Dissertations / Theses on the topic 'Pest and pathogen management'

Thesis (MScAgric)--University of Stellenbosch, 2006.<br>ENGLISH ABSTRACT: Phaeomoniella chlamydospora, Eutypa lata, Phomopsis, Phaeoacremonium, and Botryosphaeria spp. are important trunk disease pathogens that cause premature decline and dieback of grapevine. Previous research has focused primarily on wine grapes and the incidence and symptomatology of these pathogens on table grapes were largely unknown. A survey was therefore conducted to determine the status and distribution of these pathogens and associated symptoms in climatically diverse table grape growing regions. Fifteen farms were identified in the winter rainfall (De Doorns, Paarl and Trawal) and summer rainfall (Upington and Groblersdal) areas. Samples were taken in July and August 2004 from Dan-ben-Hannah vineyards that were 8 years and older. Distal ends of arms were removed from 20 randomly selected plants in each vineyard. These sections were dissected and isolations were made from each of the various symptom types observed: brown or black vascular streaking, brown internal necrosis, wedge-shaped necrosis, watery necrosis, esca-like brown and yellow soft wood rot, as well as asymptomatic wood. Fungal isolates were identified using molecular and morphological techniques. Pa. chlamydospora was most frequently isolated (46.0%), followed by Phaeoacremonium aleophilum (10.0%), Phomopsis viticola (3.0%), Botryosphaeria obtusa (3.0%), B. rhodina (2.2%), B. parva (2.0%), Fusicoccum vitifusiforme (0.6%), B. australis, B. dothidea and an undescribed Diplodia sp. (0.2% each), while E. lata was not found. Most of these pathogens were isolated from a variety of symptom types, indicating that disease diagnosis can not be based on symptomatology alone. Pa. chlamydospora was isolated from all areas sampled, although most frequently from the winter rainfall region. Pm. aleophilum was found predominantly in Paarl, while P. viticola only occurred in this area. Although B. obtusa was not isolated from samples taken in De Doorns and Groblersdal, it was the most commonly isolated Botryosphaeria sp., being isolated from Upington, Paarl and Trawal. B. rhodina occurred only in Groblersdal and B. parva in Paarl, Trawal and Groblersdal, while B. australis was isolated from Paarl only. The rest of the isolates (33%) consisted of sterile cultures, Exochalara, Cephalosporium, Wangiella, Scytalidium, Penicillium spp. and two unidentified basidiomycetes, which were isolated from five samples with yellow esca-like symptoms from the Paarl area. These findings clearly illustrate that grapevine trunk diseases are caused by a complex of fungal pathogens, which has serious implications for disease diagnosis and management. Protection of wounds against infection by any of these trunk disease pathogens is the most efficient and cost-effective means to prevent grapevine trunk diseases. However, previous research on the effectiveness of chemical pruning wound protectants has mostly focused on the control of Eutypa dieback only. Fungicide sensitivity studies have been conducted for Pa. chlamydospora, P. viticola and Eutypa lata, but no such studies have been conducted for the pathogenic Botryosphaeria species from grapevine in South Africa. Ten fungicides were therefore tested in vitro for their efficacy on mycelial inhibition of the four most common and/or pathogenic Botryosphaeria species in South Africa, B. australis, B. obtusa, B. parva and B. rhodina. Iprodione, pyrimethanil, copper ammonium acetate, kresoxim-methyl and boscalid were ineffective in inhibiting the mycelial growth at the highest concentration tested (5 μg/ml; 20 μg/ml for copper ammonium acetate). Benomyl, tebuconazole, prochloraz manganese chloride and flusilazole were the most effective fungicides with EC50 values for the different species ranging from 0.36-0.55, 0.07-0.17, 0.07-1.15 and 0.04-0.36 μg/ml, respectively. These fungicides, except prochloraz manganese chloride, are registered on grapes in South Africa and were also reported to be effective against Pa. chlamydospora, P. viticola and E. lata. Results from bioassays on 1-year-old Chenin Blanc grapevine shoots indicated that benomyl, tebuconazole and prochloraz manganese chloride were most effective in limiting lesion length in pruning wounds that were inoculated with the Botryosphaeria spp after fungicide treatment. The bioassay findings were, however, inconclusive due to low and varied re-isolation data of the inoculated lesions. Benomyl, tebuconazole, prochloraz manganese chloride and flusilazole can nonetheless be identified as fungicides to be evaluated as pruning wound protectants in additional bioassays and vineyard trials against Botryosphaeria spp. as well as the other grapevine trunk disease pathogens.<br>AFRIKAANSE OPSOMMING: Phaeomoniella chlamydospora, Eutypa lata, Phomopsis, Phaeoacremonium, en Botryosphaeria spesies is die mees belangrikste stamsiekte patogene wat agteruitgang en vroeë terugsterwing van wingerd veroorsaak. Voorafgaande navorsing het hoofsaaklik gefokus op wyndruiwe en die voorkoms en simptomatologie van hierdie patogene op tafeldruiwe is dus grootliks onbekend. ‘n Opname is gevolglik gedoen in verskillende klimaaatsareas waar tafeldruiwe verbou word om die voorkoms en verspreiding, asook die simptome geassosieer met hierdie patogene, te bepaal. Vyftien plase is geïdentifiseer in die winter- (De Doorns, Paarl en Trawal) en somer-reënval (Upington en Groblersdal) streke. Wingerde (8 jaar en ouer) met die kultivar Dan-ben-Hannah is gekies vir opname en monsters is gedurende Julie en Augustus 2004 geneem. Die distale deel van ‘n arm is verwyder vanaf 20 lukraak gekose plante in elke wingerd. Hierdie dele is ontleed en isolasies is gemaak vanuit elke simptoomtipe wat beskryf is, naamlik bruin en swart vaskulêre verkleuring, bruin interne nekrose, wig-vormige nekrose, waterige nekrose, esca-geassosieerde bruin en geel sagte houtverrotting en asimptomatiese hout. Identifikasie van die swamagtige isolate is gedoen op grond van morfologiese eienskappe en molekulêre tegnieke. Pa. chlamydospora is die meeste geïsoleer (46.0%), gevolg deur Phaeoacremonium aleophilum (10.0%), Phomopsis viticola (3.0%), Botryosphaeria obtusa (3.0%), B. rhodina (2.2%), B. parva (2.0%), Fusicoccum vitifusiforme (0.6%), B. australis, B. dothidea en ‘n onbeskryfde Diplodia sp. (0.2% elk), terwyl E. lata nie geïsoleer is nie. Hierdie patogene is elk geïsoleer vanuit ‘n verskeidenheid simptoomtipes, wat daarop dui dat siektediagnose nie alleenlik op simptomatologie gebaseer kan word nie. Pa. chlamydospora is geïsoleer vanuit al die gebiede, alhoewel die patogeen opmerklik meer voorgekom het in die winter-reënval area. Pm. aleophilum het hoofsaaklik voorgekom in Paarl, terwyl P. viticola slegs in hierdie area voorgekom het. Alhoewel B. obtusa nie voorgekom het in die De Doorns en Groblersdal areas nie, was dit die mees algemeen geïsoleerde Botryosphaeria sp. en het in Upington, Paarl en Trawal voorgekom. B. rhodina het slegs in Groblersdal voorgekom, B. parva in Paarl, Groblersdal en Trawal en B. australis het slegs in Paarl voorgekom. Die res van die isolate (33%) het bestaan uit steriele kulture, Exochalara, Cephalosporium, Wangiella, Scytalidium, en Penicillium spesies asook twee onbekende basidiomycete isolate, geïsoleer vanuit vyf monsters met geel eska-geassosieerde simptome vanuit die Paarl area. Hierdie resultate illustreer dus die feit dat wingerdstamsiektes deur ‘n kompleks van swampatogene veroorsaak word, wat belangrike implikasies het vir die bestuur en diagnose van hierdie siektes. Wondbeskerming teen infeksie van enige van hierdie stamsiekte patogene is die mees doeltreffende en koste-effektiewe manier om wingerdstamsiektes te voorkom. Vorige navorsing aangaande die effektiwiteit van chemiese wondbeskermingsmiddels het egter slegs gefokus op die beheer van Eutypa terugsterwing. In vitro swamdoder sensitiwiteitstoetse is gedoen vir Pa. chlamydospora, P. viticola en Eutypa lata, maar geen studies is al gedoen ten opsigte van die patogeniese Botryosphaeria spesies op wingerd in Suid-Afrika nie. Tien swamdoders is dus getoets vir inhibisie van in vitro miseliumgroei van die vier mees algemene en/of patogeniese Botryosphaeria spesies wat in Suid-Afrika voorkom, naamlik B. australis, B. obtusa, B. parva en B. rhodina. Iprodione, pyrimethanil, koper ammonium asetaat, kresoxim-metiel en boscalid was oneffektief by die hoogste konsentrasies getoets (5 μg/ml; 20 μg/ml vir koper ammonium asetaat). Benomyl, tebuconasool, prochloraz mangaan chloried en flusilasool was die mees effektiewe swamdoders met EC50 waardes tussen 0.36-0.55, 0.07-0.17, 0.07-1.15 en 0.04-0.36 μg/ml, onderskeidelik vir die verskillende spesies. Hierdie fungisiedes, behalwe prochloraz mangaan chloried, is geregistreer op druiwe in Suid-Afrika en is ook effektief gevind teenoor Pa. chlamydospora, P. viticola en E. lata. Resultate van biotoetse op 1-jaar-oue Chenin Blanc wingerd lote het getoon dat benomyl, tebuconasool en prochloraz mangaan chloried die effektiefste was om die lengte van letsels in snoeiwonde, geinokuleer met Botryosphaeria spesies na die aanwending van swamdoder behandelings, te verminder. Die bevindinge was egter onbeslis as gevolg van die lae en variërende her-isolerings data. Benomyl, tebuconasool, prochloraz mangaan chloried en flusilasool kan egter geïdentifiseer word as swamdoders wat verder geevalueer kan word as snoeiwond beskermingsmiddels teen Botryosphaeria spesies asook ander wingerd stamsiekte patogene in verdere biotoetse en wingerdproewe.

Au cours des dernières décennies, la détérioration de la santé des forêts a entraîné des épidémies fréquentes des ravageurs et pathogènes. Ces phénomènes menacent la capacité des forêts à fournir des biens et services écosystémiques à la société. Il est donc nécessaire de maintenir la santé des arbres et de réduire les effets des parasites et des agents pathogènes. Cette thèse considère trois problèmes de gestion du point de vue économique : l'invasion actuelle, l'invasion attendue d'un agent pathogène, et les attaques d'un parasite endémique. À partir de ces trois problèmes de gestion, la thèse vise à évaluer les impacts des ravageurs et des pathogènes forestiers et à informer sur la manière dont les ressources peuvent être réparties de façon optimale pour assurer la fourniture de biens et de services par la forêt à long terme.Les invasions biotiques ont un impact sur les prix des produits du bois du fait des chocs d'approvisionnement qui, à leur tour, influencent les choix de gestion forestière. Ceci permet d'introduire des effets de réaction entre les dynamiques écologiques et de marché. Le premier article vise à évaluer ces impacts en combinant un modèle d’équilibre partiel avec des modèles de diffusion spatiale et de mortalité, calibrés pour représenter le dépérissement du Frêne en France (causé par le pathogène Hymenoscyphus fraxineus). Les résultats montrent que les impacts dépendent généralement de la distribution des ressources, de la propagation du pathogène et de la structure du marché. On observe que les choix d’adaptation des gestionnaires forestiers (c'est-à-dire les choix de régénération et de récolte) sont une composante non négligeable de la perte de volume totale.Le deuxième article est axé sur la surveillance et le contrôle d’une invasion attendue. La surveillance et la détection précoce des espèces envahissantes sont importantes pour atténuer les dommages et réduire les coûts de contrôle. Dans le cas où plusieurs propriétaires sont concernés, l’effort de surveillance des propriétaires plus proches du point d'introduction n’est pas optimal, car il ne prend pas en compte les effets négatifs de l'invasion dans les propriétés voisines. Grâce à un jeu différentiel, combiné à un modèle épidémiologique, nous avons calculé la solution non coopérative et coopérative. Nous avons conçu un paiement monétaire pour soutenir la coopération en fonction d'une décomposition intertemporelle du système de négociation de Nash. Les résultats nous montrent que ce paiement garantit que l’accord entre les deux propriétaires est crédible et incitatif. Le modèle est calibré pour l’éventuelle invasion du nématode du pin (Bursaphelenchus xylophilus) dans le Massif Landais.L'objectif principal du troisième article est d'adapter la gestion forestière aux perturbations biotiques et abiotiques. On combine le modèle classique de Faustmann avec un modèle dynamique de population de ravageurs et un modèle de tempête pour calculer l'âge de coupe optimale et le bénéfice actualisé en séquence infinie (BASI) pour différents scénarios de perturbations. Le modèle est appliqué aux dégâts de la chenille processionnaire du pin (Thaumetopoea pityocampa) dans les Landes. Nos résultats ont montré que les tempêtes ont tendance à réduire l'âge optimal de la récolte, alors que le parasite tend à l'augmenter. Les éclaircies augmentent la rentabilité et constituent une stratégie de couverture efficace contre les deux risques. Dans le troisième article, nous avons introduit une règle de décision cut-or-keep pour modéliser le problème du propriétaire forestier après une tempête. Ces implications en termes de gestion sont étudiées plus en détail dans le quatrième article. Notre règle de décision conduit à des gains plus élevés (dans environ 75% des cas) qu’en suivant la règle, généralement utilisée en économie, qui consiste à couper et à replanter les arbres survivants indépendamment du niveau de dégâts<br>In recent decades, the deterioration of forest health resulted in frequent pests’ outbreaks and the diffuse pathogens’ presence. These phenomena threaten forests’ ability to supply ecosystem goods and services to the society. It is therefore necessary to maintain tree health and reduce pest’s and pathogen’s impacts. This thesis approaches three management problems from an economic perspective such as the current invasion and the incumbent invasion of a forest pathogen as well as the outbreaks of a native pest. Starting from these three pest and pathogen management problems, the thesis aims at assessing the impacts of forest pests and pathogens and, secondly, informing how resources can be optimally allocated for assuring the long-term provision of good and services.Pest and pathogens invasions have an impact on the prices of wood products via supply shocks, which, in turn, influence forest management choices, thus introducing feedback effects between market and ecological dynamics at a large scale. The first paper aims at evaluating these impacts by combining a recursive partial equilibrium model with spatial-explicit pathogen-spread and pathogen-induced mortality models calibrated to represent the ash dieback in France (caused by the pathogen Hymenoscyphus fraxineus). Results showed that impacts are not homogeneous across regions and generally depend on the resource distribution, pathogen spread and market structure. We observed that the behavioural adaptation of forest managers (i.e., regeneration and harvesting choices) is a non-negligible component of the total standing volume loss.The second paper focusses on monitoring and control of an incumbent invasion. Monitoring and early detection of invasive species is important to mitigate the damages and reduce the control costs. However, when multiple decision-makers are involved, the monitoring effort of frontier landowners (landowners closer to the introduction point) is suboptimal because it does not consider the negative impacts of the invasion spreading to neighbouring properties. Through a two-player differential game combined with an epidemiological compartmental model, we computed the non-cooperative and the cooperative solution. We designed a monetary payment to sustain cooperation based on an intertemporal decomposition of the Nash bargaining scheme. We showed that this payment assured time-consistent outcomes, meaning that the ex-ante agreement between the two landowners was credible and self-enforcing. The model was calibrated for the possible invasion of the pine wilt nematode (Bursaphelenchus xylophilus) in south-western France.In the last two papers, the analysis is downscaled from the landscape level to the stand level and concentrates on a native defoliator pest. The main objective of the third paper is to adapt forest management to biotic and abiotic disturbances. The classic Faustmann model was combined with a pest population model and a windstorm model to compute the optimal rotation age and the land expectation value (LEV) for different disturbances scenarios. The model was calibrated for maritime pine (Pinus pinaster) plantations in south-western France and Pine Processionary Moth (PPM, Thaumetopoea pityocampa) cyclical outbreaks. Our results showed that storms tend to reduce the optimal harvest age, whereas PPM tends to increase it. Overall, the impact of PPM on the rotation length prevails and, here, risks increase rather than decrease the optimal rotation length. Thinnings increased profitability and constitute an effective hedging strategy against both risks. In the third paper, we introduced a cut-or-keep decision rule to model the forest owner problem after a storm event. Its economic and management implications are further investigated in the fourth paper. Unlike previous economic studies which assumed clearing and replanting regardless of the level of damages, the cut-or-keep condition led to higher payoffs in roughly 75% of the cases

Master of Science<br>Entomology<br>Brian McCornack<br>Several lepidopteran species infest developing panicles. Larval identification is challenging and time intensive, so current recommendations are often simplified by treating all larvae equally across species. Consequently, the yield-loss model developed for corn earworm (Helicoverpa zea) by Buckley and Burkhardt (1962) has been the foundation for management recommendations in modern sorghum Integrated Pest Management (IPM) programs for the last 49 years. Additionally, although pest populations primarily include both fall armyworm (Spodoptera frugiperda) and corn earworm, only a single species damage estimate is used in economic threshold (ET) and economic injury level (EIL) calculations despite multi-species infestations. This research demonstrates both the validation of current management recommendations for corn earworm and the verification of previously assumed damage potentials for fall armyworm feeding in developing sorghum panicles. These results have important implications for sorghum producers faced with making a management decision for multi-species infestations.

La réduction de la dépendance aux pesticides des systèmes de culture de laitue constitue un objectif à relativement court terme, partagé par les pouvoirs publics et les acteurs de la filière de production. Atteindre cet objectif suppose de disposer de moyens techniques permettant de substituer aux pesticides d’autres méthodes limitant les dégâts de bio-agresseurs de la laitue.Ces techniques peuvent être destinées à minimiser l’entrée d’inoculum dans les parcelles, à limiter la propagation des bio-agresseurs, à diminuer la sensibilité des plantes, ou à éradiquer les bio-agresseurs présents sur les cultures. L’évolution des systèmes de culture repose sur la démonstration de l’efficacité, en termes de protection des plantes, de ces techniques alternatives aux pesticides lorsqu’elles sont intégrées et combinées dans les itinéraires techniques. Elle dépend aussi de l’impact socio-économique et environnemental des itinéraires techniques alternatifs, dans un contexte commercial et réglementaire exigeant. L’objet de cette thèse a été de développer des stratégies alternatives de gestion des bio-agresseurs de la laitue d’hiver cultivée sous abri froid,plus économes en pesticides, et d’évaluer leurs performances agronomiques, économiques et environnementales,garantes de la durabilité des systèmes de production.Sur la base des techniques déjà disponibles, deux stratégies alternatives, nommées stratégie intermédiaire et stratégie bas-intrant ont été conçues, et testées dans deux exploitations agricoles et un domaine expérimental de l’INRA pendant deux hivers, en comparaison avec une stratégie conventionnelle, représentative des pratiques actuelles. Les stratégies intermédiaire et bas-intrant ont permis de réduire de 32% et 48% l’usage des pesticides, respectivement, et ont été suffisamment efficaces pour obtenir une qualité visuelle et des rendements équivalents à la stratégie conventionnelle. Le bénéfice environnemental de leur mise en oeuvre a également été démontré. La mise en place de ces stratégies a cependant entrainé un surcoût de production,essentiellement lié à la lutte biologique, d’environ 10 à 13%. Parallèlement, deux orientations techniques originales, dont l’efficacité n’était pas caractérisée, ont été explorées. Une première série d’essais expérimentaux a porté sur l’influence du génotype de l’hôte et de l’environnement de la plante sur sa sensibilité à deux champignons pathogènes d’importance majeure, Botrytis cinerea et Sclerotinia sclerotiorum. Il a été montré que le choix d’un génotype moins sensible couplé à une optimisation du rapport fructose : saccharose de la plante diminuait les symptômes observés après inoculation. Une deuxième démarche expérimentale, portant sur la lutte biologique contre le puceron Nasonovia ribisnigri, a révélé l’incapacité de parasitoïdes du genre Aphidius à contrôler les pucerons en fin de culture, lorsque la structure du couvert végétal devient trop complexe.En plus d’inscrire ces travaux de recherche dans un processus d’amélioration continue de l’efficacité et des performances des stratégies alternatives aux pesticides, la démarche scientifique utilisée, articulant approche analytique et approche intégrative, a permis d’étudier des techniques ayant potentiellement un impact sur plusieurs bio-agresseurs, telles que la réduction de la fertilisation azotée ou l’optimisation de l’espacement entre les laitues, qui pourraient permettre une meilleure gestion des pathogènes responsables de la pourriture du collet et des pucerons<br>The reduction of pesticide reliance in lettuce cropping systems is a short term objective sharedby public authorities and by the stakeholders of lettuce market. Reaching this goal implies thesubstitution of pesticides by others techniques which may limit pest and pathogen damage. Thesetechniques can be intended to mitigate pest and pathogen invasion or propagation, to increaseplant defenses or to remove pests and pathogens from the crop. The improvement of currentcropping systems relies on i) the demonstration of the ability of alternative techniques to managediseases and pests when they are combined and integrated during the crop cycle; ii) theassessment of the socio-economic and environmental impacts of alternative strategies in a stringentcommercial and regulatory context. The objective of this thesis was to design alternativestrategies for pest and pathogen management of lettuce grown in winter under shelter, with fewerpesticide applications, and to assess their agronomic, economic and environmental performancesso as to ensure the sustainability of production.Based on currently available techniques, two alternative strategies, called intermediate andlow-input, were designed, and tested in two farms and an INRA experimental station duringtwo winters and compared to a conventional strategy representing current practices. The alternativestrategies enabled to reduce pesticide applications by 32% and 48% respectively. Theywere efficient enough to obtain similar yield and quality as compared to the conventional strategy.The environmental benefits of their implementation were also demonstrated. However, thesestrategies required a 10-13% extra production costs, almost exclusively due to biological controlproducts.In parallel, two original technical orientations, which efficacy had not been previously described,were examined. In a first set of experiments, the impact of lettuce genotype and growthconditions on plant susceptibility to two major pathogens, Botrytis cinerea and Sclerotinia sclerotiorum,was investigated. The use of a genotype displaying low susceptibility to these fungi,associated with an optimization of the ratio of fructose : sucrose in plants, appeared to reducethe symptoms after inoculation. A second experimental approach, dealing with biological controlagainst the aphid Nasonovia ribisnigri, highlighted the inability of Aphidius parasitoids tocontrol aphid populations at the end of the crop cycle, when the canopy structure becomes toocomplex.In addition to a contribution to cropping systems improvement, the scientific method used,combining analytical and integrative approaches enabled us to highlight the effect of techniquesacting on several pests and/or pathogens, such as the reduction of nitrogen fertilization or theoptimization of plant spacing, which could improve the management of fungi causing basal rotas well as aphids

7 pp.<br>Melon production in the Southwestern United States occurs primarily in the desert growing areas of Arizona, and Southern California. Melons in Arizona are grown in very diverse cropping systems, where a variety of vegetable, agronomic and seed crops are cultivated concurrently throughout the year. Numerous insect species can be found on melon plants, but only a few have been determined to be economically important. This publication discusses several key insects that cause economic damage to melons, and the tactics commonly used to manage infesting populations.

Foliar-applied insecticides and the soil-applied insecticide, Admire, were evaluated for their ability to control citrus mealybug on lemons while having a minimal impact on parasitoids. All of the foliar-applied insecticide exhibited activity towards citrus mealybug. The standard insecticide, Lorsban, performed very well, but since this product is especially harmful to parasitoids it is not considered to have a good fit in IPM programs where parasitoid conservation is emphasized. The currently labeled alternative, Applaud, was an effective treatment and should be considered for citrus mealybug control to avoid destruction of parasitoids. Several experimental insecticides showed promise: NNI-850, NNI-750C and NNI-010. However, NNI-0101 at the lower rate of 0.24 lbs-ai/ac appeared to be weak. The addition of narrow range crop oil, NR-415 at 1.0 gal/ac, appeared to be beneficial for initial mealybug knock-down, especially for the slower acting insecticides such as Applaud. Soil injection of Admire at 16 and 32 oz/ac appeared to have very good activity, but due to variability in the mealybug population, more data should be collected to confirm this finding.

For the first time in many decades, a hemp pilot program was initiated in Virginia in 2016. Outdoor surveys were conducted in the 2017 and 2018 field seasons to record insect presence and feeding injury to plants. Multiple insect pests were present, including corn earworm (Helicoverpa zea [Boddie]) (Lepidoptera: Noctuidae), brown marmorated stink bug (Halyomorpha halys [Stål]) (Hemiptera: Pentatomidae), and cannabis aphid (Phorodon cannabis) (Hemiptera: Aphididae). In 2019, indoor production surveys revealed that cannabis aphid, twospotted spider mite (Tetranychus urticae Koch) (Acari: Tetranychidae), and hemp russet mite (Aculops cannabicola [Farkas]) (Acari: Eriophyidae) would likely cause production issues. Very little is known about the impact of insect defoliation in hemp so studies were conducted in 2018-2020 to determine impacts on yield and cannabinoid content of grain and cannabinoid variety hemp due to leaf surface area loss. In Virginia over two growing seasons, manual removal of leaf tissue in grain and CBD cultivars did not significantly impact observable effects on physical yield (seed or bud weight) or cannabinoid content (CBD or THC) at time of harvest. Corn earworm is the major pest of hemp produced outdoors and studies occurred to evaluate monitoring and management strategies. Pheromone traps may be valuable in determining when corn earworm moths are present in the vicinity of hemp fields but are not useful in predicting larval presence in buds or final crop damage. Larval presence and final crop damage are related. Brown marmorated stink bug does not appear to be a concern in hemp, at least at this time.<br>Doctor of Philosophy<br>For the first time in many decades, a hemp pilot program was initiated in Virginia in 2016. Outdoor surveys were conducted in the 2017 and 2018 field seasons to record insect presence and feeding injury to plants. Multiple insect pests were present, including corn earworm, brown marmorated stink bug, and cannabis aphid. In 2019, indoor production surveys revealed that cannabis aphid, twospotted spider mite, and hemp russet mite would likely cause production issues. Very little is known about the impact of leaf area loss due to insect feeding in hemp so studies were conducted in 2018-2020 to determine impacts on yield and cannabinoid content of grain and cannabinoid variety hemp due to leaf surface area loss. In Virginia over two growing seasons, manual removal of leaf tissue in grain and CBD cultivars did not significantly impact observable effects on physical yield (seed or bud weight) or cannabinoid content (CBD or THC) at time of harvest. Corn earworm is the major pest of hemp produced outdoors and studies occurred to evaluate monitoring and management strategies. Pheromone traps may be valuable in determining when corn earworm moths are present in the vicinity of hemp fields but are not useful in predicting larval presence in buds or final crop damage. Larval presence and final crop damage are related. Brown marmorated stink bug does not appear to be a concern in hemp, at least at this time.

The Virginia Integrated Pest Management Expert for Wheat was designed to combine the best available information regarding wheat pest management of disease pathogens, weeds, and insects into a decision support system that would provide potential outbreak risk and pest control information to the Comprehensive Resource Planning System (CROPS). In addition, the system stands alone as an educational tool for farmers and Extension personnel. <p>This is a rule-based system developed on the Microsoft Windows platform. Knowledge about crops and pest management is represented in the form of IF/THEN rules, demons, and "when-changed" methods. The inference engine analyzes specific crop system information entered by the user to determine potential risks of outbreak for wheat crop pests common to Virginia. These potential outbreak risks are presented as low, medium, and high levels of risk and are presented for each of 15 pests of wheat in Virginia. <p>The system was evaluated using thirty random cropping system scenarios. By comparing expert system output with output from human experts, it was shown that the expert system agreed with human expert opinions in 84 percent of the decisions made. Statistical analysis of the insect pest data showed that there was no significant statistical difference between the distribution of the human expert predictions and the expert system predictions. Statistical analysis of the disease pest data showed that there were some significant statistical differences between the distribution of the human expert predictions and the expert system predictions.<br>Master of Science

Pests can impact significantly upon the economy, the environment and on human and animal health. However, for pest birds there are surprisingly few studies of these impacts and how to reduce them. The aim of this thesis is to advance our understanding of the ecology, impacts, and management of pest birds using case studies for each of the three main impacts. In considering economic impacts I estimate pest bird abundance, describe a novel method for measuring bird damage, and evaluate the efficacy of lethal and non-lethal methods in vineyards and orchards. Using data across 185 property years, netting was found to be the most effective in reducing bird damage. Shooting was not as effective but was one-third of the cost and had 13% lower damage compared with nil-treatments. Scaring with electronic devices and visual deterrents had no effect on bird damage. Despite their widespread use, lethal methods had limited effectiveness for reducing pest abundance. In considering environmental impacts introduced mallards on Lord Howe Island were used as a case study. Phenotypic characteristics suggest that mallards have supplanted the native Pacific black duck on Lord Howe Island. Management alternatives are evaluated and discussed. In considering health-related impacts wild birds and avian influenza in Australia was used as a case study. Here, the ecology of Australia’s Anseriformes, and the epidemiology, modes of transmission, and the factors influencing the prevalence of avian influenza in Australia’s wild birds are investigated. Risk profiles to improve the efficiency and relevance of wild-bird surveillance are also provided. The case studies presented demonstrate that an understanding of a pest’s ecology, efficient measures of impacts, and thorough evaluations of surveillance and management strategies are essential for effectively managing their economic, environmental and health-related impacts.

Integrated pest management (IPM) is a multi-layered approach to reducing pest pressure, primarily in agriculture, but also in national parks and urban settings. Its purpose is to maintain acceptable levels of productivity whilst avoiding the adverse effects associated with indiscriminate chemical control, such as pesticide resistance, secondary infestation, resurgence and harm to human health and the environment. It is a complex system, science-driven and information-based, and there are a wide range of actors involved in its development and implementation. These actors occupy various social locations. They are grouped in institutions for research and extension, in industry and related associations, in funding bodies, policy-making departments, and agricultural communities. IPM requires concerted effort from all involved; yet in some cases, social inequality characterises relations between the groups. Consequently, different groups address different layers of the IPM whole. Some groups have greater societal power to promote their developmental activities than others do, and when these differing activities meet in practice, as they must, conflict and contradiction can arise. This thesis attempts to understand the social construction of IPM by examining the process of IPM development and implementation. It follows the Science and Technology Studies (STS, also termed Science, Technology and Society) theoretical framework of the interrelationship, rather than separateness, of science, technology and society. It examines the way social relations influence technological developments in IPM, and the way IPM technologies influence social relations.<br>Thesis (PhD Doctorate)<br>Doctor of Philosophy (PhD)<br>Faculty of Science and Technology<br>Science, Environment, Engineering and Technology<br>Full Text

The purpose of this study was to assess the adoption response of cotton growers to Integrated Pest Management (IPM) programs, identify the extension strategies used to promote IPM, and provide descriptive comparison of IPM programs between the foremost eleven cotton-producing states in the United States. Integrated pest management is presented as an alternative agricultural production strategy referred to as sustainable agriculture. IPM programs for cotton were evaluated by use of a survey instrument and telephone interviews with the IPM coordinators for the eleven cotton-producing states. The most significant findings were that programs vary considerably between states; the most widely employed IPM techniques were selective use of chemicals, use of economic thresholds and sampling for pests; the Cooperative Extension Service worked closely with private consultants and grower associations; and adoption of a wide variety of IPM techniques has been extensive for cotton producers in the eleven foremost cotton-producing states.

Integrated pest management (IPM) has gained recognition worldwide as a key tool for sustainable arable farming. Promoting natural pest control, strategic use of insecticides, and farmer participation are three important elements in IPM. However, knowledge gaps exist related to the economic value of natural pest control service, insecticides’ efficacies and side effects, and farmers’ incentives to adopt natural pest control in arable fields. This thesis addresses these gaps using UK and European arable crop systems. With a natural enemy exclusion experiment and economic surplus method, the annual economic value of predators and parasitoids for the summer grain aphid (Sitobion avenae) control in wheat (Triticum spp.) in South East England was estimated to be £0-2.3 Million, depending on the aphid infestation levels. Insecticidal sprays based on action thresholds would enhance the value of this ecosystem service. By conducting a UK online survey among experts on insecticide efficacies and side effects in oilseed rape (Brassica napus) protection, relatively older chemical groups were perceived to have lower efficacies for target arthropod pests than newer ones. Foliar sprays were perceived to have greater negative impacts than seed treatments on users’ health, natural enemies, pollinators, soil and water. Many foliar active ingredients pose potential risks for non-target arthropod species in UK oilseed rape fields. Through an interview of European arable farmers participating in an agri-environmental project, respondents’ willingness to encourage natural (animal) pest control was relatively low. In comparison, using insecticides to control pests was the typical practice. Ordinal logistic regression indicated that farmers’ decision to promote natural pest control was positively associated with the perceived importance of this ecosystem service on crop production, but negatively associated with the perceived number of important pests in the fields. The implications of these findings and avenues for future research to enhance IPM in arable crops are discussed.

The focus of this study was to explore current methodology for evaluating plant health surveillance systems for their ability to provide confidence towards demonstrating pest freedom using surveillance for Tilletia indica, an exotic fungal pathogen of wheat, in Western Australia as a model. Tilletia indica causes a disease commonly known as Karnal bunt and is an important pathogen in international trade, with many countries having phytosanitary restrictions. If T. indica were to become established in Australia it would cause considerable damage to the country’s economy through loss of domestic and international markets. Maintaining pest free status for T. indica is important to maintain Australia’s grain export markets. Integral to effective surveillance for T. indica are methods involved in the collection of grain samples and the sensitivity of the laboratory tests used in the surveillance systems. These surveillance ‘tools’ have been investigated and the current techniques have been shown to be effective. Grain sampling occurring at delivery during harvest provides an efficient way to collect samples representative of export quality grain. Stochastic modelling of the sampling process shows that test samples obtained using the current protocol will contain teliospores at detectable levels. In samples from delivery parcels there is a high probability (> 95%) that test samples will contain 5 or more teliospores where the prevalence is at least 1 infected grain in 100 kg. For test samples collected from general siding samples there is a greater than 75% probability that teliospores will be present in the samples where the prevalence is at least 0.5% of delivery parcels and 10 infected grains per kg within parcels. Investigations also indicated that clustering of teliospores within infected grains did not influence the probability of test samples being infected. Evaluation of the diagnostic protocols currently used in the surveillance programs for T. indica using traditional ‘gold-standard’ methods and a Bayesian statistical framework indicates that the sieve-wash protocol with microscopic observation has a high diagnostic sensitivity (> 84.8%) and specificity (> 96.0%) for detection of teliospores of T. indica, and similar results were obtained for related Tilletia species. The molecular protocol, proposed as the new ‘enhanced’ surveillance tool for detection of T. indica in grain samples, did not perform as well, with a sensitivity and specificity of 48.0% and 48.4% respectively. The estimates were comparable between the two evaluation methods, suggesting that the current protocol, sieve-wash test with microscopic examination, is still the most suitable protocol for grain surveillance for Tilletia species. The expectation, under the SPS Agreement, that claims of pest freedom be supported by scientific evidence means that there is an increasing need for methods to evaluate the information collected during surveillance activities to provide a quantitative level of confidence upon which claims of freedom can be based. Ten years of historical grain surveillance, utilising samples collected at delivery and the sieve-wash test with microscopic examination, were evaluated using scenario tree methodology and have been shown to provide a high probability of freedom (>95%) from T. indica for Western Australia. The active surveillance systems were evaluated at a range of prevalence levels and were shown to provide a high probability of freedom for design prevalences above one in five regions infected, with 0.25% delivery parcels infected at a rate of 1 infected grain in 100 kg after evaluation of the ten years of surveillance. Passive surveillance systems can also provide evidence to support claims of pest freedom. The reporting mechanisms in Western Australia for grains pests were investigated, along with attitudes and behaviours relating to the likelihood that members of the grains industry would report a suspect pest or disease. The information gathered was used to inform an evaluation of two passive surveillance system components operating in Western Australia, grower reporting and routine seed testing. Grower reporting was found to provide a high probability of freedom (> 95%) at a design prevalence level of one in five regions infected with 0.25% delivery parcels infected at a rate of 10 infected grains in 1 kg. The Seed Testing surveillance system component was found to provide little contribution to confidence in freedom, due to the low number of wheat samples tested annually. This study demonstrates that passive surveillance provides significant confidence in freedom for T. indica, but that the active surveillance programs provide additional confidence that Western Australia is free from T. indica at lower prevalence levels. Finally, recommendations are provided for future surveillance activities to maintain Western Australia’s confidence in from T. indica.

31 pp.<br>Many pests encountered in homes and structures can be prevented by using simple techniques collectively known as “pest-proofing”. If done correctly, pest-proofing your home saves you money by reducing pest management costs, and more importantly, reduces potential pesticide exposure. This publication describes general indoor and outdoor pest-proofing measures and some of the major pests encountered in and around homes and structures.

This research was conducted to assess the intersection of gender and pesticide knowledge to identify gendered dynamics that may prove important to consider when implementing an Integrated Pest Management (IPM) program. Key findings include knowledge being associated with task undertaken, not necessarily the gender of a person. Often, due to social conceptions of appropriate gender roles, similar knowledge may be associated with a certain gender because they are engaging in similar tasks, but it is not their sex or gender that inherently gives them such knowledge. Therefore, knowledge generally associated with women can be associated with men if they are engaging in similar work. Additionally, triangulation of data through using various research methodologies, and interdisciplinary research are imperative for developing comprehensive research or development programs. Finally, even people who are concerned with the negative human and environmental health effects of pesticides may not be using them in a cautious manner. Outside factors such as market sale, education and income level must be taken into account when assessing why pesticides are used and the best methods to introduce an alternative pest control method, such as IPM.<br>Master of Public and International Affairs

12 pp.<br>This document is intended to help you develop an implementable IPM Plan for your school or school district. We have provided a modifiable template which can be downloaded at: http://cals.arizona.edu/apmc/westernschoolIPM.html#pubs.

El moteado del níspero, causado por el hongo Fusicladium eriobotryae es la principal enfermedad que afecta al cultivo del níspero, produciendo pérdidas importantes en la cosecha en los años con condiciones climáticas adecuadas. Sin embargo, no existen estudios sobre la epidemiología y el control de esta enfermedad, por lo que éstos constituyen el principal objetivo de la presente Tesis. Para ello, se va ha caracterizar in vitro y en campo la influencia de las principales variables climáticas en el desarrollo de F. eriobotryae, desarrollándose ecuaciones matemáticas que modelicen esta relación. Por otro lado, se va a llevar a cabo un modelo epidemiológico para el moteado del níspero capaz de predecir, en función de las principales variables climáticas el riesgo de infección. Además, se realizará un estudio del control de la enfermedad que comprenderá, por un lado, la evaluación in vitro y en planta de la efectividad de las principales materias activas utilizadas para el control del moteado del níspero, y por otro la evaluación del grado de resistencia de una colección de aislados de F. eriobotryae a DMI y Metil-Tiofanato y la caracterización molecular de la misma.<br>González Domínguez, E. (2014). Biology, epidemiology and control of Fusicladium eriobotryae, causal agent of loquat scab [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/38715<br>TESIS

La demanda mundial d’aliments ha dut al desenvolupament d’una intensa activitat agrícola produint la fragmentació, modificació i simplificació dels hàbitats naturals ja documentats com una de les principals causes de l’extinció i pèrdua de la diversitat d’espècies. La biodiversitat que tenen els ecosistemes proveeix d’una sèrie de serveis ecosistèmics a l’ésser humà i el control biològic natural de plagues es un dels serveis que s’ha vist alterat especialment als agroecosistemes. Tot i que existeix una creixent literatura científica que suggereix que la presència d’hàbitats naturals beneficia als enemics naturals als groecosistemes, l’eficiència del control biològic segueix sent un dels principals reptes en aquests estudis, oncs els efectes varien molt entre espècies i entre estudis. Entendre els patrons d’abundància i moviment de les espècies d’enemics naturals i d’herbívors, així com les interaccions entre aquests en els paisatges agrícoles, es espacialment i temporal complex. Si bé la gestió dels hàbitats agrícoles ofereix solucions per a reduir la pèrdua del rendiment degut a les plagues, en el cas dels virus, la simplificació excessiva de la diversitat dels cultius, els sistemes intensius de cultiu i l’ús de productes fitosanitaris interfereixen amb les funcions ecològiques dels agroecosistemes alterant la epidemiologia de malalties a les plantes. Amb l’objectiu d’oferir una perspectiva general sobre la’influència que el paisatge agrícola pot tenir sobre el control biològic i la epidemiologia viral, aquesta tesis s’ha enfocat en analitzar els efectes del paisatge agrícola des d’una perspectiva de composició espacial i del maneig del camp sobre espècies d’insectes herbívors i depredadors, així com en els principals virus que afecten al cultiu del panís a la zona de la Vall de l’Ebre. La primera part de la tesis està orientada a (1) l’ampliació en el coneixement de quins són els tipus d’estudis que s’estan duent a terme per analitzar els efectes de l’agroecosistema en el control biològic, les diferents metodologies i els resultats més recents (Capítol 1), i (2) els diferents efectes que té l’estructura (composició i configuració) del paisatge i les variables locals en les espècies de depredadors i herbívors presents en el cultiu de panís (Capítol 2). La segona part de la Tesi està orientada a estudiar els efectes del paisatge sobre tres dels principals virus que afecten al cultiu de panís (1) dos virus generalistes de vector: el virus del mosaic de la canya de sucre (SCMV) i el virus del mosaic nanitzant del panís (MDMV) (Capítol 3), i un virus especialista de vector: el virus del nanisme rugós del panís (MRDV) (Capítol 4). Les principals conclusions d’aquesta tesis doctoral són: (1) els estudis de caràcter funcional on s’estudia composició del paisatge han demostrat que les espècies d’enemics naturals necessiten hàbitats specífics, però que altres variables com són els efectes locals del cultiu també poden afectar a les seves dinàmiques i les de les plagues amb més força; (2) la superfície de fruiters afecta negativament als depredadors potencials del panís, però que les cobertes vegetals d’aquests afecten positivament a certes espècies d’herbívors en absència del panís; (3) l’alfals actua com un cultiu que aporta depredadors i herbívors al cultiu de panís actuant com un recurs per a les espècies més importants dels hàbitats seminaturals; (4) la incidència viral al panís està influïda principalment per la data de sembra i per la cobertura i presència d’espècies de gramínies als marges. Aquests resultats obren una via en el coneixement dels efectes que produeixen tant la composició del paisatge agrícola com el maneig del propi camp en l’abundància i distribució d’herbívors, depredadors i de virus en el cultiu de panís. Aquests resultats a més suggereixen que s’han de contemplar mesures de gestió a escala local que garanteixin nivells mínims de biodiversitat i sostenibilitat com a base inicial per al desenvolupament de programes més eficients de control biològic de plagues i virus.<br>La demanda mundial de alimentos ha llevado al desarrollo de una intensa actividad agrícola produciendo una fragmentación, modificación y simplificación de los hábitats naturales ya documentada como una de las principales causas de la extinción y pérdida de la diversidad de especies. La cantidad, estructura y forma de la superficie de estos hábitats naturales fragmentados genera efectos positivos o negativos sobre la abundancia y diversidad de las especies. La biodiversidad que tienen los ecosistemas provee de una serie de servicios ecosistémicos al ser humano, y el control biológico natural de plagas es uno de los servicios que se ha visto alterado especialmente en los agroecosistemas. Aunque existe una creciente literatura científica que sugiere que la presencia de hábitats naturales beneficia a los enemigos naturales en los agroecosistemas, la eficiencia del control biológico sigue siendo uno de los principales retos en estos estudios, pues los efectos varían mucho entre especies y entre estudios. Entender los patrones de abundancia y movimiento de las especies de enemigos naturales y de herbívoros en los paisajes agrícolas, así como las interacciones entre estos, es espacial y temporalmente complejo. Si bien la gestión de los hábitats agrícolas ofrece soluciones para reducir la pérdida de rendimiento debido a las plagas, en el caso de los virus la simplificación excesiva de la diversidad de los cultivos, los sistemas intensivos de cultivo y el uso de productos fitosanitarios interfieren con las funciones ecológicas de los agroecosistemas alterando la epidemiología de enfermedades en las plantas. Con el objetivo de ofrecer una perspectiva general sobre la influencia que el paisaje agrícola puede tener sobre el control biológico y la epidemiología viral, esta tesis se ha centrado en analizar los efectos del paisaje agrícola desde una perspectiva de composición espacial y del manejo del campo sobre especies de insectos herbívoros y depredadores, así como en los principales virus que afectan al cultivo de maíz en la zona del Valle del Ebro. La primera parte de la tesis está orientada a (1) la ampliación en el conocimiento de cuáles son los tipos de estudios que se están realizando para analizar los efectos del agroecosistema en control biológico, las diferentes metodologías y los resultados más recientes (Capítulo 1), y (2) los efectos que tiene la estructura (composición y configuración) del paisaje y las variables locales en las especies de depredadores y herbívoros presentes en el cultivo del maíz (Capítulo 2). La segunda parte de la tesis está orientada a estudiar los efectos del paisaje sobre tres de los principales virus que afectan al cultivo del maíz (1) dos virus generalistas de vector: el virus del mosaico de la caña de azúcar (SCMV) y el virus del mosaico enanizante del maíz (MDMV) (Capítulo 3), y un virus especialista de vector: el virus del enanismo rugoso del maíz (MRDV) (Capítulo 4). Las principales conclusiones de esta tesis son: (1) los estudios de carácter funcional donde se analiza la composición del paisaje han demostrado que las especies de enemigos naturales necesitan de hábitats específicos, pero que otras variables como son los efectos locales del cultivo también pueden afectar a las dinámicas de los enemigos naturales y los herbívoros con más fuerza; (2) la superficie de frutales afecta negativamente a los depredadores potenciales en el maíz, pero que las cubiertas vegetales de estos afectan positivamente a ciertas especies de herbívoros; (3) la alfalfa actúa como un cultivo que aporta depredadores y herbívoros al cultivo del maíz actuando como un recurso para las especies con mayores efectos que los hábitats semi-naturales; (4) la incidencia viral en el maíz está influenciada principalmente por la fecha de siembra y por la cobertura y presencia de especies de gramíneas en los márgenes. Estos resultados abren una vía en el conocimiento de los efectos que produce tanto la composición del paisaje agrícola como el manejo del propio campo en la abundancia y distribución de herbívoros, depredadores y de virus en el cultivo del maíz. Además, son una base para predecir las consecuencias de la modificación de las prácticas agrícolas en el control biológico de plagas y de virus en el cultivo del maíz. Estos resultados además sugieren que deben de contemplarse medidas de gestión a escala local que garanticen niveles mínimos de biodiversidad y sostenibilidad como base inicial para el desarrollo de programas más eficientes de control biológico de plagas y virus.<br>The global demand for food has led to the development of intense agricultural activity resulting in fragmentation, modification and simplification of natural habitats already documented as one of the main causes of extinction and loss of species diversity. The quantity, structure and surface shape of these fragmented natural habitats generate positive or negative effects on the abundance and diversity of species. The biodiversity that ecosystems have provides a series of ecosystem services to humans, and natural biological control is one of the services that has been altered, especially in agroecosystems. Although there is growing scientific literature that suggests that the presence of natural habitats benefits natural enemies in agroecosystems, the efficiency of biological control remains one of the main challenges in these studies, as the effects vary greatly between species and between studies. Understanding the patterns of abundance and movement of natural enemies and herbivores, as well as understanding the interactions between them, is spatially and temporarily complex in agricultural landscapes. While agricultural habitat management offers solutions to reduce yield loss due to pests, in the case of viruses, the excessive simplification of crop diversity, intensive cropping systems and the use of phytosanitary products interfere with the ecological functions of agroecosystems, altering the epidemiology of diseases in plants. With the aim of offering a general perspective on the influence that the agricultural landscape can have on biological control and viral epidemiology, this thesis has focused on analysing the effects of the agricultural landscape from a spatial composition and field management perspective on species of herbivorous and predatory insects, as well as in the main viruses that affect the cultivation of maize in the area of the Ebro Valley. The first part of the thesis is aimed at (1) broadening the knowledge of identifying the types of studies that are being conducted to analyse the effects of agroecosystem on biological control, the different methodologies and the most recent results (Chapter 1), and (2) the effects of the structure (composition and configuration) of the landscape and the local variables in the predators and herbivores present in the cultivation of maize (Chapter 2). The second part of the thesis is aimed at studying the effects of the landscape on three of the main viruses that affect the cultivation of maize (1) two generalist vector viruses: the sugarcane mosaic virus (SCMV) and the maize dwarf mosaic virus (MDMV) (Chapter 3), and a vector specialist virus: the maize rough dwarf virus (MRDV) (Chapter 4). The main conclusions of this thesis are as follows: (1) functional studies where landscape composition is studied have shown that natural enemy species need specific habitats, while other variables such as the local effects of the crop can also affect the dynamics of natural enemies and herbivores with greater weight; (2) the surface of orchards negatively affects potential predators in maize, but the plant cover of these positively affects certain species of herbivores; (3) alfalfa acts as a crop that contributes predators and herbivores to the cultivation of maize acting as a resource for species with higher effects than semi-natural habitats; and (4) the viral incidence in maize is mainly influenced by the planting date and the cover and presence of grass species at the edges. These results offer additional knowledge about the effects produced by both the composition of the agricultural landscape and the management of the field itself in the abundance and distribution of herbivores, predators and viruses in the cultivation of maize. In addition, they provide a basis for predicting the consequences of the modification of agricultural practices in the biological control of pests and viruses in the cultivation of maize. These results also suggest that local management measures that guarantee minimum levels of biodiversity and sustainability should be considered as the initial basis for the development of more efficient biological control programmes for pests and viruses.

<p>The essay covers the subject of pest management in the developing world with focus on Africa. A small study was conducted in the Babati district in Tanzania. The division of labour is usually quite gender specific. Men have the main responsibility for cash crops while women often are responsible for the families food crops as well as household work and taking care of the children. Pest management often also falls on their lot. Yet women get very little information and education as well as gain access to important resources that could lighten their work load. Farmers generally use chemical pesticides as their main method. In the larger cash crops fields especially, farmers feel that it is too difficult to use other methods with exception for crop rotation and in some cases intercropping. In the smaller plots for family use it was however more common that other methods were used. However chemical pesticides were still used if they could be afforded. Tasks being so gender specific women have different needs than men but they are rarely asked what they need and how they perceive things. There seems to be a lot of bias and great misconceptions when it comes to the importance of women in agriculture.</p>

Canada thistle is a clone forming perennial weed that spreads aggressively and is difficult to control. One approach to managing invasive weeds is integrating numerous tactics instead of relying on a single tactic. Therefore, the objectives of this research were: 1) assess impacts of Hadroplontus litura, common sunflower competition, and soil nutrients on Canada thistle, and 2) investigate head capsule morphometrics and model H. litura developmental timing. Common sunflower competition, low soil nutrients, and H. litura herbivory negatively impacted aspects of Canada thistle growth and reproduction, but effects varied. Additionally, H. litura effects on thistle morphology were mild whereas the effects of soil nutrition and competition were persistent throughout the experiment. Histogram analysis and verification via Dyar?s rule produced adequate larvae categorization by instar number. Logistic thermal time models developed to predict mean developmental time were most accurate for first instar larvae and least accurate for egg stage.

The bluegrass billbug (Sphenophorus parvulus Gyllenhal) and hunting billbug (Sphenophorus venatus vestitus Chittenden) have become important pests of orchardgrass (Dactylis glomerata L.) grown in Virginia, causing 40 - 100% stand losses according to a 2005 survey of over 324 ha (800 ac) of orchardgrass. Their sheltered feeding habits combined with a lack of labeled insecticides for orchardgrass make billbug control extremely difficult for this crop. Over two seasons, orchardgrass fields were surveyed for paired feeding holes caused by feeding of the billbug spring adult. Simultaneously, barrier pitfall traps, a standard method for determining the presence of billbugs in orchardgrass, were used to trap billbug adults in the fields. A comparison of these methods using a Wilcoxon sign-ranked test found no significant differences in the time when paired feeding holes were first observed in fields and when billbug adults were first trapped, showing that the methods are equally satisfactory for determining the presence of billbugs in orchardgrass. In addition, temperature data from SkyBit E-Weather® service, which are currently used to alert growers and other interested parties of pertinent billbug activity in orchardgrass, was compared to data from a field-based weather data logger over the two seasons. A comparison of these data showed high coefficients of correlation, indicating a close relationship between these two degree-day collection methods. Therefore, the SkyBit system can continue to be used for the alert system. A field-border application of Metarhizium anisopliae (Metschnikoff) Sorokin strain F52 (Met-52), an entomopathogenic fungus, was evaluated against billbug adults as they enter orchardgrass fields in the spring. Randomized pairs of treated and untreated plots were placed along the edge of an orchardgrass field in studies over two seasons. Plots were monitored for billbug adults using barrier pitfall traps, and billbug adults were checked for Met-52 infection. The Met-52 proved unsatisfactory for controlling billbugs in this study. A field efficacy trial was used to evaluate several insecticides and Met-52 against billbug adults in orchardgrass over two seasons. A randomized complete block design, four insecticide treatments and an untreated control were used in each of two trials. Samples from each treatment plot were dissected and checked for billbug life stages and for injury to orchardgrass plants. In one trial, plants in the Sevin XLR Plus® treatment were found to have a significantly higher percentage of injury to the crowns than all other treatments except Mustang Max. No other significant differences were seen in this study.<br>Master of Science in Life Sciences

Genetic transformation techniques for pest insects have enabled the development of novel methods to mitigate the enormous harm done by insects to human health (through transmission of diseases) and to agriculture (through damage to crops or livestock). I use mathematical modelling to analyse strategies using autocidal genetic constructs (dominant lethal genes that are repressible during mass-rearing); in parallel several research groups are developing the strains and the laboratory and field experimental work. Engineered insects would be released in large numbers and compete for mates, and their progeny would inherit one copy of a dominant lethal gene and die. The lethal mechanism can be made stage- or sex-specific. The aim is to reduce the number of pest insects in a population, suppressing numbers to a less harmful level or local elimination. I examine the evolutionary, ecological, and economic cost and benefit aspects of these novel interventions. I consider application of this genetic technology against agricultural pest insects, combined with genetically modified crop plants engineered to produce insecticidal toxins, to which field-evolved resistance is emerging. Using a theoretical framework, I analyse the gene frequency evolution of resistant alleles and show that strategies using genetic constructs that are selectively lethal only to females could help to manage both pests and resistance. I investigate potential resistance to the lethal mechanism of the genetic construct itself. I use population genetics and population dynamics models to explore the impact of heritable biochemically-based resistance on the effectiveness of genetic strategies for reducing populations of important pests in agriculture or public health. Released insects are homozygous for susceptibility to the lethal construct; this has an inherent element of resistance dilution. Finally, I analyse genetic vector control methods to reduce the transmission of human disease. I combine vector population dynamics and epidemiological models with techniques for assessing cost-effectiveness of a genetic strategy for controlling a vector mosquito, and show that disease elimination is feasible on a practical timescale and economically beneficial.

Thesis (M.S.)--West Virginia University, 2001.<br>Title from document title page. Document formatted into pages; contains vii, 48 p. Vita. Includes abstract. Includes bibliographical references (p. 33-34).

Five foliar insecticide treatments (Esteem, two rates of Provado, two rates of Applaud, Prev-am, and Danitol + Lorsban) were evaluated for their control of woolly whitefly infestations in grapefruit. All of these products demonstrated efficacy in mitigating woolly whitefly populations. Danitol + Lorsban was the best knock-down treatment evaluated, but for sustained control, Esteem appeared to be most effective. Applaud demonstrated good activity, but the rate we tested may be a little low; the 1.0 lb/ac rate should be evaluated. Provado at 19 oz/ac was a good treatment, while the 10 oz/ac rate appears to be sub-par. Prev-am is a oil based contact material and demonstrated good initial activity. Soil injections of 16 and 32 oz/ac of Admire were very effective against WWF, and there were no detectable differences between the two rates. Previous experiments with soil injections of Admire in citrus suggested that as much as six weeks needs to pass before the trees have enough time to adequately take up the Admire from the soil. However, these data suggest that smaller trees, about 10 ft tall, may require as little as two weeks to pick up the material.

Growers, Pest Control Advisors and Cooperative Extension, University of Arizona personnel coordinated areawide pest management activities in an area near Gila Bend, AZ to maximize the effectiveness of strategies to control pink bollworm and whitefly. Data on insect populations and pesticide applications is held within a database that is shared with cooperators on a real time basis. Control measures are discussed and common goals reached for reduction of pests within the area. Assessments from growers support the whitefly survey activities of the personnel. Fields were surveyed once per week. Data describing the population is faxed or phoned to the Pest Control Advisor and remedial action implemented at their discretion. Cooperative Extension personnel suggested pesticide use patterns to reduce resistance of whitefly and checked for field populations using University of Arizona recommendations. In 1995 an areawide pin head square program was followed based on Heat Units After Planting for timing pink bollworm susceptible stage of the cotton plant for each field and combined with the Heat Unit Model for pink bollworm emergence to determine percent emergence of the population. In 1996, many of the growers planted genetically engineered cotton and used lures to reduce pink bollworm and used the insect growth regulators under the Section 18 for whitefly control.

Eight foliar insecticide treatment regimes (single applications of Esteem, Danitol + Lorsban, Applaud, Provado and Prev-am, and two applications of Applaud, Provado, and Prev-Am) were evaluated for management of woolly whitefly infestations in grapefruit. All of these products demonstrated efficacy in mitigating woolly whitefly populations. Danitol + Lorsban appeared to be the best knock-down treatment evaluated, but Provado and Prev-Am also demonstrated good activity. For sustained control, all of the treatments were effective; however, Prev-Am required an additional application to achieve equivalent control. Soil injections of 16 and 32 fl-oz/ac of Admire were very effective against WWF, and there were no detectable differences between the two rates. The Admire appeared to require about 27 days after injection to demonstrate consistent activity.

Thesis (MSc)--Stellenbosch University, 2015.<br>ENGLISH ABSTRACT: Grapevine leafroll disease (GLD), caused by the members of the family Closteroviridae, is one of the most economic important viral diseases affecting grapevine. Grapevine leafroll associated virus 3 (GLRaV-3), of the genus Ampelovirus, is the most widespread member of the leafroll associated virus family. To prevent the spread of GLD, management strategies such as rogueing and insect vector control are required to limit crop losses. Alternative control strategies based on genetic modification of the grapevine genome, such as pathogen-derived resistance (PDR), is proven to be effective in conferring resistance to several viruses. Therefore, the focus of this study was to evaluate pathogen-derived resistance strategies for GLRaV-3 using the following two approaches; 1) evaluation of transgenic plants expressing a dysfunctional GLRaV-3 heat shock protein 70 homolog (HSP70h) in order to confer resistance against GLRaV-3, and 2) the construction of artificial microRNAs (amiRNAs) to use as a tool for silencing specific sequences of GLRaV-3 in the grapevine host and the development of an amiRNA-mediated silencing validation system. In the first part of this study, six transgenic plant lines (plant lines #1, #3, #9, #14, #15 and #17) as well as a non-modified plant line, were inoculated with GLRaV-3 by grafting buds of each onto GLRaV-3 infected plant material. After approximately five months, GLRaV-3 virus titres of all grafted plants were quantified relative to two reference genes using RT-qPCR. Results were evaluated by comparing the relative virus titre of each transgenic plant line to that of the non-modified control plant line. Results showed that resistance levels of plant line #3 was significantly enhanced (>99%) and remarkably, plant line #14, showed to be more susceptible to the virus. The second part of the study was the construction and validation of amiRNAs targeting GLRaV-3 sequences. Two 21 nt regions of GLRaV-3 were successfully incorporated into miRNA backbone vvi167b of grapevine. Moreover, target constructs were developed by incorporating corresponding GLRaV-3 target sequences into the 3’ UTR of a green fluorescence protein (GFP) gene. Subsequently, the target constructs were co-infiltrated with the constructed amiRNA in Nicotiana benthamiana and GFP expression levels were quantified to determine the silencing efficiency of the amiRNAs. Results showed that the amiRNAs were successful in silencing the GFP target construct, however, they were not specific in silencing exclusively their corresponding target. These amiRNA constructs are ideal for further viral studies to determine the efficiency of silencing GLRaV-3 in GLD infected grapevines.<br>AFRIKAANSE OPSOMMING: Wingerd rolblaar siekte (GLD), wat veroorsaak word deur die lede van die familie Closteroviridae, is een van die ekonomies mees belangrike virus siektes van wingerd. Grapevine leafroll-associated virus 3 (GLRaV-3), van die genus Ampelovirus, is die mees wydverspreide lid van die rolblaar geassosieerde virus familie. Om die verspreiding van GLD te voorkom, is bestuur strategieë, soos die verwydering van geïnfekteerde plante en insekvektor beheer, ’n vereiste om oes verliese te beperk. Alternatiewe beheer strategieë gebaseer op genetiese modifikasie van die wingerdgenoom, soos patogeen-afgeleide weerstand (PDR), is bewys om effektief te wees in die verlening van weerstand teen verskeie virusse. Daarom was die fokus van hierdie studie om patogeen-afgeleide weerstand strategieë vir GLRaV-3 te evalueer met behulp van die volgende twee benaderings; 1) die evaluering van transgeniese plante wat 'n disfunksionele GLRaV-3 hitte-skok proteïen 70 homoloog (HSP70h) uitdruk, ten einde weerstand te verleen teen GLRaV-3, en 2) die konstruksie van kunsmatige mikroRNAs (amiRNAs) om te gebruik as 'n instrument vir die ondrukking van spesifieke genoomvolgordes van GLRaV-3 in die wingerd gasheer en die ontwikkeling van ’n stelsel om amiRNA-bemiddelde onderdrukking te bevestig. In die eerste deel van hierdie studie, is ses transgeniese plant lyne (plant lyne # 1, # 3, # 9, # 14, # 15 en # 17) sowel as 'n nie-gemodifiseerde gesonde plant lyn, geïnokuleer met GLRaV- 3 deur enting van ogies van elk op GLRaV-3 besmette plantmateriaal. Na ongeveer vyf maande, is GLRaV-3 virus konsentrasies van alle ingeënte plante gekwantifiseer relatief tot twee verwysing gene deur gebruik te maak van tru-transkripsie kwantitatiewe PCR (RTqPCR). Resultate is geëvalueer deur die relatiewe virus konsentrasie van elke transgeniese plant lyn te vergelyk met dié van die nie-gemodifiseerde kontrole lyn. Resultate het getoon dat weerstand vlakke van plant lyn # 3 beduidend verbeter is (> 99%) en merkwaardig is plant lyn # 14 bewys om meer vatbaar vir die virus te wees. Die tweede deel van die studie was die konstruksie en bevestiging van kunsmatige mikroRNAs (amiRNAs) wat GLRaV-3 genoomvolgordes teiken. Twee 21 nt streke van GLRaV-3 is suksesvol geïnkorporeer in die ruggraat van wingerd mikroRNA vvi167b. Verder is teiken konstrukte ontwikkel deur die inkorporering van ooreenstemmende GLRaV-3 teiken genoomvolgordes in die 3'UTR (3’ ongetransleerde area) van 'n groen fluoressensie proteïen (GFP) geen. Daarna is die teiken konstrukte gesamentlik geïnfiltreer met die gekonstrueerde amiRNA in Nicotiana benthamiana en GFP uitdrukkingsvlakke is gekwantifiseer deur die onderdrukkingsdoeltreffendheid van die amiRNAs te bepaal. Resultate het getoon dat die amiRNAs suksesvol was in die onderdrukking van die GFP teiken konstruk, maar hulle was egter nie-spesifiek in die eksklusiewe onderdrukking van die ooreenstemmende teiken. Hierdie amiRNA konstrukte is ideaal vir verdere virus studies om die doeltreffendheid van GLRaV-3 onderdrukking in GLD besmette wingerdstokke te bepaal.