Plant Extracts as an Alternative to Control Leucoptera coffeella (Guérin-Mèneville) (Lepidoptera: Lyonetiidae)

We evaluated the effects of crude extracts from the plantain Plantago lanceolata and the bitter gourd Momordica charantia on the oviposition preference and development of the coffee leaf miner Leucoptera coffeella Guérin-Mèneville & Perrottet under laboratory and/or greenhouse conditions. The ovicidal effects of these extracts were also studied in a greenhouse. Plantago lanceolata and M. charantia extracts also underwent fractionation directed by oviposition tests with the coffee leaf miner. The extracts of both plants reduced L. coffeella oviposition and egg hatching, apparently as a result of action of plant metabolites on the embryo. Adults originating from eggs treated with the extracts exhibited similar survival rates, but a higher female/male ratio. Fecundity was reduced for females obtained from eggs treated with the M. charantia extract. Partial chemical analysis indicated that both extracts produced polar fractions that reduced the oviposition of L. coffeella on coffee leaves under laboratory conditions. The extracts of P. lanceolata and M. charantia have potential for use in the development of new products to control the coffee leaf miner.

Inibição da tripsina de bicho-mineiro do cafeeiro por um fator não-protéico presente em extratos de folhas de mamona / Coffee leaf miner trypsin inhibition with castor bean leaf extracts mediated by a non-protein agent

Inibidores de tripsina representam uma estratégia de controle de insetos e, por isso, a identificação e caracterização desses inibidores são etapas muito importantes para que novas formas de controle de pragas sejam desenvolvidas. Os inibidores de tripsina atuam na digestão primária de proteínas e comprometem o processo digestivo por completo, reduzindo a disponibilidade de aminoácidos ao inseto. A incorporação de inibidores de tripsina na dieta de insetos-praga é uma forma de controle cuja eficácia foi verificada por diferentes autores. Este projeto foi conduzido a fim de se observar a eficiência de extratos de folhas de mamona na inibição "in vitro" de proteinases do tipo tripsina do bicho-mineiro do cafeeiro. Após testes realizados com os extratos de folhas de mamona não-fervidos e fervidos com e sem a adição de β-mercaptoetanol 0,2 por cento (v/v) e mediante precipitações com acetona, verificou-se que o inibidor é uma molécula termoresistente e não-protéica. Desta forma, iniciou-se um processo de purificação da molécula inibidora por meio de cromatografia de adsorção com posterior análise em espectrômetro de massas. Os resultados dos testes de inibição indicaram a presença de um inibidor de tripsina eficaz contra o bicho-mineiro do cafeeiro nos extratos de folhas de mamona capaz de inibir 2,48 + 0,15 UTI, o que representa aproximadamente 40 por cento de inibição. Em testes realizados com tripsina bovina observou-se que o extrato de folhas de mamona não apresenta poder de inibição sobre essa enzima.

Trypsin inhibitors stand for a strategy of insect control and, therefore, the identification and characterization of these inhibitors are very important steps for new forms of pest control to be developed. Trypsin inhibitors act in the primary digestion of proteins and endanger the digestive process wholly, reducing the availability of aminoacids to the insect. The incorporation of trypsin inhibitors in the diet of pest insects is a control form whose efficacy was verified by different authors. In order to observe the efficiency of castor bean leaf extracts in inhibiting trypsin-like enzymes of the coffee leaf miner, an experiment was carried out with the purpose of observing an "in vitro" inhibition phenomenon. The results of the trypsin inhibition tests with normal and boiled with and without β-mercaptoethanol 0.2 percent (v/v) castor bean leaf extracts and the results of the acetone precipitation process indicated that the inhibitor is a heat-resistant molecule and it is not a protein. This way, the purification process was made by adsorption chromatography with later analysis in mass spectrometer. The reached results indicated that the presence of a trypsin inhibitor of the coffee leaf miner in the castor bean leaf extracts is capable of inhibiting 2.48 + 0.15 UTI, which stands for about 40 percent of inhibition. Tests performed with bovine trypsin indicated that the castor bean leaf extract have no inhibiting power on this enzyme.

Efeitos de variáveis ambientais, irrigação e vespas predadoras sobre Leucoptera coffeella (Guérin-Méneville) (Lepidoptera: Lyonetiidae) no cafeeiro / Effects of irrigation, environmental variability and predatory wasp on Leucoptera coffeella (Guérin-Méneville) (Lepidoptera: Lyonetiidae), in coffee plants

A densidade populacional do bicho-mineiro do cafeeiro Leucoptera coffeella (Guérin-Méneville) pode ser afetada por variáveis ambientais em agroecossistemas irrigados e vespas predadoras tais como Vespidae. Assim, objetivou-se neste trabalho avaliar os efeitos das variáveis ambientais, de lâminas de irrigação via gotejamento, e da predação por vespas na densidade populacional de L. coffeella. O experimento foi conduzido entre os anos de 2004 e 2005, em lavoura de Coffea arabica L. no município de Jaboticatubas, MG, Brasil. As diferentes lâminas de irrigação, aplicadas via gotejamento, foram estabelecidas tomando por referência a lâmina diária requerida pelo programa IRRIPLUS, que foi igual a 100 por cento e, duas outras abaixo, 51 por cento e 72 por cento, e acima, 124 por cento e 145 por cento, com a testemunha sem irrigação. Para a avaliação da densidade populacional do bicho mineiro e da predação determinou-se o número de minas ativas e predadas no quarto par de folhas do ramo mediano em dez plantas. Para estudar as interações entre as variáveis ambientais, lâminas de irrigação com as densidades de minas de L. coffeella e vespas predadoras foram realizadas análise multivariada, análises de regressão linear simples e trilha. Conclui-se que a maior precipitação pluvial, radiação solar e lâminas de irrigação reduzem a densidade populacional do bicho-mineiro. Além disso, o aumento na densidade das vespas predadoras foi dependente dos níveis populacionais de L. coffeella.

The population density of the coffee leaf miner Leucoptera coffeella (Guérin-Méneville) can be affected by environmental variables in irrigated agroecosystems and the occurrence of predatory wasps such as Vespidae. In here, we aimed to evaluate the effects of environmental variables, drip irrigation depths and predation by wasps on the population density of L. coffeella. The experiment was carried out during 2004 and 2005 in a Coffea arabica plantation cultivated in the county of Jaboticatubas, Minas Gerais State, Brazil. The different irrigation depths set through drip were established considering the daily depth required by the IRRIPLUS program, which was equal to 100 percent, and two other lower (51 percent and 72 percent) and higher (124 percent and 145 percent) values, having the control without irrigation. In order to evaluate the coffee leaf miner population density and predation, the number of active and preyed mines was determined on the fourth pair of leaves in a group of ten plants. For the study of interactions among the environmental variables, irrigation depths with the mine density of L. coffeella and predatory wasps, the following methods were used: multivariated analysis, simple linear regression and trail. We concluded that higher pluvial precipitation, solar radiation and irrigation depths would reduce population density of the coffee leaf miner. Furthermore, the increase in density of the predatory wasps was dependent on the population level of L. coffeella.

Enzimas digestivas do bicho-mineiro do cafeeiro Leucoptera coffeella (Guérin-Mèneville & Perrottet, 1842) (Lepidoptera: Lyonetiidae) / Coffee leaf miner's digestive enzymes Leucoptera coffeella (Guérin-Mèneville & Perrottet, 1842) (Lepidoptera: Lyonetiidae)

Os insetos possuem diferentes enzimas digestivas que catalisam as reações de hidrólise do alimento consumido e essas se diferenciam entre os insetos de acordo com suas dietas e estado fisiológico. Foram avaliadas as atividades de algumas enzimas digestivas da praga do cafeeiro - Leucoptera coffeella (Guérin-Mèneville & Perrottet, 1842) (Lepidoptera: Lyonetiidae) - popularmente conhecida como bicho-mineiro do cafeeiro, para o entendimento de seu processo digestivo. Lagartas do bicho-mineiro do cafeeiro foram coletadas em campo e em casa-de-vegetação. O extrato enzimático utilizado foi obtido pela maceração das lagartas em água (4ºC). Determinaram-se os pH's ótimos e as atividades das enzimas α e β-glicosidases, α-amilase, aminopeptidase, fosfatase alcalina, sacarase, trealase e tripsina, incubando o extrato enzimático do bicho-mineiro do cafeeiro com substratos específicos. A análise dos resultados sugere que o processo digestivo e o ambiente intestinal do bicho-mineiro do cafeeiro sejam similares com o dos demais lepidópteros encontrados na literatura.

Insects are fitted with different digestive enzymes that catalyses the food hydrolysis. Those enzymes differ from one insect to another according to their diets and physiological status. In this work, one intended to verify the activities of some digestive enzymes of the coffee leaf miner - Leucoptera coffeella (Guérin-Mèneville & Perrottet, 1842) (Lepidoptera: Lyonetiidae) - as a pre-requisite to understand its digest process, since this insect is a major plague in coffee production systems. Coffee leaf miner caterpillars were collected in fields and in greenhouse. The enzyme extract utilized in determining the enzyme activities was obtained through grinding the caterpillars in cold water. The optimum pH and the activities of the enzymes α and β-glucosidases, α-amylase, aminopeptidase, alkaline phosphatase, saccharase, trehalase and trypsin were measured by incubating the enzyme extract with specific substrates. The analysis of the optimum pH's indicated that the digestive process and intestinal environment of this insect are similar to another lepidopterans consulted in the literature.

Seletividade de inseticidas a vespas predadoras de Leucoptera coffeella (Guér.-Mènev. ) (Lepidoptera: Lyonetiidae) / Selectivity of insecticides to predatory wasps of Leucoptera coffeella (Guér.-Mènev. ) (Lepidoptera: Lyonetiidae)

Estudos de toxicidade relativa dos inseticidas organo-fosforados dissulfotom, etiom, paratiom-metílico e clorpirifós às vespas predadoras Brachygastra lecheguana Latreille, Polybia paulista Ihering e Protopolybia exigua Saussure e sua presa, o bicho-mineiro do cafeeiro Leucoptera coffeella (Guérin-Mèneville), foram realizados em condições de laboratório. As concentrações que mataram 99 por cento dos indivíduos de L. coffeella foram: 0,08; 83,95; 0,43; 0,07 mg i.a/cm² para dissulfotom, etiom, paratiom-metílico e clorpirifós, respectivamente. Essas concentrações foram usadas para avaliar a seletividade destes compostos em ensaio com papel de filtro impregnado com resíduo seco dos inseticidas. Paratiom-metílico e clorpirifós foram altamente tóxicos a essas espécies de vespas predadoras, enquanto disulfotom e etiom mostraram-se seletivos em favor delas.

Studies of relative toxicity of the organophosphate insecticides disulfoton, ethion, methyl-parathion e chlorpyrifos to the predatory wasps Brachygastra lecheguana Latreille, Polybia paulista Ihering e Protopolybia exigua Saussure and their prey, the coffee leaf-miner Leucoptera coffeella (Guérin-Mèneville), were carried out in laboratory. The concentrations which killed 99 percent of individuals of L. coffeella were: 0.08; 83.95; 0.43; 0.07 mg i.a/cm² of disulfoton, ethion, methyl-parathion and chlorpyrifos, respectively. These concentrations were used to assess the selectivity of insecticides in impregnated paper filter assays. Methyl-parathion and chlorpyrifos were highly toxic to these wasp species, while disulfoton and ethion were selective in their favour.