RESUMO

The neem tree (Azadirachta indica A. Juss) is grown mainly for shade, fuel, and numerous non-timber forest products using its leaves, fruit, and bark. It produces an essential oil that is used as a source for obtaining bioinsecticides, with a broad spectrum of action in agricultural production. Its bioinsecticidal activity is due to the presence of triterpenes, such as azadirachtin, a product in continued growth of the global biopesticide market. Optimal conditions for neem oil extraction using response surface methodology (RSM) and microwave-assisted extraction (MAE) methods have been defined. However, the extraction conditions for these methods tend to consume high volumes of organic solvent and long extraction times. The aim of the present study is to determine the optimal conditions for the extraction of azadirachtin from neem seeds in a hydroalcoholic medium using MAE and RSM with a Box-Behnken design (BBD). A BBD was applied to evaluate the effects of the factors, magnetron voltage (X1), extraction time (X2), and pH of the extraction medium (X3), on the yield of the azadirachtin extraction process. The effect of each variable on the extraction yield was studied independently, considering the pure coefficients (linear and quadratic) on the three levels that were studied in the experiments. Moreover, the study experiments were conducted in triplicate, data were presented as mean and standard deviation, homogeneity of variances was estimated using Levene's test, and a two-way ANOVA with Tukey's post hoc analysis was performed to identify the experimental conditions that allowed us to find the highest extraction yield and to analyze whether the response surface model adequately described our data. The most significant effects of the model correspond to quadratic and interaction effects (p < 0.0001); the quadratic terms voltage (X1), extraction time (X2), and pH (X3); and the interaction effects between voltage-pH (X1*X3) and time-pH (X2*X3), which had a significant influence on the model. Moreover, a canonical analysis was performed. The optimal conditions were as follows: 69.22 V, 6.89 min, and a pH value of 4.35, coinciding with the zones shown in the contour plots. Furthermore, the response obtained at the optimal conditions was 37.5 µg of azadirachtin per gram of pretreated seed.

RESUMO

The objective of this study was to evaluate the physicochemical compatibility of mixtures of synthetic and botanical limonoid-based insecticides, as well as the toxicity of these associations, in the management of Spodoptera frugiperda (J.E. Smith) under laboratory and field conditions. For this, the associations of 4 commercial botanical insecticides based on neem registered in Brazil (Azamax, Agroneem, Azact CE, and Fitoneem) were tested with synthetic insecticides from the group of growth regulators (IGRs [triflumuron, lufenuron, methoxyfenozide and tebufenozide]). When mixed, all combinations caused a significant reduction in the pH of the mixture and a significant increase in electrical conductivity. However, all tested combinations showed similar stability behavior to the negative control (distilled water), which demonstrated their physicochemical compatibility. Furthermore, in laboratory and field bioassays, mixtures of IRGs with limonoid-based formulations provided satisfactory effects in the management of S. frugiperda. However, binary mixtures of insecticide Intrepid 240 SC with Azamax or Azact CE (at LC25 previously estimated) showed the highest toxicities on S. frugiperda larvae in laboratory bioassays and damage reduction caused by S. frugiperda in a 2-yr field experiments. Therefore, mixtures of IGRs with limonoid-based botanical insecticides are promising alternatives for the management of S. frugiperda and important component of integrated pest management and insect resistance management programs.

Assuntos

RESUMO

The objective of this study was to evaluate the effects of growth-regulating insecticides of synthetic (e.g., Certero 480 SC, Intrepid 240 SC, Match EC and Mimic 240 SC) and botanical origins (e.g., Azamax 1.2 EC, Agroneem 850 EC, Azact 2.4 EC and Fitoneem 850 EC) on the biological parameters and fertility life table of Spodoptera frugiperda (J.E. Smith) under laboratory conditions. Larvae were fed insecticides that were incorporated into artificial diets. To develop the fertility life table, the following biological parameters were evaluated: survival at 7 days after infestation (d.a.i) and survivorship at adult eclosion, duration of the neonate-to-adult eclosion period, larval and pupal weights and total fecundity (number of total eggs per female). The results indicated that S. frugiperda neonates surviving LC25 or LC50 concentrations of the evaluated insecticides showed longer larval and egg-to-adult periods, lower larval and pupal weights and reduced fecundity, when compared to the control treatment. Larvae exposed to Azamax at LC25 or LC50 concentrations showed the greatest increase in generation duration (75 d). In addition, S. frugiperda adults emerged from pupae when larvae reared on an artificial diet containing growth regulating insecticides of synthetic and botanical origins produced fewer females per female per generation (Ro). As well as, lower rates of natural population increase per day (rm) compared to insects fed the control diet. Our findings indicated that, neem-derived products and growth-regulating insecticides of synthetic origin may be employed within integrated management strategies that aim to keep populations of S. frugiperda below levels that cause economic damage. Similarly, they offer alternatives for insecticide resistance management programs.

Assuntos

RESUMO

Sustainable agriculture encourages practices that present low risks to the environment and human health. To this end, zein (corn protein) can be used to develop nanocarrier systems capable of improving the physicochemical properties of biopesticides, reducing their possible toxicity. Neem oil extracted from the Azadirachta indica tree contains many active ingredients including azadirachtin, which is the active ingredient in multiple commercially available biopesticides. In this study, we describe the preparation and characterization of neem oil-loaded zein nanoparticles, together with evaluation of their toxicity towards nontarget organisms, using Allium cepa, soil nitrogen cycle microbiota, and Caenorhabditis elegans aiming to achieve the safer by design strategy. The spherical nanoparticles showed an average diameter of 278 ±â€¯61.5 nm and a good stability during the experiments. In the toxicity assays with A. cepa, the neem oil-loaded zein nanoparticles mitigated the increase in the DNA relative damage index caused by the neem oil. Molecular genetic analysis of the soil nitrogen cycle microbiota revealed that neem oil-loaded zein nanoparticles did not change the number of genes which encode nitrogen-fixing enzymes and denitrifying enzymes. In C. elegans, the neem oil-loaded zein nanoparticles had no toxic effect, while neem oil interfered with pharyngeal pumping and GST-4 protein expression. These neem oil-loaded zein nanoparticles showed promising results in the toxicity studies, opening perspectives for its use in crop protection in organic agriculture.

Assuntos

RESUMO

The market trend for pitaya is increasing, although the preservation of the quality of this fruit after the harvest is challenging due to microbial decay, dehydration, and oxidation. In this work, the application of antimicrobial chitosan-based coatings achieved successful postharvest preservation of pitaya (Stenocereus pruinosus) during storage at 10 ± 2 °C with a relative humidity of 80 ± 5%. The solution of cross-linked chitosan with hydroxypropylmethylcellulose with entrapped Neem oil (16 g·L-1) displayed the best postharvest fruit characteristics. The reduction of physiological weight loss and fungal contamination, with an increased redness index and release of azadirachtin from the microencapsulated oil, resulted in up to a 15 day shelf life for this fruit. This postharvest procedure has the potential to increase commercial exploitation of fresh pitaya, owing to its good taste and high content of antioxidants.

Assuntos

RESUMO

Large-scale pesticide application poses a major threat to bee biodiversity by causing a decline in bee populations that, in turn, compromises ecosystem maintenance and agricultural productivity. Biopesticides are considered an alternative to synthetic pesticides with a focus on reducing potential detrimental effects to beneficial organisms such as bees. The production of healthy queen stingless bees is essential for the survival and reproduction of hives, although it remains unknown whether biopesticides influence stingless bee reproduction. In the present study, we investigated the effects of the biopesticide azadirachtin on the survival, behavior, morphology, development, and reproduction of queens of the stingless bee Partamona helleri (Friese, 1900). The neonicotinoid imidacloprid was used as a toxic reference standard. Queens were orally exposed in vitro to a contaminated diet (containing azadirachtin and imidacloprid) during development. Azadirachtin resulted in reduced survival, similarly to imidacloprid, altered development time, caused deformations, and reduced the size of the queens' reproductive organs. All of these factors could potentially compromise colony survival. Results from the present study showed azadirachtin posed a toxicological hazard to P. helleri queens.

Assuntos

RESUMO

The bioactivity of a newly registered annonin-based formulation (Anosom® 1 EC) was investigated for use against the fall armyworm Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), both singly and mixed with a limonoid-based formulation (Azamax® 1.2 EC) using dietary exposure bioassays. Anosom® 1 EC caused significant mortality in S. frugiperda larvae exposed to treated artificial media, with the activity level dependent on both the concentration and the exposure time. In addition to exhibiting acute toxicity, this formulation (tested at LC50) also caused growth inhibition of S. frugiperda, as demonstrated by a significant reduction in pupal weight and viable larval and pupal phases and an increase in the duration of the larval stage. Moreover, the bioinsecticide caused an increase in the proportion of deformed or defective pupae; these were characterized by the retention of exuvia from the last larval instar. The bioinsecticide (at the previously estimated LC90) was, in a time-dependent manner, equally as toxic as the limonoid-based biopesticide (Azamax® 1.2 EC), which was tested at concentrations recommended for the management of S. frugiperda in Brasil. Moreover, the binary mixture (1/2 LC90 of Anosom® 1 EC + 1/2 the recommended rate of Azamax® 1.2 EC) of both bioinsecticides caused a similar level of mortality compared to the bioinsecticides tested individually (full concentration), demonstrating an additive effect of these commercial bioinsecticides. In light of these findings, this standardized formulation based on extract of Annona squamosa can constitute a useful component in the framework of S. frugiperda management, mainly in organic food production systems.

Assuntos

RESUMO

Azadirachtin (Aza) is a promisor biopesticide used in organic production and aquaculture. Although this compound is apparently safe, there is evidence that it may have deleterious effects on fish. Behavioral and hematological tests are grouped into a set of parameters that may predict potential toxicity of chemical compounds. Here, we investigate the effects of Aza, in the commercial formulation Neenmax™ , on carp (Cyprinus carpio) by defining LC50 (96 h), and testing behavioral and hematological parameters. In our study, LC50 was estimated at 80 µL/L. We exposed carp to Aza at 20, 40, and 60 µL/L, values based on 25, 50, and 75% of LC50 , respectively. At 60 µL/L, Aza promoted significant changes in several parameters, increasing the distance traveled and absolute turn angle. In addition, the same concentration decreased the time spent immobile and the number of immobile episodes. Hematological parameters, such as hematocrit, hemoglobin, hematimetrics index, and red cell distribution, were decreased at 60 µL/L Aza exposure. In conclusion, our study demonstrates that 60 µL/L Aza altered locomotor activity, motor pattern, and hematological parameters, suggesting potential toxicity to carp after acute exposure. In addition, this is the first report that evaluates the actions of a chemical contaminant using automated behavioral tracking of carp, which may be a useful tool for assessing the potential toxicity of biopesticides in conjunction with hematological tests. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1381-1388, 2016.

Assuntos

RESUMO

This study identified the threshold concentration of limonoids for the complete inhibition of oviposition of Ceratitis capitata (Wiedemann) in grapes 'Itália.' Choice and no-choice experiments with the insect were performed. The three no-choice bioassays were conducted following a completely randomized design with 18 treatments (three densities of insects [one, two, or three females]×five concentrations of limonoids and control) and 20 replicates. In a free choice bioassay, two fruits per cage (a treatment grape and a control) were provided for ovipositing. Three densities of insects (one, two, or three females) were used, with 15 replicates. Bioassays were conducted at 25±2°C, 60±10% relative humidity, and a photoperiod of 14:10 (L:D) h. The inhibition of oviposition of C. capitata was concentration dependent, with infestation occurring at lower concentrations of azadirachtin (+3-tigloylazadirachtol) and complete inhibition occurring at concentrations at or exceeding 100 ppm azadirachtin (+28.5 ppm of 3-tigloylazadirachtol), maintaining protective effects even at the most densely populated treatment (three females per fruit). When the pest had a free choice of host grapes (treatment vs. control), severe inhibition was observed at concentrations≥50 ppm azadirachtin (+14.3 ppm of 3-tigloylazadirachtol). We conclude that a threshold concentration of 100 ppm azadirachtin (+28.5 ppm of 3-tigloylazadirachtol) is capable of preventing grape infestation. This concentration is likely to provide a reliable level of protection, as the experimental population density of three females per fruit usually does not occur in the field and wild flies usually have more host options.

Assuntos

RESUMO

The acute static renewal test of a botanical pesticide - azadirachtin for the freshwater catfish, Heteropneustes fossilis has been performed to determine the LC50 values at different exposure period. The LC50 values at various exposure periods are 173.06 mg L-1 for 24h; 80.69 mg L -1 for 48h; 58.57 mg L-1 for 72h and 52.35 mg L -1 for 96h. The upper confidence limits were 196.87, 86.91, 79.20 and 70.04 mg L-1 for 24, 48, 72 and 96 h and lower confidence limits were 154.01, 74.24, 37.33 and 33.83 mg L-1, respectively. These results indicate that azadirachtin exposure to the fish caused toxic effects.

A renovação do ensaio estático agudo de um pesticida botânico - azadiractin para o peixe de água doce, Heteropneustes fossilis foi realizada para determinar os valores de LC50 em diferentes períodos de exposição. Os valores de LC50 em diferentes períodos de exposição são 173,06 mg L-1 por 24h; 80,69 mg L-1 por 48h; 58,57 mg L-1 por 72 h e 52,35 mg L-1 por 96h. Os limites de confiança superiores foram 196,87; 86,91; 79,20 e 70,04 mg L-1 para 24, 48, 72 e 96h os limites inferior e confiança foram 154,01; 74,24; 37,33 e 33,83 mg L-1, respectivamente. Estes resultados indicam que a exposição do peixe à azadiractin causou efeitos tóxicos.

Assuntos

RESUMO

The acute static renewal test of a botanical pesticide - azadirachtin for the freshwater catfish, Heteropneustes fossilis has been performed to determine the LC50 values at different exposure period. The LC50 values at various exposure periods are 173.06 mg L-1 for 24h; 80.69 mg L-1 for 48h; 58.57 mg L-1 for 72h and 52.35 mg L-1 for 96h. The upper confidence limits were 196.87, 86.91, 79.20 and 70.04 mg L-1 for 24, 48, 72 and 96 h and lower confidence limits were 154.01, 74.24, 37.33 and 33.83 mg L-1, respectively. These results indicate that azadirachtin exposure to the fish caused toxic effects.

RESUMO

The acute static renewal test of a botanical pesticide - azadirachtin for the freshwater catfish, Heteropneustes fossilis has been performed to determine the LC50 values at different exposure period. The LC50 values at various exposure periods are 173.06 mg L-1 for 24h; 80.69 mg L-1 for 48h; 58.57 mg L-1 for 72h and 52.35 mg L-1 for 96h. The upper confidence limits were 196.87, 86.91, 79.20 and 70.04 mg L-1 for 24, 48, 72 and 96 h and lower confidence limits were 154.01, 74.24, 37.33 and 33.83 mg L-1, respectively. These results indicate that azadirachtin exposure to the fish caused toxic effects.

RESUMO

Much attention has been given to the development of botanical insecticides to provide effective natural control of cattle ectoparasites without harming animals, consumers, and environment. This study evaluated the efficacy of a commercial neem cake in controlling Haematobia irritans infestation on cattle. The study was conducted at the Embrapa Southeast Cattle Research Center (CPPSE), in São Carlos, SP, Brazil, from April to July 2008. The neem cake mixed in mineral salt in a 2 percent concentration was provided to 20 Nelore cows during nine weeks and had its efficacy evaluated by comparison of the infestation level against a control group. Fly infestations were recorded weekly by digital photographs of each animal from both groups and the number of flies was later counted in a computer-assisted image analyzer. Quantification of neem cake components by high-performance liquid chromatography revealed the presence of azadirachtin (421 mg.kg-1) and 3-tigloyl-azadirachtol (151 mg.kg-1) in the tested neem cake. Addition of the 2 percent neem cake reduced mineral salt intake in about 22 percent. The 2 percent neem cake treatment failed to reduce horn fly infestations on cattle during the 9-week study period.

Muita atenção tem sido dada ao desenvolvimento de inseticidas vegetais buscando-se um efetivo controle de ectoparasitas de bovinos, sem prejudicar animais, consumidores e meio ambiente. Este estudo, realizado de abril a julho de 2008, na Embrapa Pecuária Sudeste, em São Carlos, SP, Brasil, avaliou a eficácia de uma torta comercial de nim (Azadirachta indica) no controle da mosca-dos-chifres (Haematobia irritans) em bovinos. A torta de nim, misturada ao sal mineral na concentração de 2 por cento, foi fornecida a 20 vacas Nelore, durante nove semanas, e sua eficácia foi monitorada através de contagens semanais nos grupos tratado e controle. Infestações individuais foram registradas por meio de fotos digitais em todos os animais de ambos os grupos, e o número de moscas foi, posteriormente, quantificado com o auxílio de um sistema de análise de imagem computadorizado. A quantificação dos componentes da torta de nim, por cromatografia líquida, revelou a presença de azadiractina (421 mg.kg-1) e 3-tigloyl-azadirachtol (151 mg.kg-1). A adição da torta de nim a 2 por cento reduziu o consumo de sal mineral em cerca de 22 por cento. O tratamento com torta de nim a 2 por cento não reduziu as infestações por mosca-dos-chifres em bovinos durante as nove semanas do estudo.

Assuntos

RESUMO

Este trabalho teve como objetivo avaliar a ação do inseticida botânico nim em larvas de Ceratitis capitata, bem como no parasitismo destas larvas por Diachasmimorpha longicaudata. Para tanto, larvas de 3o ínstar de C. capitata foram mergulhadas por 30 segundos em soluções contendo as concentrações de 0,5%, 1% e 1,5% de um produto comercial à base de óleo de nim a 0,37% (3.686 ppm), além da testemunha mergulhada apenas em água destilada. Em seguida, as larvas foram expostas ao parasitismo de D. longicaudata por um período de 2 horas e 30 minutos. No experimento sem chance de escolha, para cada tratamento, uma única "unidade de parasitismo" foi pendurada no interior da gaiola. No experimento com livre escolha, as "unidades de parasitismo" foram penduradas no interior de uma mesma gaiola, de forma que os parasitoides tivessem livre acesso a todos os tratamentos. No experimento sem livre escolha, foi constatado que o aumento da concentração de nim diminuiu a atração das fêmeas, o número de fêmeas que efetuaram postura, o índice de parasitismo e a emergência dos parasitoides. No experimento com livre escolha, verificou-se que a emergência dos parasitoides e o índice de parasitismo também foram prejudicados nas maiores concentrações de nim. A ação isolada do nim, quando em contato com as larvas de 3o instar, não afetou a emergência de C. capitata.

The purpose of this work was to evaluate the action of the botanic insecticide neem oil on larvae of Ceratitis capitata, as well as in the parasitism of these larvae by Diachasmimorpha longicaudata. Third-instar larvae were immersed for 30 seconds in a neem solution, in concentrations of 0.5%, 1% and 1.5% of a commercial product composed of 0.37% (3.686 ppm) neem oil, while the controls were immersed only in distilled water. Soon afterwards the larvae were exposed to parasitism of D. longicaudata for 2 hours and 30 minutes. In the no-choice experiment, for every treatment, a single "parasitism unit" was hung inside the cage. In the experiment with free choice, "parasitism units" were hung inside another cage, so that the parasitoids had free access to all treatments. In the no-choice experiment, it was ascertained that the increase of the neem oil concentration decreased the attraction of the females, the number of females that lay, the parasitism rate and parasitoid emergency. In the experiment with free choice, it was ascertained that the emergence of parasitoids and parasitism rate were harmed at the larger neem oil concentrations. The isolated action of neem oil, when in contact with the third-instar larvae, did not affect the emergence of C. capitata.

Assuntos

RESUMO

Much attention has been given to the development of botanical insecticides to provide effective natural control of cattle ectoparasites without harming animals, consumers, and environment. This study evaluated the efficacy of a commercial neem cake in controlling Haematobia irritans infestation on cattle. The study was conducted at the Embrapa Southeast Cattle Research Center (CPPSE), in São Carlos, SP, Brazil, from April to July 2008. The neem cake mixed in mineral salt in a 2% concentration was provided to 20 Nelore cows during nine weeks and had its efficacy evaluated by comparison of the infestation level against a control group. Fly infestations were recorded weekly by digital photographs of each animal from both groups and the number of flies was later counted in a computer-assisted image analyzer. Quantification of neem cake components by high-performance liquid chromatography revealed the presence of azadirachtin (421 mg.kg-1) and 3-tigloyl-azadirachtol (151 mg.kg-1) in the tested neem cake. Addition of the 2% neem cake reduced mineral salt intake in about 22%. The 2% neem cake treatment failed to reduce horn fly infestations on cattle during the 9-week study period.

Muita atenção tem sido dada ao desenvolvimento de inseticidas vegetais buscando-se um efetivo controle de ectoparasitas de bovinos, sem prejudicar animais, consumidores e meio ambiente. Este estudo, realizado de abril a julho de 2008, na Embrapa Pecuária Sudeste, em São Carlos, SP, Brasil, avaliou a eficácia de uma torta comercial de nim (Azadirachta indica) no controle da mosca-dos-chifres (Haematobia irritans) em bovinos. A torta de nim, misturada ao sal mineral na concentração de 2%, foi fornecida a 20 vacas Nelore, durante nove semanas, e sua eficácia foi monitorada através de contagens semanais nos grupos tratado e controle. Infestações individuais foram registradas por meio de fotos digitais em todos os animais de ambos os grupos, e o número de moscas foi, posteriormente, quantificado com o auxílio de um sistema de análise de imagem computadorizado. A quantificação dos componentes da torta de nim, por cromatografia líquida, revelou a presença de azadiractina (421 mg.kg-1) e 3-tigloyl-azadirachtol (151 mg.kg-1). A adição da torta de nim a 2% reduziu o consumo de sal mineral em cerca de 22%. O tratamento com torta de nim a 2% não reduziu as infestações por mosca-dos-chifres em bovinos durante as nove semanas do estudo.

RESUMO

ABSTRACT The purpose of this work was to evaluate the action of the botanic insecticide neem oil on larvae of Ceratitis capitata, as well as in the parasitism of these larvae by Diachasmimorpha longicaudata. Third-instar larvae were immersed for 30 seconds in a neem solution, in concentrations of 0.5%, 1% and 1.5% of a commercial product composed of 0.37% (3.686 ppm) neem oil, while the controls were immersed only in distilled water. Soon afterwards the larvae were exposed to parasitism of D. longicaudata for 2 hours and 30 minutes. In the no-choice experiment, for every treatment, a single parasitism unit was hung inside the cage. In the experiment with free choice, parasitism units were hung inside another cage, so that the parasitoids had free access to all treatments. In the no-choice experiment, it was ascertained that the increase of the neem oil concentration decreased the attraction of the females, the number of females that lay, the parasitism rate and parasitoid emergency. In the experiment with free choice, it was ascertained that the emergence of parasitoids and parasitism rate were harmed at the larger neem oil concentrations. The isolated action of neem oil, when in contact with the third-instar larvae, did not affect the emergence of C. capitata.

RESUMO Este trabalho teve como objetivo avaliar a ação do inseticida botânico nim em larvas de Ceratitis capitata, bem como no parasitismo destas larvas por Diachasmimorpha longicaudata. Para tanto, larvas de 3o ínstar de C. capitata foram mergulhadas por 30 segundos em soluções contendo as concentrações de 0,5%, 1% e 1,5% de um produto comercial à base de óleo de nim a 0,37% (3.686 ppm), além da testemunha mergulhada apenas em água destilada. Em seguida, as larvas foram expostas ao parasitismo de D. longicaudata por um período de 2 horas e 30 minutos. No experimento sem chance de escolha, para cada tratamento, uma única unidade de parasitismo foi pendurada no interior da gaiola. No experimento com livre escolha, as unidades de parasitismo foram penduradas no interior de uma mesma gaiola, de forma que os parasitoides tivessem livre acesso a todos os tratamentos. No experimento sem livre escolha, foi constatado que o aumento da concentração de nim diminuiu a atração das fêmeas, o número de fêmeas que efetuaram postura, o índice de parasitismo e a emergência dos parasitoides. No experimento com livre escolha, verificou-se que a emergência dos parasitoides e o índice de parasitismo também foram prejudicados nas maiores concentrações de nim. A ação isolada do nim, quando em contato com as larvas de 3o instar, não afetou a emergência de C. capitata.

RESUMO

ABSTRACT The objective of this work was to evaluate the effects of Nim-I-Go on pupae and adults of Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae). The neem-based insecticide Nim-I-Go was used in the following concentrations (%) in the pupae trial: 0.5; 1.0; 2.0 and 5.0; equivalent to (in mg of azadirachtin/L of water) 5 mg/L, 10 mg/L, 20 mg/L and 50 mg/L, respectively. In the larvae trial the following concentrations were used: 0.25; 0.5; 0.75; 1.0 and 2.0; equivalent to (in mg of azadirachtin/L) 2.5 mg/L, 5.0 mg/L, 7.5 mg/L, 10 mg/L and 20 mg/L, respectively. Chlorpyrifos was used as a negative control (0.48 g a.i./L) in both trials, and water as a positive control. The bioassays were carried out at 25 ± 2o C, RH of 70 ± 10%, and 12-h of photophase. The sprayings were carried out using a Potters tower, ensuring the application of 1.5 ± 0.5 mg/cm2. Survival of pupae and adults, and the effects of the insecticides on the reproductive capacity of this predator were evaluated. The total toxic effect (E) of the insecticides was calculated according to the standard methodology established by IOBC. Nim-I-Go was harmless to pupae and adults of C. externa. Chlorpyrifos was harmful to this natural enemy.

RESUMO O objetivo do presente trabalho foi avaliar os efeitos do Nim-I-Go® sobre pupas e adultos de Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae). As concentrações (%) do Nim-I-Go® utilizadas no experimento com pupas foram as seguintes: 0,5; 1,0; 2,0 e 5,0; correspondendo a (mg de azadirachtina/L de água) 5 mg/L, 10 mg/L, 20 mg/L e 50 mg/L, respectivamente. No experimento com adultos foram utilizadas as seguintes concentrações: 0,25; 0,5; 0,75; 1,0 e 2,0; correspondendo a (mg de azadirachtina/L) 2,5 mg/L, 5,0 mg/L, 7,5 mg/L, 10 mg/L e 20 mg/L, respectivamente. Clorpirifós foi utilizado como testemunha negativa (0,48 g i.a./L) nos dois experimentos e água como testemunha positiva. Os bioensaios foram conduzidos a 25 ± 2 o C, UR de 70 ± 10% e fotofase de 12 horas. As pulverizações foram realizadas por meio de torre de Potter com aplicação de 1,5 ± 0,5 mg de calda química/cm2. Avaliaram-se a viabilidade dos ovos, a sobrevivência de pupas e adultos e o efeito dos inseticidas sobre a capacidade reprodutiva dos indivíduos. A toxicidade foi calculada em função do efeito total (E), conforme metodologia padrão estabelecida pela IOBC. Nim-I-Go® nas diversas concentrações foi inócuo a pupas e adultos do predador. Clorpirifós foi nocivo para pupas e adultos de C. externa.

RESUMO

ABSTRACT The objective of this work was to evaluate the effects of azadirachtin and some synthetic insecticides used in the cotton crops on eggs and firstand fourth-instar larvae of Cycloneda sanguinea (Linnaeus). The neem-based insecticide Nim-I-Go was used in the following concentrations: 1% (10 mg of azadirachtin/L), 5% (50 mg of azadirachtin/L) and 10% (100 mg of azadirachtin/L). The synthetic insecticides teflubenzuron (Nomolt 150 SC) (0.15 g a.i./ L), lambdacyhalothrin (Karate Zeon 250 CS (0.08 g a.i./L) and chlorpyrifos (Vexter 480 CE) (1.6 g a.i./L) also were used in this study. Distilled water was used as control. A fully randomized experimental design was used, with seven treatments and six replicates, each one formed of three eggs or larvae of C. sanguinea. A manual sprayer was used to spew the solutions. The bioassays were kept in a room at 25±2oC, RH of 70±10% and 12h photophase. The insects were fed with Schizaphis graminum (Rondani). Lambdacyhalothrin and chlorpyrifos were harmful to all stages of C. sanguinea. Azadirachtin at 50 and 100 mg;L was toxic to fourth-instar larvae of C. sanguinea. Based in its low toxicity, azadirachtin 10 mg/L and teflubenzuron present favorable characteristics for use in the integrated pest management where C. sanguinea is an important factor of natural mortality of pests.

RESUMO Este trabalho objetivou avaliar os efeitos do azadirachtina e de alguns inseticidas sintéticos utilizados na cultura do algodoeiro sobre ovos e larvas de primeiro e quarto instares do predador Cycloneda sanguinea (Linnaeus). Nim-I-Go® (azadirachtina) foi utilizado nas concentrações de 1%, 5% e 10%, correspondendo a 10 mg/L, 50 mg/L e 100 mg/L de azadirachtina, respectivamente. Os inseticidas utilizados foram teflubenzurom (Nomolt 150 SC) (0,15 g i.a./L), lambdacialotrina (Karate Zeon 250 CS) (0,08 g i.a./L) e clorpirifós (Vexter 480 CE) (1,6 g i.a./L). O tratamento testemunha foi composto somente por água destilada. Utilizaram-se sete tratamentos com seis repetições, sendo cada parcela formada por três ovos ou larvas de C. sanguinea, sendo as aplicações realizadas com um pulverizador manual. Os bioensaios foram mantidos a 25 ± 2o C, UR de 70 ± 10% e fotofase de 12h. Os insetos foram alimentados ad libitum com o pulgão-verde-do-sorgo Schizaphis graminum (Rondani). Todos o compostos avaliados reduziram a viabilidade de ovos. Lambdacialotrina e clorpirifós foram altamente tóxicos para larvas de 1 o e 4o instar de C. sanguinea. Azadirachtina a 50 e 100 mg/L foi tóxico para larvas de quarto instar de C. sanguinea. Em função da baixa toxicidade apresentada, azadirachtina 10 mg/L e teflubenzuron apresentam as características mais favoráveis para uso em associação com C. sanguinea, para o controle de pragas na cultura algodoeira, dentre os compostos testados.

RESUMO

The effects of azadirachtin A, a tetranortriterpenoid from the neem tree Azadirachta indica J., on both development and interaction between Trypanosoma cruzi, the causative agent of Chagas' disease, and its vector Rhodnius prolixus were studied. Given through a blood meal, a dose-rsponse relationship of azadirachtin was established using antifeedant effect and ecdysis inhibition as effective parameters. A singlo dose of azadirachtin A was able to block the onset of mitosis in the epidermis and ecdysteroid titers in the hemnolymph, determined by radioimmuneassay, were too low for an induction of ecadysis. The survival of T. cruzi was also studied in R. prolixus treated with the drug. If the trypomastigotes were fed in presence of azadirachtin A the number of parasites drastically decreased. If the drug was applied after infection of the bug with T. cruzi, the parasite was still abolished from the gut. If the insect was pretreated with azadirachtin A before infection the same observation was obtained. A single dose of azadirachtin A was enough for a permanent resistance of the insect host against its reinfection with T. cruzi and for blocking the ecdysis for a long time. The effects of azadirachtin A on the hormonal balance of the host and growth inhibition of the parasite will be discussed on the basis of the present results.

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