Navegando por Autor "Lopes, Mayara Cristina"
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Item Bioassay method for toxicity studies of insecticide formulations to Tuta absoluta (meyrick, 1917)(Ciência e Agrotecnologia, 2011-09) Galdino, Tarcísio Visintin da Silva; Picanço, Marcelo Coutinho; Morais, Elisangela Gomes Fidelis de; Silva, Nilson Rodrigues; Silva, Geverson Aelton Rezende da; Lopes, Mayara CristinaChemical control is the main method for controlling the tomato leafminer, Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae). Reported techniques for the evaluation of insecticide toxicity to the tomato leafminer are not in agreement with field conditions and do not allow us to verify whether doses used in the field are efficient for control. Thus, the objective of this work was to develop a bioassay methodology to study the toxicity of insecticide formulations to T. absoluta that represent field conditions for fast-acting insecticides (neurotoxics and inhibitors of respiration) and slow-acting insecticides (Bacillus thuringiensis and insect growth regulators). The leaf-dip method was the most efficient method for toxicity studies of insecticides formulations to T. absoluta. We verified that bioassays with fast-acting insecticides should be performed with glass Petri dishes containing one tomato foliole from the 4th leaf from the plant apex infested with 10 larvae of 3rd instar and these bioassays can last 48 hours. Conversely, bioassays with slow-acting insecticides should be performed with two-liter transparent PET bottles containing the 4th leaf from the plant apex, with their petioles immersed in a glass bottle containing 120 mL of water, and this leaf should be infested with 10 larvae of 2nd instar and this bioassays can last seven days.Item Decision-making system and natural factors determining the intensity of Liriomyza huidobrensis attack to tomato crops(Universidade Federal de Viçosa, 2019-02-18) Lopes, Mayara Cristina; Picanço, Marcelo Coutinho; http://lattes.cnpq.br/3613170591135852The evaluation of agroecosystems and decision-making systems are essential in integrated pest management programs. Liriomyza huidobrensis (Diptera: Agromyzidae) is one of the major pests of tomato crops. Despite the importance of this pest, to date, there is no research on its spatiotemporal dynamics and on decision-making systems in tomato crops. Thus, the aims of this study were to determine: (i) the natural factors that regulate L. huidobrensis populations in tomato crops, (ii) conventional sampling plan, (iii) economic injury level (EIL) and (iv) sequential sampling plan for L. huidobrensis in tomato crops. The main natural enemies of L. huidobrensis were the parasitoids Diglyphus sp. (Hymenoptera: Eulophidae) and Opius sp. (Hymenoptera: Braconidae). The basal leaf of the middle section of the plant canopy was the best plant part for sampling. Leafminer densities were fitted to the negative binomial distribution with a common aggregation parameter (Kcommon = 0.7289). The sampling plan consists of 73 samples per field, irrespective of field size (1, 5 or 10 ha). Evaluations using this sampling plan were performed in 47 min, 1 h 9 min and 1 h 25 min with a cost of US $1.74, 2.54 and 3.12 per sampling in fields of 1, 5 and 10 ha, respectively. The EIL was 3.24 larvae per leaf. The sequential sampling plans made correct decisions in 100% of the situations, with sampling time and cost savings of 87%. Therefore, integrated management programs for L. huidobrensis should aim to preserve populations of Diglyphus sp. and Opius sp., which are important in the population regulation of this pest. The ideal sample for the evaluation of L. huidobrensis is the most basal leaf of the middle section of the tomato. The conventional sampling plan consists of 73 samples and is accurate, fast, representative and inexpensive. The EIL for L. huidobrensis in tomato crops is 3.24 larvae per leaf. The sequential L. huidobrensis sampling plan is suitable for use in integrated management programs in tomato crops for making correct decisions with time and costs savings.Item Insecticidal activity of dienamides on cabbage caterpillar and beneficial insects(Química Nova, 2018-04) Lopes, Mayara Cristina; Alvarenga, Elson Santiago; Aguiar, Alex Ramos; Santos, Izailda Barbosa dos; Silva, Gerson Adriano; Arcanjo, Lucas de Paula; Picanço, Marcelo CoutinhoThe demand for new insecticides is increasing due to the appearance of insect populations that are resistant to currently used products. New insecticides should be efficient in controlling pests and present low toxicity to non-target organisms. Ascia monuste (Lepidoptera: Pieridae) is a destructive pest of cole vegetables, and the fire ant Solenopsis saevissima (Hymenoptera: Formicidae) is an important predator of these caterpillars in brassica crops. Tetragonisca angustula (Hymenoptera: Apidae) is very important in pollinating many plants and providing honey. Therefore, this study evaluated the toxicity of synthetic amides to A. monuste and its selectivity in favor of S. saevissima and T. angustula. The amides (2E,4E)-N-propylhexa-2,4-dienamide (3) and (2E, 4E)-N-butylhexa-2,4-dienamide (4) caused high (96 and 93%, respectively) and fast (48 h) mortality of A. monuste. The amides 3 and 4 were not harmful to the predator (mortality of 5.7% for amide 3 and 7.14% for amide 4) and were slightly harmful to the pollinator (mortality of 38.57% for amide 3 and 28.12% for amide 4). The amides 3 and 4 are promising, as insecticides, due to the high and rapid mortality of A. monuste with low and moderate toxicity to S. saevissima and T. angustula, respectively.Item Sequential sampling plans and economic injury levels for Empoasca kraemeri on common bean crops at different technological levels(Pest Management Science, 2017-09-06) Moura, Marcelo Fialho de; Lopes, Mayara Cristina; Pereira, Renata Ramos; Parish, Jorgiane Benevenute; Chediak, Mateus; Arcanjo, Lucas de Paulo; Carmo, Daiane das Graças do; Picanço, Marcelo CoutinhoEmpoasca kraemeri is an important pest on common bean crops at different technological levels. However, for this pest on this crop, economic injury levels have not yet been determined and plan for sequential sampling plans has not yet been developed. Thus, the objectives of this research were to develop E. kraemeri sequential sampling plans and to determine economic injury levels in the common bean at different crop technological levels. Common bean plants tolerate low attack intensities of this pest (up to 1 adult plant-1). However, with an increase in attacks, there is a reduction in grain production by the plants. The economic injury levels were 0.48, 0.39 and 0.35 adults sample-1 (leaf beating on a tray) for crops with low (1200 kg ha-1), medium (1800 kg ha-1) and high (2400 kg ha-1) technological levels, respectively. Sequential sampling plans and the standardized plan produced similar decisions. However, in these decisions there was a time saving of more than 60% compared with the standardized plan. All three economic injury levels determined and the sequential sampling plans developed in this study are suitable for incorporation into integrated management programs for common bean pests because they can be used by farmers operating at various technological levels to make adequate and rapid decisions. © 2017 Society of Chemical IndustryItem Toxicidade de novas amidas a Ascia monuste, ao predador Solenopisis saevissima e ao polinizador Tetragonisca angustula(Universidade Federal de Viçosa, 2015-02-20) Lopes, Mayara Cristina; Picanço, Marcelo Coutinho; http://lattes.cnpq.br/3613170591135852A demanda por novos inseticidas é crescente devido à seleção de populações de insetos resistentes aos produtos existentes no mercado. Estes novos produtos devem ser eficientes no controle das pragas e ter baixa toxicidade aos organismos não-alvo como os inimigos naturais e polinizadores. Uma alternativa para a síntese de pesticidas de baixo impacto sobre organismos não-alvo é a utilização de moléculas naturais como modelo. Um exemplo destas moléculas naturais são as amidas extraídas da planta Piper nigrum. A Ascia monuste (Lepidoptera: Pieridae) é praga-chave em brássicas nas Américas e Solenopisis saevissima (Hymenoptera: Formicidae) é um importante predador desta praga. Já a abelha Tetragonisca angustula (Hymenoptera: Apidae) é um importante polinizador de plantas na região Neotropical. Assim, os objetivos deste trabalho foram determinar a toxicidade de nove amidas sintéticas (cuja atividade inseticida é desconhecida) ao inseto- praga A. monuste e sua seletividade em favor do predador S. saevissima e ao polinizador T. angustula. As amidas 3 e 4 causaram altas (>80%) e rápidas (<48h) mortalidades ao inseto-praga A. monuste. Estas duas amidas também foram pouco tóxicas ao predador (mortalidade <10%) e ao polinizador (mortalidade <40%).