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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Diversidade de vespas sociais em cultivo de cana-de-açúcar

Silva, Newton José de Jesus 10 February 2012 (has links)
Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-05-31T12:20:10Z No. of bitstreams: 1 newtonjosedejesussilva.pdf: 2463847 bytes, checksum: 0f82240e71aba8ce6325845e5404dbf3 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-07-02T12:27:32Z (GMT) No. of bitstreams: 1 newtonjosedejesussilva.pdf: 2463847 bytes, checksum: 0f82240e71aba8ce6325845e5404dbf3 (MD5) / Made available in DSpace on 2016-07-02T12:27:32Z (GMT). No. of bitstreams: 1 newtonjosedejesussilva.pdf: 2463847 bytes, checksum: 0f82240e71aba8ce6325845e5404dbf3 (MD5) Previous issue date: 2012-02-10 / CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico / O Brasil ocupa atualmente o primeiro lugar na lista dos produtores de cana-de-açúcar, sendo o estado de Minas Gerais segundo maior produtor da região sudeste. O comportamento predatório das vespas sociais está intimamente relacionado à fase larval de insetos pertencentes à ordem Lepidoptera, muitas delas, pragas em sistemas agrícolas. Este trabalho objetivou conhecer a diversidade de vespas sociais (Hymenoptera: Vespidae, Polistinae) em cultivo de cana-de-açúcar, identificando quais espécies são capazes de nidificar neste ambiente, bem como analisar sua propensão a mudanças na diversidade e abundância, em face às fases de desenvolvimento da cana e às variáveis climáticas (temperatura (°C), umidade relativa do ar (%) e precipitação (mm)). Complementarmente foi avaliada a eficiência das formas de amostragem utilizadas. As coletas foram efetuadas de julho de 2010 a junho de 2011, sendo baseadas em dois métodos de amostragem (armadilhas atrativas contendo suco de maracujá, água com açúcar, caldo de sardinha e água e buscas ativas). Neste estudo foram coletadas 1091 vespas sociais, distribuídas em sete gêneros e 20 espécies, sendo Agelaia vicina a mais abundante. Pelo índice de eficiência, a busca ativa foi o método com melhor desempenho capturando 90% das espécies, seguida por suco de maracujá (35%) caldo de sardinha (20%) e água com açúcar (5%). Foi observada estabilidade na curva acumulativa de espécies a partir do oitavo mês de amostragens e uma tendência a assíntota na curva de variância confeccionada pelo estimador de diversidade Jackknife. Das espécies estimadas, 95% foram amostradas, indicando um esforço amostral próximo do ideal. A maior riqueza foi encontrada nos meses quente/úmido (outubro/2010 a abril/11), com pico referente ao mês de outubro de 2010 (12 espécies). Não foi encontrada correlação significativa entre nenhuma das variáveis climáticas avaliadas (temperatura (°C), umidade relativa do ar (%) e precipitação (mm) e a riqueza de espécies (r=0,2379; p=0,4566), (r=-0,5208; p=0,0825) e (r=0,0860; p=0,7905) assim como entre variáveis climáticas e a abundância das vespas, (rs=-0,3713; p=0,2347), (rs=-0,4476; p=0,1445) e (rs=-0,3916; p=0,2080). No entanto, houve significativa correlação negativa entre riqueza de vespas e altura da cana-de-açúcar (r= -0,4360; p= 0,05). Das espécies com nidificações encontradas em meio ao cultivo, Mischocyttarus drewseni e Polistes simillimus, foram qualificadas como constantes, ao final deste estudo. Foi ainda observada presença das vespas sociais durante todo o período de estudos, possuindo picos máximos de abundância e diversidade em meses coincidentes 23 aos períodos de brotamento e desenvolvimento da cultura de cana-de-açúcar. Das espécies amostradas, ao menos nove são conhecidas como predadoras de insetos praga em sistemas agrícolas, sendo que cinco destas tem como parte de sua fonte alimentar, lagartas de insetos fitófagos em culturas de cana-de-açúcar, sugerindo que as vespas sociais têm potencial para serem utilizadas como inimigos naturais de insetos pragas em culturas similares. / Brazil is nowadays the world's first sugar cane producer, being the state of Minas Gerais the second biggest in the southwest region. The predatory behavior of social wasps is intrinsically connected to the larval phase of insects of the Lepidotera order, many of them being pests in agricultural systems. This research’s objective is the know the variety of social wasps in the growing of sugar cane, identifying species that are cable to nest in such places. Also to analyze its tendency to change in diversity and number, regarding the sugar cane's growing phases and the weather variations (temperature (°C), relative humidity (%) and precipitation (mm)).The methods of sampling efficiency was also evaluated. The samplings took place between July 2010 and June 2011, using two different methods [attractant snares (passion-fruit juice, water and sugar and sardine broth) and active search]. Within the study 1091 social wasp were collected, ranging between seven genres and 20 species, Agelaia vicina being the most common. By its efficiency index, the active search was the most effectual method attracting 90% of the species, followed by the passion-fruit juice (35%), sardine broth (20%) and water and sugar (5%). Stability was observed on the cumulative species curve starting in the eighth month of sampling and a asymptote tendency on the variance curve made by the Jackknife diversity estimator, indicating satisfactory sampling effort. The Biggest species richness was found during hot/humid months (October/2010 to April 2011), with maximum being in October 2010 (12 species). Relation between the observed climatic variables was not found (temperature (°C), relative humidity (%) and precipitation (mm) and species richness (r=0,2379; p=0,4566), (r=-0,5208; p=0,0825) e (r=0,0860; p=0,7905) so as, between climatic variables and abundance of wasps, (rs=-0,3713; p=0,2347), (rs=-0,4476; p=0,1445) and (rs=-0,3916; p=0,2080), but there was a discernible negative co-relation between the number of wasps and the sugar cane's height (r= -0,4360; p= 0,05).In the end of the research, between the species in which nests were found around the growing area, Mischocyttarus drewseni e Polistes simillimus, were qualified as constant. It was also observed the constant presence of social wasps throughout the whole research period, having maximum number of abundance and diversity in the months of sprouting and development of the sugarcane crop growing. From the sampled species, at least nine are known as pest insects’ predators in agricultural systems, five of them having as part of its source of nourishment, caterpillars of herbivore insects in sugar cane growing areas, 25 suggesting that social wasps have potential to be utilized as natural enemies of pest insects in crops of similar characteristics.
72

Variability in abundance of the rosy apple aphid (Dysaphis plantaginea), the role of its alternate host (Plantago major), and potential control strategies in organic apple orchards in British Columbia

Brown, Amanda Erica 05 1900 (has links)
The rosy apple aphid, Dysaphis plantaginea, (Homoptera: Aphididae) is a serious pest of apples in British Columbia (BC), Canada and especially in organic orchards where conventional controls cannot be used. The goals of this study were to determine the environmental or management factors of an orchard that lead to high aphid populations, to conduct an economic assessment of the damage, to determine the timing of autumn migration, and to test several autumn and spring chemical control methods and two novel autumn mechanical control methods targeting the aphids while on their alternate host, Plantago major. To explain the variation among orchards, I evaluated several potential correlates of aphid density: abundance of the alternate host (plantain, Plantago major), foliar tree nitrogen, tree age, tree planting density, and the application of an oil treatment in spring. Stepwise regression indicated that foliar nitrogen and tree age explain 27% of the variation. Orchards receiving a spring oil application had a 53% lower average aphid infestation level. Plantain abundance was not related to aphid population on apple. However, experimental manipulation of leaf angle from the ground and size showed that significantly more alate and apterous aphids occurred on large, low angle leaves. Mowing prior to spring aphid migration was associated with 75% fewer alatae and apterae on the plantain. The loss in harvest resulting from aphid damage ranged from 3% to 76% of the crop. Effective autumn control depends on accurate timing of aphid flight. The peak of female flight occurred on the 27th of September, 2007 at 11:56 hours daylength (sunrise to sunset) and the peak of male flight occurred on the12th of October, 2007 at 11:02 hours daylength. Aphid densities in the spring of 2008 were very low, making comparisons between treatments and controls difficult. Autumn applications of Superior dormant oil and kaolin clay were not effective. The PureSpray Green treatments of two October applications and one April application showed a significant reduction in rosy apple aphid infested clusters compared with the untreated control. Mowing and rotavating did not result in a significant reduction in aphid infestation level. / Land and Food Systems, Faculty of / Graduate
73

Determining the response of the bed bug (<i>Cimex lectularius</i> L.) to heat exposure at the population, behavioral, and physiological levels

Aaron R Ashbrook (8771363) 29 April 2020 (has links)
The focus of this dissertation is on bed bug thermal biology. How bed bugs react to heat exposure at the population, behavioral, and physiological levels was explored. The thermal tolerance of different bed bug populations and sublethal effects heat exposure were investigated. The temperatures that cause bed bugs to flee from their harborages was determined using a custom made arena. How bed bug physiology changes after heat exposure was determined using RT-qPCR. Finally, how conspecifics react to bed bugs that have been lethally exposed to heat was determined using still air bioassays.<br>
74

IPM in Midwestern Agriculture: Implications to Pests, Pollinators, and Yield

Jacob R Pecenka (11797601) 19 December 2021 (has links)
<p>There is an existing conflict thrust upon U.S. food production systems; optimize crop yield to provide sustenance to a growing population while minimizing ecological impacts of high-intensity agriculture. This balancing act is experienced by Indiana’s watermelon growers who must maintain marketability of a crop that is reliant on insect pollinators. The dependence on pollinators to produce yield means that growers have to consider the negative impacts pesticide applications may have on both the desired pest and non-target pollinators. Navigating these trade-offs must be considered not just in the watermelon fields, but the surrounding agricultural landscape that has become increasingly reliant on prophylactic insecticides to control pests. This dissertation work results from an intensive set of experiments replicating grower practices in experimental fields throughout Indiana to assess the relationships of pests, pollinators, and crop yield.</p> Beginning with a priming year in 2017, watermelon plots were planted within larger corn fields to replicate the agriculture landscape and provide a “snapshot” of typical environment. These plots were paired at multiple locations and provided a contrast between a conventional management system that replicates grower insecticide programs with an IPM approach that removes insecticide applications outside of those based on scouting recommendations. I found that, while pest abundance and damage was higher in IPM fields, the increased pollinator visits in IPM fields led to higher yields in watermelons while corn yield was unaffected by an absence of insecticide use. Managed pollinator hives were placed in these fields and IPM resulted in the colonies exhibiting greater weight gain, lower mortality, increased reproductive growth, and higher insecticide residue accumulation. Insecticide residues were found more frequently at higher levels in the leaf tissue, crop pollen, field soil, and honey bee-collected pollen taken from CM fields. Despite these findings, there was a variable effect of the surrounding land use on the quality of collected pollen or the insecticides gathered by pollinators. These experiments demonstrate that IPM is a viable set of practices for specialty crop growers in the Midwest; successfully monitoring insect pests and conserving pollination services from both managed and wild pollinators. These findings provide a comprehensive look at the effect of IPM practices not just on the a specialty crop, but to the surrounding agricultural landscape as well. An IPM approach can be implemented by growers to decrease non-target effects from insecticides while maintaining or even improving productivity and profitability.
75

COUPLING BOTANICAL EPIDEMIOLOGY AND MATHEMATICAL MODELING FOR THE CONTROL OF BOTRYTIS CINEREA IN VINEYARDS / Coupling botanical epidemiology and mathematical modeling for the control of Botrytis cinerea in vineyards

FEDELE, GIORGIA 17 April 2020 (has links)
Il marciume del grappolo, causato da Botrytis cinerea, è una delle principali malattie che colpiscono la vite. Botrytis cinerea si sviluppa e cresce attivamente come patogeno necrotrofo e saprofita su diversi substrati. In vigneto, B. cinerea può produrre un ampio numero di conidi in un’ampia gamma di condizioni ambientali. Botrytis cinerea ha diversi pathway d’infezione e le infezioni occorrono principalmente in due periodi: dalla fioritura allo sviluppo dei giovani grappoli, e dopo invaiatura alla raccolta. A causa della complessità del ciclo di vita di B. cinerea e all’esistenza di questi diversi pathway d’infezione, i fungicidi vengono normalmente applicati a fine della fioritura (A), pre-chiusura del grappolo (B), invaiatura (C), e prima della raccolta (D). Le applicazioni durante la prima parte della stagione (A e B) hanno come obiettivo: i) la riduzione della germinazione dei conidi e le infezioni fiorali, ii) la prevenzione delle infezioni latenti delle bacche, e iii) la disinfezione dei residui di fioritura. Le applicazioni successive all’invaiatura (C e D) hanno lo scopo non solo di prevenire le infezioni durante la maturazione ma anche di disinfestare i residui di fioritura rimasti all’interno del grappolo. Questa strategia, basata su quattro trattamenti, garantisce una buona protezione contro il marciume del grappolo in vigneto, tuttavia presenta alcuni limiti: i) si tratta di un approccio preventivo che non considera il reale rischio d’infezione, con il conseguente effetto di eseguire trattamenti non necessari; ii) aumenta la probabilità che si sviluppino popolazioni resistenti ai fungicidi; iii) implica potenziali risvolti negativi sulla salute umana e sull’ambiente. Negli ultimi anni, nuove tipologie di prodotti, come gli agenti di biocontrollo (BCAs) e i botanicals, sono state proposte per ridurre l’uso eccessivo di prodotti chimici e aumentare la sostenibilità del controllo del marciume del grappolo in vigneto. Lo scopo di questa tesi di Dottorato è stato: i) comparare diverse strategie di controllo e valutare l’interazione tra fungicidi con diversi timing di applicazione, ii) valutare l’effetto sulla colonizzazione e sporulazione di B. cinerea su residui fiorali di diversi prodotti (fungicidi, agenti di biocontrollo, e botanicals) applicati con diversi timing; iii) valutare un modello meccanicistico sviluppato da González-Domínguez et al. (2015); e iv) includere all’interno di un modello per il biocontrollo, sviluppato da Jeger et al. (2009), l’effetto delle condizioni ambientali sulle interazioni BCA-patogeno. / Botrytis bunch rot (BBR), caused by Botrytis cinerea, is one of the main diseases affecting grapevine. Botrytis cinerea develops and actively grows as necrotrophic pathogen and as saprophyte on different substrates. In grapevine, B. cinerea can produce a large number of conidia on bunch and leaf trash and rotted berries under a wide range of environmental conditions. Botrytis cinerea has multiple infection pathways and infection mainly occurs in two periods: from flowering to young cluster development, and after veraison to harvest. Due to the complexity of the B. cinerea life cycle and the existence of these different infection pathways, fungicides are usually applied at the end of flowering (A), pre-bunch closure (B), veraison (C), and before harvest (D). The early season applications (A and B) are aimed at: i) reducing conidial germination and infection of flowers, ii) preventing latent infections of berries, and iii) disinfesting the bunch trash. The later-season applications (i.e., the applications from veraison until harvest; C and D) are aimed not only at preventing berry infection during ripening but also at disinfesting bunch trash in order to reduce the inoculum load. This fungicide schedule may results in unnecessary sprays because the applications are preventive and do not take into account the real risk of BBR infections. In the last decades, new products, like biological control agents (BCAs) and botanicals, have been proposed for reducing the excessive use of chemicals in agriculture and increase the sustainable of BBR control in vineyards. The aim of this Doctoral work was to: i) compare different control strategies and evaluate the interactions among fungicides applied at different timings; ii) investigate the effects of different products (fungicides, biological control agents, and botanicals) applied at different timings on B. cinerea bunch trash colonization and sporulation; iii) evaluate a weather-driven mechanistic model developed by González-Domínguez et al. (2015); and iv) include into a model for biological control, developed by Jeger et al. (2009), the effect of environmental conditions on the pathogen-BCA interactions.
76

Assessment of blackfly (Diptera : Simuliidae) problem status and potential biological control agents along the Vaal and Orange Rivers in South Africa

De Beer, Chantel Janet 30 July 2009 (has links)
Blackflies (Diptera: Simuliidae) are major pests in the livestock and labour-intensive farming systems along the major rivers in South Africa. At present, blackflies are controlled with the larvicide Bacillus thuringienses var. israelensis (B.t.i.). As part of establishing an environmentally friendly and cost-effective Integrated Pest Management (IPM) program against blackflies, investigations were initiated to support the present blackfly-control strategy in South Africa. Emphasis was placed on potential predators and parasites of the blackflies’ aquatic stages. Questionnaires were presented to livestock farmers along the Vaal and Orange Rivers to determine public views concerning blackfly annoyance. Furthermore, blackfly populations at thirteen sites along the Orange River, twelve along the Vaal River and one site along each of two tributaries to the Vaal River, namely the Riet and Harts Rivers, were monitored seasonally for one year. The abundance of the aquatic stages of blackflies and potential predators on stones and vegetation in the river was determined using the 10-point visual ranking system of Palmer (1994) and the South African Scoring system (SASS 5), respectively. The abundance of algae as well as other environmental factors, namely water flow, water temperature and turbidity, were also monitored. Farmers who were contacted along both the Vaal and Orange rivers indicated that they experience severe blackfly problems during the summer months and that the majority of farmers were not aware of any products available that could protect their animals against blackfly attacks. The farmers also indicated that they were willing to be involved in blackfly research to improve this situation. Blackfly larvae and pupae were found in high abundance in both the Vaal and Orange Rivers. Simulium chutteri was the most abundant species in the Orange River and S. adersi in the Vaal River. In both the Vaal and Orange Rivers there was no significant correlation between immature blackfly abundance and water flow and turbidity. Water temperature also played a role in the seasonal build-up of blackflies in the winter months. The three most abundant algae classes were Bacillariophyceae, Chlorophyceae and Cyanophyceae. Cyanophyceae was the only algae group that had a negative correlation with blackfly immature abundance in the Orange River; this was not statistically significant. There were no negative correlations in the Vaal River. In both the Vaal and Orange rivers, blackflies were infected with Mermithidae nematodes and Microspora protozoans. In the Vaal River, the infection prevalence in natural conditions was the highest for Microspora and in the Orange River the highest for Mermithidae. The most important families of blackfly predators identified were Hydropsychidae and Gyrinidae. Hydropsychidae was the only family recorded in high abundance but this predator had no effect on abundance of immature blackfly. Gyrinidae gave a negative correlation with immature blackfly abundance; however, this was not significant. The biological control agents identified in this research need to be evaluated further for use in an IPM approach with the current control system, B.t.i. Copyright / Dissertation (MSc)--University of Pretoria, 2008. / Veterinary Tropical Diseases / unrestricted
77

Developing attractants and deterrents for a push-pull striped cucumber beetle management system

Christie N Shee (12635509) 25 May 2022 (has links)
<p>In insect pest management, the plant volatiles and pheromones associated with host-plant location can be used to manipulate insect pest behavior by attracting or “pulling” insects from a valuable resource. Conversely, deterrents can be used to prevent behaviors or “push” insects away from a resource. If combined, attractants and deterrents can have powerful synergistic effects that promote greater response than the individual components. This dissertation explores the use of attractants and deterrents of the specialist herbivore and challenging agricultural pest, the striped cucumber beetle, <em>Acalymma vittatum</em>, to ultimately develop a push-pull management system. </p> <p><br></p> <p>In first chapter, we examine the combination of two striped cucumber beetle attractants in attract-and-kill mass trapping: live striped cucumber beetles as a proxy for aggregation pheromone, and cucurbit floral volatiles. In the second chapter, we examine natural products—essential oils, pawpaw extract, squash bugs, and kaolin clay—as a means for repelling or deterring beetles from cucurbit crops. Lastly, we combine the findings of previous chapters as way of using both attractive and deterrents to further modify striped cucumber beetle behavior and to observe potential synergies in removing these pests from cucurbit crops. In this, we use the aggregation pheromone and floral lures in attract-and-kill trapping with the deterrent kaolin. </p> <p><br></p> <p>We found that while aggregation pheromones and floral lures were useful in trapping striped cucumber beetles, floral lures may potentially distract pollinators. Striped cucumber beetle response to floral lures varied across the season and were most attractive in the late growing season, when plants were in bloom. The tested natural products did not successfully prevent beetles from colonizing plants, but instead deterred the specialist herbivore from feeding. While the attractant and deterrent did not have a synergistic effect, they remained complementary in that aggregation pheromones were useful in reducing pest populations, while kaolin clay deterred feeding. Thus, pest management systems should be flexible in timing and type of management used, and should look toward other metrics, such as feeding damage, rather than population density thresholds to measure management success. </p>
78

Adoption Analysis and Impact Evaluation of Potato IPM in Ecuador

Carrion Yaguana, Vanessa Del Rocio 02 July 2013 (has links)
There are several well-known negative side effects associated with pesticide use such as health problems and environmental pollution.  Integrated Pest Management (IPM) seeks to minimize pesticide use while reducing pest infestation to economically tolerable levels.  The introduction of IPM CRSP activities in Ecuador to institutionalize IPM methods focused on priority crops in the country. This study analyzes adoption and the economic impacts of IPM technologies on potato production in the province of Carchi. A model is estimated in which IPM adoption is discrete and ordered and pesticides expenditures are estimated as a function of education, farming experience, wealth, plot size and farmer being sick due to pesticide use for each level of IPM adoption. Results indicate that farmers who were exposed to certain IPM information sources increased adoption of IPM practices on potatoes, but farmers\' education and experience were not important factors in explaining IPM adoption. The calculated economic benefits in terms of aggregate cost savings per production cycle were $823,000. / Master of Science
79

Understanding Japanese Maple Scale Biology to Inform Sustainable Pest Management Practices in Virginia Nurseries

Wyatt, Mollie McDonnell 04 June 2024 (has links)
Lopholeucaspis japonica (Cockerell) (Hemiptera: Diaspididae), commonly known as Japanese maple scale (JMS), is an invasive pest established in the United States in 1914. Over the past decade, JMS infestations have escalated, posing a significant threat to the nursery industry, and resulting in economic losses from unsellable infested plants. The limited understanding of JMS hampers the development of effective management strategies, intensifying the financial impact of this destructive pest. To contribute to the development of a sustainable pest management program, it is crucial to acquire knowledge of JMS's natural history, biology, and dispersal capabilities. Management costs can be reduced by determining the optimal timing for scouting and spraying through peak crawler emergence and the identification of overwintering life stages. Understanding JMS dispersal patterns within tree canopies can lead to the refinement of scouting methods, such as strategically placing the tape method (for monitoring crawlers). A two-year study took place at two separate locations and on boxwoods (2022-2023) and red maples (2023). Our phenology findings indicated that there were two generations and prolonged crawler presence which can extend over a period of 34 weeks (March-October) during the growing season. The first generation of crawler emergence on boxwoods started as early as the second week of March [110-114 Growing Degree Days in base 50°F (GDD50)], with the first peak occurring in mid-June [1179-1514 GDD50]. The second generation depending on the year began in July and peaked between early September and mid-August due to overlapping from prolonged presence of crawlers. Crawler emergence on maples indicated the first peak during the second week of July, followed by the second peak during the third week of August. Management practices, including monitoring and chemical control and based on phenology data, could be suggested to begin early March and continue throughout the season putting high pressure on crawlers during the peaks of activity. Overwintering studies from this project suggested JMS could be developing throughout winter with immatures found in January and February while in March the highest population was adults. Using horticultural oil during the winter months may help with JMS infestations. To investigate dispersal patterns, the canopy of experimental plants of maples and boxwoods were divided into top, middle, and bottom sections based on plant height. Comparative analysis of JMS crawler densities within the canopies of maples indicated that the middle canopy sections exhibited higher crawler densities compared to the top sections. However, when evaluating all three sections (top, middle, and bottom), the bottom sections displayed the highest crawler densities. Examination of cardinal points within the top and middle canopies of maples revealed a widespread distribution pattern. In contrast, no significant differences in crawler densities were observed between the various canopy sections of boxwoods, indicating a uniform distribution across the plant. / Master of Science in Life Sciences / Japanese maple scale (JMS), scientifically known as Lopholeucaspis japonica, is an invasive pest damaging ornamental plants in the United States since 1914, particularly affecting the nursery industry in the Southeast, including Virginia. This study aimed to enhance the understanding of JMS phenology, overwintering biology, and dispersal patterns. A two-year study took place at two separate locations and on boxwoods (2022-2023) and maples (2023). Phenology and dispersal patterns were monitored using the tape method to count crawlers per cm². Over two years, 100 JMS specimens were inspected monthly for three consecutive winter months to record overwintering life stages. Across both years and crops there were two peaks of activity with the first peak being between June and July and the second falling in between August and September. For overwintering, higher numbers of JMS immatures were found in January and February, and adults in March. To investigate dispersal patterns, the canopy of experimental plants of maples and boxwoods were divided into top, middle, and bottom sections based on plant height. Comparing JMS crawler densities in maples between the top and middle canopy sections revealed higher densities in the middle. However, when all three sections in maples were compared, the bottom had the highest density of crawlers. Cardinal points within the top and middle canopies were investigated for maples only and showed a widespread distribution when examining those points. For boxwoods, no significant difference was found in crawler densities between plant sections. This knowledge will empower nursery growers to make informed decisions, optimize their efforts in monitoring and control, and minimize the economic impact caused by JMS infestations.
80

Understanding Red Headed Flea Beetle Biology to Inform Sustainable Pest Management Practices in Virginia Nurseries

Lane, Eleanor Lynn 16 February 2023 (has links)
Systena frontalis (F.) (Coleoptera: Chrysomelidae), the red headed flea beetle (RHFB), is a ubiquitous pest of ornamental nursery crops in the eastern United States. Defoliation by adults renders plants unsaleable. Control costs and economic losses from injured plants have become a top concern among Virginia nurseries in the past decade. Current management tactics include spraying insecticides up to three times a week during the adult active season. The frequent use of insecticides poses a risk to the environment, non-target organisms, and evolution of resistance within the targeted beetle population. To develop a sustainable pest management program, more information is needed to understand pest biology, quantify the injury potential, and explore control tactics. Methods to monitor this beetle were used to observe peak activity throughout the growing season as well as the adult daily activity levels. There were three observed generations with population peaks in late June, late July, and late August into early September. Within the scale of one day, adult beetles were found to be diurnal with peaks in activity in the middle of the day. These findings will inform growers of the most efficient times to scout and spray, ultimately reducing insecticide usage. Quantification of feeding damage to individual leaves, the entire plant, and preference between older and newer growth may relate plant injury with specific population densities. The use of phenyl ethyl alcohol as an attractant lure, was explored to bolster pest control. Finally, insecticide bioassays were performed to compare those currently used to others yet untested. / Master of Science in Life Sciences / The red headed flea beetle (RHFB) is an important pest of ornamental crops in open-field nurseries along the Eastern United States. Defoliation caused by adult feeding renders plants unsellable. Japanese hollies, hydrangeas, and sweetspire iteas are among the most affected plants. Infested nurseries suffer severe economic losses due to insecticide costs and plant inventory reductions. Growers are spraying insecticides up to three times a week to manage RHFB. Frequent use of insecticides poses risks to the environment non-target organisms. This study will help improve control tactics for this pest and potentially minimize non-target effects by reducing insecticide usage. Understanding when beetles are active throughout the day, and throughout the growing season, may inform timing of scouting and insecticide sprays to maximize effectiveness. With populations highest in late June, late July, and late August, RHFB is estimated to have three generations per year. Adults are most active in the middle of the day and sedentary at night. It was observed how different densities of beetles cause injury to individual leaves and entire plants, and compared feeding preference on older versus newer growth. Chemical control tactics were explored including insecticides labeled and not labeled for RHFB such as iscycloseram. Finally, the effectiveness of phenyl ethyl alcohol as an attractant lure for RHFB was assessed and found ineffective within the open-field nursery ecosystem.

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