Tannins have long been thought of as antifeedants owing to their presumed digestibility-reducing properties. In this thesis information, at the molecular level, is presented in a reassessment of this assumption and the apparency theory of plant chemical defence which is dependent upon it. An introductory review provides chemical and opperational descriptions of tannins and a general outline of their ecological impact. Detailed attention is given to (i) tannin-protein complex formation and (ii), an assesment of in vivo evidence concerning the effects of tannins on herbivores. It is concluded that the evidence does not support the hypothesis that tannins uniformly reduce digestion, even though they do generally act as antifeedants. A series of crude tannin-containing plant extracts were prepared and characterised by chemical analyses and by their ability to precipitate protein and inhibit pepsin/cellulase digestion of celulose. Results indicated between-tannin variation but not that the chemical properties of crude tannins might be used to predict their interaction with the other components of a herbivore's diet. Experiments under conditions where soluble tannin-protein complexes formed and which modelled some digestive systems, showed that tannins could under varying circumstances, inhibit or promote the digestion of protein. Soluble tannin-protein complexes were also formed in the presence of bile salts when they would otherwise have occured as precipitates. In these conditions clear relief from digestibility reduction was found. In the light of these results a new model describing the effects of tannins on digestion, consistent with results obtained in vivo, is proposed.

One great issue of reforestation is the infestation of pest insects. The pine weevil (Hylobius abietis L.) is one of the economically most important pest insects in Europe and Asia. When insects feed on the trees the plants emit compounds that repel the insects. Methyl salicylate (MeSA) is one substance known to be emitted by conifer seedlings after herbivore feeding. Similar compounds are emitted by fungus isolated from pine weevil frass. Female pine weevils add frass to the egg laying site to protect the eggs from other pine weevils. The goal of the project was to cultivate the fungi Ophiostoma pluriannulatum and analyze the volatile substances. The fungus was cultivated using natural pine weevil frass (NF) as main substrate. Later new batches were prepared using lignin and potato dextrose broth (PDB), as feeding media to compare the results. Two sampling methods were used, SPME and adsorption with Porapak™ polymer column packing material. These samples were analyzed using GC-MS. Methyl salicylate was found in NF fungi cultures, peaking after ten days. Another, unexpected, product of the fungi was a sesquiterpene hydrocarbon. The lignin and the PDB samples did not produce MeSA. However, the sesquiterpene could be found in the lignin samples.

Visando explorar o potencial bioativo de plantas da família Solanaceae como fonte alternativa para o manejo de Spodoptera frugiperda (Lepidoptera: Noctuidae), a lagarta-do-cartucho-do-milho, realizou-se, primeiramente, uma triagem de extratos etanólicos preparados de diferentes partes de 25 espécies vegetais. Após sete dias de exposição das lagartas em dietas tratadas, constatou-se que os extratos etanólicos de folhas de Acnistus arborscens e de Datura stramonium, na concentração de 4.000 mg kg -1, foram os mais promissores causando inibição do ganho de peso de 97,85 e 95,72%, respectivamente. A seguir, foi realizado um fracionamento biomonitorado, a partir do qual, a fração diclorometânica foi selecionada como a mais ativa para essas duas espécies, causando efeito subletal (inibição do ganho do peso) e letal (mortalidade), porém este inferior ao causado pela formulação comercial Azamax® 1,2 EC (controle positivo). Em sequencia, foi possível estimar as concentrações letais para as frações diclorometânicas durante o período de 168 horas. Em relação ao efeito sobre o desenvolvimento do inseto, os extratos etanólicos foram testados na concentração de 4.000 mg kg -1 e as frações diclorometânicas na concentração letal mediana (4.088 e 3.694 mg kg -1 para D. stramonium e A. arborescens, respectivamente). Na fase larval, os extratos etanólicos de D. stramonium e A. arborescens ocasionaram 77,50 e 62,50% de mortalidade, respectivamente, e, além disso, ambos os tratamentos causaram alongamento dessa fase, e mortalidade, deformidade e redução do peso pupal. A fração diclorometânica de A. arborescens proporcionou 100% de mortalidade das lagartas expostas, enquanto a mortalidade em D. stramonium foi 83,19% e, as lagartas necessitaram de 41,75 dias para atingir a fase pupa, que apresentou baixo peso (158,60 mg) e altas deformidades (40%) em comparação ao controle (255,90 mg e 8,26%, respectivamente). Além disso, as frações diclorometânicas ocasionaram atividade fagodeterrente nas CL25, CL50 e CL90. Novamente, utilizando-se a fração diclorometânica, foi realizado novo fracionamento, e após sete dias de exposição das lagartas neonatas, todas as subfrações ocasionaram efeitos subletais. Com isso, tornaram-se necessárias novas investigações químicas a fim de se compreender o (s) composto (os) responsável (is) pela bioatividade, porém a complexidade de algumas subfrações não permitiu uma caracterização química. Ainda assim, foi constatada nas subfrações acetato de etila e metanólica de D. stramonium a presença de compostos pertencentes à classe dos vitanolidos. Dessa forma, os derivados de Solanaceae apresentam potencial bioativo passíveis de serem estudados mais profundamente visando ao emprego dos mesmos no manejo de S. frugiperda. / Aiming to explore the bioactive potential of Solanaceae plants as alternative resources for the management of Spodoptera frugiperda (Lepitoptera: Noctuidae), the fall armyworm, it was performed, firstly, a screening of ethanolic extracts prepared from different parts of 25 plant species. After seven days of exposure of caterpillars to treated diets, it was verified that ethanolic extracts of Acnistus arborscens and Datura stramonium leaves in the concentration of 4,000 mg kg-1 were the most promising, causing an inhibition of 97.85% and 95.72%, respectively, in weight gain. After this, a bioguided fractionation was performed, from which the dichloromethane fraction was selected as the most active in both species, causing sublethal (inhibition of weight gain) and lethal (mortality) effects, although both were less effective than the Azamax® 1,2 EC commercial formulation (positive control). Following the previous step, it was possible to estimate the lethal concentrations for dichloromethane fraction during the period of 168 hours. In relation to the effect on the insect development, the ethanolic extracts were tested in the concentration of 4,000 mg kg-1 and the dichloromethane fractions in their median lethal concentrations (4,088 and 3,694 mg kg-1 for D. stramonium and A. arborescens, respectively). In the larval phase, ethanolic extracts of D. stramonium and A. arborescens lead to 77.50% and 62.50% of mortality, respectively, and both treatments lead to the elongation of this phase, mortality, deformity and pupal weight reduction. The dichloromethane fraction of A. arborescens lead to 100% of mortality of the exposed caterpillars, while mortality of D. stramonium was 83.19%, and the caterpillars needed 41.75 days to reach the pupal stage, which presented low weight (158.60 mg) and were highly deformed (40%) in comparison with the negative control (255.90 mg and 8.26%, respectively). Furthermore, the dichloromethane lead to antifeedant activity in CL25, CL50 and CL90. Once again, using the dichloromethane fraction, another fractionation was performed, and after seven days of exposure of neonates caterpillars, all subfractions lead to sublethal effects. Therefore, new chemical evaluations are necessary to understand the compounds responsible for bioactivity, however, the complexity of some subfractions did not permit chemical characterization. Nevertheless, it was verified in the ethyl acetate and methanolic subfractions of D. stramonium the presence of withanolides compounds. Therefore, derivatives of Solanaceae present bioactive potential that may be liable for further evaluation aiming their employment in the management of S. frugiperda.

Visando explorar o potencial bioativo de plantas da família Solanaceae como fonte alternativa para o manejo de Spodoptera frugiperda (Lepidoptera: Noctuidae), a lagarta-do-cartucho-do-milho, realizou-se, primeiramente, uma triagem de extratos etanólicos preparados de diferentes partes de 25 espécies vegetais. Após sete dias de exposição das lagartas em dietas tratadas, constatou-se que os extratos etanólicos de folhas de Acnistus arborscens e de Datura stramonium, na concentração de 4.000 mg kg -1, foram os mais promissores causando inibição do ganho de peso de 97,85 e 95,72%, respectivamente. A seguir, foi realizado um fracionamento biomonitorado, a partir do qual, a fração diclorometânica foi selecionada como a mais ativa para essas duas espécies, causando efeito subletal (inibição do ganho do peso) e letal (mortalidade), porém este inferior ao causado pela formulação comercial Azamax® 1,2 EC (controle positivo). Em sequencia, foi possível estimar as concentrações letais para as frações diclorometânicas durante o período de 168 horas. Em relação ao efeito sobre o desenvolvimento do inseto, os extratos etanólicos foram testados na concentração de 4.000 mg kg -1 e as frações diclorometânicas na concentração letal mediana (4.088 e 3.694 mg kg -1 para D. stramonium e A. arborescens, respectivamente). Na fase larval, os extratos etanólicos de D. stramonium e A. arborescens ocasionaram 77,50 e 62,50% de mortalidade, respectivamente, e, além disso, ambos os tratamentos causaram alongamento dessa fase, e mortalidade, deformidade e redução do peso pupal. A fração diclorometânica de A. arborescens proporcionou 100% de mortalidade das lagartas expostas, enquanto a mortalidade em D. stramonium foi 83,19% e, as lagartas necessitaram de 41,75 dias para atingir a fase pupa, que apresentou baixo peso (158,60 mg) e altas deformidades (40%) em comparação ao controle (255,90 mg e 8,26%, respectivamente). Além disso, as frações diclorometânicas ocasionaram atividade fagodeterrente nas CL25, CL50 e CL90. Novamente, utilizando-se a fração diclorometânica, foi realizado novo fracionamento, e após sete dias de exposição das lagartas neonatas, todas as subfrações ocasionaram efeitos subletais. Com isso, tornaram-se necessárias novas investigações químicas a fim de se compreender o (s) composto (os) responsável (is) pela bioatividade, porém a complexidade de algumas subfrações não permitiu uma caracterização química. Ainda assim, foi constatada nas subfrações acetato de etila e metanólica de D. stramonium a presença de compostos pertencentes à classe dos vitanolidos. Dessa forma, os derivados de Solanaceae apresentam potencial bioativo passíveis de serem estudados mais profundamente visando ao emprego dos mesmos no manejo de S. frugiperda. / Aiming to explore the bioactive potential of Solanaceae plants as alternative resources for the management of Spodoptera frugiperda (Lepitoptera: Noctuidae), the fall armyworm, it was performed, firstly, a screening of ethanolic extracts prepared from different parts of 25 plant species. After seven days of exposure of caterpillars to treated diets, it was verified that ethanolic extracts of Acnistus arborscens and Datura stramonium leaves in the concentration of 4,000 mg kg-1 were the most promising, causing an inhibition of 97.85% and 95.72%, respectively, in weight gain. After this, a bioguided fractionation was performed, from which the dichloromethane fraction was selected as the most active in both species, causing sublethal (inhibition of weight gain) and lethal (mortality) effects, although both were less effective than the Azamax® 1,2 EC commercial formulation (positive control). Following the previous step, it was possible to estimate the lethal concentrations for dichloromethane fraction during the period of 168 hours. In relation to the effect on the insect development, the ethanolic extracts were tested in the concentration of 4,000 mg kg-1 and the dichloromethane fractions in their median lethal concentrations (4,088 and 3,694 mg kg-1 for D. stramonium and A. arborescens, respectively). In the larval phase, ethanolic extracts of D. stramonium and A. arborescens lead to 77.50% and 62.50% of mortality, respectively, and both treatments lead to the elongation of this phase, mortality, deformity and pupal weight reduction. The dichloromethane fraction of A. arborescens lead to 100% of mortality of the exposed caterpillars, while mortality of D. stramonium was 83.19%, and the caterpillars needed 41.75 days to reach the pupal stage, which presented low weight (158.60 mg) and were highly deformed (40%) in comparison with the negative control (255.90 mg and 8.26%, respectively). Furthermore, the dichloromethane lead to antifeedant activity in CL25, CL50 and CL90. Once again, using the dichloromethane fraction, another fractionation was performed, and after seven days of exposure of neonates caterpillars, all subfractions lead to sublethal effects. Therefore, new chemical evaluations are necessary to understand the compounds responsible for bioactivity, however, the complexity of some subfractions did not permit chemical characterization. Nevertheless, it was verified in the ethyl acetate and methanolic subfractions of D. stramonium the presence of withanolides compounds. Therefore, derivatives of Solanaceae present bioactive potential that may be liable for further evaluation aiming their employment in the management of S. frugiperda.

No description available.

The large pine weevil, Hylobius abietis L., is a major insect pest on conifer seedlings in northern Europe. Due to its feeding newly planted trees get girdled, resulting in high seedling mortality (up to 80%). As a consequence great financial losses to the forest industry occur. Today the seedlings are protected with the pyrethroid insecticide cypermethrin. This insecticide is toxic to aquatic organisms and is, from 2010, prohibited for use in Sweden by the Swedish Chemicals Inspectorate. An alternative to insecticides is to protect the seedlings with antifeedants, compounds that, either through taste or smell or both, deter the weevils from feeding. This thesis describes the search for and the synthesis of such antifeedant compounds. Bark extracts of several woody species, known to be non-palatable to the weevil, were prepared and found to display antifeedant activity against H. abietis. The major chemical constituents of the extracts were tested for antifeedant activity. Antifeedants such as eugenol, 2-phenylethanol and benzylalcohol, but also feeding stimulants such as β-sitosterol and linoleic acid, were identified. An extract of linden bark, Tilia cordata, was shown to contain nonanoic acid, a highly active antifeedant. Other aliphatic carboxylic acids were also found to display high antifeedant activities against the weevil, both in laboratory and in field tests. The enantiomers of dihydropinidine, a piperidine alkaloid present in several conifer species, were prepared by dimethylzinc mediated allylation of 2- methyltetrahydropyridine-N-oxide. When tested in micro feeding assays, no difference in antifeedant activity was found for the enantiomers. In a field test high antifeedant activity, comparable with that of the presently used insecticide cypermethrin, was found for (±)-dihydropindine. Other naturally occurring piperidine alkaloids were synthesised and also found to display high antifeedant activities in laboratory tests. Structure-activity relationships were evaluated for methoxy substituted benzaldehydes, benzoic acids and cinnamic aldehydes, -acids, -esters and -alcohols. While the carboxylic acids were inactive or even feeding stimulants, the aldehydes were the most active antifeedants / QC 20110124

<p>The large pine weevil, Hylobius abietis L., is a major insect pest on conifer seedlings in northern Europe. Due to its feeding newly planted trees get girdled, resulting in high seedling mortality (up to 80%). As a consequence great financial losses to the forest industry occur. Today the seedlings are protected with the pyrethroid insecticide cypermethrin. This insecticide is toxic to aquatic organisms and is, from 2010, prohibited for use in Sweden by the Swedish Chemicals Inspectorate. An alternative to insecticides is to protect the seedlings with antifeedants, compounds that, either through taste or smell or both, deter the weevils from feeding. This thesis describes the search for and the synthesis of such antifeedant compounds.</p><p>Bark extracts of several woody species, known to be non-palatable to the weevil, were prepared and found to display antifeedant activity against H. abietis. The major chemical constituents of the extracts were tested for antifeedant activity. Antifeedants such as eugenol, 2-phenylethanol and benzylalcohol, but also feeding stimulants such as β-sitosterol and linoleic acid, were identified. An extract of linden bark, Tilia cordata, was shown to contain nonanoic acid, a highly active antifeedant. Other aliphatic carboxylic acids were also found to display high antifeedant activities against the weevil, both in laboratory and in field tests.</p><p>The enantiomers of dihydropinidine, a piperidine alkaloid present in several conifer species, were prepared by dimethylzinc mediated allylation of 2- methyltetrahydropyridine-N-oxide. When tested in micro feeding assays, no difference in antifeedant activity was found for the enantiomers. In a field test high antifeedant activity, comparable with that of the presently used insecticide cypermethrin, was found for (±)-dihydropindine. Other naturally occurring piperidine alkaloids were synthesised and also found to display high antifeedant activities in laboratory tests.</p><p>Structure-activity relationships were evaluated for methoxy substituted benzaldehydes, benzoic acids and cinnamic aldehydes, -acids, -esters and -alcohols. While the carboxylic acids were inactive or even feeding stimulants, the aldehydes were the most active antifeedants</p>

No description available.