Effect of different rates of quercetin and rutin on the biology of Anticarsia gemmatalis

Durante os anos de 1994 e 1995, foram realizados três ensaios de laboratório, na Embrapa-Centro Nacional de Pesquisa de Soja, em Londrina, PR, com o objetivo de avaliar o efeito de diferentes doses de rutina e de quercetina - compostos fenólicos (flavonóides) encontrados em folhas jovens dos genótipos de soja PI 227687 e 229358, resistentes a insetos -, na biologia da lagarta-da-soja, Anticarsia gemmatalis Hübner, 1818 (Lepidoptera, Noctuidae). Cada flavonóide foi incorporado, em diferentes concentrações, na dieta artificial do inseto, sendo um experimento conduzido com adição de rutina, e dois, com adição de quercetina. Tanto a quercetina quanto a rutina causaram aumento do número de dias de duração do terceiro ao sexto ínstar, do ciclo total (terceiro ínstar até fase adulta) e aumento da taxa de mortalidade de lagartas, de forma crescente, de acordo com o acréscimo das doses incorporadas à dieta artificial. Com a adição de quercetina, foi observada mortalidade de pupas e redução do peso de pupas em um dos experimentos, porém a duração da fase não foi alterada pelos tratamentos. Os resultados indicaram que os efeitos dos flavonóides sobre os insetos se manifestam a partir do terceiro ou quarto ínstar, porém são mais intensos no quinto e sexto ínstar.Along the years of 1994 and 1995, three laboratory experiments were set up at Embrapa-Centro Nacional de Pesquisa de Soja, in Londrina, PR, Brazil, aiming to evaluate the effect of different rates of rutin and quercetin, phenolic compounds (flavonols) found in young leaves of the resistant soybean genotypes PI 227687 and 229358, on the biology of the velvetbean caterpillar, Anticarsia gemmatalis Hübner, 1818 (Lepidoptera, Noctuidae). Each flavonol was incorporated in the diet, in diferent rates; one experiment was set up incorporating rutin and two incorporating quercetin. Both quercetin and rutin lead to an increase on the duration of larval instars, and from 3rd instar to adult emergence, as well as to increased mortality of larvae, being the effects related to the increasing incorporated rates. Addition of quercetin to the diet caused pupal mortality and also pupal weight reduction in one of the tests, but the duration of this stage was not affected by treatments. Results indicated that effects of the flavonols on the insects begin on the 3rd or 4th instar, but they are more evident during the 5th and 6th instars

Effect of soil management on the white grub population and damage in soybean

Foram realizados vários experimentos para avaliar o efeito de diferentes sistemas de manejo de solo na população de corós (Phyllophaga cuyabana Moser), e seus danos em soja, em áreas de plantio direto e de preparo convencional do solo (preparo primário com arado de discos e uma gradagem niveladora). Vários implementos utilizados no preparo primário de solo, como arado de aivecas, arado de discos, escarificador e grade aradora também foram avaliados. A flutuação populacional de corós e a intensidade de dano causado por eles foram similares nas áreas de plantio direto e de preparo convencional. Os implementos de preparo primário do solo afetaram a população de corós diferentemente, dependendo da época em que o preparo de solo foi executado. A mortalidade larval pode ser atribuída mais à exposição a fatores adversos logo após o preparo, do que a mudanças nas condições do solo. A redução na população de corós foi mais evidente nas parcelas preparadas com implementos mais pesados, como arado de aivecas. O manejo de solo pode ser um componente dentro do manejo de pragas do solo em soja, porém sua utilização não pode ser generalizada.To evaluate the effect of soil management systems on population of white grubs, (Phyllophaga cuyabana Moser), and on its damage in soybean, experiments were set up under no-tillage and conventional tillage (one disk plow, and a leveling disk harrow) areas. Primary tillage equipment, used in other soil management systems, such as moldboard plow, disk plow, chisel plow and heavy duty disk harrow were also tested. Fluctuation of P. cuyabana population and the extent of its damage to soybean was similar under no-tillage and conventional tillage systems. Results comparing a range of primary tillage equipment showed that it affected soil insect populations differently, depending on the time during the season in which tillage was executed. Larval mortality could mostly be attributed to their exposure to adverse factors, soon after tillage, than to changes in soil conditions. Reduction of white grub population was more evident in plots managed by heavier equipment, such as the moldboard plow. Soil tillage could be one component within the soil pest management system in soybean, however, its use can not be generalized

Post-ingestive effects of flavonoids in the midgut epithelium of Anticarsia gemmatalis (Hübner 1818) (Lepidoptera: Erebidae) larvae

An alternative control to soybean caterpillar has been the use of insect resistant plants that present phenolic flavonoids. The midgut is the main access pathway of food and chemical substances ingested. The present study examined morphological alterations in the midgut epithelium of the soybean caterpillar, after the ingestion of soybean genotypes containing the flavonoids rutin and genistin. The caterpillars and genotypes (BRS 257 - control, BR 16, Dowling, PI 229358, IAC 100 and PI 227687) were obtained from the insect rearing facility at the Embrapa Soja. The midguts were collected, fixed in Karnovsky, processed and analyzed under a light microscope. All treatments caused alterations in the midgut epithelial cells. These alterations in the columnar cells were more assiduous than the on other cell types, showing an increase of cytoplasmic protrusions and vacuoles. The goblet cells showed few changes for all genotypes tested, while the regenerative cells presented alterations mainly for the Dowling and PI 227687 treatments. The peritrophic membrane was absent for genotypes IAC100 and PI 227687. We conclude that the Dowling and PI 227687 genotypes were effective and promoted great morphological alterations in the midgut of the soybean caterpillars, being able to be very effective for the control of this plague

Nitrogen fertilization in the contents of secondary compounds in cassava cultivars

The production of chemical substances is a strategy of plants to defend against the attack of pest insects. The synthesis of secondary compounds in plants is influenced by genotype and cultural management, such as the use of nitrogen fertilizers. Thus, the objective of this work is to evaluate the effect of doses of nitrogen fertilizer over time on the production of secondary compounds in two industrial cassava cultivars. The experiment was carried out in a greenhouse (25 ± 5 °C) of Embrapa Soybean in Londrina, Paraná, with the cultivation of potted plants (4l) in a 2 × 4 × 3 factorial scheme, with five replications. Two genotypes of industrial cassava (‘Baianinha’ and ‘Caiuá’) and four different nitrogen doses (0, 30, 60, and 90 kg ha-1) were used, with sampling at 15, 30, and 45 d after fertilization. Nitrogen fertilization was performed 50 d after sprouting. In the apical leaves, the levels of rutin, caffeic, p-coumaric and ferulic acids were evaluated in a high performance liquid chromatograph (HPLC). Exploratory analyses were performed on the data variables to verify the assumptions for analysis of variance (ANOVA), such as the independence and normality of errors, homogeneity of treatment variances and non-additivity of the model (they were submitted to analysis of homogeneity and normality, respectively. After these tests, ANOVA and Tukey’s test (p ? 0.05) were performed. For the quantitative data concerning the N rates, regression study analyzes were performed. The Caiuá cultivar was found to have a higher ferulic acid content. The caffeic acid content decreased over time after the application of N in both cultivars. The rutin content in both cultivars did not increase with an increase in nitrogen dose. At a dose of 90 kg ha-1, both cultivars presented a lower p-coumaric acid content after 30 d

Níveis de infestação de Sternechus subsignatus Boheman. 1836; influência nos rendimentos e características agronômicas da soja

uring the 1983/84, 1984/85, 1985/86 and 1986/87 soybean growing seasons, field experiments were conducted to evaluate the effect of five infestation levels of Sternechus subsignatus Boheman on plant population, number of damaged plants, plant height, insertion of first pod, and yield. Infestation was made on caged soybean plants at two phenological stages of development (V3 e V6). Infestations of one adult/m of row at V3 and two adults/m of row at V6 caused signifscant reductions on yield and plant height when compared to uninfested plants. Increasing number of insects/m increased damaged plants and decreased plant population. Significant positive correlations were observed between yield, plant population and plant height. A significant negative correlation was obtained for yield and number of damaged plantaForam instalados experimentos em gaiolas, no campo, durante as safras 1983/84, 1984/85, 1985/86 e 1986/87, para avaliar o efeito de níveis de infestação de Sternechus subsignatus Boheman, 1836 na população de plantas, no número de plantas danificadas, na altura das plantas, na inserção da primeira vagem e no rendimento de grãos. As infestações foram realizadas em dois estádios fenológicos da cultura (V3 e V6). A partir de um e dois adultos por metro de fileira, respectivamente nos estádios V3 e V6, foram observadas diferenças no rendimento e na altura da planta, era relação à testemunha. A população das plantas diminuiu e o número de plantas atacadas aumentou, à medida que aumentou o número de insetos/m. Foram obtidas correlações positivas significativas do rendimento com a população e a altura da planta, e correlação negativa significativa entre o número de plantas danificadas e o rendimento

Detrimental effect of rutin on Anticarsia gemmatalis

O efeito de dieta contendo rutina (quercetina 3-O-rutinosídeo) no comportamento e na nutrição do principal desfolhador da soja, Anticarsia gemmatalis Hübner (Lep.: Noctuidae) foi avaliado do terceiro ínstar até a formação da pupa. Rutina é um dos flavonóis glicosídicos identificados em folhas da soja selvagem PI 227687. O peso das lagartas e o consumo decresceram com o aumento na concentração de rutina na dieta. Houve interação entre o tempo de alimentação e a dieta no crescimento do inseto; lagartas alimentadas com dieta pura, cujo tempo de alimentação prolongou-se, originaram pupas mais pesadas. O peso das pupas alimentadas com dieta contendo rutina permaneceu estável, apesar do maior tempo de alimentação. Rutina afetou negativamente o crescimento do inseto, não somente pela inibição alimentar, mas também em conseqüência de eventos pós-ingestivos, já que depois do ajuste do peso de pupa pelo consumo (covariável), o efeito do tratamento permaneceu significativo. Assim, o efeito negativo de rutina em A. gemmatalis resulta de efeitos pré-ingestivos, indicados pela redução no consumo, e pós-ingestivos, indicados por baixas conversões do alimento ingerido em biomassa e assimilação de alimentos.Behavioral and nutritional effect of rutin (quercetin 3-O-rutinosídeo) on Anticarsia gemmatalis Hübner (Lep.: Noctuidae), a major soybean defoliator in Brazil, was evaluated from the third instar to pupation. Rutin is one of the flavonol glycosides identified in the leaves of the wild soybean PI 227687. Larval weight and amount of ingested food decreased as rutin concentration in the diet increase. An interactive effect between feeding time and diet (treatment) was observed on insect growth; when larvae fed on pure-diet, feeding time elongation resulted in heavier pupae. Differently, the weight of larvae fed on rutin-diet remained almost stable, in spite of eating for longer. A. gemmatalis growth was negatively influenced by rutin-diet not only by feeding deterrence but also by post-ingestive effect on insect growth, since after adjustment of pupal weight by the amount of ingested food (covariate), the effect of diet remained significant. Rutin negatively influenced A. gemmatalis growth as result of pre-ingestive effect, indicated by reduction in food consumption, and post-ingestive effect, indicated by lower conversion of ingested food into body mass and food assimilation

Transcriptional profile of genes involved in the production of terpenes and glyceollins in response to biotic stresses in soybean

Terpenes produced by plants comprise a diverse range of secondary metabolites, including volatile organic compounds (VOCs). Terpene VOC production may be altered after damage or by biological stimuli such as bacterial, fungal and insects, and subsequent triggering of plant defense responses. These VOCs originate in plants from two independent pathways: the mevalonate and the methylerythritol phosphate pathways, which utilize dimethylallyl and isopentenyl diphosphates to form the terpenoidal precursors. Phakopsora pachyrhizi fungi causes Asian soybean rust, limiting soybean production and resulting in losses of up to 80% if no control strategies are applied. By using a transcriptome datasets, we investigated the regulation of genes of the mevalonate pathway under different biotic stresses. We studied the impact of P. pachyrhizi infection in vivo expression profile of genes involved in terpenoid and glyceollin biosynthesis in genotypes harboring different resistance genes (Rpp), and across the infection cycle. In addition, we used UPLC and UPGC analysis to evaluate glyceollin and VOC production, respectively, to identify metabolites associated with soybean responses to pathogen infection. The regulation of soybean genes involved in terpene production was influenced by genotypes, depending on the Rpp gene, while glyceollin was induced in all genotypes. Furthermore, a sesquiterpene was identified as a potential marker associated with rust symptoms on soybean