzem a mortalidade das lagartas, causada por AgMNPV em ambas as formas de produção, quando a oferta das folhas às lagartas ocorre no mesmo dia da aplicação. As formas de preparo do AgMNPV influenciaram na persistência do vírus aos seis DAP. Nesta avaliação, a taxa de mortalidade foi superior a 90%, quando o produto bruto foi aplicado e inferior a 50% para o produto liofilizado. Esses resultados indicam que a eficiência de AgMNPV não é afetada por chuvas de até 30mm em uma hora, para ambas as formas de preparo do AgMNPV. Entretanto, ao longo dos dias, o método de preparo bruto apresenta-se mais eficiente, devido à maior persistência sobre a área foliar da soja após a lavagem pela água.

Pochonia parasitizes the eggs and females of plant-parasitic nematodes (PPN). The fungus-nematode interaction involves a complex series of events which can be affected by the environment. Thus, an understanding of the bionomics of this interaction is essential in order to improve the efficiency of the biological management of PPN. In this chapter, we provide an overview of the process of infection of nematodes by Pochonia and the role of the environment on the fungus-nematode interaction. Firstly, we focus on the events and the mechanisms underlying adhesion, penetration and colonisation of nematodes by Pochonia. We discuss how the infection process is driven by both mechanical forces, induced by the appressoria, and enzymatic activity, specifically by the serine proteases (P32, VCP1, SCP1) and chitinases. Environmental factors have a profound influence on the Pochonia-nematode interaction and these are discussed in detail. Temperature, pH, soil type, soil microbiota and roots can enhance or reduce the parasitism of the nematode by the fungal antagonist. Finally, we discuss how the method of application of Pochonia and its timing can impact on the establishment of the fungus in the soil and, consequently, on the control of nematodes.

In 2009 and 2014, roots presumably infected with root-knot nematodes (Meloidogyne spp.) were collected from water oak (Quercus nigra), Alachua County, FL, and sent to the Nematode Diagnostic Laboratory, Division of Plant Industry, Florida Department of Agriculture and Consumer Services, Gainesville, FL. Small galls were observed on secondary and tertiary roots, large galls were found only on secondary roots. Females were found inside of the galls and egg masses were outside. Nematode species were identified using both morphological and molecular analyses. A notably thickened region between the stylet cone and stylet shaft in males (n = 10) and swollen rectums with deep longitudinal grooves were present in second-stage juveniles (n = 20): two defining morphological characteristics reported in the original description of Meloidogyne partityla (Kleynhans 1986). Perineal patterns of females and body length and width, stylet, and tail length of second stage juveniles (n = 20) were consistent with that previously reported for M. partityla. At least 10 single females were extracted from roots and molecular identification was performed using isozyme and DNA analyses. Isozyme phenotypes (EST = Mp3; MDH = N1a) were identical to earlier reports of this species (Brito et al. 2008). An amplicon of 530 bp was produced with mtDNA primers C2F3 (5′-GGTCAATGTTCAGAAATTTGTGG-3′) and 1108 (5′-TACCTTTGACCAATCACGCT-3′) (Powers and Harris 1993), which coincided to previously published data for M. partityla (Powers et al. 2005). Based on the result attained with the mtDNA primers, two regions were subsequently chosen to sequence to confirm species identification. First, a region in the ribosomal ITS was amplified with ITS-1 F (5′-CGCAGTGGCTTGAACCGG-3′) and a species-specific primer, MpSpec (5′-TGAACTTTTATTGGTGAAAG-3′) (Stamler 2009). This primer set produced a fragment of 630 bp, identical to M. partityla found infecting pecan in Arizona, Florida, Georgia, New Mexico, Oklahoma, and Texas (GenBank Accession No. KR047556) (Stamler 2009; Brito et al. 2008). Secondly, the 18S region was amplified and sequenced (KT825143) using primers 18Ss1.2 (5′-GGCGATCAGATACCGCCCTAGTT-3′) and 18SR2B (5′-TACAAAGGGCAGGGACGTAAT-3′) (Baldwin et al. 1997). A GenBank BLAST search produced a 99% match to an isolate of M. partityla from New Mexico (AY757874.1). This finding strengthens the hypothesis that this nematode species can survive in the wild on hosts outside of Juglandaceae. This is of particular importance when establishing both new pecan nurseries and orchards. To our knowledge, this is the first report of M. partityla occurring on Q. nigra. Fil: Brito, J. A.. University of Florida; Estados Unidos Fil: Smith, T. E.. University of Florida; Estados Unidos Fil: Achinelly, Maria Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; Argentina Fil: Monteiro, T. S. A.. Universidad de Viscosa; Brasil Fil: Dickson, D. W.. University of Florida; Estados Unidos

The melon crop (Cucumis melo L.) is the most exported fruit of Brazil and consist in an important agribusiness to the producers on Northeastern Region of Brazil, having as the main producers the Rio Grande do Norte and Ceará states. Among the limiting factors of this crop, root-knot nematode (Meloidogyne spp.) stand out a major treat, that causes on severed attacked plants malnourishment, poor development of the above-ground portion and shorter root system due to the galls, which is the most characteristic symptom of this disease. With the lack of management tools to the root-knot nematode, alternative measures are needed to avoid losses. In this context, the main objective of the present work was to evaluate the influence of resistance inducers and biological control agents on the control of M. incognita on melon plants, as the influence of these agents on melon plant development and their effects on different M. incognita stages. For these purposes, greenhouse experiments were performed. The first one aimed to verify the host status of melon hybrids to M. incognita and additional three were carried out to verify the influence of resistance inducers and biological control organisms on melon development and on the control of M. incognita on this crop (trials #1, #2 and #3). Also, an additional greenhouse trials were carried out to verify different doses of P. chlamydosporia (Rizotec® ) on the control of M. incognita in melon plants and to verify the potential of culture filtrates (Cf) obtained from biological control organisms on the control of M. incognita and on the melon plant development. In these greenhouse experiments, the reproductive variables final population (Pf), reproduction factor (R value) and nematodes per gram of root (Nem/g) were obtained at the end of the experiments. Additionally, it was evaluated the fresh and dry weight of the aerial portion, the plant height, root weight, fruit weight, stem diameter (measured on stem basis, middle and apex) and chlorophyll content. Additionally, in vitro assays were performed to verify the effect of Cfs on melon seeds and to verify the effect of the Cfs and the partially purified thaxtomin A (PPT) on M. incognita egg hatching. Moreover, three additional assays were carried out to verify the effect of resistance inducers acibenzolar-S-methyl (ASM) and PPT in the penetration and post-penetration of M. incognita second stages juveniles in melon roots. As results, all tested genotypes were susceptible to M. incognita. The Pf values ranged from 2,381.06 to 7,806 nematodes, the R value ranged from 5.95 to 19.5. Also, nem/g values ranged from 271 to 1,791. In trial #1, melon plants treated with resistance inducers presented lower height; despite no statistically differences were found for fresh and dry weight. Also, plants treated with ASM (inoculated and non-inoculated), Paecilomyces lilacinus, (non-inoculated) and Pochonia chlamydosporia (inoculated) produced heavy fruits. On trial #2, all inoculated plants differed statistically on root weight and presented heavier roots than non-inoculated plants, which was due the large amount of galls caused by M. incognita. In addition, treated plants with the biological control agents presented fewer symptoms than control plants. Treated melon plants exhibited higher chlorophyll content on young leaves, when compared with both controls. Moreover, on both treatments the M. incognita population was reduced, except by P. chlamydosporia on the experiment 1. When tested separately, all P. chlamydosporia doses reduced the Pf, however the most efficient were the dose 4 (1g/plant) and dose 5 (2g/plant). Regarding Cf, promising results were obtained. Both Cf from P. lilacinus and Bacillus amyloliquefaciens reduced the M. incognita population, in greenhouse experiment. Additionally, P. lilacinus Cf increased the fruit weight, and B. amyloliquefaciens Cf increased the root weight, despite being inoculated or not. Furthermore, the tested Cfs presented suppressive effect on M. incognita egg hatching, but further evidence is necessary due to lack of statistical differences with the potato-dextrose broth medium (PD). Additionally, the filtrates improved the germination of melon seeds, despite the suppressed effect of PD broth medium on them. Also,i> P. chlamydosporia treatment induced hairy roots, which were not observed on the other treatments. Regarding the penetration assays, juveniles were not observed at 3 days after inoculation (DAI). No effect of ASM in penetration and post-penetration of M. incognita J2 was 13 observed on both experiments. Concerning PPT, penetration was not observed at 3 DAI, but it was observed on the other assessed periods. Furthermore, our data points out that the TPP may speed the nematode cycle on melon roots. In conclusion, the obtained data point out the potential of the resistance inducers, biological control organisms and their culture filtrates on the control of M. incognita on melon plants. Atualmente, o melão (Cucumis melo L.) consiste na fruta mais exportada do Brasil, consistindo em importante agronegócio para os produtores da região Nordeste do país, tendo como maiores produtores os estados do Ceará e Rio Grande do Norte. Dentre os fatores limitantes para essa cultura, o nematoide das galhas (Meloidogyne spp.) se destaca entre as principais doenças do meloeiro. Plantas sob alta infestação apresentam deficiência nutricional, baixo desenvolvimento da porção aérea e deformação do sistema radicular devido as galhas, que consiste no sintoma mais característico dessa doença. Com a falta de ferramentas de manejo, medidas alternativas são necessárias para evitar maiores perdas. Nesse contexto, o presente trabalho teve por objetivo avaliar a influência de agentes de controle biológico e indutores de resistência no controle de M. incognita em plantas de melão, bem como a influência desses agentes no desenvolvimento do meloeiro em casa de vegetação, além de seus efeitos em diferentes estádios de M. incognita. Dessa forma, experimentos de casa-de-vegetação foram conduzidos, sendo um para verificar a reação de hospedeiro de híbridos de melão à M. incognita, três para verificar a influência de indutores de resistência e agentes de controle biológico no desenvolvimento do meloeiro e no controle de M. incognita (Experimento 1, 2 e 3). Adicionalmente, um experimento foi conduzido para verificar a dose-resposta de Pochonia chlamydosporia (Rizotec®) para controle de M. incognita e dois para verificar o uso potencial de filtrados obtidos a partir de organismos de controle biológico no desenvolvimento do meloeiro e no controle de M. incognita. Nesses experimentos, o fator de reprodução (valor R), população final (Pf) e nematoides por grama de raiz (Nem/g) foram obtidos ao final dos ensaios. Adicionalmente, foram avaliados a massa fresca e seca da parte aérea, altura das plantas, massa das raízes, massa dos frutos por planta, diâmetro do caule (base, meio e ápice) e conteúdo de clorofila. Ademais, realizou-se um experimento para se verificar o efeito de filtrados nas sementes de melão e três para verificar o efeito dos filtrados e da taxtomina parcialmente purificada (TPP) na eclosão dos ovos de M. incognita. Adicionalmente, três experimentos foram realizados para verificar o efeito de indutores de resistência na penetração e desenvolvimento de juvenis J2 de M. incognita nas raízes de meloeiro. Como resultados, todos os genótipos testados foram suscetíveis a M. incognita. A Pf variou de 2.381 à 7.806 nematoides, o valor R variou de 5,7 à 19,5 e o Nem/g foi de 271 à 1.791. No experimento 1, meloeiros tratados com indutores de resistência apresentaram menor altura, embora, nenhuma diferença estatística foi encontrada nas massas frescas e secas das plantas. Adicionalmente, plantas tratadas com acibenzolar-S-metil (ASM) (inoculadas e não inoculadas), P. lilacinus (-N) e P. chlamydosporia (+N) apresentaram frutos mais pesados. Com relação ao experimento 2, todos os tratamentos inoculados apresentaram maior peso das raízes, quando comparada aos tratamentos não inoculados, causado pela deformação da porção radicular. Adicionalmente, plantas tratadas com agentes de controle biológico apresentaram raízes com menos sintomas, quando comparados ao controle. Ademais, plantas tratadas apresentaram maior quantidade de clorofila em folhas jovens, quando comparadas aos controles. Todos os tratamentos, com exceção a P. chlamydosporia no experimento 1, reduziram a população final de M. incognita. Quando testado separadamente, todas as doses de P. chlamydosporia reduziram a Pf de M. incognita, embora as mais eficientes tenham sido a dose 4 (1g/planta) e dose 5 (2g/planta). Com relação aos filtrados, resultados promissores foram obtidos. Os filtrados obtidos a partir de B. amyloliquefaciens e P. lilacinus reduziram as populações finais de M. incognita, embora apenas B. amyloliquefaciens tenha diferido estatisticamente. Adicionalmente, aumento na massa das raízes e na massa dos frutos foram observados para plantas tratadas com filtrados de B. amyloliquefaciens e P. lilacinus, respectivamente. Ademais, todos os filtrados aceleraram a germinação das sementes quando comparado ao meio batata- dextrose, que suprimiu a germinação. Sementes tratadas com o filtrado obtido a partir de P. chlamydosporia apresentaram radículas pilosas, o que não foi observado nos outros tratamentos. Com relação aos experimentos de penetração, juvenis J2 de M. incognita foram observados no interior das raízes em todos os ensaios. Nenhum efeito do ASM foi observado em ambos os experimentos. Com relação a TPP, os dados apontam que o tratamento acelerou o ciclo do nematoide no interior das raízes. Conclui-se, que os dados obtidos apontam para o potencial dos indutores de resistência e agentes de controle biológico e seus filtrados no controle de M. incognita em meloeiro.