Nogueira J.H.C.,Instituto Biologico |
Goncalez E.,Instituto Biologico |
Facanali R.,Instituto Agronomico |
Marques M.O.M.,Instituto Agronomico |
Felicio J.D.,Instituto Biologico
International Journal of Food Microbiology | Year: 2010
Aflatoxin B 1 (AFB 1) is a highly toxic and carcinogenic metabolite produced by Aspergillus species on food and agricultural commodities. Inhibitory effects of essential oil of Ageratum conyzoides, on the mycelial growth and aflatoxin B 1 production by Aspergillus flavus were studied. Cultures were incubated in yeast extract-sucrose (YES) broth for days at 25 °C at the following different concentrations of the essential oil (from 0.0 to 30 μg/mL). The essential oil inhibited fungal growth to different extents depending on the concentration, and completely inhibited aflatoxin production at concentrations above 0.10 μg/mL. The analysis of the oil by GC/MS showed that its main components are precocene II (46.35%), precocene I (42.78%), cumarine (5.01%) and Trans-caryophyllene (3.02%). Comparison by transmission electron microscopy of the fungal cells, control and those incubated with different concentrations of essential oil, showed ultra-structural changes which were concentration dependent of the essential oil of A. conyzoides. Such ultra-structural changes were more evident in the endomembrane system, affecting mainly the mitochondria. Degradation was also observed in both surrounding fibrils. The ability to inhibit aflatoxin production as a new biological activity of A.conyzoides L. indicates that it may be considered as a useful tool for a better understanding of the complex pathway of aflatoxin biosynthesis. © 2009 Elsevier B.V. All rights reserved.
Nicastro R.L.,Biological Institute |
Sato M.E.,Biological Institute |
Sato M.E.,Instituto Biologico |
da Silva M.Z.,Biological Institute
Experimental and Applied Acarology | Year: 2010
Studies on artificial laboratory selections with milbemectin, stability of milbemectin resistance and possible cross-resistance with abamectin were carried out with Tetranychus urticae Koch to provide basic information for a milbemectin resistance management program. Selections for resistance and susceptibility to milbemectin were performed in a population of T. urticae, collected from a commercial chrysanthemum field in the State of São Paulo, Brazil. After six selections for resistance and five selections for susceptibility, susceptible (S) and resistant (R) strains of T. urticae to milbemectin were obtained. The resistance ratio (R/S) at the LC50 reached 409-fold value. The stability of milbemectin resistance was also studied under laboratory conditions, using a population with initial frequency of 75% of resistant mites. The frequencies of milbemectin resistance were evaluated monthly for a period of 7 months. In order to observe possible correlation between milbemectin and abamectin resistance, the frequencies of abamectin resistance were also evaluated for that population, during the same period. The frequency of milbemectin resistance decreased from 75 to 14.5%, while the percentage of abamectin resistant mites decreased from 57 to 9.1%, in 7 months. The frequencies of milbemectin and abamectin resistance were also evaluated in 25 field populations of T. urticae, collected from several crops in the State of São Paulo. The frequencies of milbemectin resistance varied from 4.1 to 89.5%, and of abamectin, from 7.0 to 90.5%. A positive and significant correlation was observed between the frequencies of milbemectin and abamectin resistance, indicating positive cross-resistance between these acaricides. The results indicate that abamectin should be avoided for managing milbemectin resistance in T. urticae. This is the first report on milbemectin resistance in T. urticae in Brazil. © Springer Science+Business Media B.V. 2009.
Esper R.H.,Instituto Biologico |
Goncalez E.,Instituto Biologico |
Marques M.O.,Instituto Agronomico |
Felicio R.C.,University Estadual Of Santa Cruz |
Felicio J.D.,Instituto Biologico
Frontiers in Microbiology | Year: 2014
Aflatoxin B1 (AFB1) is a highly toxic and carcinogenic metabolite produced by Aspergillus species on food and agricultural commodities. Inhibitory effects of essential oils of Ageratum conyzoides (mentrasto) and Origanum vulgare (oregano) on the mycelial growth and aflatoxin B1 production by Aspergillus flavus have been studied previously in culture medium. The aim of this study was to evaluate aflatoxin B1 production by Aspergillus flavus in real food systems (corn and soybean) treated with Ageratum conyzoides (mentrasto) and Origanum vulgare (oregano) essential oils. Samples with 60 g of the grains were treated with different volumes of essential oils, 200, 100, 50, and 10 μL for oregano and 50, 30, 15, and 10 μL for mentrasto. Fungal growth was evaluated by disk diffusion method. Aflatoxin B production was evaluated inoculating suspensions of A. flavus containing 1.3 × 10 spores/mL in 60 g of grains (corn and soybeans) after adjusting the water activity at 0.94. Aflatoxin was quantified by photodensitometry. Fungal growth and aflatoxin production were inhibited by essential oils, but the mentrasto oil was more effective in soybeans than that of oregano. On the other hand, in corn samples, the oregano essential oil was more effective than that of mentrasto. Chemical compositions of the essential oils were also investigated. The GC/MS oils analysis showed that the main component of mentrasto essential oil is precocene I and of the main component of oregano essential oil is 4-terpineol. The results indicate that both essential oils can become an alternative for the control of aflatoxins in corn and soybeans. © 2014 Esper, Gonçalez, Marques, Felicio and Felicio.
de Sousa A.P.A.,University of Sao Paulo |
de Andrea M.M.,Instituto Biologico
Sensors | Year: 2011
The pyrethroid insecticide cypermethrin is used for agricultural and public health campaigns. Its residues may contaminate soils and the beneficial soil organisms, like the earthworms, that may ingest the contaminated soil particles. Due to its ecological relevance, earthworms Eisenia andrei/fetida have been used in different ecotoxicological tests. The avoidance of soils treated with cypermethrin by compost worms Eisenia andrei was studied here as a bioindicator of the influence of treatment dosage and the pesticide formulation in three different agricultural soils indicated by the Brazilian environmental authorities for ecotoxicological tests. This earthworms' behavior was studied here as a first attempt to propose the test for regulation purposes. The two-compartment test systems, where the earthworms were placed for a two-day exposure period, contained samples of untreated soil alone or together with soil treated with technical grade or wettable powder formulation of cypermethrin. After 48 h, there was no mortality, but the avoidance was clear because all earthworms were found in the untreated section of each type of soil (p < 0.05). No differences were found by the Fisher's exact test (p ≤ 1.000) for each soil and treatment, demonstrating that the different soil characteristics, the cypermethrin concentrations and formulation, as well as the smaller amounts of soil and earthworms did not influence the avoidance behavior of the earthworms to cypermethrin. The number and range of treatments used in this study do not allow a detailed recommendation of the conditions applied here, but to the best of our knowledge, this is the first reported attempt to identify the avoidance of pesticide treated tropical soils by earthworms. © 2011 by the authors; licensee MDPI, Basel, Switzerland.
Boro M.C.,Instituto Biologico |
Beriam L.O.S.,Centro Experimental do Instituto Biologico |
Guzzo S.D.,Instituto Biologico
Tropical Plant Pathology | Year: 2011
Control of bacterial leaf spot of yellow passion fruit using the abiotic resistance inducer, acibenzolar-S-methyl (ASM), and the biotic agents, harpin protein and glycoproteins extracted from two Xanthomonas species, was evaluated. The inducers were applied by spraying the leaves 72 h before the inoculation with Xanthomonas axonopodis pv. passiforae. The inducers were also applied by seed immersion and the inoculation was performed when the seedlings had four true leaves. The results showed that ASM conferred a protection up to 70% at the concentration of 12.5 μg a.i. mL-1, while harpin led to an increase in bacterial symptoms. The glycoproteins from Xanthomonas spp. conferred up to 72% protection in plants against the bacterium. ASM or harpin provided up to 90% and 47% protection, respectively, in yellow passion fruit seedlings raised from treated seeds. Thus, leaf treatment with ASM or the glycoproteins from Xanthomonas spp. and seed treatment with ASM or harpin are potent inducers of resistance in passion fruit plants against X. axonopodis pv. passiforae.© by the Brazilian Phytopathological Society.
Fontenelle A.D.B.,Instituto Biologico |
Guzzo S.D.,Instituto Biologico |
Lucon C.M.M.,Instituto Biologico |
Harakava R.,Instituto Biologico
Crop Protection | Year: 2011
In tomato crop, the induction of resistance emerges as an important alternative for achieving the reduction of chemicals in disease control. This study aimed to evaluate the ability of 28 Trichoderma isolates to promote the growth of tomato seedlings and to induce systemic resistance (ISR) against Xanthomonas euvesicatoria and Alternaria solani, the causal agents of bacterial spot and early blight, respectively. Twelve isolates promoted the increase of plant dry matter mass (DMM) above 100%, showing the great potential of these strains. All isolates were able to colonize the root system of tomato plants. The plant growth-promoting isolates were further evaluated for potential elicitation of ISR. Treatment of the soil with all Trichoderma isolates provided protection in tomato plants from 24.13 to 95.94% against X. euvesicatoria and 30.69 to 95.23% against A. solani. The most efficient isolates in reducing the severity of bacterial spot and early blight were the isolates IB 28/07, IB 30/07, IB 37/01 and IB 28/07, IB 30/07 and IB 42/03, respectively. The effect of different time intervals between Trichoderma application and inoculation with pathogens in inducing systemic resistance in tomato plants was evaluated for the isolate IB 28/07. IB 28/07 conferred protection against both diseases at all time intervals, confirming the ability of the isolate to reduce the severity of these diseases up to 21 days after treatment of tomato plants. In vitro assays revealed that all isolates of Trichoderma were able to degrade cellulose. Only the isolate IB 34/08 showed antagonistic activity against X. euvesicatoria and none caused reduction in the in vitro mycelial growth of A. solani. Trichoderma isolates were identified at species level by DNA sequencing. © 2011 Elsevier Ltd.
Zorzenon F.J.,Instituto Biologico |
De C. Campos A.E.,Instituto Biologico
Sociobiology | Year: 2014
One of the most important problems in urban trees is termite infestation. Simple observations of damages on outside trunks or dead branches and leaves do not always confirm infestations. Several trees may present severe termite damage internally that can only be observed through drilling. This paper presents a methodology to evaluate estimated percentages of internal damage caused by termites in urban trees. Tests were made on 1,477 plants in a neighborhood in the city of São Paulo, Brazil and 27% of them were infested by subterranean termites. The results showed that the methodology is simple to use, fast and inexpensive, and it allows assessment of termite internal damage which may help in making decisions on tree management. The trees did not show any phytosanitary problems along the 9 year study after being submitted to the new technique.
Queiroz M.C.V.,Instituto Biologico |
Sato M.E.,Instituto Biologico
Experimental and Applied Acarology | Year: 2016
Phytoseiulus macropilis Banks (Acari: Phytoseiidae) is an effective predator of Tetranychus urticae Koch (Acari: Tetranychidae). The objectives of this research were to study the stability of fenpropathrin resistance and the cross-resistance relationships with different pyrethroids, and also to evaluate the effect of synergists [piperonyl butoxide (PBO), diethyl maleate (DEM) and S,S,S-tributyl phosphorotrithioate (DEF)] on fenpropathrin resistant and susceptible strains of this predaceous mite. The stability of fenpropathrin resistance was studied under laboratory conditions, using P. macropilis populations with initial frequencies of 75 and 50 % of resistant mites. The percentages of fenpropathrin resistant mites were evaluated monthly for a period of up to 12 months. A trend toward decreased resistance frequencies was observed only during the first 3–4 months. After this initial decrease, the fenpropathrin resistance was shown to be stable, maintaining constant resistance frequencies (around 30 %) until the end of the evaluation period. Toxicity tests carried out using fenpropathrin resistant and susceptible strains of P. macropilis indicated strong positive cross-resistance between fenpropathrin and the pyrethroids bifenthrin and deltamethrin. Bioassays with the synergists DEM, DEF and PBO were also performed. The maximum synergism ratio (SR = LC50 without synergist/LC50 with synergist) detected for the three evaluated synergists (PBO, DEM, DEF) was 5.86 (for DEF), indicating low influence of enzyme detoxification processes in fenpropathrin resistance. © 2015, Springer International Publishing Switzerland.
Terao D.,EMBRAPA - Empresa Brasileira de Pesquisa Agropecuária |
de Carvalho Campos J.S.,University of Campinas |
Benato E.A.,Instituto Biologico |
Hashimoto J.M.,EMBRAPA - Empresa Brasileira de Pesquisa Agropecuária
Food Engineering Reviews | Year: 2014
The demand for clean, safe and sustainable alternative control measures of postharvest diseases of fruit has increased in recent years, and the use of UV-C irradiation is a potential option. This study focused on evaluating UV-C dose effect on in vitro and in vivo development of fungi species and also on postharvest decay on mango cv. Tommy Atkins. The evaluated fungi which cause decay were as follows: Botryosphaeria dothidea, Lasiodiplodia theobromae, Alternaria alternata and Colletotrichum gloeosporioides. Fungus mycelium was exposed to increasing doses of UV-C irradiation: 0 (control), 2.0, 3.0, 5.0, 10.0 and 20 kJ m-2. L. theobromae and A. alternata received dose up to 59.7 kJ m-2. Mangos artificially inoculated with B. dothidea were treated with doses of UV-C irradiation: 0.0, 0.5, 1.0, 2.5, 5.0, 7.5 e 10.0 kJ m-2 and stored at 10 °C for 15 days and for 2 days at 22 °C, observing the rot on daily basis. The trials were conducted in a completely randomized design with six replicates for in vitro tests and four replicates with seven fruit as experimental unit. The in vitro trials demonstrated that even high dose of UV-C (20 kJ m-2) was not able to control the fungi development. Nonetheless, low dose of UV-C irradiation at 2.5 kJ m-2 controlled around 70 % of fruit rot severity. Higher doses (>5 kJ m-2) caused damage on mango peel increasing the rot severity. Results suggest that, the application of low dose (<3 kJ m-2) of UV-C irradiation can contribute to the integrated management of postharvest diseases on mango, and that, the mechanisms of control involved are not directly related to the fungi development. © 2014 Springer Science+Business Media New York.
Clemente Z.,Laboratorio Of Ecotoxicologia E Biosseguranca |
Clemente Z.,University of Campinas |
Castro V.L.S.S.,Laboratorio Of Ecotoxicologia E Biosseguranca |
Moura M.A.M.,Instituto Biologico |
And 3 more authors.
Aquatic Toxicology | Year: 2014
The popularity of TiO2 nanoparticles (nano-TiO2) lies in their wide range of nanotechnological applications, together with low toxicity. Meanwhile, recent studies have shown that the photocatalytic properties of this material can result in alterations in their behavior in the environment, causing effects that have not yet been fully elucidated. The objective of this study was to evaluate the toxicity of two formulations of nano-TiO2 under different illumination conditions, using an experimental model coherent with the principle of the three Rs of alternative animal experimentation (reduction, refinement, and replacement). Embryos of the fish Danio rerio were exposed for 96h to different concentrations of nano-TiO2 in the form of anatase (TA) or an anatase/rutile mixture (TM), under either visible light or a combination of visible and ultraviolet light (UV). The acute toxicity and sublethal parameters evaluated included survival rates, malformation, hatching, equilibrium, and overall length of the larvae, together with biochemical biomarkers (specific activities of catalase (CAT), glutathione S-transferase (GST), and acid phosphatase (AP)). Both TA and TM caused accelerated hatching of the larvae. Under UV irradiation, there was greater mortality of the larvae of the groups exposed to TM, compared to those exposed to TA. Exposure to TM under UV irradiation altered the equilibrium of the larvae. Alterations in the activities of CAT and GST were indicative of oxidative stress, although no clear dose-response relationship was observed. The effects of nano-TiO2 appeared to depend on both the type of formulation and the illumination condition. The findings contribute to elucidation of the factors involved in the toxicity of these nanoparticles, as well as to the establishment of protocols for risk assessments of nanotechnology. © 2013 Elsevier B.V.