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The effects of nitrogen and sulfur fertilization on the oviposition, feeding preferences, and larval performance of Ceutorhynchus obstrictus (Marsham) (Coleoptera: Curculionidae) on Brassica napus L. were examined in a series of laboratory experiments. The associations between C. obstrictus adults, larvae and parasitoids, and environmental factors including plant vigor indicators and soil and plant nutrients were evaluated within two commercial fields of B. napus in southern Alberta. Nitrogen fertilization, and sulfur fertilization at low levels of nitrogen fertilization had positive effects on oviposition preference. Nitrogen had a positive effect on larval development times and no effect on larval weights. Within one field, gravid C. obstrictus females were dissociated with high levels of plant nutrients including nitrogen. The synthesis of the lab and field experiments seems to support the plant stress and the preference-performance hypotheses. Differences in olfactory and visual cues are identified as a possible mechanism for the observed differences. / Ecology

Made available in DSpace on 2016-12-06T17:42:05Z (GMT). No. of bitstreams: 1 PGPV14DA005.pdf: 6438650 bytes, checksum: 182a141bdad6caf9c577ba111b2903b2 (MD5) Previous issue date: 2014-09-12 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The Rocha1 pear is a relatively new portuguese cultivar for Brazil and has a wide acceptance in the consumer Market. Currently there are some difficulties in management so you can optmize your farming, among which standes out the excessive vigor of the plants and the low effective productivity and fruit set. the aim of this study was to evaluate the afronomic effectiveness Stimulate®, Promalin® and Retain® concentrations and the of trunk cutting practice in european Rocha pear grafted rootstock on Pyrus calleryana at conditions of São Joaquim, state Santa Catarina, Brazil and evaluate agonomic efficacy of single and combined cooncentrations of Stimulate® and Sett® and Hold® fertilizers on fruit set, yield and quality of Rcoha pear grafted on rootstock BA 29 quince at conditions of Vacaria, State Rio Grande do Sul, Brazil. The experimental design was a randomized block design with three blocks. In São Joaquim, treatments the trunk vutting were performed at the end of the dormant period (September 2011) in two Heights of the stem of each plant (20 and 40 centimeter from the ground) and two-dimensional cutting with the diameter (½ and ⅓ of the stem); and treatments with growth regulators were performed at diferente growth stages (early, full and end flowering) anda t various concentrations, applying GA₄₊₇ + BA 6 (Promalin®) at a concentration of 1 mL L¯¹ combined with Aminoethoxyvinylglycine (ReTain®) at concentrations of 0.2, 0.4 and 0.8 g L¯¹. The Stimulate® (IBA 0.005 %, 0.009 % kinetin and gibberellic acid 0.005 %) was applied at rates of 1, 2 and 3 mL L¯¹. In Vacaria, the Stimulate ® (2 mL L¯¹) and Sett® fertilizer (3 L¯¹) were applied at full blossom time and Hold® fertilizer (1 mL L¯¹ ) was applied 15 days after full bloom. In witness has applied water only (control). In both study sites were obtained for the positive controlo f vegetative growth and increased fruit set of Rocha pear. Can be inferred that, at conditions of São Joaquim, Brazil, the trunk cutting practice into 1Rocha1 pear plants on Pyrus calleryana reduces the growth of shoots and provides incresead fruit set and yield; using 1 mL L¯¹ Promalin® combined with 0.6 and 0.8 g L¯¹ of ReTain® provide more effectivefruitproduction and productivity of Rocha pear grafted on Pyrus calleryana; and using Stimulate® concentrations of 2 and 3 mL L¯¹, regardless of the number of applications (in two or three seasons) provides incresead fruit set and yield per plant Rocha pear on Pyrus calleryana. At conditions Vacarina, Brasil, the isolated application or combined use of Stimulate®, Sett® and Hold® not influence fruit set, yield and physico-chemical characteristcs of fruit pear Rocha on quince rootstock BA 29 / A pereira Rocha é uma cultivar portuguesa relativamente nova para o Brasil e possui grande aceitação pelo mercado consumidor. Atualmente, existem algumas dificuldades de manejo para que se possa otimizar seu cultivo, dentre elas destacam-se o excessivo vigor das plantas, a baixa frutificação efetiva e produtividade. O objetivo deste trabalho foi avaliar a eficácia agronômica de doses de Stimulate®, Promalin® e ReTain® e a prática de manejo de corte do tronco em pereira europeia Rocha enxertada sobre Pyrus calleryana, nas condições edafoclimáticas de São Joaquim, SC. Também avaliar a eficácia agronômica do uso isolado e combinado de doses do bioestimulante Stimulate® e dos fertilizantes Sett® e Hold® na frutificação efetiva, produção e qualidade de pereira Rocha enxertada sobre o marmeleiro BA 29 , nas condições edafoclimáticas de Vacaria, RS. O delineamento experimental utilizado foi de blocos ao acaso, contendo três blocos. Em São Joaquim, SC, os tratamentos de corte do tronco foram realizados no final do período de repouso vegetativo (setembro de 2011) em duas alturas do colo da planta (20 e 40 cm do solo) e duas dimensões de corte com relação ao diâmetro (½ e ⅓ do tronco); e os tratamentos com reguladores de crescimento foram realizados em diferentes estádios fenológicos (início, plena e final da floração) e em diferentes doses, aplicando-se GA4+7 + 6 BA (Promalin®) na dose de 1 mL L-1 combinado com Aminoetoxivinilglicina (ReTain®) nas doses de 0,2, 0,4, 0,6 e 0,8 g L-1. O bioestimulante Stimulate® (ácido índolbutírico 0,005 %, cinetina 0,009 % e ácido giberélico 0,005 %) foi aplicado nas doses de 1, 2 e 3 mL L-1. Em Vacaria, RS, o Stimulate® (2 mL L-1) e o Sett® (3 mL L-1) foram aplicados em plena floração e o Hold® (1 mL L-1) foi aplicado 15 dias após a plena floração. Na testemunha aplicou-se somente água (controle). Nos dois locais em estudo obtiveram-se resultados positivos para o aumento da frutificação efetiva. Pode-se inferir que, nas condições edafoclimáticas de São Joaquim, SC, a técnica de corte do tronco reduz o crescimento dos ramos do ano e proporciona aumento da frutificação efetiva e produtividade; o uso de 1 mL L-1 de Promalin® combinado com 0,6 e 0,8 g L-1 de ReTain® proporcionam maior frutificação efetiva, produção e produtividade; e o uso de Stimulate® nas doses de 2 e 3 mL L-1, independente do número de aplicações (em duas ou três épocas) proporciona maior frutificação efetiva e produção por planta de pereira Rocha enxertada sobre Pyrus calleryana. Nas condições edafoclimáticas de Vacaria, RS, o uso isolado ou combinado de Stimulate®, Sett® e Hold® não influenciam a frutificação efetiva, a produtividade e as características físico-químicas dos frutos de pereira Rocha sobre marmeleiro BA 29 nas condições edafoclimáticas de Vacaria, RS

Les pucerons sont des ravageurs importants des principales espèces fruitières en France, pêcher et pommier notamment. Dans le but de réduire l’usage des produits phytosanitaires, différentes alternatives sont envisagées pour contrôler les pucerons en verger. Nous avons commencé ce travail de thèse par une synthèse des différentes méthodes alternatives de contrôle envisageables et leur positionnement au cours des différentes étapes du cycle biologique du puceron. Puis nous avons étudié les effets de la modulation des caractéristiques de la plante hôte, via les pratiques culturales, sur l’abondance des pucerons. Notre étude se base sur l’hypothèse « Plant Vigor » qui énonce que les insectes phytophages sont plus performants sur les plantes ou les organes de forte vigueur. Par conséquent, sur nos deux dispositifs expérimentaux factoriels nous avons combiné des suivis dynamiques de croissance végétative et d’abondance de pucerons : Prunus persica - Myzus persicae (2 niveaux d’irrigation × 2 niveaux d’apport azoté) et Malus domestica - Dysaphis plantaginea (2 niveaux d’irrigation × 2 génotypes d’arbre). Les facteurs ont été choisis pour leur impact potentiel sur la croissance végétative et la qualité nutritionnelle de la plante hôte. Les expérimentations ont été menées sur de jeunes arbres en pot, ne portant pas de fruit. Au niveau du rameau, l’abondance des pucerons est positivement corrélée à la croissance végétative sur les deux systèmes étudiés. Sur pêcher, la relation disponibilité en azote et abondance de pucerons semble être médiée par le fort impact de l’azote sur la croissance végétative. L’effet négatif de la restriction hydrique sur l’abondance de pucerons ne semble pas lié à un impact sur la croissance végétative. Aussi sur le second système étudié : pommier-puceron cendré, nous avons choisi de faire varier les apports en eau et de travailler sur deux génotypes, pour tester la généricité de la réponse observée. A l’échelle du rameau, l’effet de la restriction hydrique sur l’abondance de pucerons est négatif pour un génotype et positif pour l’autre. Par contre à l’échelle de l’arbre, sur les deux génotypes l’abondance de pucerons est corrélée positivement à la croissance végétative et la restriction hydrique impacte négativement l’abondance de pucerons, ce qui suggère que la performance des pucerons est limitée sur les arbres en restriction hydrique par une autre composante que la vigueur de l’arbre. Ce travail de thèse montre que la restriction hydrique et le contrôle de la vigueur via les apports azotés peuvent s’avérer être des leviers pour le contrôle des pucerons en verger fruitier. Cependant les relations mises en évidence sont dépendantes du génotype, ainsi que de l’échelle d’analyse. Il reste à évaluer l’applicabilité de telles mesures sur des arbres en conditions de production, en prenant en compte notamment l’effet des restrictions hydrique et azotée sur la production fruitière. / Aphids are major pests of important fruit trees in France, especially peach and appletrees. In order to reduce chemical use, various alternatives can be implemented for themanagement of aphids in orchards. This thesis starts by a review of the different alternativemanagement methods and their positioning at different aphid life cycle stages. Then our workfocuses on the study of the effects of modulation of host plant characteristics, through culturalpractices, on aphid abundance. Our study is based on the Plant Vigor Hypothesis which statesthat phytophagous insects are more performant on vigorous plant or organ. Thus, in theexperimental part we combined dynamic assessment of vegetative growth and aphid abundanceduring two factorial experiments: Prunus persica – Myzus persicae (2 levels of water supply ×2 levels of nitrogen supply) and Malus domestica – Dysaphis plantaginea (2 levels of watersupply × 2 tree genotypes). We chose those factors for their possible impact on vegetativegrowth and nutritional quality of the host plant. We conducted the experiments on young nonbearingpotted trees. At shoot scale, aphid abundance is positively correlated to vegetativegrowth for both studied systems. On peach tree, the positive impact of nitrogen availability onaphid abundance seems to be mediated by the strong positive impact of nitrogen on vegetativegrowth. The negative effect of water restriction on aphid abundance seems to be unrelated toan impact of water availability on vegetative growth. Thus on the second studied system: appletree – rosy apple aphid, we chose to vary water supply and to work on two genotypes to test thegenericity of the observed pattern. At shoot scale, water restriction has a positive effect on aphidabundance on one tree genotype and a negative effect on the other one, whereas at tree scalefor both tree genotypes aphid abundance is positively correlated to vegetative growth and waterrestriction negatively impacts aphid abundance. These results suggest that aphid performanceon water restricted trees is limited by another host plant characteristics than vegetative growth.This thesis shows that water restriction and vigour management through nitrogen fertilizationcan be implemented to manage aphids in fruit orchards. However, the patterns evidenced aredependent on tree genotype and on the scale of analysis. The applicability of these alternativemethods remains to be assessed in producing orchards, taking into account the effects of waterand nitrogen restrictions on fruit production.