Dissertations / Theses on the topic 'Insect; Disease'

Forest insect and disease pests alter the appearance of trees, thereby impacting visual resources. Because of the complexity of most forest landscapes, the degree of visual impact of pest-infested forest stands is difficult to quantify. This paper describes a method of measuring visual impacts of pest-infested forest stands. Photographs of healthy Ponderosa pine trees were entered into a computer video-image-processing system. Using this system, images of trees were altered to simulate different degrees of infestation by limb rust, a forest pathogen. The altered and unaltered images were shown to groups of observers who rated the scenes in terms of "scenic beauty." The great majority of individuals were able to detect a change in the appearance of trees infected with limb rust disease even when only small sections of a tree were altered. There was also general agreement within the groups of observers that the presence of limb rust disease had a detrimental effect on the visual quality of the forest scenes. The tests also suggested that the location of infestation in the tree crown, the amount of crown mortality, and the number of infected Ponderosa pine in a stand influenced the degree to which visual quality was impacted.

Parkinson’s disease (PD) is the second most common neurodegenerative disorder, affecting approximately 1% of the population over the age of 65. Around 5% of these cases can be linked to mutations in known genes, one of which is the PINK1 gene, first linked to PD a decade ago. Since then, over 30 mutations in PINK have been described. The PINK1 gene encodes an unusual serine/threonine protein kinase; uniquely among protein kinases, PINK1 is anchored to the mitochondria and furthermore possesses three unusual insertions of unknown function in the N-lobe of its kinase domain. Recently, two important PINK1 substrates have been identified - the ubiquitin E3 ligase Parkin and ubiquitin itself. Phosphorylation of both of these substrates has further been shown to be necessary for the activation of Parkin E3 ligase activity. At the start of this project, little was known about the catalytic properties of PINK1 or the effects of the identified PD- linked mutations due to the lack of a robust in vitro assay for PINK1 activity. In addition, the mechanisms by which PINK1 phosphorylation activated Parkin were not understood. The work described in this thesis was carried out with the aim of overcoming these hurdles by using a PINK1 homologue from a more tractable species. In Chapter III of this thesis, I describe the identification of a PINK1 homologue from the insect species Tribolium castaneum (TcPINK1) and its validation as a bona fide model for human PINK1. The activity assay established with TcPINK1 is used to show the PINK1 C-terminal domain is required for kinase activity and that TcPINK1 strongly prefers peptide substrates with a +1 proline. Interestingly, this requirement is absent when intact protein substrates are used. TcPINK1 is then used as a model to analyse the effects of PD- linked disease mutations, revealing that all the tested point and truncating mutations lead to a decrease in kinase activity. In most cases activity is completely abolished. In Chapter IV, progress towards the crystal structure of TcPINK1 is described. Several TcPINK1 VI. Summary constructs were expressed and purified to homogeneity and used for crystallisation trials. Crystals were obtained under multiple conditions and some progress was made towards improving their diffraction resolution, although this project did not reach a point at which data could be collected. Lastly, in Chapter V, preliminary data describing the molecular mechanism by which PINK1 phosphorylation of the Parkin Ubl domain at residue Ser65 leads to Parkin activation is presented. An AlphaScreen assay was used to produce data suggesting that PINK1 phosphorylation of the Parkin Ubl domain relieves autoinhibitory binding of the Ubl domain to Parkin. Overall, this work provides the PINK1 field with a useful tool in the form of a robust and reproducible activity for PINK1 activity using TcPINK1, which has already been utilised several times to facilitate discoveries in both this lab and others. Significant progress has been made towards determination of the crystal structure of TcPINK1, which will provide insight into the molecular mechanisms of PD-linked mutations and may shed light onto PINK1 regulation and function. Finally, preliminary data suggests that PINK1- phosphorylation of the Parkin Ubl domain may activate Parkin via alterations in autoinhibitory intramolecular interactions.

Cassava is the main staple crop in Nigeria. Using primary data from four south eastern states in Nigeria, the study assessed the gender impacts of improved cassava varieties. Comparative statistical analysis reveals that total female labor is higher than total male in cassava production, processing and marketing. Women spend more labor days than males for planting, weeding, harvesting, marketing and processing. The total female family labor is higher for adopters of new improved cassava varieties. There is however lower family labor input for both male and female adopters for clearing and plowing which are normally done by men. Significant determinants of female labor supply are number of children in the household, percent of females in the household providing labor on the farm, area under improved cassava varieties and total land area. There is a positive unexpected relationship between total female labor supply and number of children. For each of the decision making variables, there is a significant association between the gender of the spouse and the decision made except for the decision on family labor allocation. Probit results show a significant decrease in the probability that the wife makes the decision for family labor allocation, what inputs to buy and borrowing and traditional cassava income control with adoption. Results indicate that both men and women spend their income on services directly linked to the householdâ s welfare. More than half of the women ranked food as number one.<br>Master of Science

Studies were undertaken to determine the dispersal mechanisms of Verticicladiella procera Kendrick, the causal agent of Procera Root Disease (PRD). Propagule germinability in artificially infested soil decrease rapidly under natural and controlled conditions. Colonization of seedlings in artificially infested soil was rare and symptoms were not displayed by colonized seedlings. Natural populations of V. procera were closely associated with colonized root tissue. Colonization of field planted seedlings was related to proximity to root collars of diseased trees and insect activity on the seedlings. Insects (Coleoptera) contaminated with V. procera were found in plantations both with and without PRD. The percent of weevils and bark beetles contaminated with V. procera was 64 and 0.76 respectively. Verticicladiella procera was transmitted to white pine bolts in the field and under controlled conditions following visitation by contaminated insects. Verticicladiella procera was associated with larval galleries and frass in trap bolts and was observed fruiting in insect galleries in root systems of diseased trees. This evidence suggests that transmission by insects, especially weevils, is the more important mechanism for dispersal and that soil-borne propagules have a minor role in pathogen spread.<br>M.S.

The ultimate goal of this research was to perform a domain exchange between a computer identified insect specificity region of the mosquito larvicidal protein Cry IVB and a previously identified domain in a related protein toxin which targets lepidopteran insect larvae. If the insect specificity domain has been correctly identified, an exchange of DNA in this manner transfers the toxicity of one peptide to another by an exchange of the insect specificity domains. New, chimeric peptides may be designed which will target a larger spectrum of insect larvae.In previous research a domain exchange was performed between the two genes carried on plasmid vectors in E. coli and low levels of toxicity to mosquito larvae were observed. Initial efforts of this research attempted to identify these recombinants. However, stability was not achieved by sequential colony screens. Furthermore, a recently published three-dimensional structural model for all the B. thuringiensis crystalline toxins became available and it was quickly determined that the first exchanges excluded most of the f3-sheet domain that is responsible for insect cell receptor binding, the feature that gives the toxins their specificity. Therefore, it was decided that a larger, more inclusive region of Cry IVB DNA must be exchanged between the two toxins.Extensive computer analyses of the Cry IVB sequence and retroactive comparison of these sequences to the three-dimensional model yielded a fragment of DNA that encoded more than 60% of the putative insect specificity domain. Oligonucleotide primers were subsequently designed to flank this region so that the polymerase chain reaction could be employed to amplify the region. Additionally, the primers were engineered to contain terminal restriction endonuclease sites to ease in the exchange of the domain encoding region into Cry IA(c). The region of Cry IVB DNA flanked by the oligonucleotide primers was successfully amplified by the PCR and cloned into the plasmid vector pUC 19 as a reservoir for a future domain exchange.<br>Department of Biology

Congress passed a revised Farm Bill in 2014 that amended the Healthy Forest Restoration Act (HFRA) to, hopefully, increase the speed with which natural resource issues could be addressed. Federal land management has often been condemned for being time-consuming and burdensome, chiefly in situations that require rapid response, such as insect disease and fire. The amendment in the 2014 Farm Bill is meant to address this concern. The amendment would allow for the insect and disease restoration projects on U.S.D.A. Forest Service land to fall under the National Environmental Policy Act (NEPA) as categorical exclusions, provided that collaboration occurs while creating and implementing the projects. This new provision could allow for the U.S.D.A. Forest service to create and implement restoration projects at a faster rate than ever before. Each state's Governor was required to nominate restoration lands in their National Forests. These Nominations ranged from very comprehensive to extremely ambiguous and from just a few acres to entire national forests. This research documents why there was variation in designation nominations and what potential benefit this new amendment could bring to future natural resource management.

4 pp.<br>This is part of a series on climate variability and forested ecosystems<br>Recent events in the forests of the Southwest have prompted scientists to consider the role of climate variability in insect and disease cycles. Over 70 million pine trees along with millions of other conifers died in 2002-03. Average temperature increases of 3°C enabled the MPB at those high elevations to achieve univoltine (having one generation per year) reproduction leading to previously unheard of outbreaks in white bark pine at high elevation sites in Idaho.Aspen defoliation in Arizona and New Mexico averaged ~ 20,375 acres from 1990 to 1997. A series of events has contributed to the decline of aspen since 1997.

Various strains of Bacillus thuringiensis Mt.) produce crystalline endotoxins specific for larvae of different insect classes. Two strains, B.t. subspp. israelensis and kurstaki produce similar 130 kDa toxins encoded by the CryIVB gene (toxic to Diptera) and the CryIA gene (toxic to Lepidoptera), respectively. The N-terminal region of the CryIVB gene was cloned into the Escherichia coli expression vector pKX223-3. A mosquitocidal transformant was obtained as determined by mosquito bioassays. The gene fragment, if stable, can be cloned into cyanobacteria to achieve biological control of mosquito-borne diseases. A second goal was to identify the binding specificity domain of the CryIVB gene which encodes the portion of the protein toxin that binds the insect midgut causing cell lysis and death. Two potential insect binding specificity domains identified by computer analyses were switched with a known binding specificity region of the CryIA gene. The polymerase chain reaction was utilized to obtain gene fragments of the CryIVB gene which replaced the CryIA gene binding specificity domain. The resulting recombinant clones carrying the CryIA gene containing the .000nd proposed insect binding specificity domain of the CryIVB gene were fotsd to be mosquitocidal.<br>Department of Biology

A three-year (1998-2000) field and laboratory study conducted in Fredericton, New Brunswick, Canada analyzed and quantified the dispersal of adult Colorado potato beetles within and between conventional and transgenic potato plots established according to the high-dose/refuge strategy. More specifically, the study addressed the following four predictions: (1) Adult Colorado potato beetle abundance or flight activity in transgenic potato fields is positively correlated to the abundance or flight activity in the immediately adjacent refuge field. (2) Colorado potato beetle intraspecific competition on potato plants will increase the flight take-off frequency of adult CPB; tolerating relatively high numbers of CPB egg masses or larvae or a high level of CPB defoliation on potato plants in the refuge could therefore be considered to increase the movement of beetles from the refuge to the transgenic field. (3) CPB flight take-off frequency will be higher on potato plants at the bloom than at the vegetative stage; planting of the non transgenic potato crop in the refuge earlier than the Bt transgenic potato crop in the main field could therefore be considered to increase movement of the Colorado potato beetles from the refuge to the transgenic field. (4) The aggregated distribution of CPB populations in the potato crop is caused by the presence of mating pairs; strategies changing the distribution of males and females in the refuge field could therefore be considered to increase dispersal from the refuge to the main crop field.<br>Population monitoring using plant counts, flight interception traps, flight landing traps and pitfall traps established that a transient population of adult CPB is present in the transgenic potato fields throughout the crop season and that the abundance of the beetle is higher than that required by the high dose/refuge strategy models. Furthermore results showed that the beetles invading the transgenic field population originate as much from the surrounding fields of conventional cultivars as from the adjacent refuges. It would therefore be possible to relax existing requirements for the refuge to be located immediately adjacent to the transgenic crop.<br>Like most insects, the adult CPB populations are aggregated and can be fitted to a negative binomial distribution over the crop season. This study revealed that the distribution results from the presence of mating pairs for the overwintered population and from the clumped pupation for the non breeding summer population. The activity of the males in search of females is at least partly responsible for the higher dispersal activity observed with the overwintered than with the summer populations. The comparatively low level of dispersal activity with the summer population could affect the efficacy of the high/dose refuge strategy during the later part of the crop season.<br>Results of flight chamber tests demonstrated that plant phenology and intraspecific competition have a positive effect on flight take-off frequency. These findings suggest that summer adult dispersal between the refuges and the transgenic crops could be stimulated by manipulating planting dates and the abundance of the different CPB life stages on the plants.<br>Together, the results of the thesis provide support for some of the premises of the high dose/refuge strategy and offer new information on the CPB dispersal that could be used to further improve its efficacy. Although the transgenic potato (NewLeaf) is not commercially available at this time, the threat of CPB resistance to new products or resistant cultivars under development makes it important to continue the research required by CPB resistance management plans.

Glucose was present in substantially greater concentrations in whole body extracts of fourth instar Aedes aegypti L. larvae than was trehalose; in contrast, trehalose was more abundant than glucose in haemolymph extracts. Preliminary studies suggested that infection of Ae. aegypti by the entomopathogenic digenean Plagiorchis elegans Rudolphi alters the carbohydrate metabolism of fourth instar larvae. Within 24 hours of cercarial penetration, total body extracts of infected fourth instar larvae exhibited decreased trehalase activity, increased trehalose-6-phosphatase activity, and an accumulation of trehalose in comparison to uninfected larvae. Concentrations of glucose, glycogen and lipids, and the activity of glycogen phosphorylase a were similar in extracts of infected and control larvae. The predominant fatty acids, in both control and infected larvae, were C 18:0, C 18:1 and C 18:3. There were no significant differences in the types and proportions of fatty acids found in control and infected larvae. Parasitic infection is discussed in terms of impaired trehalose metabolism.

DNA similarity studies were used to determine the species of thirty-one strains of bacteria isolated from the hemolymph of infected larvae from Mexico and throughout Central and South America. Twenty-one of the strains were determined to be <I>Paenibacillus popilliae</I> and ten were found to be more closely related to <I>Paenibacillus lentimorbus</I>. Only one of the <I>P. popilliae</I> strains, an isolate from Mexico, was resistant to the antibiotic vancomycin, a trait characteristic of <I>P. popilliae</I> strains from other geographic areas. As expected, all <I>P. lentimorbus</I> strains were sensitive to vancomycin. The polymerase chain reaction (PCR) was used to amplify a portion of a ligase gene necessary for vancomycin resistance in the Mexican strain. Sequencing of the amplicon revealed a sequence identical to that obtained from a North American strain of <I>P. popilliae</I> previously described. The ability of <I>P. popilliae</I> and the inability of <I>P. lentimorbus</I> to grow on medium supplemented with 2% sodium chloride has been used as a phenotypic trait for differentiating between the two species. Approximately 86% of the <I>P. popilliae</I> strains were capable of growth on medium supplemented with 2% sodium chloride and 60% of the <I>P. lentimorbus</I> strains were not capable of growth on this medium. Microscopic examination revealed that all of the Mexican and Central and South American strains of <I>P. popilliae</I> and <I>P. lentimorbus</I> produced a parasporal body. <p> PCR was used to amplify two different regions of the <I>cry18Aa1</I> gene encoding the paraspore in all of the isolates. One primer pair, CryBP2, detected the <I>cry18Aa1</I> gene in 17 of the 21 <I>P. popilliae</I> strains and in all ten of the <I>P. lentimorbus</I> strains. The second primer pair, CryBP4, detected the parasporal gene in 20 of the 21 <I>P. popilliae</I> strains and in all ten of the <I>P. lentimorbus</I> strains. Thirty of the thirty-one <I>P. popilliae</I> and <I>P. lentimorbus</I> strains produced amplicons of approximately 616 bp with the CryBP4 primers. The CryBP4 primers did not detect the paraspore gene in one of the <I>P. popilliae</I> strains. The CryBP2 primer pair produced amplicons of three different sizes, indicating possible variability in the parasporal proteins of <I>P. popilliae</I> and <I>P. lentimorbus</I>. Eleven of the <I>P. popilliae</I> strains produced CryBP2 amplicons approximately 660 bp in size and six of the <I>P. popilliae</I> strains produced CryBP2 amplicons approximately 1100 bp in size. The <I>cry</I> gene was not detected in four of the <I>P. popilliae</I> strains with the CryBP2 primers. The <I>P. lentimorbus</I> strains produced CryBP2 amplicons approximately 750 bp in size. Three PCR products representing the variable CryBP2 amplicon sizes were sequenced and compared to the published <I>cry18Aa1</I> gene sequence. Sequencing data revealed that the Central and South American CryBP2 amplicons are similar to the published <I>cry18Aa1</I> sequence, however, the 1100 bp amplicon has a 453 bp insert that is not found in the published <I>cry18Aa1</I> gene sequence. <p> Paraspores are produced by <I>P. popilliae</I> and <I>P. lentimorbus</I> and is not a reliable phenotypic trait for differentiation between the two species. The ability of Mexican and Central and South American strains of <I>P. lentimorbus</I> to produce paraspores supports the previous findings of a North American group of <I>P. lentimorbus</I> strains that were also capable of producing paraspores. Except for one Mexican strain of <I>P. popilliae</I>, the Central and South American strains of <I>P. popilliae</I> are sensitive to vancomycin. This was unexpected since all North American strains of <I>P. popilliae</I> are vancomycin resistant. Vancomycin resistance could be useful in identifying strains of <I>P. popilliae</I> from North America but not for identifying strains of <I>P. popilliae</I> from Central and South America. So far, no vancomycin resistant strains of <I>P. lentimorbus</I> have been identified. There was variability in the ability of these organisms to grow on medium supplemented with 2% sodium chloride so the usefulness of this trait is debatable. However, the majority of <I>P. popilliae</I> strains from Mexico and Central and South America will grow on medium supplemented with 2% sodium chloride and the majority of the <I>P. lentimorbus</I> strains from these same areas will not grow on this medium. North American strains of <I>P. popilliae</I> and <I>P. lentimorbus</I> also showed variability of growth on medium supplemented with 2% sodium chloride. <p><br>Master of Science

The mosquito Aedes polynesiensis, a member of the Aedes scutellaris complex, is the main vector in the South Pacific region of the Wuchereria bancrofti parasite, the causative agent of lymphatic filariasis (LF), and is also a major nuisance biter. Decades of Mass Drug treatment (MDA) have not been successful in elimination LF. Two non-vector species in the Ae. scutellaris complex were introgressed with Ae. polynesiensis to attempt to obtain lines that would produce cytoplasmic incompatibility (CI) with wild populations and/or LF-refractoriness. Despite selection of progeny from Brugia-challenged, non-infective females at each backcross, no refractory line was acquired. However, three lines from crosses between aposymbiotic Ae. polynesiensis and Ae. riversi displayed CI and male mating competiveness suitable for the purpose of population suppression using the incompatible insect technique (IIT). A population study was conducted of potential release sites and the evaluation of monitoring tools for Ae. polynesiensis on Moorea and Tetiaroa, French Polynesia. There was no evidence of active migration between selected islets on the atoll of Tetiaroa, suggesting it is a suitable site for field releases of CI males. The BioGents Sentinel trap was shown to be an efficient and convenient trap suitable for Ae. polynesiensis monitoring. The effects of temperature and larval density on life-table parameters relevant to IIT were examined, including: larval survivorship, developmental time to pupation, male to female ratio, male pupae yield, male size and adult male survival. These findings were used to design and conduct a 14-week field experiment testing CI male strain against an isolated population, using optimized rearing conditions. Approximately 8000 males were released weekly on motu Onetahi, Tetiaroa atoll. Significant sterility was induced by Wolbachia in the targeted female population, supporting the development and scale-up of this approach toward Ae. polynesiensis nuisance and LF transmission reduction.

O brócolis (Brassica oleraceae var. italica) é uma das hortaliças mais importantes do país, cujo volume de comercialização na CEAGESP é de aproximadamente 13 mil toneladas por ano. Recentemente, uma nova doença tem causado perdas relevantes para as culturas instaladas na maior região produtora do Estado de São Paulo. Os sintomas característicos da doença são expressos pelo enfezamento da planta e necrose dos vasos de floema. Devido ao fato destes sintomas indicarem a presença de fitoplasmas nas culturas de repolho e couve-flor, localizadas na mesma região geográfica onde foi observada esta nova doença, levantou-se a suspeita de que estes mesmos agentes patogênicos pudessem estar associados com as plantas doentes de brócolis. Assim, o DNA total de plantas de brócolis sintomáticas foi analisado por PCR com primers específicos para a região 16S rDNA de fitoplasmas. Os resultados revelaram que estes patógenos estavam associados com as plantas doentes. Através das técnicas de RFLP do sequenciamento de nucleotídeos desta mesma região genômica, os fitoplasmas foram identificados como pertencentes aos grupos 16SrI, 16SrIII e 16SrXIII. Através de análise de RFLP, fitoplasmas também foram identificados em diversas espécies de plantas daninhas e em cigarrinhas da família Cicadellidae coletadas em áreas adjacentes a campos de produção de brócolis. Fitoplasmas do grupo 16SrIII foram identificados em plantas daninhas das espécies Agetarum conyzoides (mentrasto), Crotalaria lanceolata (crotalária), Lepidium virginicum (mentruz), Nicandra physalodes (juá-de-capote), Paulicourea marcgravii (erva-de-rato), Ricinus communis (mamona), Sida rhombifolia (guanxuma), Sonchus oleraceae (serralha amarela), Bidens pilosa (picão preto), Erigeron bonariensis (buva), Emilia sonchifolia (falsa serralha), Leonorus sibiricus (rubim), enquanto que fitoplasmas do grupo 16SrVII foram encontrados as últimas quatro espécies citadas. Com relação aos insetos, fitoplasmas foram detectados em indivíduos das subfamílias Deltocephalinae, Agalliinae e Typhlocybinae. Dentro da subfamília Deltocephalinae, a cigarrinha Balclutha hebe portava fitoplasma do grupo 16SrI, enquanto que cigarrinhas das espécies Atanus nitidus, Planicephalus flavicosta e Schapytopius fuliginosus abrigavam fitoplasmas do grupo 16SrIII. Nos tecidos de duas cigarrinhas da subfamília Agalliinae e uma da Typhlocybinae, as quais não foram identificadas quanto a espécie, foram encontrados fitoplasmas do grupo 16SrIII. As análises epidemiológicas revelaram um padrão espacial agregado de plantas doentes e a ocorrência de um maior progresso da doença nos bordos dos campos de cultivo de brócolis, que estão localizados nas proximidades de áreas com a presença de plantas daninhas.<br>Broccoli (Brassica oleraceae var. italica) is one of the most important vegetables in Brazil, whose trading volume in CEAGESP is approximately 13 000 tons per year. Recently, a new disease has caused significant losses in this crop cultivated in the largest producing region of the São Paulo State. The characteristic symptoms of the disease are expressed by plant stunting and necrosis of phloem vessels. Because these symptoms indicate the presence of phytoplasmas in cabbage and cauliflower crops, grown in the same geographical region, it was suspected that the same pathogens could be associated with the affected broccoli plants. Therefore, the total DNA from symptomatic plants of broccoli was analyzed by PCR with specific primers for the 16S rDNA of phytoplasmas. Through the techniques of RFLP and nucleotide sequencing of the same genomic region, the phytoplasmas were identified as belonging to the groups 16SrI, 16SrIII and 16SrXIII. Through RFLP analysis, phytoplasmas were also identified in several species of weeds and leafhoppers in the family Cicadellidae collected in adjacent areas of broccoli fields. Phytoplasmas belonging of the 16SrIII group were identified in the weeds belonging to the species Agetarum conyzoides, Crotalaria lanceolata, Lepidium virginicum, Nicandra physalodes, Paulicourea marcgravii, Ricinus communis, Sida rhombifolia, Sonchus oleraceae, Bidens pilosa, Erigeron bonariensis, Emilia sonchifolia, Leonorus sibiricus, while phytoplasmas of the 16SrVII group were found in the last four mentioned species. In respect to insects, phytoplasmas were detected in individuals from subfamilies Deltocephalinae, Agalliinae and Typhlocybinae. Within the subfamily Deltocephalinae, the leafhopper Balclutha hebe carried phytoplasmas of the 16SrI group, while that of the species Atanus nitidus, Planicephalus flavicosta e Schapytopius fuliginosus harbored phytoplasmas of the 16SrIII group. In the tissues of two leafhoppers of the subfamily Agalliinae and one of the Typhlocybinae, which were not identified as specie, were found phytoplasmas of the 16SrIII group. The epidemiological analysis revelead an aggregated pattern of the diseased plants and a higher progress of the diseased in the border of the broccoli fields, whitch were located nearby areas where the presence of weeds was abundant.

Defoliating insect systems, defined for the purposes of this thesis as being composed of insects which defoliate forest trees and the species with which they interact, such as their host trees and their natural enemy complexes, exhibit a wide variety of population behaviors. Similarly, a number of theories and models have been proposed to explain these behaviors. These theories emphasize the importance of different ecological processes, often concentrate on the defoliator and overlook the importance of other components. Also, much of the current understanding of the dynamics of these systems has come from forest pest research and management programs, tailored towards specific pest problems and often very short term in nature. This thesis develops and begins to test a general approach for the local dynamics of defoliating insect systems. This framework outlines the system components that are necessary to predict the behavior of defoliating insect systems. It includes ways in which the equilibrium structure of defoliating insect systems, defined as the number of equilibria for each system component, the population levels at which the equilibria occur, and the processes creating the equilibria, might be found. The framework also includes methods of inducing the qualitative behavior of these sys- terns, defined as the periodicity of defoliator outbreaks, the length of outbreaks, and the dynamics of other important system components between, during, and in the decline of defoliator outbreaks. The study begins with a detailed literature review of historical theories of defoliating insect system behavior and of the documented behavior patterns of these systems. Major classes of behavior are identified, as well as the various ecological processes which have been invoked to explain these behaviors. An analysis and documentation of the equilibrium structure and behavior of three defoliating defoliating insect systems, the eastern blackheaded budworm, the eastern spruce budworm, and the jack pine sawfly, are then used to develop general rules about how equilibrium structure and behavior can be explained. This analysis, coupled with the literature review, is used to develop the framework. The framework is then tested against historical defoliator population data and general syntheses of defoliating insect system research to assess its utility and predictability. The major results of the thesis are as follows. First, it appears that the structure and behavior of a defoliating insect system can be explained with five dynamic variables: the abundances of the defoliator; the foliage; the forest; the parasitoid; and the disease; and the effects of weather acting on the defoliator. Second, there appear to be 4 classes of defoliating insect system behavior. Third, the behavior that a defoliating insect system will exhibit seems to be determined by the magnitude of weather effects on defoliator survival and recruitment, the parasitoid numerical response to changing defoliator densities, the disease numerical response to changing defoliator densities, and the vulnerability of the forest to defoliation. Fourth, there seem to be four equilibrium structures the defoliator can exhibit, and one each for the parasitoid, the foliage, the forest, and the disease. Finally, the framework suggests that defoliating insect system structure and behavior can be induced with a particular, well-defined set of information. The framework is successful when applied to particular defoliating insect systems for explaining their behavior, but less successful in explaining defoliator equilibrium structure for other systems. Opportunities for more thorough testing of the framework exist if the particular types of data outlined above are gathered for defoliating insect systems. This lack of data for testing the framework make it currently difficult to clearly define those systems in which the framework is useful and those systems in which it is not. Experiments to test the framework are described and suggestions for future types of applied research on defoliating insect systems are presented.<br>Science, Faculty of<br>Zoology, Department of<br>Graduate

O crisopídeo Ceraeochrysa cubana (Hagen, 1861) é um importante predador na cultura dos citros. Apesar da grande importância de C. cubana, pouco se conhece sobre a biologia e o efeito dos inseticidas a este crisopídeo, o que seria fundamental para um programa de Manejo Integrado de Pragas. Com essa pesquisa objetivou-se avaliar o efeito: a) letal e subletal de inseticidas aplicados sobre ovos com 3 idades diferentes; b) letal e subletal de inseticidas sobre larvas de primeiro instar; c) letal e subletal de inseticidas aplicados sobre pupas e adultos; d) do manejo de Diaphorina citri Kuwayama (Hemiptera: Liviidae) na população de crisopídeos; e) de seis temperaturas sobre a biologia de C. cubana. Verificou-se que não houve diferença significativa das variáveis avaliadas entre os tratamentos, dentre os ovos com 24, 72 e 120 horas. O produto Lorsban® 480 BR afetou a viabilidade dos ovos das três idades e foi o inseticida que mais afetou o predador quando aplicado sobre os ovos, classificado como moderadamente nocivo (classe 3). Em larvas, os inseticidas Lorsban® 480 BR e Malathion® 1000 EC tiveram efeito letal, causando 100% de mortalidade 24h após a aplicação e os inseticidas Azamax® e Engeo Pleno® foram os únicos produtos que tiveram efeito subletal sobre as pupas oriundas das larvas tratadas e nenhum dos produtos testados foram classificados como inócuos (classe 1) ao predador. Nenhum dos inseticidas testados teve efeito letal e subletal quando aplicados sobre as pupas, sendo classificados como inócuos, já, quando aplicados sobre adultos, os inseticidas Actara® 250 WG, Ampligo®, Engeo Pleno®, Lorsban® 480 BR e Malathion® 1000 EC causaram 100% de mortalidade e todos os produtos testados sobre os adultos foram nocivos, exceto Evidence® 700 WG, Imidan® 500 WP e Tiger® 100 EC, que foram classificados como moderadamente nocivos. Nas coletas de crisopídeos feitas em campo, a espécie Ceraeochrysa cincta (SCHNEIDER, 1851) foi a mais coletada, observou-se também que na propriedade com manejo menos intensivo de D. citri foi coletado um número maior de indivíduos comparado com a propriedade com manejo rigoroso. Em relação à biologia, verificou-se um aumento na velocidade do desenvolvimento das fases do predador em função da temperatura e a viabilidade da fase de ovo e larva não foi afetada, porém, a temperatura de 18°C afetou a viabilidade da pupa e no ciclo ovoadulto, além dessa temperatura, a de 32°C também afetou a viabilidade. Para o ciclo total de C. cubana foram necessários 354,61 GD e a temperatura base (Tb) foi de 12,72°C.<br>The lacewing Ceraeochrysa cubana (Hagen, 1861) is an important predator of citrus pests. Still, little is known about the biology and the effect of insecticides on this green lacewing, which is essential for an Integrated Pest Management program. The aim of this study was to evaluate: a) lethal and sublethal effects of insecticides applied on eggs at 3 different ages, b) lethal and sublethal effects of insecticides on the first larval instar c) lethal and sublethal effects of insecticides applied to pupae and adults; d) effects of the management of Diaphorina citri Kuwayama (Hemiptera: Liviidae) in a lacewing population e) effects of six temperatures on the C. cubana biology. We found no significant differences for the variables in the treatments for eggs at 24, 72 and 120 hours. The insecticide Lorsban® 480 BR affected the viability of the eggs at the three ages and most affected the predator when applied on the eggs, classified as moderately harmful (class 3). On the larvae, the insecticides Lorsban® 480 BR and Malathion® 1000 EC had lethal effect, occurring 100% mortality of the larvae 24h after application of insecticides, and Azamax® and Engeo Pleno® were the only products that presented sublethal effects on pupae from treated larvae and none of the products tested were classified as harmless (class 1) to the predator. None of the insecticides tested had lethal and sublethal effect when applied on the pupae, and were classified as harmless. When applied to adults, insecticides Actara® 250 WG, Ampligo®, Engeo Pleno®, Lorsban® 480 BR and Malathion® 1000 EC caused 100% of mortality of the adult predator and all products tested on adults were harmful, except for Evidence® 700 WG, Imidan® 500 WP and Tiger® 100 EC, which were classified as moderately harmful. In the collections of green lacewings in the field, the species Ceraeochrysa cincta was predominant. We also observed that in orchards under less intensive management of D. citri, a larger number of individuals were collected compared to the orchards under a strict management system. Regarding biology, we observed an increase in growth speed in instars of the predator due to temperature, but the viability of eggs and larvae were not affected. However, the temperature of 18°C affected the pupae viability and the eggadult cycle. The temperature of 32°C also affected viability. For total cycle of C. cubana took 354.61 degrees day (DD) and thermal threshold (Tb) was 12.72°C.

Triatoma sordida é considerada de importância secundária no ciclo da Doença de Chagas humana, uma vez que vem ocupando o lugar de Triatoma infestans no peri-domicílio das casas. Triatoma costalimai é considerada uma espécie silvestre e endêmica do cerrado brasileiro. Recentemente tem ocorrido um aumento do número de invasões domiciliares por T. sordida e T. costalimai, devido ao impacto causado pelo homem no meio ambiente. Ambas as espécies já foram encontradas naturalmente infectadas por Trypanosoma cruzi e, portanto, contribuem para o ciclo antropozoótico da doença. O presente trabalho teve como objetivo verificar a variabilidade genética e morfológica dessas duas espécies, por morfometria geométrica alar e da cabeça e marcadores moleculares mitocondriais sendo T. sordida coletado nos estados de Mato Grosso do Sul (5 populações), Goiás (4 populações) e Minas Gerais (3 populações); e T. costalimai coletados nos estados da Bahia (1 população), Goiás (2 populações) e Minas Gerais (1 população). A hipótese Os resultados mostram que as populações de T. sordida encontram-se altamente estruturadas geneticamente, e que a morfologia alar apresenta uma heterogeneidade, o que permite concluir que mesmo estruturadas geneticamente, não há um processo de especiação ocorrendo para essa espécie. As populações de T. costalimai apresentam alta variabilidade morfológica do conexivo, embora as asas e cabeças apresentam certa similaridade entre as populações estudadas. Os marcadores genéticos indicam distinção entre espécimes que apresentam uma linha laranja continua no conexivo daqueles que apresentam manchas laranjas triangulares. As diferenças encontras sugerem que T. costalimai compreende duas subespécies, com diferenças morfológicas e cromáticas.<br>Triatoma sordida is considered of secondary importance in the cycle of Human Chagas Disease, since it has occupied the place of Triatoma infestans in the peri-domicile of the houses. Triatoma costalimai is a wild and endemic species of Brazilian cerrado. Recently there has been an increase in the number of home invasions by these species, due to the impact caused by man in the environment. Both species have already been found naturally infected by Trypanosoma cruzi and, therefore, contribute to the antropozootic cycle of the disease. The present work had as objective to verify the genetic and morphological variability of these two species, through the geometric morphometry of the head and mitochondrial molecular markers. The results show that the populations of T. sordida are highly structured genetically, and that the wing morphology shows heterogeneity in the wing shape, which allows to conclude that even if genetically structured, there is no speciation process occurring for this species. The populations of T. costalimai have high morphological variability of the connexivum, although the wings and heads present some similarity between the populations studied. Genetic markers indicate a distinction between specimens with a continuous orange line in the connexivum of those with triangular orange spots. The differences found suggest that T. costalimai comprises two subspecies, with morphological and chromatic differences.

Genetic control strategies are a novel method for reducing populations of pest insects such as the yellow fever mosquito Aedes aegypti, a major vector of several important arboviral diseases. This thesis describes efforts to develop new tools to engineer the Ae. aegypti genome and to better understand existing tools, and furthermore to use these to engineer a gene drive system in Ae. aegypti. The piggyBac transposon was found to be extremely stable in the germline of Ae. aegypti, and transposons engineered into the germline could not be remobilized with either an endogenous or exogenous source of piggyBac transposase. Conversely, somatic remobilization of piggyBac transposons was found to be readily detectable in the presence of a source of active transposase, the first report of such remobilization in Ae. aegypti. Toward new tools for genome engineering, the site-specific integrase from the phage φC31 was successfully used to promote exchange between a transgene cassette inserted into the genome of Ae. aegypti and a cassette in a plasmid vector, in the first demonstration of recombinase mediated cassette exchange technology in a pest insect species. The integrases from phages φRV1 and Bxb1 were not found to be active in the germline of the mosquito. Finally, development of a gene drive system in Ae. aegypti using an RNAi-mediated killer-rescue mechanism was attempted. Tissue-specific expression of tTAV-regulated-toxic effectors genes, using the promoter regions of the blood meal induced genes Carboxypeptidase A-1, 30Kb and Vitellogenin A, was possible, but sex-specificity was not achieved. A blood meal inducible lethal phenotype was not possible using the chosen promoters, with expression of the effectors either leading to death in early development or to a sublethal phenotype. RNAi against tTAV fused to the Mnp fragment of the dengue virus’ genome was tissue specific, but was found to be highly effective in the fat body suggesting that the Vitellogenin A was the best candidate for the engineering of killer-rescue systems in the mosquito.

Providence virus (PrV) is a member of the Tetraviridae, a family of small, positive sense, single-stranded RNA viruses, which characteristically infect the midgut tissue of heliothine larvae. PrV is the only known tetravirus that replicates in cultured insect cells. The virus comprises a monopartite genome resembling members of the genus Betatetravirus with the capsid precursor protein undergoing autoproteolytic cleavage at its C-terminus consistent with other tetravirus capsid precursor proteins. Analysis of viral cDNA predicted the presence of three potential overlapping gene products (from 5` to 3`): (1) p130, a protein of unrecognized nucleotide or amino acid homology with a 2A-like processing site at its N-terminus; (2) p104, the replicase ORF, which was found to be phylogenetically related to tombus-and umbraviruses replicases. The presence of a read-through stop signal in the p104 ORF was proposed to produce and amino terminal product with a predicted MW of 40 kDa (p40) and (3) the capsid protein precursor (81 kDa) which has two 2A-like processing sites at its N-terminus. Metabolic radiolabelling of viral translation products in persistently infected MG8 cells and in vitro translation of the individual ORFs were performed in order to analyse the expression of PrV gene products. p130 was translated with no evidence of 2A-like processing. Two products of 40 kDa and 104 kDa were translated from the p104 ORF, indicating that the read-through stop signal was likely to be functional. Finally, the capsid protein precursor ORF produced a major translation product of 68 kDa corresponding to the capsid protein precursor as well a peptide of 15 kDa that was attributed to the activity of the second 2A-like site at the N-terminus of the p81 ORF. The subcellular distribution of viral RNA (vRNA) and p40 in MG8 cells was investigated using immunofluorescence and biochemical fractionation. The results showed that p40/p104 and vRNA accumulated in polarized, punctate structures in some but not all MG8 cells and in some cases, co-localization was observed. This thesis concludes that PrV is a novel tetravirus with significant similarities plant carmolike viruses that should be re-classified at the family level.

A doença de Chagas é causada pelo protozoário Trypanosoma cruzi e atinge cerca de 12 milhões de pessoas no continente americano, a forma clássica de transmissão ocorre por intermédio do inseto vetor da subfamília Triatominae, popularmente chamado de barbeiro.Em um trabalho anterior, foi realizada uma análise de segregação complexa que indicou a presença de um gene principal, com um componente multifatorial influenciando a predisposição à infecção por Trypanosoma cruzi. A população é composta por 4697 indivíduos pertencentes a 886 famílias vindas do Nordeste do Brasil e tiveram os dados e amostras de sangue e saliva coletados entre 1969 e 1970.No presente estudo foi utilizada uma amostra de 69 indivíduos, sendo 18 positivos para a infecção por Trypanosoma cruzi e 51 negativos, distribuídos em 14 famílias. Os indivíduos tiveram seu DNA extraído e genotipado utilizando microarranjos de DNA de 260 K SNPs (GeneChip Mapping Affymetrix). Testes de associação mostraram significância entre a infecção por T. cruzi e o SNP rs17469997 do cromossomo 10, com P=0,015 após a correção de Bonferroni. Para validar estes inéditos resultados, análises de ligação multi-ponto foi feita com o programa GeneHunter (KRUGLYAK et al., 1996) e ligação dois-pontos com o programa SuperLink (FISHELSON e GEIGER, 2002), mas ambas não apresentaram resultados significativos, devido ao pequeno número de famílias informativas.<br>Chagas disease is caused by the protozoan Trypanosssoma cruzi and is usually transmitted by Triatominae bugs and affects about 12 million people in the American continent. In a previous study, segregation analysis showed evidence of a major gene with a small multifactorial component influencing the predisposition to the Trypanosoma cruzi infection in a population composed by 4697 individuals of 886 families from Northeastern Brazil in 1969-1970 at São Paulo, Brazil. In the present work, 69 individuals (18 positives to T. cruzi infection and 51 negative) belonging to 14 families were selected. They had the DNA extracted and genotyped using 250K SNPs DNA microarrays (GeneChip Mapping Affymetrix). 18 SNPs showed evidence of association between infection to T. cruzi with P<10-5, although after Bonferroni\'s correction only the SNP rs17469997 (minor allele frequency = 0.1667, adjusted-Bonferroni P = 0.015) on chromosome 10 was significant. The other 17 SNPs that showed association with T. cruzi infection with P<10-5 can still be informative in linkage analyses. On an effort to validate these findings, a multi point linkage analyses was performed with GeneHunter (KRUGLYAK et al., 1996) program and a two point linkage analyses were performed with SuperLink (FISHELSON e GEIGER, 2002) program, both analyses showed no significant results.

A cultura do tomateiro (Solanum lycopersicum L.) é importante mundialmente devido ao alto consumo de seus frutos. Nos últimos anos surgiram nesta cultura no Brasil alguns vírus emergentes com altas taxas de disseminação, como begomovírus e crinivírus, transmitidos pela Bemisia tabaci biótipo B, que podem causar danos à produção do tomateiro. A espécie de begomovírus atualmente mais encontrada no Brasil, em plantios de tomateiro, é o Tomato severe rugose virus (ToSRV). De 2002 a 2004, pesquisadores relataram incidências desse vírus em mais da metade das amostras com sintomas de geminiviroses coletadas em vários estados brasileiros e sua presença continua sendo verificada frequentemente. No ano de 2006, um crinivírus, o Tomato chlorosis virus (ToCV), foi relatado no Brasil, infectando plantas de tomate no Estado de São Paulo e atualmente encontra-se presente em diveros estados brasileiros. Os objetivos desse trabalho foram: determinar os períodos mínimos de acesso à aquisição e à inoculação do ToSRV e do ToCV pela B. tabaci biótipo B; identificar o período de retenção do ToSRV no inseto e a interação do ToSRV e do ToCV na aquisição e na transmissão por esse aleirodídeo. Também foi avaliada a eficiência do inseticida cloridrato de cartape no controle da disseminação primária e secundária do ToSRV pela B. tabaci biótipo B em tomateiros em gaiolas em casa de vegetação. Finalmente avaliou-se a eficiência do aleirodídeo Trialeurodes vaporariorum na transmissão de um isolado brasileiro do ToCV. Os períodos mínimos de acesso à aquisição e à inoculação de ambos os vírus pela B. tabaci biótipo B foram de cinco minutos. O tempo de retenção do ToSRV em B. tabaci biótipo B foi de 25 dias. A eficiência de um único adulto de B. tabaci na transmissão simultânea do ToSRV e do ToCV para tomateiros foi de 44,7%, similar àquela da transmissão isolada do ToRSV (47,4%) e do ToCV (44,7%). A eficiência de T. vaporariorum na transmissão do ToCV foi inferior à da B. tabaci biótipo B. Usando 40 insetos por vaso com duas plantas as eficiências de transmissão foram 57,7% e 100%, respectivamente. O inseticida cloridrato de cartape reduziu a infecção secundária do ToSRV pela B. tabaci biótipo B, mas não foi eficiente para reduzir a infecção primária em tomateiros.<br>Tomato (Solanum lycopersicum) is one of the leading vegetables grown and consumed in Brazil and in the world, after potato. The importance of tomato is related to its high consumption worldwide and also its nutritive value. Presently the most important virus diseases responsible for yield losses on tomato crops in Brazil are those caused by begomovirus and crinivirus, both transmitted by Bemisia tabaci biotype B. At the moment the prevalent species of begomovirus is Tomato severe rugose virus (ToSRV). From 2002 to 2004, researchers reported incidence of this virus in more than half of the symptomatic tomato samples collected in several Brazilian states. In 2006, a crinivirus, Tomato chlorosis virus (ToCV), was reported for the first time in Brazil, infecting tomato plants in the State of São Paulo and at present the virus occurs in several Brazilian states. The objectives of this study were to determine the minimum acquisition and inoculation access periods of ToSRV and ToCV by B. tabaci biotype B; identify the retention period of ToSRV in the insect; and the interaction of ToSRV and ToCV on the transmission by this aleyrodidae. It was also evaluated the effectiveness of the insecticide cartap hydrochloride in controlling the primary and secondary spread of ToSRV by B. tabaci biotype B on tomato plants in a greenhouse. Finally, it was evaluated the efficiency of Trialeurodes vaporariorum in the transmission of a Brazilian isolate of ToCV. The minimum acquisition and inoculation access periods for both viruses by B. tabaci biotype B were five minutes. The maximum retention time of ToSRV in B. tabaci biotype B was 25 days. The efficiency of a single adult of B. tabaci to simultaneously transmit ToSRV and ToCV to tomato plants was 44.7%, similar to the transmission of ToRSV (47.4%), and ToCV (44.7%) separately. T. vaporariorum was less efficient than B. tabaci on the transmission of ToCV. Using 40 insects per pot with two plants, transmission efficiencies were 57.7% and 100%, respectively. The insecticide cartap hydrochloride reduced secondary infection of ToSRV transmitted by B. tabaci biotype B, but was not effective in reducing the primary infection in tomato.

The risks posed by rapidly evolving RNA viruses to human and animal health are well recognized. Epidemics in managed and wildlife populations can lead to considerable economic and biodiversity losses. Yet, we lack understanding of the ecological and evolutionary factors that promote disease emergence. Host-switching viruses may be a particular threat to species important for human welfare, such as pollinating bees. Both honeybees and wild bumblebees have faced sharp declines in the last decades, with high winter mortality seen in honeybees. Infectious and emerging diseases are considered one of the key drivers of declines, acting in synergy with habitat loss and pesticide use. Here I focus on multihost viruses that pose a risk to wild bumblebees. I first identify the risk factors driving viral spillover and emergence from managed honeybees to wild bumblebees, by synthesising current data and literature. Biological factors (i.e. the nature of RNA viruses and ecology of social bees) play a clear role in increasing the risk of disease emergence, but anthropogenic factors (trade and transportation of commercial honeybees and bumblebees) creates the greatest risk of viral spillover to wild bees. Basic knowledge of the pathogenic effect of many common pollinator viruses on hosts other than A. mellifera is currently lacking, yet vital for understanding the wider impacts of infection at a population level. Here, I provide evidence that a common bumblebee virus, Slow bee paralysis virus (SBPV), reduces the longevity of Bombus terrestris under conditions of nutrition stress. The invasion of Varroa destructor as an ectoparasitic viral vector in European honeybees has dramatically altered viral dynamics in honeybees. I test how this specialist honeybee vector affects multi-host pathogens that can infect and be transmitted by both honeybees and wild bumblebees. I sampled across three host species (A. mellifera, B. terrestris and B. pascuorum) from Varroa-free and Varroa-present locations. Using a combination of molecular and phylogenetic techniques I find that this specialist honeybee vector increases the prevalence of four multi-host viruses (deformed wing virus (type A and B), SBPV and black queen cell virus) in sympatric wild bumblebees. Furthermore, wild bumblebees are currently experiencing a DWV epidemic driven by the presence of virus-vectoring Varroa in A. mellifera. Overall this thesis demonstrates that wild bumblebees are at high risk of viral disease emergence. My research adds to the ever-expanding body of evidence indicating that stronger disease controls on commercial bee operations are crucial to protect our wild bumblebees.

Huanglongbing (HLB), considerada uma das mais graves doenças dos citros, está associada a Candidatus Liberibacter spp., bactérias endógenas restritas ao floema e de difícil cultivo em meio de cultura. Diferentemente de outras doenças que afetam plantas cítricas, ainda não foram encontradas dentro do gênero Citrus espécies resistentes ao HLB. Genes de interesse agronômico têm sido empregados na transformação genética de citros visando a resistência a doenças. Dentre estes, destacam-se os que conferem resistência a bactérias incluindo attA, que codificam os peptídeos antibacterianos atacinas, e hrpN, que ativam a produção de proteínas harpinas, relacionadas ao sistema de defesa. O objetivo deste trabalho foi avaliar a resistência de plantas de laranja doce contendo o gene da atacina A (attA) ou o gene da harpina (hrpN) à Candidatus Liberibacter asiaticus (CLas) utilizando duas formas de inoculação: borbulhões infectados e o inseto vetor da bactéria, Diaphorina citri. Para as plantas contendo o gene hrpN, apenas o segundo método foi utilizado. Os principais sintomas do HLB foram observados aos quatro e oito meses após a inoculação por borbulhões. A infecção das plantas foi confirmada com a detecção de CLas por PCR (quatro e oito meses) e Rt-qPCR (oito meses). Em plantas inoculadas por D. citri, os sintomas foram observados oito e doze meses após a inoculação, assim como a detecção da bactéria por PCR. Após 15, 17 e 18 meses, foi realizada uma nova avaliação por Rt-PCR a partir de spots (imprints em membrana) de folhas. Rt-PCR foi empregado também em spots dos psilídeos utilizados na inoculação. Não foi possível avaliar a resistência ao HLB em plantas contendo o gene attA ou hrpN a partir da inoculação por D. citri. Os resultados de detecção da bactéria nas plantas e nos psilídeos utilizados para inoculação indicam que, possivelmente, não ocorreu a inoculação devido ao baixo percentual de psilídeos que continham CLas utilizados. Dentre as plantas transgênicas contendo o gene attA inoculadas por borbulhões infectivos, oito eventos (cinco de laranja Pera, dois de laranja Hamlin e um de laranja Valência) apresentaram menores títulos bacterianos e algumas também demonstraram redução dos sintomas do HLB quando comparadas com plantas não transgênicas, oito meses após a inoculação, indicando uma possível ação do peptídeo atacina A contra o agente causal do HLB.<br>Haunglongbing (HLB), considered one of the most serious diseases of citrus, is associated to Candidatus Liberibacter spp., endogenous and phloem-inhabiting bacteria not easily grown in culture medium No species within the genus Citrus is known to resist this bacterial infection. The use of genes of agronomic interest for genetic transformation aiming disease resistance in citrus has been reported. Among these genes, attA that codes for the antibacterial peptides attacin, and hrpN, that codes for proteins harpin that activate the plant defense system may have potential in searching for HLB resistance. The objective of this study was to evaluate the resistance of sweet orange containing attA or hrpN to Candidatus Liberibacter asiaticus (CLas) inoculated through infected budstick grafting or the insect vector, Diaphorina citri. For the plants containing hrpN, only the second method was used. The most obvious HLB symptoms were observed four and eight months after inoculation by infected budstick when CLas also was detected by PCR (four months) and RT-qPCR (eight months). For those inoculated with D. citri, symptoms were observed and bacteria detected eight and twelve months after inoculation. Fifteen, 17 and 18 months after inoculation, a new attempt was made for CLas detection, now through Rt-PCR from leaf and psyllids imprinting spots on membrane. It was not possible to evaluate the HLB resistance in plants containing attA or hrpN gene from D. citri inoculation. The results of CLas detection in plants and psyllids indicate that possibly there was no inoculation due the low rate of psyllids contained CLas used. Among the plants containing attA, five, two and one event of, respectively, Pera, Hamlin, and Valencia sweet orange had lower bacterial titers than those non transgenic plants and some also showed milder HLB symptoms, eight months after inoculation, suggesting a possible effect of attacin A against the causal agent of HLB.

Made available in DSpace on 2015-03-26T13:30:51Z (GMT). No. of bitstreams: 1 texto completo.pdf: 408527 bytes, checksum: 3f5ff39d24998982838ce196768d85c4 (MD5) Previous issue date: 2011-02-18<br>Conselho Nacional de Desenvolvimento Científico e Tecnológico<br>Predators capture, kíll and consume theír prey. Thís ís the only ap- proach consídered ín rnost studíes Of predator-prey ínteractíons. However, sorne recent studíes have been concerned Wíth the índírect effects Of pre- datíorL When threatened, prey can change theír behavíor, thus reducing theír chances Of death. Frorn thís perspectíve, experíments performed wíth rnosquítoes specíes ín aquatíc envíronments shows that, ín several ínstances, preys are able to ídentífy the presence Of predators. Thís perceptíon leads to behavíoral alteratíons such as fernale ovíposítíon repellency and reduced foragíng 1arvae. However, the type Of sígnal perceíved by the prey, the írn- portance Of índuced responses to the survíval Of índívíduals, and the reasons for these evolve ín sorne species and not others, remain under díscussíon. The objectíve Was to deterrníne Whether chemícal cues of predator larva Toxorhyn- chites theobaldi (Díptera: Culícídae) are capable Of ínñuencíng the behavíor Of fernales and ímmatures ín three prey species Of the sarne farníly, although wíth Very dístínct behavíor (Culea: molli8, Limatus durhamii and Aedes al- bopictu5). We found that, the ínfusíon Where T. theobaldi larvae Was shel- tered, probably releasíng chernícal sígnals, had a lower proportíon of larvae (5.4 %) of C. molli5, cornpared Wíth control (95.6 %), índícatíng ovíposítíon repellency. Meanwhíle, the other two specíes ovíposíted índíscrímínately on ínfusíon treated and controL We also observed that the presence of traces of the sarne predator, C. mollis larvae spend rnost of theír tíme ín rest (82.7 compared Wíth no sígns of T. theobaldi (49.3 %). However. L. durhamii and A. albopictus larvae do not show behavíoral changes ín the presence of the sarne sígnals. Yet, C. mollis larvae ís preyed upon ín a smaller proportíon than the others, suggestíng that these changes ínñuence ín species Vulnera- bílíty. Frorn these results, ít ís argued that the líkelíhood of the development of defensive responses índuced by predatíon rísk ís related to several factors such as hístoríc of contact Wíth the predator, the ovíposítíon strategy of the females and the ñxed and ñexíble behavíor standard and posítíoníng of 1ar- Vae. Also ís díscussed the ímportance of natíve predators to curb the ínvasíon of exotíc species and díseases spread by these Vectors.<br>Predadores capturam, abatem e consomem suas presas. Esta é a única abordagem considerada na maior parte dos estudos da ínteração predador- presa. Entretanto, alguns trabalhos recentes têrn se preocupado com os efeitos indiretos da predação. Quando ameaçadas, presas podem alterar seu comportamento, reduzindo suas chances de morte. Sob essa perspectiva, experimentos realizados com espécies de mosquitos em ambientes aquáticos demonstram que, em diversas situações, presas são capazes de identificar a presença de predadores. Tal percepção induz alterações comportamentais como a repelência de ovíposição das fêmeas e redução no forrageamento das 1arvas. Entretanto, o tipo de sinal percebído pelas presas, a importância das respostas induzidas para a sobrevivência dos indivíduos, e as razões destas evoluírem ern algumas espécies, e não em outras, permanecem em discussão. O objectivo do trabalho foi verificar se pistas químicas da presença larva predadora Toxorhynchites theobaldi (Díptera: Culícídae) influenciam o comportamento tanto de fêmeas ovípositantes quanto de imaturos de três espécies de presas da mesma famílía, entretanto com comportamentos bastante distintos, sendo elas Culex molli5, Limatus durhamii e Aedes albopictus (Díptera: Culícídae). Verificamos que, na infusão onde larvas de T. theobaldi permaneceram abrigadas previamente, liberando possíveis sinais químicos, foi encontrada uma menor proporção de larvas (5,4%) de C. molli5, quando comparado com o controle (95,6%) , indicando repelência na ovíposição Enquanto isso, as outras duas espécies ovíposítaram indiscriminadamente na infusão tratada e na controle. Observamos tarnbérn que, na presença de indícios desse mesmo predador, imaturos de C. mollis passaram maior parte do tempo ern repouso (82,7%), quando compadrado com a ausência de sinais de T. theobaldi (49,3%). Entretanto, ímaturos de L. durhamii e A. albopic- tus não apresentam alterações comportamentais na presença dos mesmos sinais. Ainda, C. mollis é predado em uma menor proporção que as demais, sugerindo que essas alterações influenciam na Vulnerabilidade das espécies. A partir desses resultados, é discutido que a probabilidade da evolução de respostas defensivas induzidas pelo risco de predação está relacionada a diversos fatores como o histórico de contato com o predador, a estratégia de ovíposição das fêmeas e o padrão fixo e flexicível de comportamento e posícionarnento das 1arvas. É abordada também a importância dos predadores nativos em conter a invasão de espécies exóticas e a disseminação de doenças por elas Veiculadas.

O Greening ou Huanglongbing (HLB) é a doença mais devastadora dos citros na atualidade. Levantamentos mostram que a enfermidade está presente em cerca de 60% dos talhões do parque citrícola paulista, demostrando sua grande capacidade de disseminação. O psilídeo-asiático-dos-citros, Diaphorina citri Kuwayama (Hemiptera: Psylidae) é um importante vetor dos agentes causais associados ao HLB. Sua capacidade de dispersão está intimamente relacionada ao progresso da doença no campo. Não se tem conhecimento dos principais fatores que possam interferir no deslocamento do inseto até plantas cítricas. Sendo assim, a presente pesquisa teve como objetivo investigar a influência de alguns fatores ambientais sobre a dispersão do psilídeo D. citri, discutindo-os em relação à epidemiologia do HLB dos citros. Inicialmente foram realizados testes em laboratório para adaptação da metodologia de marcação, liberação e recaptura usando pó fluorescente. Grupos de psilídeos adultos foram marcados e sua sobrevivência avaliada, verificando a influência de quatro cores distintas de pó fluorescente (amarelo, azul, rosa e verde). Posteriormente realizaram-se estudos de campo com quatro liberações de psilídeos, com marcadores distintos, em quatro áreas experimentais circulares e adjacentes, sendo formadas por círculos concêntricos localizados a 18, 24 e 30 m de cada centro de liberação. Os insetos foram monitorados visualmente e por armadilhas adesivas amarelas. Nas 1ª e 2ª liberações, foi verificado o efeito das coberturas vegetais milho (Zea mays L.) e capim-braquiária (Brachiaria decumbens Stapf.) na dispersão de D. citri. Já nas 3ª e 4ª liberações, foi estudado o efeito de brotações no deslocamento do inseto. A influência dos ventos foi avaliada em ambas as situações. A análise de sobrevivência indicou que não houve interferência das quatro cores de pó fluorescente em D. citri, sendo a marcação visível no corpo dos insetos durante os 48 dias de avaliação. De acordo com as análises fatoriais, não foi observada qualquer interferência da cobertura vegetal milho, medindo 2 m de altura, na dispersão do inseto. Na presença de brotações, adultos de D. citri dispersaram menos em busca de novos hospedeiros, acumulando-se nas primeiras linhas de plantas cítricas. Após 6 horas da liberação, a capacidade de dispersão máxima de D. citri foi três vezes maior na condição de ausência de brotações. A dispersão média e a área total abrangida variaram assimptoticamente com o tempo, ou seja, o inseto possui inicialmente grande velocidade de dispersão, porém esta tende a se estabilizar com o incremento do tempo. Esses resultados deixam claro que D. citri realiza movimentos dependendo das condições fenológicas de seus hospedeiros, ressaltando a grande importância de se intensificar métodos de controle regionais em épocas em que o fluxo vegetativo das plantas cítricas não é tão intenso.<br>Greening or Huanglongbing (HLB) is the most devastating disease of citrus today. Surveys show that the disease is present in about 60% of the park stands citrus Sao Paulo, demonstrating its great ability to spread. The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psylidae) is an important vector of the causative agents associated with HLB. Its ability to spread is closely related to disease progression in the field. There is no knowledge of the main factors that can affect the movement of the insect to citrus plants. Thus, the present study aimed to investigate the influence of some environmental factors on the dispersal of psyllid D. citri, discussing them in relation to the epidemiology of HLB of citrus. Initially tests were performed in the laboratory to adapt the methodology of marking, release and recapture using fluorescent powder. Groups of adult psyllids were marked and their survival assessed by checking the influence of four different colors of fluorescent powder (yellow, blue, pink and green). Subsequent studies were conducted with four field releases psyllids, with distinct markers on four experimental areas adjacent circular and being formed by concentric circles located at 18, 24 and 30 m for each center release. The insects were monitored visually and by yellow sticky traps. In the 1st and 2nd releases, was to determine the effect of cover crops maize (Zea mays L.) and grass (Brachiaria decumbens Stapf.) in the dispersal of D. citri. In the 3rd and 4th releases, were studied the effect of shootings in insect movement. The influence of the wind has been evaluated in both situations. Survival analysis indicated that there was no interference of the four colors of fluorescent powder on D. citri, and marking was visible on the body of insects during the 48 days of evaluation. According to the factor analysis, no interference of vegetation corn (measuring 2 m in height) was observed in the dispersal of the insect. In the presence of shoots, adult D. citri less dispersed looking for new hosts and it accumulate in the first lines of citrus plants. After 6 hours of release, the D. citri maximum dispersal was three times higher in the condition of absence of shoots. The dispersal medium and the total area covered varied asymptotically with time, ie the insect has initially high speed dispersal, but this tends to stabilize with increasing time. These results clearly show that D. citri performs movements depending on the phenology of its hosts, emphasizing the importance of intensifying regional control methods at times when the flow of plant citrus is not intense.

Maize (Zea mays L.) is one of the most important crops in South Africa that is cultivated for food, feed and as a cash crop. Maize in the Eastern Cape is typically grown for consumption and the Province is one of the least producers owing to small landholdings, poor production conditions and pests. This study investigated: (i) the different maize cropping systems smallholder farmers practice in the Eastern Cape (EC), (ii) the major maize insect pests within the identified cropping systems, (iii) the perceptions of Eastern Cape smallholder maize farmers on the effects of insect pests, and (iv) the effects of crop residues on insect pests’ population dynamics. Four major cropping systems namely: maize sole cropping without rotations by government sponsored farmers (GCP) (94 percent), maize intercropping without rotations by independent farmers (IF) (79 percent), maize sole cropping without rotations by IF (67 percent) and maize intercropping without rotations by GCP (61 percent) were identified. The choice of a cropping system by the smallholder farmers was significantly influenced by source of sponsorship, the difference in their district localities, tenure system, availability of inputs and farming equipment, percentage of farmland farmers allocate to maize, maize varieties, farming experience, fallow operations and access to irrigation facilities. The major constraints faced by the farmers in maize production are the attack by insect pests, weeds competition, drought, the lack of fencing around the fields and destruction by mammals. The major insect pests identified were stalk borers (Busseola fusca, Chilo partellus), cutworms (Agrotis spp.), aphids (Rhopalosiphum maidis), bollworms (Helicoverpa armigera) and weevils (Sitophylus spp.). The most popular control measures employed were the use of GM maize and pesticides. Results from the field trial showed that field crickets were the major ground dwelling insect pests observed followed by bollworms and cutworms. However, there were no significant influence of residue retention on the insects’ diversity indices, richness, and evenness. Above ground insects sampling revealed the domination by four major insects namely, cutworms, maize stalk borer, bollworms, and spotted stalk borer. Residue management significantly influenced the infestation by spotted stalk borer only on maize plots. However, the general trend was that there was less infestation by the insects in plots where residues were retained than the ones with residue removed. Results from the study indicate that government sponsorship is significantly influencing the maize cropping systems of the smallholder farmers of the Eastern Cape.

Bacillus thuringiensis (Bt) é uma bactéria entomopatogênica utilizada como biopesticida contra insetos, principalmente Lepidoptera, Coleoptera e Diptera, e na produção de organismos geneticamente modificados. Com a descoberta da capacidade de Bt se movimentar sistemicamente em plantas, potencialmente atingindo insetos sugadores, surge uma nova possibilidade para o controle de Diaphorina citri Kuwayama, que transmite bactérias associadas ao Huanglongbing, uma séria doença da citricultura. O objetivo do trabalho foi desenvolver sistemas de aquisição de Bt por D. citri, in vitro e in planta, para estudos de patogenicidade. Uma estirpe de Bt transformada com o gene green fluorescent protein (Btk-gfp), cultivada em meio NYSM, foi usada como marcador de aquisição pelo inseto e movimentação nas plantas. Para o sistema de aquisição in vitro, selecionaram-se dietas com base na sobrevivência e atividade alimentar de D. citri. Btk-gfp foi adicionada à dieta selecionada, composta por uma solução de sacarose a 30% em água mineral com corantes alimentícios (verde 0,1% e amarelo 0,4%). A dieta foi acondicionada em um sachê formado por duas membranas de Parafilm®, sobre a parte inferior de uma placa de Petri de 40 mm de diâmetro (gaiola de alimentação). Dez insetos foram confinados em cada gaiola para períodos de acesso à aquisição (PAA) de até 48 h, estabelecendo-se 10 gaiolas por tratamento; como controle, utilizou-se a dieta sem Btk-gfp. Para testes de aquisição in planta, suspensões de Btk-gfp foram inoculadas em ramos novos cortados e no solo, próximo à haste de seedlings de laranja doce [Citrus sinensis (L.) Osbeck] e de murta [Murraya paniculata (L.) Jack], e em diferentes concentrações, avaliando-se a movimentação da bactéria após um período de 48 h. Posteriormente, adultos e ninfas de D. citri foram confinados nestas plantas para avaliar a aquisição de Btk-gfp, usando-se plantas inoculadas apenas com água como controle. Para os bioensaios de patogenicidade a D. citri, 21 estirpes de Bt foram testadas no sistema de aquisição em ramos cortados de murta e 5 estirpes em ramos cortados de laranja para ninfas de 3º. ínstar. In vitro, testaram-se 3 estirpes contra ninfas de 3º. ínstar e 9 contra adultos. Btgfp foi absorvido pelas raízes e ramos novos cortados de seedlings de laranja doce e de murta, e translocado até as folhas, mostrando movimentação sistêmica. Esta estirpe foi adquirida por adultos e ninfas de D. citri que se alimentaram nos ramos novos cortados, mantidos em suspensão bacteriana. O sistema de alimentação in vitro permitiu a aquisição de Bt-gfp (pellet ressuspendido na dieta de sacarose com corantes) por adultos de D. citri com apenas 12 h de PAA, mas 30 h é um período ótimo para exposição do inseto ao sistema. Nenhuma das nove estirpes testadas no sistema in vitro foi patogênica aos adultos de D. citri. Das 21 estirpes testadas contra ninfas de 3º. ínstar em ramos novos de murta, cinco causaram mortalidade de 24 a 45%, em 5 dias. Essas cinco estirpes também foram testadas contra ninfas dem ramos de citros cortados, causando mortalidade de 35 a 75% em 48 h.<br>Bacillus thuringiensis (Bt) is an entomopathogenic bacterium widely used as a biopesticide against insect pests, mainly Coleoptera, Lepidoptera and Diptera, or for engineering genetically-modified plants. The recent finding that Bt is able to move systemically within plants, potentially targeting piercing-sucking insects, suggests that the bacterium may be effective for microbial control of Diaphorina citri Kuwayama, the vector of Huanglongbing-associated bacteria, a serious citrus disease. The goal of this research was to develop in vitro and in planta acquisition systems of Bt by D. citri for pathogenicity assays. A transformed Bt strain with the green fluorescent protein gene (Btk-gfp), grown in NYSM medium, was used as a marker to demonstrate bacterial acquisition by the insect and movement within the plants. Artificial diets were selected for the in vitro acquisition system based on insect survival and feeding activity. Btk-gfp was added to the selected diet, a 30% sucrose solution in mineral water with green (0.1%) and yellow (0.4%) food coloring. The diet was placed inside a Parafilm® membrane sachet, covering the opening of the lower half of a 40-mm diameter culture plate, and forming the feeding cage. Ten D. citri adults or nymphs were introduced in each cage and allowed acquisition access periods (AAP) of up to 48 h on the diet; as a control, a diet without Btk-gfp was used. For testing the in planta acquisition system, Btk-gfp suspensions were inoculated in young stem cuttings or in the soil, near the stem of Citrus sinensis (L.) Osbeck and Murraya paniculata (L.) Jack seedlings, as well as in different concentrations, and bacterial movement was assessed after 48 h; plants inoculated with water were used as controls. D. citri adults and nymphs were confined on inoculated plants to verify Btk-gfp acquisition. In pathogenicity assays, 21 Bt strains were tested against 3rd instars of D. citri using the acquisition system with stem cuttings of M. paniculata and 5 strains were tested using citrus stem cuttings. The in vitro acquisition system was used to test pathogenicity of 3 and 9 Bt strains against 3rd-instar nymphs and adults, respectively. Bt-gfp absorbed by roots or young stem cuttings of inoculated C. sinensis and M. paniculata was detected in the leaves, showing systemic movement. Bt-gfp was isolated from groups of nymphs and adults that were fed on inoculated stem cuttings or on artificial diets with bacterial suspension, showing that both in planta and in vitro acquisition take place. D. citri adults can acquire Bt-gfp within 12 h of AAP to the artificial diet with bacterium inoculum, but 30 h is the optimum AAP. None of the nine Bt strains assayed in vitro were pathogenic to D. citri adults. Of 21 strains tested for pathogenicity against nymphs using inoculated stem cuttings of M. paniculata, five caused mortality rates varying from 24 to 45% mortality within 5 days. These five Bt strains were also tested against D. citri nymphs using young stem cuttings of C. sinensis, causing mortality rates of 35 to 75% within 48 h.

Revised; Originally published: 2006<br>5 pp.<br>Recent events in the forests of the Southwest, and across western North America, have prompted scientists to consider the role of climate variability in insect and disease cycles. Studies focusing on Arizona and other southwestern states point to multiple, interacting climate-related mechanisms that increase the propensity for forest mortality. Effects of insects on forests are complex, and species and site dependent. Many influences, such as drought, decreased precipitation, increased temperature, increased vapor pressure deficit, and increased stand density, combined in nonlinear and overlapping ways to create the recent and devastating pine bark beetle outbreaks in Arizona forests. Climate clearly plays a role in many, but not all, Southwest insect cycles. It is important that educators demonstrate the complexity of all of the interplaying issues, in order to communicate no false impressions of an “easy” or “one-size- fits-all” solution” for land managers.

The objective of this thesis is to analyze how existing data can address Chagas disease transmission risk in South America given data availability. A literature review was conducted to determine prominent variables that models use to assist with Chagas disease mitigation efforts, followed by a Web search to collect publicly available spatial data pertaining to these variables. The data were then used to create maps of data availability and in an agent-based model to identify which variables are most associated with disease transmission risk. Data availability varied widely across South America, and model results indicate that datasets related to household size and spatial housing arrangement are most important to Chagas disease infection in urban areas. Governments can use this information to better direct their resources to collect data and control the spread of triatomine vectors and Chagas disease more effectively, and potentially identify more cost-effective strategies for vector elimination.

Resumo: Dos vírus que infectam o maracujazeiro no Brasil, atualmente o Cowpea aphid borne mosaic virus (CABMV), é considerado fator limitante à cultura. Dependendo da velocidade de disseminação e idade com que as plantas são infectadas no campo, a cultura torna-se comercialmente improdutiva. O presente estudo teve como objetivo, avaliar a diversidade e a dinâmica populacional dos afídeos na região da Alta Paulista, SP e a possibilidade de transmissão do vírus pela semente. Assim, quatro locais (Leste e Oeste da cidade de Marília e Municípios de Ocauçú e Guaimbê) foram monitorados durante 24 meses com armadilhas amarelas de água do tipo Moericke. Constatou-se nas quatro regiões a predominância do gênero Aphis. Outras espécies coletadas foram Myzus persicae, Geopenphigus flocculosus, Brevicoryne brassicae, Rhopalosiphum spp, Dysaphis spp e Lipaphis erysimi. A flutuação populacional de formas aladas do gênero Aphis, caracterizou-se por apresentar maiores revoadas em maio, junho, agosto e setembro. As espécies de Aphis (A. fabae, A. gossypii, A. spiraecola) devem ser os principais vetores do CABMV na região. Plantios novos, ao lado de plantações infectadas, tornam-se infectadas em três meses. Nos testes de transmissão através de sementes, do total de 13056 semeadas oriundas de plantas doentes, germinaram 10592, e em avaliações visuais dois meses após a germinação, não foram observadas plantas sintomáticas, indicando a não transmissão pela semente.<br>Abstract: From the viruses were described infecting passionfruit plants in Brasil, and the Cowpea aphid borne mosaic virus (CABMV), is considered the most hazardous. Depending on the spread velocity of aphids and the age that the plants are infected, the crops doesn’t produce commercial fruits. The present study was designed to evaluate the diversity and dynamic population of aphids in the Alta Paulista, SP region and aspects of seed transmission. For this, four regions (East and West of Marília city, Guaimbê and Ocauçú) were monitored for 24 months using yellow water Moerick trap. The predominance of the genus Aphis was observed in the four evaluated areas. Other species founded in the area were: Myzus persicae, Geopenphigus flocculosus, Brevicoryne brassicae, Rhopalosiphum spp, Dysaphis spp and Lipaphis erysimi. The population curve of alate Aphis spp showed the highest frequency of flights during May, June, August and September. The Aphis spp (A. fabae, A. gossypii, A. spiraecola) probably is the most important vector of the CABMV in the region. New crops near old infected plants, were infected in three months. To evaluate properties of seed transmission, from 13056 collected from infected plants, 10592 were germinated and evaluated during two months for the presence of visual symptoms. No plants with simptoms were observed indicating no seed transmission.<br>Orientador: Marcelo Agenor Pavan<br>Coorientador: Valdir Atsushi Yuki<br>Banca: Renate Krause Sakate<br>Banca: Aloisio Costa Sampaio<br>Banca: Alexandre Levi R. Chaves<br>Banca: Hugo Kuniyuki<br>Doutor

Capsicum baccatum var. pendulum was first grown in the Makana District in 2005. Extremely little was known about best practices for cultivation or the insects and diseases associated with the crop in this area. The study was conducted during the second year of production, November 2005 and November 2006, in an attempt to identify the composition and phenology of insects occurring on C. baccatum. In the more rural parts of the Eastern Cape, and more particularly in Grahamstown, there are very few industries. With the advent of this new agricultural venture, a processing factory has been opened in Grahamstown creating more than 600 seasonal jobs in the factory and 1000 seasonal jobs on farms for local people. This business enterprise has not only brought about the creation of jobs, but also training and skills development and empowerment, generating much-needed income in this area. An extensive literature review yielded limited information on insect pests associated with Capsicum. Data from a pilot sampling trial undertaken were statistically analyzed to establish the number of plants to be scouted per site and the most effective scouting techniques to use. Based on the data available and insects collected during the pilot sampling trial, a surveillance programme was designed. Five different types of monitoring traps were placed in each of the eight study sites. Collection of trap catches and scouting of fifteen individual plants per site was undertaken on a weekly basis over the 52-week study period. The most commonly occurring potential insect pests were African Bollworm Helicoverpa armigera (Hübner), False Codling Moth Thaumatotibia leucotreta (= Cryptophlebia leucotreta) (Meyrick), Mediterranean Fruit Fly Ceratitis capitata (Wiedemann) and several species of thrips. Population densities of these pests and their phenology on Capsicum were determined. Statistical analyses established the efficacy of the monitoring traps for each pest, tested for differences among and between study sites, calculated an estimate of the number of pods damaged and a measure of plant damage.The results show that the majority of damage caused to the Capsicum baccatum cropping system was due to Mediterranean Fruit Fly populations. It was established that, although African Bollworm and False Codling Moth were present during the study period, their numbers were negligible and only nominal damage was caused by these pests. Damage caused by thrips species was apparent but not quantifiable. Intervention strategies using an Integrated Pest Management approach, are discussed.

Thesis (PhD) -- Stellenbosch University, 1989.<br>ENGLISH ABSTRACT: Arthropod communities of five proteaceous species viz. Protea repens. P. neriifolia. P.cynaroides, Leucospermum cordifolium and Leucadendron /aureolum were studied. A faunal list of the insects was compiled according to the feeding guilds of insects. Six phytophagous guilds were recognized: flower visitors, thrips, endophages, ectophages, sap-suckers, and ants. The guild composition, species packing and seasonal distribution for the free-IMng insects, spiders and other arthropods were investigated on the different plant species. The ants, flower visitors and sap-sucking species found on the plant species, were very similar, but the number of leaf chewing species common to all the plant species was low, suggesting that some species were monophagous. Insect abundance increased during the wet winter months when the plants were in flower. Of the total number of herbivores collected, flower visitors represented 69,5%, leaf feeders 14,5% and sap-suckers 16,1 %. The chewers constituted 60,1% of the total herbivore. biomass. Leaf damage increased with age ; young leaves were practically free of herbivore damage, while older leaves were stm acceptable as food. The degree of insect damage differed amongst the plant species varying from 2% to 15%. The following leaf characteristics were investigated to determine the factors involved in defence against insect herbivory : total phenolic content, protein precipitating ability, cyanogenesis, nitrogen content, leaf toughness, woodiness and fibre content lt appears that the plant species use different mechanisms to protect their leaves. The infructescences of Protea repens were exploited by the larvae of four Coleoptera and four Lepidoptera species. The community structure of these phytophagous insects was determined largely by negative interactions. Various strategies are followed (e.g. niche segregation in time and space) to lessen interspecific competition.<br>AFRIKAANSE OPSOMMING: 'n Studie van die arthropoocl gemeenskap op vyf proteasoorte, naamlik Protea repens. P. neriffolia. P. cynaroides. Leucospennum cordffolium en Leucadendron laureolum is gedoen. 'n Faunalys van insekte volgens hul voedingsgDdes is saamgestel. Die insekte is in ses fitofage gDdes verdeel naamlik blombesoekers, blaaspootjies, endovoeders, ektovoeders, sapsuiers en miere. Die samestelling van die gDdes, spesie-rangskikking en seisoenale verspreiding is bepaal vir die vrylewende insekte, spinnekoppe en ander arthropode. Die miere, blombesoekers en sapsuierspesies wat op die plantsoorte gevind is, is byna dieselfde, maar verslalle in die blaarvoederspesies is gevind wat 'n aanduiding is dat sommige spesies monofaag mag wees. Gedurende die nat wintermaande toon die insekgetalle 'n toename. Blombesoekers verteenwoordig 69,5%, blaarvoeders 14,5% en sapsuiers 16,1% van die aantal insekherbivore wat versamel is. Die kouers vorm 60,1% van die totale herbivoor biomassa Soos die blare verouder, neem die skade op die blare toe; jong blare toon byna geen skade nie, terwyl ouer blare steeds geskik is vir insekvoedsel. Die insekskade op die blare wissel by die verslallende plante tussen 2% en 15%. Om te bepaal watter blaareienskappe moontlik 'n rol kan speel in blaarverdediging teen insekte is die volgende ondersoek: totale fenoliese inhoud, die vermoe om proteiene te presipiteer, sianogenese. stikstofinhoud, blaartaaiheid, houtagtigheid en veselinhoud. Dit wil voorkom asof die plante verskillende meganismes gebruik om die blare te beskerm. Saadkoppe van Protea repens word deur vier Coleoptera en vier Lepidoptera spesies benut Die gemeenskapstruktuur van die boarders word tot 'n groat mate bepaal deur negatiewe interaksies. Verskeie strategiee word gevolg (bv. nissegregasie in ~ en ruimte) om kompetisie tussen spesies te verminder.

O Huanglongbing (HLB) é uma das mais temidas doenças da citricultura mundial, associada a bactérias do gênero Candidatus Liberibacter, que foram detectadas no Brasil em 2004. Em 2008, detectou-se outra bactéria associada a sintomas de HLB no Estado de São Paulo, que foi caracterizada como sendo um fitoplasma do grupo 16 SrIX. Fitoplasmas são molicutes fitopatógenos restritos ao floema de plantas, disseminados por insetos vetores. O presente trabalho buscou identificar cigarrinhas potencialmente vetoras do fitoplasma associado ao HLB e plantas hospedeiras desses insetos, bem como desenvolver uma técnica de quantificação de DNA desse patógeno em insetos e plantas. Amostragens de cigarrinhas foram realizadas quinzenalmente por 12 meses em dois pomares de laranja com histórico de ocorrência do fitoplasma 16SrIX na região norte do Estado de São Paulo, usando-se armadilhas adesivas amarelas em duas alturas (0,3 e 1,5 m) da copa de árvores cítricas, e rede de varredura na vegetação espontânea. Dados faunísticos identificaram uma espécie de Agalliinae (Agallia albidula Uhler) e três de Deltocephalinae, [Balclutha hebe (Kirkaldy), Planicephalus flavicosta (Stål) e Scaphytopius (Convelinus) marginelineatus (Stål)], como os cicadelídeos (Hemiptera: Cicadellidae) mais abundantes e frequentes nas áreas estudadas. Essas espécies predominaram na amostragem com rede de varredura e na menor altura de coleta com armadilhas adesivas, indicando comportamento de alimentação em vegetação rasteira. Com observações visuais, verificou-se associação das espécies com certas plantas invasoras, e influência da composição florística da vegetação rasteira sobre a abundância das cigarrinhas. S. marginelineatus e P. flavicosta ocorreram com maior frequência em Sida rhombifolia L. e Althernantera tenella Colla, respectivamente, enquanto que A. albidula foi predominante em Conyza bonariensis (L.) Cronq., e B. hebe ocorreu exclusivamente em gramíneas, principalmente Panicum maximum Jacq.. Plantas invasoras amostradas nas áreas foram testadas para a presença do fitoplasma 16SrIX, porém sem resultados positivos. No entanto, amostras de campo da cigarrinha S. marginelineatus foram positivas por PCR e sequenciamento para o referido fitoplasma. Indivíduos de S. marginelineatus criados em laboratório e mantidos por um período de acesso à aquisição de 72 h em citros infectado com o fitoplasma 16SrIX, foram capazes de transmití-lo para citros, após 21 dias de latência, porém com baixa eficiência (0,5%). Por meio de PCR quantitativo desenvolvido para esse fitoplasma, verificou-se baixo título do patógeno tanto em S. marginelineatus, quanto em plantas cítricas infectadas, o que pode explicar, pelo menos em parte, a baixa eficiência de transmissão pelo inseto tendo citros como fonte. Isto sugere a existência de outros hospedeiros mais adequados como fontes de inóculo para aquisição do fitoplasma por S. marginelineatus ou outro vetor ainda desconhecido.<br>Huanglongbing (HLB) is a severe citrus disease associated to phloemlimited bacteria in the genus Candidatus Liberibacter, which were detected in Brazil in 2004. In 2008, another bacterium was found in association with HLB symptom in the São Paulo State, and characterized as a phytoplasma belonging to 16SrIX group. Phytoplasmas are vector-borne phytopathogenic mollicutes that inhabit plant sieve elements. The goals of this study were to identify potential leafhopper vectors of the HLB-associated phytoplasma and their host plants, as well as to establish a real-time PCR procedure for pathogen quantification in vectors and plants. Leafhoppers were sampled fortnightly for 12 months by yellow sticky cards placed at two heights (0.3 and 1.5 m) on the citrus tree canopy and by sweep net in the ground vegetation of two sweet orange groves with history of infection by the 16SrIX phytoplasma, in the northern region of São Paulo State. Faunistic analyses indicated 1 Agalliinae (Agallia albidula Uhler) and 3 Deltocephalinae [Balclutha hebe (Kirkaldy), Planicephalus flavicosta (Stål) e Scaphytopius (Convelinus) marginelineatus (Stål)] species that were the most abundant and frequent leafhoppers (Hemiptera: Cicadellidae) in the experimental areas. These species predominated in sweep net and in sticky traps catches at 0.3 m above soil, showing that they inhabit the ground vegetation. Visual observations indicated a strong association of leafhopper species with some weeds and the influence of weed species composition on leafhopper abundance in the ground vegetation. S. marginelineatus and P. flavicosta were more frequent on Sida rhombifolia L. and Althernantera tenella Colla, respectively, while A. albidula was observed more often on Conyza bonariensis (L.) Cronq., and B. hebe occurred solely on grasses, more abundantly on Panicum maximum Jacq. Fourteen weed species sampled in the area were PCR tested for infection by the 16SrIX phytoplasma, but none was found infected. Nevertheless, 3 out of 30 field-collected samples (10 adults per sample) of S. marginelineatus tested positive for this phytoplasma by PCR and sequencing. Healthy lab-reared adults of S. marginelineatus were able to transmit inefficiently (0,5%) the 16SrIX phytoplasma to healthy citrus after a 72-h acquisition access period on infected citrus plants followed by a 21-day latent period on S. rhombifolia plants. By using the qPCR method developed for this phytoplasma, a very low pathogen titer was found both in S. marginelineatus and in infected citrus plants, which may explain, at least partially, the low transmission efficiency by this vector using citrus as a source plant. It also suggests that existence of alternative hosts that might be more adequate as inoculum sources for phytoplasma acquisition and spread by S. marginelineatus or another vector yet to be discovered.

Thesis (MScAgric)--University of Stellenbosch, 2002.<br>ENGLISH ABSTRACT: Botrytis bunch rot of grape is caused by Botrytis cinerea Pers. :Fr. Conidia of the pathogen, which is dispersed by wind, water droplets and by insects, can penetrate the intact grape berry cuticle, but disease expression occurs only under predisposing conditions. Since relatively high infection rates often occur in vineyards, predisposing factors must play a fundamental role in primary infection and subsequent disease occurrence. Insects can play a very important role in this regard by depositing inocula at wound sites during feeding and by providing fresh wounds during their oviposition and feeding activities. The aim of this study was (i) to determine the potential of the Mediterranean fruit fly to transfer B. cinerea and other bunch and fruit rot fungi in natura, (ii) to investigate the transport, deposition and subsequent disease expression on grape berries in vitro, and (iii) to investigate fruit fly activities and the nature of deposited conidia and mycelia of B. cinerea by aid of digital photography and epifluorescence microscopy, respectively. Two Sensus fruit fly traps containing the para-pheromone, Capilure, were installed in orchards and five neighboring vineyards on four farms in the Stellenbosch region. Ceratitis fruit flies were collected weekly, identified and counted to determine the fluctuations in fruit fly population. Following field collection, the fruit flies were plated on Kerssies' B. cinerea selective medium and the number of flies yielding the pathogen was recorded. Two fruit fly species, C. capitata and C. rosa, were captured during the study period. Ceratitis rosa numbers comprised only 1% of the total number of fruit flies captured. Ceratitis capitata numbers, and the percentage B. cinerea contaminated flies generally increased after harvest in the different orchards and vineyards. Following harvest, the percentage flies yielding B. cinerea was higher in vineyards compared to orchards. Furthermore, in each vineyard an increase in percentage B. cinerea contaminated fruit flies was preceded by a corresponding increase in its neighboring orchard. The levels of both Penicillium and Alternaria contaminated fruit flies stayed high throughout the investigation period, especially after harvest of the orchard cultivars. Low incidence of Aspergillus, Mucor and Rhizopus spp. were recorded on C. capitata. These findings suggest that the Mediterranean fruit fly may play an important role in the dispersal of inocula of fungi associated with postharvest decay from early-maturing stone fruit orchards to mid- and late-maturing wine grape vineyards, and in disease induction under conditions unfavourable for natural infection. Three experiments were conducted to determine the potential of fruit flies in provoking B. cinerea decay. In the first experiment, transport of conidia and disease expression were investigated on rachis segments bearing unwounded berries only. In the second experiment, the effect of wounding on disease expression was investigated. In the third experiment, the effect of inoculum type (mycelia and conidia) on transportation and disease expression was investigated on rachis segments bearing unwounded berries, and on segments with wounded berries. The table grape cultivar, Dauphine, and the wine grape cultivar, Shiraz, were used at véraison, two weeks before harvest and harvest, and the transport studies were conducted in ethanol-disinfected perspex cages. Disease expression was studied in dry (~56% RH), ethanol-disinfected perspex chambers incubated at 22°C. The isolations from berries revealed that the flies deposited, without preference, high amounts of B. cinerea at various positions on the grape berry's surface. The freezing studies showed that the deposited conidia germinated and penetrated the berry skin at various positions. However, B. cinerea developed more often at the pedicel end than on the cheek or style end, which indicated a peculiar interaction between B. cinerea, the fruit fly and host tissue at this part of the berry. This phenomenon was substantiated by the finding that B. cinerea also developed more often at the pedicel end of berries that were not frozen. Further evidence for this interaction was found on intact berries exposed to flies that carried mycelia after feeding on berries without sporulating colonies of the pathogen, but showing symptoms of slippery skin. Significantly more decay developed on wounded berries compared to the unwounded berries and more so at the wound site. In addition, female fruit flies were responsible for significantly more decay development than male fruit flies. The study thus proved that the Mediterranean fruit fly can promote B. cinerea disease development under conditions unfavorable to natural infection. The activities of the Mediterranean fruit fly, Ceratitis capitata, on grape berries were monitored by aid of digital photography. In addition, the deposition of conidia and mycelia of Botrytis cinerea at three sites (pedicel end, cheek and style end) on the grape berry, germination of the fungal structures after dry (±56% RH) and moist (±93% RH) incubation and wounds inflicted during ovipositioning were examined with an epifluorescence microscope. The observations revealed that the fruit fly's activities were generally restricted to the grape berry. They visited the grape berry cheek more often, but visitations to the pedicel end of berries increased substantially from véraison to harvest, indicating the possibility of nutrient leakages at this site. Microscopy revealed that the flies deposited conidia singular, in feeding packages and in faecal excrements on the berry surface. The conidia in feeding packages were ensheathed by salivical fluids and occurred in clusters of 10 to 50 conidia. An average of 60% of the conidia in feeding packages germinated under dry conditions (±56% RH). Conidia that passed through the intestinal tract of the fruit fly and that were deposited in faecal excrements were deformed and low in viability. These conidia did not occur in cluster format, but were proportionally spread with the faeces on the surface of the grape berry. Conidia that were deposited singular and in faecal excrements did not germinate unless incubated under moist conditions (± 93% RH). Wounds inflicted by female fruit flies during ovipositioning were most frequently observed on the cheek. This predisposition to B. cinerea infection of grape berries by the activities of fruit flies, suggested an important role for the flies in the initiation of Botrytis bunch rot epidemics in vineyards.<br>AFRIKAANSE OPSOMMING: DIE ROL VAN DIE MEDITERREENSE VRUGTEVLIEG, CERATITIS CAPITATA, IN BOTRYTIS CINEREA TROSVERROTTING VAN DRUIWE Botrytis-trosverrotting van druiwe word deur Botrytis cinerea Pers. :Fr. veroorsaak. Konidia van die patogeen wat deur wind, waterdruppels en insekte versprei word, kan die intakte druiweskil binnedring, maar siekte-uitdrukking vind slegs onder spesiale omstandighede plaas. Aangesien relatief hoë infeksie vlakke algemeen in wingerde voorkom, moet predisponerende faktore 'n fundamentele rol in die primêre infeksie, en die daaruit voortspruitende siektetoestand speel. Insekte kan 'n baie belangrike bydrae lewer deur inokuia tydens voeding by wonde te deponeer. Nuwe wonde kan ook tydens oviposisionering en voeding ontstaan. Die doel van hierdie studie was om (i) die potensiaal van die Mediterreense vrugtevlieg om B. cinerea en ander tros- en vrugverrottingswamme in natura oor te dra, te bepaal; om (ii) die verspreiding, deponering en daaropvolgende siekteuitdrukking op druiwekorrels in vitro te ondersoek; en om (iii) die aktiwiteite en aard van die gedeponeerde konidia en miselia met behulp van digitale fotografie sowel as epifluoressensiemikroskopie waar te neem. Twee Sensus-vrugtelokvalle met die paraferomoon, Capilure, IS In vrugteboorde en aangrensende wingerde in die Stellenbosch-omgewing aangebring. Ceratitis-vrugtevlieë is weekliks versamel, geïdentifiseer en getel om fluktuasies in die vrugtevliegpopulasie te bepaal. Na die veldversameling is die vrugtevlieë op Kerssies se B. cinerea-selektiewe medium uitgeplaat. Gedurende die studie is twee spesies vrugtevlieë, C. capitata en C. rosa, gevang. Na oesstyd het die aantal Ceratitis-vrugtevlieë en die persentasie vrugtevlieë, besmet met B. cinerea, in die verskillende boorde en wingerde toegeneem. Na oestyd was die persentasie vrugtevlieë wat B. cinerea gedra het, hoër in die wingerde as in die boorde. Elke toename in die persentasie B. cinerea-besmette vrugtevlieë in 'n wingerd is voorafgegaan deur 'n ooreenkomstige toename in die aangrensende vrugteboord. Die aantal vrugtevlieë besmet met Penicillium en Alternaria spp. het tydens die navorsingstydperk deurgaans hoog gebly, veral nadat die vrugteboord-kultivars geoes is. Die voorkoms van Aspergillus-, Mucor- en Rhizopus spp. op Ceratitis-vrugtevlieë was deurgaans laag. Hierdie bevinding wys daarop dat vrugtevlieë 'n belangrike rol speel in die verspreiding van swarninokula, wat met na-oes verrotting geassosieer word, van vroegrypwordende steenvrugteboorde na mid- en laatrypwordende wyndruifwingerde. Drie eksperimente is in vitro onderneem om vrugtevlieë se potensiaal om B. cinereaverrotting te veroorsaak te bepaal. In die eerste eksperiment is ragi met slegs ongewonde korrels gebruik om die oordrag van konidia en siekte-ontwikkeling te ondersoek. In die tweede eksperiment is die effek van verwonding op siekte-ontwikkeling ondersoek. In die derde eksperiment is die effek van inokulumtipe (miselia en konidia) op verspreiding en siekte-ontwikkeling ondersoek deur ragis-segmente met gewonde korrels sowel as ragissegmente met ongeskonde korrels te gebruik. Die tafeldruif-kultivar Dauphine en die wyndruif-kultivar Shiraz, by kleurbreuk, twee weke voor oes en by oestyd, is in die eksperimente gebruik. Die oordragstudies is in etanol-ontsmette perspex-hokke uitgevoer. Siekte-ontwikkeling is bestudeer in droeë (±56% RH), etanol-ontsmette perspex-kamers en geinkubeer by 22°C. By ondersoek is gevind dat vlieë, sonder voorkeur, groot hoeveelhede B. cinerea op verskeie dele op die druiwekorrel-oppervlak deponeer. Bevriesingstudies het aangetoon dat die gedeponeerde konidia op verskeie dele van die korrelontkiem en die skil binnedring. Botrytis cinerea het egter meer dikwels by die korrelsteelkant as by die stempelkant, of op die wang, ontwikkel. Hierdie bevinding het 'n eiesoortige interaksie tussen B. cinerea, die vrugtevlieg en gasheerweefsel by die korrelsteelkant van die korrel aangetoon. Die verskynsel is gestaaf deur die bevinding dat B. cinerea ook meer dikwels by die korrelsteelkant van die korrels wat nie gevries is nie, ontwikkel het. Verdere bewys van hierdie interaksie is gevind by ongeskonde korrels wat aan die vlieë wat miselia gedra het blootgestel is. Die siekte het beduidend meer dikwels op gewonde as ongewonde korrels en verder aansienlik meer dikwels op die wondoppervlakte ontwikkel. Dit was ook duidelik dat vroulike vrugtevlieë baie meer vir verrotting verantwoordelik was as manlike vrugtevlieë. Die studie bewys dus dat Mediterreense vrugtevlieë die ontwikkeling van B. cinerea kan bevorder in omstandighede wat ongunstig is vir natuurlike infeksie. Die aktiwiteite van die Mediterreense vrugtevlieg C. capitata op die druiwekorrels is met behulp van digitale fotografie waargeneem. Verder is die deponering van konidia en miselia van B. cinerea op die verskillende dele (korrelsteelkant, wang en stempelkant) van die korrel, ontkieming van die swamstrukture na droeë (±56% RH) en nat (±93% RH) inkubasie en wonde wat tydens oviposisionering veroorsaak is, met epifluoressensie-mikroskopie ondersoek. Die waarnemings het onthul dat die vrugtevlieg se aktiwiteite gewoonlik tot die druiwekorrel beperk is. Hulle het korrelwange meer dikwels besoek. Besoek aan die korrelsteelkant het aansienlik toegeneem van kleurbreuk tot oestyd, wat op die moontlikheid van voedingstof-lekkasie by die deel aandui. Mikroskoopstudies het aangedui dat vlieë konidia enkel, in voedingspakkies en in fekale uitskeidings op die korreloppervlakte deponeer. Die konidia in die voedingspakkies is deur speekselvloeistof omhul en het in groepe van 10 tot 50 konidia voorgekom. Gemiddeld 60% van die konidia in voedingspakkies het in droeë omstandighede (±56% RH) ontkiem. Konidia wat deur die spysverteringskanaal van die vrugtevlieg gegaan het en in die fekale ekskresie gedeponeer is, was misvorm en het lae lewensvatbaarheid gehad. Laasgenoemde konidia was nie in groepe gedeponeer nie, maar is proporsioneel met die feces op die oppervlak van die druiwekorrel versprei. Konidia wat enkel en in feces gedeponeer is, het nie ontkiem nie, tensy toestande vogtig (±56% RH) was. Wonde wat deur die vroulike vrugtevlieë tydens oviposisionering veroorsaak is, is meer dikwels op die wang van die korrelopgemerk. Hierdie predisposisie van druiwekorrels tot B. cinerea-infeksie, meegebring deur die aktiwiteit van die vrugtevlieg, dui daarop dat die rol wat die vrugtevlieg in die inisiëring van Botrytis trosverrottingepidemies in wingerde speel, van beduidende belang is.