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São Paulo, Brazil

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.

Terao D.,EMBRAPA - Empresa Brasileira de Pesquisa Agropecuaria | de Carvalho Campos J.S.,University of Campinas | Benato E.A.,Instituto Biologico | Hashimoto J.M.,EMBRAPA - Empresa Brasileira de Pesquisa Agropecuaria
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.

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.

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.

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.

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