No abstract

The ability of the stink bug (Nezara viridula) to induce and/or increase production of chemical defenses, i.e., flavonoids, in immature seeds of five genotypes of soybean (BR-16, IAC-100, PI 227687, PI 229358, and PI 274454) was investigated under greenhouse and laboratory conditions. Samples from pods of each genotype damaged by stink bug were analyzed for flavonoid content with high performance liquid chromatography. A dual-choice test was conducted to evaluate the feeding preference of N. viridula comparing BR-16 pods treated with extracts of PI 227687 seeds (with and without stink-bug injury), with water-treated pods. Seeds of PI 227687 damaged by N. viridula presented the highest concentration (352 microg/g) of daidzin (4'-hydroxyisoflavone-7-glucoside). The same trend was observed with genistin (4',5,7-trihydroxyisoflavone-7-glucoside): PI 227687 contained 142.4 microg/g, PI 274454,31,6 microg/g, and PI 229358,38.9 microg/g. Seeds damaged by stink bugs had higher isoflavone contents (daidzin and genistin), compared to controls. However, after being damaged, PI 274454 and PI 229358 produced less genistin than the other genotypes and no differences in concentration between damaged and nondamaged plants of this genotypes were observed. The numbers of observations of the insect feeding and the numbers of stylet sheaths left in water-treated BR-16 pods were greater than in those treated with PI 227687 extracts. The insects fed for longer periods on BR-16 pods treated with extract of PI 227687 without injury compared to those that were treated with extract of PI 227687 previously injured by stink bugs. Extracts of PI 227687 pods (damaged or not) were deterrent to adults of N. viridula, and insect injury increased concentrations of daidzin and genistin in PI 227687 seeds. The deterrence seemed to be more pronounced after pods had suffered stink-bug injury.

(UEL)-CP 6001-86051-970-Londrina-PR Recebido em 15/8/97; aceito em 22/4/98 Q MODE FACTOR MULTIVARIATE CALIBRATION FOR SYSTEMS WITH OVERLAPPED BANDS. A multivariate calibration method to determine chemical compositions of systems with severely overlapped bands is proposed. Q mode factors are determined from the spectral data and subsequently rotated using the varimax and oblique transformation of Imbrie. The method is applied to two sets of simulated data to test the sensitivity of analytical results to random experimental error. The chemical concentrations of alanine and threonine mixture are determined from spectral data of the 302,5-548,5 nm region.

One of the most important problems in analytical chemistry is determining the number and concentration of chemical species in mixtures by means of spectroscopy and chromatography. A series of statistical techniques has been utilized to develop multivariate methods which extract information from spectra and chromatograms in order to identify the species present and to determine the concentrations of some or all of them. The applicability of each method depends on the data set submitted for analysis. From an analytical point of view, 1 the multivariate methods can be classified into three categories: I) spectral information is available for each individual species in the samples, II) spectral information about these species is incomplete or only partially known and, III) no information about the chemical compositions of the samples exists.This article proposes a multivariate calibration method to determine the chemical compositions of complex mixtures based on Imbrie's Q-mode factor analysis followed by varimax 2,3 and Imbrie's oblique rotations. 2 This method can be classified as one of category I as well as of category III, depending on the information available about the chemical system to be analyzed. For category I applications, this method does not require an extensive calibration set, as do the PCR, PLS, K-matrix and MLR methods. Only spectra of the pure absorbing species or standard spectra are necessary. In category III applications, the method is capable of identifying the number of absorbing species and their relative concentrations from only the set of spectra for the mixture being analyzed.An important requirement for applying all of the methods cited above is that the mixture spectra must be a linear combination of the individual spectra of the species involved, weighted by their respective concentrations. In other words, Beer's or an analogous law must be obeyed.Although quantitative analysis for amino acids is commonly used in clinical investigations, the food industry and research, there is no routine spectrophotometric method for their simultaneous determination in mixtures. In previous papers, 4 we proposed a method for the simultaneous determination of total amino acids and proteins using p-benzoquinone (PBQ). The reaction of PBQ and the amino acids was carried out at 100˚C for 20 min, since this reaction is very slow at ambient temperature. The products of the reaction have bands between 390 and 440 nm that follow Beer's law. Since this band is the resultant of a mixture of products, their individual simultaneous determinations are impossible by traditional methods, thus justifying the application of a multivariate analysis. In this report, individual amino acid determinations are discussed based on the application of Q-mode factor analysis to alanine-glutamine, threonine-glutamine and alanine-threonine binary mixtures and alanine-glutamine-threonine ternary mixtures. MethodologyThe objective of this analysis is to factor an nxp A matrix, formed by n objects (samples or mixtures) and p variabl...

-The objective of this work was to evaluate arrestant and stimulant feeding effects on Diabrotica speciosa (Ger.), using cucurbitacin-content starch-based formulations prepared with varying starch sources, and adding potassium lignate. In a glass slide assay, the wash off resistance of formulations was compared. Potassium lignate did not improve wash off resistance. Lagenaria vulgaris L. powder, in which cucurbitacin B concentration was determined as 0.28%, was added to the most adhesive formulation. The resultant material was used in a two-choice assay in which leaves of common bean, Phaseolus vulgaris L., treated with concentrations of 2.5%, 5%, 10%, 15% and 20% were offered to insects together with untreated control leaves. Greater number of insects and leaves consumed were found on leaves treated with cucurbitacin-content formulation (2.5%, 5% -greatest response -, 10% and 15% concentrations) than on untreated control leaves. The concentration, in which responses were higher, was sprayed in a bean field at 1,000, 1,900 and 3,000 g ha -1 . Greater number of beetles was found in plots treated with the highest dosage, 3 and 6 days after spraying. Ten days after spraying, no significant differences were found among dosages, probably due to washoff of the bait.Index terms: Insecta, Coleoptera, bait, semiochemical, rootworm. Respostas alimentares e arrestantes de Diabrotica speciosa a formulações contendo cucurbitacinaResumo -O objetivo deste trabalho foi avaliar os efeitos alimentares estimulantes e arrestantes para Diabrotica speciosa (Ger.), a partir de formulações amiláceas com cucurbitacina, variando-se as fontes de amido e adicionando-se lignato de potássio. Em ensaio com lâmina de vidro, comparou-se a resistência à lavagem das formulações. O lignato de potássio não aumentou a resistência à lavagem. Pó de Lagenaria vulgaris L., cuja concentração de cucurbitacina B foi determinada como sendo de 0,28%, foi adicionado à formulação mais adesiva. O material resultante foi utilizado em ensaios com dupla chance de escolha, nos quais folhas de feijão, Phaseolus vulgaris L., pulverizadas com concentrações de 2,5%, 5%, 10%, 15% e 20% foram oferecidas aos insetos juntamente com folhas não tratadas. Foram observados maior número de insetos e maior quantidade de folhas consumidas nas folhas tratadas com formulações com cucurbitacina (2,5%, 5% -maior resposta -, 10% e 15%) do que nas folhas não tratadas. A formulação cuja concentração teve maior resposta foi pulverizada em lavoura de feijão, nas dosagens de 1.000, 1.900 e 3.000 g ha -1 . O maior número de adultos de D. speciosa foi encontrado nas parcelas tratadas com a maior dosagem, aos 3 e 6 dias após a pulverização. Dez dias após a pulverização, não foram encontradas diferenças entre as dosagens, provavelmente por causa da lavagem da isca pelas chuvas.Termos para indexação: Insecta, Coleoptera, isca, semioquímico, larva alfinete.