Dissertations / Theses on the topic 'Insect populations'
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1
Banks, John E. "The effects of landscape heterogeneity on insect populations : a study of pattern and scale /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/5166.
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Higgins, Charlene J. "Spatial distribution and reproductive biology of western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera : Thripidae)." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/29873.
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Western flower thrips (WFT), Frankliniella occidentalis (Pergande), are haplodiploids. Virgin females produce sons parthenogenetically but must be mated to produce daughters. As a result, primary and secondary (adult) sex ratios can diverge from the 1:1 ratio commonly observed in diploid systems. Field studies were conducted to examine the spatial distribution of WFT on two greenhouse crops, Bell peppers, Capsicum annuum (Linn.) and Long English cucumbers, Cucumis sativus (Linn.) to determine if there was a correlation between sex ratio and density. Leaf and flower samples were taken weekly. All adult and immature WFT were counted and sex of adults determined. Yellow sticky traps were used to monitor density and sex ratio of the dispersing adult population. Lab studies were also done to investigate if male availability affected the sex ratio and number of offspring produced by individual females. Laboratory experiments were done to assess the effects of sperm availability and maternal age on sex ratio of progeny produced.
On both crops, 84 to 95 % of adult WFT in flowers were females and most larvae (> 85 %) were found on leaves. Male WFT were rare on all plant parts even when caught in high numbers on traps. Approximately 75 % of females found on plants in the greenhouse were mated. Most (70 - 90 %) WFT on traps at low densities (< 200 individuals/trap) were males. This suggests that WFT populations are initiated by virgin females that likely overwintered as pseudopupae in the greenhouse. These females initially produce only sons, and may have to wait for these to emerge before they mate and produce daughters. As WFT density within a greenhouse increases, females are probably mated soon after emergence. Sex ratio of adults on traps becomes more female biased as density increases within a greenhouse. Heavily female biased (> 65 %) sex ratios were found on traps at high population densities (> 200 individuals/trap). Sex ratio
of adults on traps remained male biased in the pepper greenhouse (WL) where the population density of WFT remained low. Information regarding within-plant distribution of thrips is essential for population monitoring and control. Used together, regular examination of flowers and counts of adults on sticky traps allow quick detection of potential "hot spots" of WFT density. Sex ratio and density are highly correlated. Sex ratio of the dispersing adult population is a good predictor of outbreak potential of the extant WFT population.
Two WFT predators found in greenhouses were also monitored to document their effects on WFT population density and sex ratio. Mass introductions of the predatory mite, Amblysieus cucumeris, did not successfully control WFT in most greenhouses monitored. A natural infestation of pirate bugs, Orius tristicolor occurred in the only pepper house monitored. WFT density remained low throughout the growing season. O. tristicolor shows promise for future use in integrated pest management programs designed to control F. occidentalis in commercial greenhouses.
Lab studies showed that sex ratio of offspring produced by mated females was influenced by sperm supply and maternal age. Mated females produced sons and daughters which suggests that females control sex of offspring produced through selective fertilization. Once mated, two-thirds of offspring produced are females. Older females produced fewer daughters than younger females.
A principle conclusion from this study is that sex ratio of the WFT population within a greenhouse can be used to predict future population dynamics. Male availability may be the most important factor affecting the number of daughters produced by individual females which in turn may determine the potential of WFT populations to increase.Science, Faculty of
Zoology, Department of
Graduate
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Hitchman, Richard B. "Pathogen variability and dynamics in insect populations." Thesis, Oxford Brookes University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247600.
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Latto, John. "The analysis of density dependence in insect populations." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47531.
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McNamee, Peter James. "The equilibrium structure and behavior of defoliating insect systems." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/27439.
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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.Science, Faculty of
Zoology, Department of
Graduate
6
Ballard, Meg. "Insect populations on early successional native and alien plants." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 50 p, 2006. http://proquest.umi.com/pqdweb?did=1203553531&sid=1&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Gaston, K. J. "Patterns in the dynamics and distribution of insect populations." Thesis, University of York, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235013.
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Wilcock, Helen Rachel. "Geographic and genetic structure of highly fragmented freshwater insect populations." Thesis, Queen Mary, University of London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.481520.
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Morrison, Peter D. S. "Host plant variation and population limitation of two introduced insects." Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/27464.
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The response to host plant variation shapes the long-term success of phytophagous insects. Two gall-forming tephritid flies, Urophora affinis and U. quadrifasciata, oviposit in flower buds of Centaurea diffusa and C. maculosa (Asteraceae). Females of both fly species chose among plants, among groups of buds on plants, and among buds. Among plant choices were correlated with buds per plant. Among bud choices corresponded to larval developmental requirements. Insect attack led to gall formation, bud abortion, and reduced seed production. Bud abortion, caused by probing females, limited gall densities.
Increased densities of U. affinis females relative to oviposition sites led to more U. affinis galls, increased bud abortion, fewer U. quadrifasciata galls, and fewer seeds. A temporal refuge for seed production was observed. Plants compensated only slightly for aborted buds.
Bud abortion may increase the search time between successful ovipositions. A simulation model based on this premise implied that bud abortion may dramatically reduce total gall formation.
Plant quality was manipulated in an attempt to shift three population limiting factors. Plants responded to fertilization and watering with an increase in bud numbers. Except for two year-site-treatment combinations, galls per developed bud did not differ significantly between treatments. Treated plants did not differ in their propensity to abort buds. U. affinis larvae developed faster in fertilized plants. Among year comparisons showed that the density of buds available for oviposition was limited by precipitation, non-random insect attack, and, in the longer term, by the reduction in seed production due to fly attack. Bud densities, in turn, limited gall densities.Science, Faculty of
Zoology, Department of
Graduate
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Chu, C. C., and T. J. Henneberry. "Cultural Control and Pink Bollworm Populations." College of Agriculture, University of Arizona (Tucson, AZ), 1996. http://hdl.handle.net/10150/210914.
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A cotton management program in the Imperial Valley, CA was designed to reduce pink bollworm, Pectinophora gossypiella (Saunders), populations. The program established I March as the earliest planting date, 1 September for defoliant or plant growth regulator application and 1 November for cotton stalk destruction and plowdown. In-season gossyplure-baited pink bollworm male moth activity monitoring and immature green cotton boll inspections for larval infestation were encouraged as decision making aids to determine the need for additional control action. Male pink bollworm moth catches in gossyplure-baited Lingren and delta sticky traps were significantly reduced each year from 1990 to 1994 following the initiation of the management program in 1989. Fewer larvae per cotton boll occurred in the years from 1990 to 1992. Fiber quality of commercial cotton sampled was also improved from 1989 to 1994, as compared to the 1984 to 1988 average. Cotton production, in general, was reduced during 1989 to 1994 in areas surrounding Imperial Valley and may have contributed partially to reduced populations in Imperial Valley.
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Kowles, Katelyn A. "Dynamics of aggregation formation in Japanese beetles, Popillia japonica /." View online, 2009. http://repository.eiu.edu/theses/docs/32211131559299.pdf.
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Sinka, Marianne. "The ecological effects of above-ground insect herbivores on Collembola populations." Thesis, Imperial College London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.407404.
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Hackett, Sean. "The optimal control of dynamic pest populations." Thesis, University of Oxford, 2018. http://ora.ox.ac.uk/objects/uuid:5035e7a5-1d81-4288-8eb0-ec05b2fd95a2.
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In the management of agricultural insect pests, short-term costs must be balanced against long-term benefits. Controls should be selected to account for both their immediate and downstream effects upon the demography and genetics of the pest, enabling suppression today without threatening suppression tomorrow. The iterative, algorithmic method of dynamic programming can provide optimal solutions to problems of this type, in which actions are taken sequentially and each action may influence those which follow it. However, this approach is fundamentally constrained with regards to the magnitude of the problems it may solve. As questions of insect pest management can be subject to ecological and evolutionary complexities, this may place them beyond the scope of dynamic programming. When it is the intricacies of a problem that are of interest, it may be more productive to utilise approximate dynamic programming (ADP) methods which can attempt problems of arbitrary complexity, although at the expense of no longer guaranteeing optimality. In this thesis I first challenge a dynamic programming algorithm with the management of a hypothetical insect pest feeding upon a transgenic insecticidal crop. The model explores how different realisations of fitness costs to resistance influence the algorithms suggested actions. I then apply a brute-force variant of ADP, a lookahead policy, to the management of a stage-structured, continuously reproducing pest population. This was to explore the extent to which an algorithm with a limited temporal perspective is able to balance the timetable of pest demography against the timescale over which insecticidal sprays and bisex-lethal sterile insect releases unfold. This same decision framework is then applied to a modified problem in which resistance to insecticidal toxins may evolve and releases are now male-selecting. This was used to assess the efficacy with which simple lookahead policies utilise a control with delayed benefits (the male-selecting releases) and possible constraints on their capacity to respond to resistance evolution. Dynamic programming and ADP methods offer a versatile toolbox for accounting for the potential impacts of the evolutionary and ecological peculiarities of particular pests upon control decisions.
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Bright, Jennifer Anne. "Insects on farmland and their importance to granivorous birds." Thesis, University of Stirling, 2004. http://hdl.handle.net/1893/2158.
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Many species of farmland birds have shown huge declines in numbers and range since the 1970s due to agricultural intensification, and these declines have been worst amongst granivorous species. Recent studies have suggested that low abundance of invertebrate chick food may have been important in driving the declines of a number of granivorous species, however causation has still only been proved for the Grey Partridge, whose decline has been attributed to low chick survival due to the indirect effects of herbicides reducing invertebrate abundance. We investigated invertebrate declines and how they may have affected farmland bird populations in a number of ways. There is little long-term data on abundance of farmland invertebrates. Thus we first looked at how representative data from a long-running suction trap was of invertebrate abundance on local farmland. Suction trap catches reflected abundance of aerial invertebrates on local farmland, and also to abundance of epigeal invertebrates in many cases, particularly abundances in predominant crop types. Secondly, we looked at spatial and temporal distribution of invertebrates on farmland in order to make recommendations about how to increase invertebrate availability to farmland bird populations. Field margins were by far the most invertebrate rich habitats sampled. Most differences in invertebrate abundance between different crop types were found early in the season, at this time spring barley and spring oilseed rape had very low abundances. Winter wheat had relatively high invertebrate abundance compared to spring barley at this time. Winter oilseed rape and set-aside had relatively high abundances of the crop types sampled. We investigated how low invertebrate abundance may have affected populations of granivorous passerines by looking for evidence of reproductive trade-offs in a population of Tree Sparrows, and by supplementary feeding experiments with Tree Sparrow and Yellowhammer chicks. There was no evidence for reproductive trade-offs within years, conversely an effect of individual quality was found. There was some evidence of reproductive trade-offs between years. Supplementary feeding increased the mass of Tree Sparrow first broods early in May but not later in May, and also of chicks with yearling parents, who had a lower provisioning rate. Chicks fledged early in May had a lower survival rate to the following year than chicks fledged later, supplementary feeding and parental age had no effect on chick survival. Supplementary feeding a parent's first brood had no effect on their later reproductive output that season, or on their survival to the next breeding season. Supplementary feeding Yellowhammer chicks early season increased their mass, but had no effect later in the season. This complies with results from a previous study of Yellowhammers in southern England, which showed that a higher proportion of chicks fledge late in the season. Further analysis of this data showed that this was because chicks were more likely to starve early in the season, and also that chick mass was lower early season, even when just looking at chicks which went on to fledge. Thus, it would appear that low invertebrate abundance was affecting the granivorous passerines looked at most in the early season, and through chick mass and survival. Measures to increase invertebrate abundance at this time would be beneficial to populations of granivorous passerines.
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Steffan, Shawn Alan. "Biodiversity and fear ecology the cascading effects of species richness and nontrophic interactions /." Pullman, Wash. : Washington State University, 2009. http://www.dissertations.wsu.edu/Dissertations/Spring2009/s_steffan_041709.pdf.
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Santos, Luan Alberto Odorizzi dos. "Contribution of marginal non-crop vegetation and semi-natural habitats to the regulation of insect pest populations by their natural enemies /." Jaboticabal, 2017. http://hdl.handle.net/11449/150943.
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Orientador: Odair Aparecido FernandesCoorientador: Armin Bischoff
Banca: Pierre Franck
Banca: Daniel Junior de Andrade
Banca: Olivier Blight
Banca: Raphael de Campos Castilho
Abstract: The expansion of agricultural areas has led to the loss of biodiversity due to the reduction of natural and semi-natural habitats in agricultural landscapes. With the increase of agricultural production in the world, environmentally sound techniques are increasingly discussed that allow a sustainable management of surrounding habitats. The effects of these habitats on the population of insect pests and their natural enemies are still poorly understood. The objective of this thesis was to understand the effects of natural and semi-natural environments on the population of insect pests and natural enemies in tropical (Brazil) and temperate (France) regions. In Brazil (Chapter II) the effect of the distance of fragments on the population of predatory and omnivorous ants in sugarcane was evaluated. The results showed that the species richness decrease with distance from forest fragments and that the dominance of the species Dorymyrmex bruneus and Pheidole oxyops increase. Ant species colonizing sugarcane fields were also found in forest fragments suggesting that the latter habitats are refuges for predatory ant species during periods of disturbance such as sugarcane harvest or soil tillage. This was confirmed by stronger differences in ant communities after sugarcane harvest (dry season) than four months later (rainy season) when absence of disturbance allowed re-colonosiation by ants. There was also a difference in the richness of ant species between different fragment types (ri... (Complete abstract click electronic access below)
Résumé: L'expansion des zones agricoles a conduit à la perte de biodiversité due à la réduction des habitats naturels et semi-naturels dans les paysages agricoles. Avec l'augmentation de la production agricole dans le monde, des techniques écologiquement rationnelles sont de plus en plus discutées qui permettent une gestion durable des habitats environnants. Les effets de ces habitats sur la population des insectes nuisibles et de leurs ennemis naturels sont encore mal connus. L'objectif de cette thèse était de comprendre les effets des environnements naturels et semi-naturels sur la population des insectes nuisibles et des ennemis naturels dans les régions tropicales (Brésil) et tempérées (France). Au Brésil (chapitre II), on a évalué l'effet de la distance des fragments sur la population de fourmis prédatrices et omnivores dans la canne à sucre. Les résultats montrent que la richesse en espèces diminue avec la distance des fragments forestiers et que la prédominance des espèces Dorymyrmex bruneus et Pheidole oxyops augmente. Des espèces de fourmis colonisant les champs de canne à sucre ont également été trouvées dans des fragments forestiers, ce qui suggère que ces derniers habitats sont des refuges pour les espèces de fourmis prédatrices pendant les périodes de perturbation comme la récolte de la canne à sucre ou le travail du sol. Cela a été confirmé par des différences plus fortes dans les communautés de fourmis après la récolte de la canne à sucre (saison sèche) que quatre mois... (Résumé complet accès életronique ci-dessous)
Resumo: A expansão das áreas agrícolas levou à perda de biodiversidade devido à redução dos habitats naturais e semi-naturais nas paisagens agrícolas. Com o aumento da produção agrícola no mundo, são cada vez mais discutidas técnicas ambientais que permitem uma gestão sustentável dos habitats do entorno. Os efeitos desses habitats sobre a população de insetos-pragas e seus inimigos naturais ainda são mal compreendidos. O objetivo desta tese foi compreender os efeitos dos ambientes naturais e semi-naturais na população de insetos-pragas e inimigos naturais nas regiões tropicais (Brasil) e temperadas (França). No Brasil (Capítulo II) foi avaliado o efeito da distância de fragmentos sobre a população de formigas predadoras e omnívoras em cana-de-açúcar. Os resultados mostraram que a riqueza de espécies diminui com a distância dos fragmentos florestais e que a dominância das espécies Dorymyrmex bruneus e Pheidole oxyops aumenta. As espécies de formigas que colonizam áreas de cana-de-açúcar também foram encontradas em fragmentos de florestas, sugerindo que estes últimos são abrigos para espécies de formigas predatórias durante períodos de perturbação como colheita de cana-de-açúcar ou preparo do solo. Isto foi confirmado por diferenças mais fortes nas comunidades de formigas após a colheita da cana (estação seca) do que quatro meses depois (estação chuvosa) quando a ausência de perturbação permitiu recolonização por formigas. Houve também uma diferença na riqueza de espécies de formigas e... (Resumo completo, clicar acesso eletrônico abaixo)
Doutor
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Butler, G. D. Jr, T. J. Henneberry, and H. H. Jr Perkins. "Sweetpotato Whitefly Populations in Cotton Genotypes at Poston, Arizona in 1988." College of Agriculture, University of Arizona (Tucson, AZ), 1990. http://hdl.handle.net/10150/208312.
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Studies were conducted to identify potential sources of cotton germ plasm resistant to sweetpotato whitefly (SPW), Bemisia tabaci (Gennadius). Numbers of adult SPW sampled using black pan and vacuum methods showed reduced numbers of SPW on GC-EXP-7007 experimental variety vs. all other entries. However, numbers of SPW pupae on leaf samples in most cases were not different. Pima P-62 had the high numbers of SPW adults per blackpan sample, and highest number of pupae/leaf sample.
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Watson, T. F., J. C. Silvertooth, and A. Tellez. "Varietal and Nitrogent-level Effects on Sweepotato Whitefly Populations in Cotton." College of Agriculture, University of Arizona (Tucson, AZ), 1994. http://hdl.handle.net/10150/209646.
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Four cotton varieties, each differing in leaf pubescence, and three nitrogen (N) levels were investigated for effects upon development of SPWF populations. The N treatments appeared to have no effect upon population development. However, there was a direct correlation of increased SPWF numbers with increased hairiness. Both DPL 5415 and SALCOTIO had significantly lower seasonal means of all stages than did the more hairy varieties of CB1135 and STV453.
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Naranjo, Steven E., and Peter C. Ellsworth. "Mortality Factors Affecting Whitefly Populations in Arizona Cotton Management Systems: Life Table Analysis." College of Agriculture, University of Arizona (Tucson, AZ), 1999. http://hdl.handle.net/10150/197274.
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Direct-observation studies were conducted in replicated experimental plots to identify causes and estimate rates of mortality of whiteflies in cotton over the course of six generations from late June through late October. In plots receiving no whitefly or Lygus insecticides, predation and dislodgment were major sources of egg and nymphal mortality, and overall survival from egg to adult ranged from 0-18.2%. Similar patterns were observed in plots treated with the insect growth regulator (IGR) Knack. Applications of the IGR Applaud or a mixture of endosulfan and Ovasyn caused high levels of small nymph mortality and reduced rates of predation on nymphs during the generation immediately following single applications of these materials in early August. Whitefly populations declined to very low levels by mid-August in all plots, and few differences were observed in patterns of whitefly mortality among treated and control plots 4-6 weeks after application. The population crash was associated with an unknown nymphal mortality factor which reduced immature survivorship during this first posttreatment generation to zero. The application of insecticides for control of Lygus in subplots modified patterns of mortality in all whitefly treatments by generally reducing mortality from predation during generations observed from mid-July through August. Parasitism was a very minor source of mortality throughout and was unaffected by whitefly or Lygus insecticides.
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Henneberry, T. J., T. Meng, B. Deeter, and P. Price. "Effects of PREP on Cotton Fruiting, Boll Opening and Boll Weevil Populations." College of Agriculture, University of Arizona (Tucson, AZ), 1987. http://hdl.handle.net/10150/204494.
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Prep applied to cotton on 15, 23, and 29 September reduced numbers of squares, immature green bolls < 1 inch in diameter, and accelerated mature boll opening. Reduced cotton fruiting forms in Prep- treated plots resulted in reduced boll weevil population development.
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Rethwisch, Michael D., Mark Reay, Lois Berger, Erica Hawpe, Jessica Grudovich, Roger Perez, and David Ramos. "Comparisons of Insecticides on Fall Alfalfa Insect Populations, and Resultant Hay Yields and Quality." College of Agriculture, University of Arizona (Tucson, AZ), 2004. http://hdl.handle.net/10150/203869.
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Three insecticide active ingredients (cyfluthrin, indoxacarb, and zetacypermethrin) were evaluated for their efficacy on several insects found in fall alfalfa in the low desert. Both liquid and wettable formulations were included for both cyfluthrin and zetacypermethrin, and four rates of indoxacarb were applied. Insect pressures were fairly low throughout the study. Pyrethroid chemistries (cyfluthrin, zetacypermethrin) provided excellent control of threecornered alfalfa hoppers for seven days after application while cyfluthrin applications resulted in lowest numbers of pale striped flea beetles during the same time period. All chemistries resulted in excellent control of the South American bean thrips (Caliothrips phaseoli). Indoxacarb treatments resulted in significantly increased levels of spotted alfalfa aphid, thought due to a reduction of big eye bugs noted with usage of this chemistry. Wettable formulations of both cyfluthrin and zetacypermethrin resulted in significant hay yield increases (0.1 tons/acre) when compared with their liquid formulations. An inverse yield trend was noted with indoxacarb rate. Usage of the liquid cyfluthrin chemistry also resulted in an unexplained quality decrease in this experiment.
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Rethwisch, Michael D., Marvin D. Butler, and Mike Meadows. "Evaluation of Head Lettuce Varieties for Liriomyza trifolii Leafminer Populations." College of Agriculture, University of Arizona (Tucson, AZ), 1989. http://hdl.handle.net/10150/214266.
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Silva, Ivana Fernandes da 1986. "Desempenho de populações geográficas de Helicoverpa armigera (Hübner) (Lepidoptera : Noctuidae) em dietas naturais e artificial e caracterização por microssatélites /." Botucatu, 2017. http://hdl.handle.net/11449/150891.
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Orientador: Edson Luiz Lopes BaldinCoorientador: Alexandre Specht
Banca: José Paulo Gonçalves Franco da Silva
Banca: Carlos Frederico Wilcken
Banca: Daniel Ricardo Sosa-Gomez
Banca: André Luiz Lourenção
Resumo: Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) possui ampla distribuição geográfica e é reponsável por perdas econômicas em várias culturas de importância agrícola ao redor do mundo. As lagartas apresentam grande plasticidade em termos de exigência nutricional e, devido à polifagia, se adaptam a diversos hospedeiros, com valores nutricionais variados, os quais podem afetar seu desenvolvimento biológico. Considerando a recente introdução do inseto no Brasil (2013), aliada à falta de consenso sobre a origem das populações a campo, dificuldades no estabelecimento de criações massais, bem como a necessidade de maior entendimento sobre sua interação com os hospedeiros em nosso país, este estudo teve como objetivos: disponibilizar uma dieta padronizada para criações de H. armigera em laboratório (25±2°C, 70±10% U.R. e 14h de fotofase), caracterizar molecularmente três populações, de São Paulo, Bahia e Distrito Federal, avaliar o desempenho biológico e o potencial biótico de indivíduos provenientes de diferentes populações em dieta artificial e investigar a performance de H. armigera em estruturas vegetativas e reprodutivas de algodão, milho e soja. As análises moleculares mostraram similaridade elevada entre indivíduos das três populações, indicando uma origem única para H. armigera no Brasil. O método de criação, bem como os índices nutricionais da dieta artificial oferecida se revelaram adequados para o inseto. A viabilidade média das fases larval e pré-pupal foi semelhan... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) has a wide geographical distribution and contributes to economic losses in several crops of agricultural importance around the world. The larvae present great plasticity in terms of nutritional requirement and, due to polyphagia, they adapt to several hosts with varied nutritional values which may affect their biological development. Taking into account the recent introduction of these insects in Brazil (2013), along with the lack of consensus on the origin of their populations in the field, as well as the difficulties in establishing mass creations, and the need for greater understanding of their interaction with the hosts in our country, this study had as its objectives: to provide a standardized diet for laboratory H. armigera (25±2°C, 70±10% R.H., and 14h of phototophase); to molecularly characterize three populations from São Paulo (SP), Bahia (BA), and Distrito Federal (DF); to evaluate the biological performance and biotic potential of individuals from different populations on artificial diet; and to investigate the performance of H. armigera in vegetative and reproductive structures of cotton, corn and soybean. The molecular analyzes showed a high similarity between individuals of the three populations, which indicates a unique origin for H. armigera in Brazil. The breeding method, as well as the nutritional indexes of the artificial diet offered, was adequate for the insects. The mean viability of the larval and ... (Complete abstract click electronic access below)
Doutor
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Osman, Abdelgadir A., Theo F. Watson, and Sakunlala Sivasupramaniam. "Susceptibility of Field Populations of Pink Bollworm (Lepidoptera: Gelechiidae) to Azinphosmethyl and Permethrin." College of Agriculture, University of Arizona (Tucson, AZ), 1991. http://hdl.handle.net/10150/208354.
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Responses of five field -collected populations of the pink bollworm. Pectinophora gossypiella (Saunders). from Arizona and southern California. were compared with those of a standard. susceptible -laboratory strain. Field strains showed less than twofold difference in response to azinphosmethyl at LD₅₀ but had variable levels (1.3- to 18.3-fold) of response to permethrin. Strains from Yuma and Phoenix (Arizona) and Westmoreland (California) had highest levels of resistance to permethrin.
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Kadango, Tendayi Lovemore. "Farmers' perceptions of insect pests in the Eastern Cape maize-based cropping systems and the effects of crop residue management on insect pest populations." Thesis, University of Fort Hare, 2018. http://hdl.handle.net/10353/6202.
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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.
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Blochel, Alexander. "Population demography’s potential effect on stoichiometry : Assessing the growth rate hypothesis with demography." Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-130908.
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The elemental composition within structured insect populations was tested by creating a new method to analyze how variables (survival, growth and fecundity) within a population matrix could potentially affect the stoichiometric regime of a structured population at steady state. This was done by focusing on if the growth rate hypothesis, which states that there is a linear relationship between an individual growth rate and the percent of phosphorus within the individual, works at a population level. This was analyzed by creating and combining two matrices: the matrix-population containing the variables and a matrix containing the element phosphorus and dry weight. Data from a beetle species, Chrysomela tremulae F., was used as a guideline to create eight stoichiometric generic populations, where survival, growth and fecundity were tested in each of the eight generic populations. The results showed deviations from the growth rate hypothesis, suggesting that the hypothesis does not always work within structured populations. However, more research is needed to predict exactly how this hypothesis works in populations. Overall, this new method for analyzing stoichiometry within structured populations is a useful analytical tool, but there is a need for analyzing the results from these models in a more efficient way.
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Knowles, Katherine L. Jr. "Impact of Low-Spray Mating Disruption Programs on Aphidophagous Insect Populations in Virginia Apple Orchards." Thesis, Virginia Tech, 1997. http://hdl.handle.net/10919/31098.
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The populations of aphidophagous insects in low-spray and conventional programs were surveyed in Virginia apple orchards. Two sampling methods were utilized;aphid colony collection and beating tray collection. The low-spray blocks employed the use of mating disruption for control of the key direct pests, codling moth, Cydia pomonella (Linnaeus), and leafrollers. The abundance and diversity of aphid predators in low-spray mating disruption programs and conventionally controlled apple orchards was compared. Both sampling methods suggested that aphid predators were more plentiful in the mating disruption blocks. Several mating disruption blocks were found to accumulate significantly more predator-days and diversity than the matched control blocks. The reduction of insecticide input into the low-spray blocks may have allowed higher populations of aphidophagous insects to occur. Aphid populations in mating disruption blocks sometimes declined faster and had less resurgence than those in the conventionally controlled blocks.
The tufted apple bud moth (TABM), Platynota idaeusalis (Walker), populations in four apple orchards in Winchester, Virginia, were compared for resistance to azinphosmethyl. These orchards were suspected by the growers to have resistant populations of TABM. Pheromone traps with insecticide incorporated into the adhesive were used to collect and test the moths. The results were not analyzed due to the low number of moths collected and high variability in mortality.Master of Science
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Coetzee, J. H. (Jacobus Hendrik). "Arthropod communities of Proteaceae with special emphasis on plant-insect interactions." Thesis, Stellenbosch : Stellenbosch University, 1989. http://hdl.handle.net/10019.1/66615.
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Thesis (PhD) -- Stellenbosch University, 1989.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.
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.
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Izeppi, Tiago Sabongi [UNESP]. "Distribuição espacial e dinâmica populacional de Sphenophorus levis (Coleoptera: Curculionidae) em cana-de-açúcar." Universidade Estadual Paulista (UNESP), 2015. http://hdl.handle.net/11449/128076.
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000848680.pdf: 1393196 bytes, checksum: b6649096d280babc199fe3c920a2ea86 (MD5)O conhecimento da dinâmica populacional e do padrão de distribuição de insetos em ecossistemas agrícolas é importante para o desenvolvimento de estratégias de manejo mais eficazes, auxiliando em uma melhor tomada de decisão. O objetivo deste trabalho foi estudar a distribuição espacial e a dinâmica populacional de Sphenophorus levis Vaurie (Coleoptera: Curculionidae) em cana-de-açúcar. No estudo da distribuição espacial, foram realizadas amostragens em 14 áreas comerciais de cana-de-açúcar, avaliando 100 pontos de amostragem por área, através de trincheiras na linha de cana de 50 x 50 x 30 cm, para contagem de larvas, pupas e adultos de S. levis e de seus danos, representados pela porcentagem de rizomas danificados pela praga. Nas áreas 6 a 14, na ocasião da amostragem, foram distribuídas iscas para contagem dos adultos presentes fora dos rizomas. A distribuição espacial foi estudada através da análise geoestatística. Para o estudo da dinâmica populacional, foi utilizada uma área comercial de cana soca em 2° corte cultivada com a variedade SP81-3250, no município de Américo Brasilense, SP. Foram feitas amostragens mensais através da abertura de 20 trincheiras na linha de cana, de 50 x 50 x 30 cm, para contagem de formas biológicas da praga presentes no rizoma (larvas, pupas e adultos). Nas mesmas ocasiões foram distribuídas na área 20 iscas, para contagem dos adultos. As larvas, formas biológicas totais (larvas + pupas + adultos) e o dano de S. levis distribuíram-se de maneira agregada, enquanto pupas e adultos distribuíram-se aleatoriamente em campo. Os valores de alcance obtidos e os mapas de interpolação por krigagem mostraram grande variabilidade das populações do inseto e seu dano em todas as áreas estudadas. Com base no alcance médio obtido para as variáveis estudadas, sugere-se que para estimar as populações do inseto e seu dano em canaviais os pontos de amostragem devem ser...
The knowledge of the population dynamics and insect distribution pattern in agricultural ecosystems is important for the development of more effective management strategies, assisting in better decision making. The objective of this work was to study the spatial distribution and population dynamics of Sphenophorus levis Vaurie (Coleoptera: Curculionidae) in sugarcane. In the study of spatial distribution, sampling was performed in 14 commercial areas of sugarcane, evaluating 100 sampling points per area through the trenches of 50 x 50 x 30 cm made in the line, for counting larvae, pupae, and S. levis adults and their damage, represented by the percentage of rhizomes damaged. In areas 6 to 14, at the time of sampling, baits were distributed for adult counts present outside the rhizomes. The spatial distribution was studied by geostatistical analysis. For the study of population dynamics, we used a commercial area of sugarcane in 2nd cut cultivated with SP81-3250 variety in the city of Américo Brasilense, SP. Monthly samples were taken through the opening 20 trenches in the cane row, 50 x 50 x 30 cm, for counting biological forms of pest present in the rhizome (larvae, pupae and adults). In the same occasion 20 baits were distributed in the area to count adults. The larvae, total biological forms (larvae + pupae + adults) and the damage S. levis were agregate, while pupae and adults distributed randomly in the field. The range of values obtained and the kriging interpolation maps showed large variability in insect populations and their damage in all studied areas. Based on the mid-range obtained for the variables studied, it is suggested that to estimate insect populations and their damage the sampling points should be spaced at 40 m. All the insect biological forms were found in the area during the year, however, the population peaks of adults occurred in rainy and warm time of year, in February and March, while larvae and pupae in more ...
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Izeppi, Tiago Sabongi. "Distribuição espacial e dinâmica populacional de Sphenophorus levis (Coleoptera: Curculionidae) em cana-de-açúcar /." Jaboticabal, 2015. http://hdl.handle.net/11449/128076.
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Orientador: José Carlos BarbosaCoorientador: Leila Luci Dinardo-Miranda
Banca: Nilza Maria Martinelli
Banca: Renata Moreira Leal
Resumo: O conhecimento da dinâmica populacional e do padrão de distribuição de insetos em ecossistemas agrícolas é importante para o desenvolvimento de estratégias de manejo mais eficazes, auxiliando em uma melhor tomada de decisão. O objetivo deste trabalho foi estudar a distribuição espacial e a dinâmica populacional de Sphenophorus levis Vaurie (Coleoptera: Curculionidae) em cana-de-açúcar. No estudo da distribuição espacial, foram realizadas amostragens em 14 áreas comerciais de cana-de-açúcar, avaliando 100 pontos de amostragem por área, através de trincheiras na linha de cana de 50 x 50 x 30 cm, para contagem de larvas, pupas e adultos de S. levis e de seus danos, representados pela porcentagem de rizomas danificados pela praga. Nas áreas 6 a 14, na ocasião da amostragem, foram distribuídas iscas para contagem dos adultos presentes fora dos rizomas. A distribuição espacial foi estudada através da análise geoestatística. Para o estudo da dinâmica populacional, foi utilizada uma área comercial de cana soca em 2° corte cultivada com a variedade SP81-3250, no município de Américo Brasilense, SP. Foram feitas amostragens mensais através da abertura de 20 trincheiras na linha de cana, de 50 x 50 x 30 cm, para contagem de formas biológicas da praga presentes no rizoma (larvas, pupas e adultos). Nas mesmas ocasiões foram distribuídas na área 20 iscas, para contagem dos adultos. As larvas, formas biológicas totais (larvas + pupas + adultos) e o dano de S. levis distribuíram-se de maneira agregada, enquanto pupas e adultos distribuíram-se aleatoriamente em campo. Os valores de alcance obtidos e os mapas de interpolação por krigagem mostraram grande variabilidade das populações do inseto e seu dano em todas as áreas estudadas. Com base no alcance médio obtido para as variáveis estudadas, sugere-se que para estimar as populações do inseto e seu dano em canaviais os pontos de amostragem devem ser...
Abstract: The knowledge of the population dynamics and insect distribution pattern in agricultural ecosystems is important for the development of more effective management strategies, assisting in better decision making. The objective of this work was to study the spatial distribution and population dynamics of Sphenophorus levis Vaurie (Coleoptera: Curculionidae) in sugarcane. In the study of spatial distribution, sampling was performed in 14 commercial areas of sugarcane, evaluating 100 sampling points per area through the trenches of 50 x 50 x 30 cm made in the line, for counting larvae, pupae, and S. levis adults and their damage, represented by the percentage of rhizomes damaged. In areas 6 to 14, at the time of sampling, baits were distributed for adult counts present outside the rhizomes. The spatial distribution was studied by geostatistical analysis. For the study of population dynamics, we used a commercial area of sugarcane in 2nd cut cultivated with SP81-3250 variety in the city of Américo Brasilense, SP. Monthly samples were taken through the opening 20 trenches in the cane row, 50 x 50 x 30 cm, for counting biological forms of pest present in the rhizome (larvae, pupae and adults). In the same occasion 20 baits were distributed in the area to count adults. The larvae, total biological forms (larvae + pupae + adults) and the damage S. levis were agregate, while pupae and adults distributed randomly in the field. The range of values obtained and the kriging interpolation maps showed large variability in insect populations and their damage in all studied areas. Based on the mid-range obtained for the variables studied, it is suggested that to estimate insect populations and their damage the sampling points should be spaced at 40 m. All the insect biological forms were found in the area during the year, however, the population peaks of adults occurred in rainy and warm time of year, in February and March, while larvae and pupae in more ...
Mestre
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Dennehy, T. J., G. C. Cramer, and J. DeBolt. "Susceptibility of Arizona Populations of Lygus Bugs to Acephate (Orthene®) and Bifenthrin (Capture®)." College of Agriculture, University of Arizona (Tucson, AZ), 1995. http://hdl.handle.net/10150/210324.
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Adult lygus bugs were collected from alfalfa fields in 6 different cotton producing areas of Arizona. The standardized, glass vial method was used to estimate susceptibility of the collected populations to the organophosphate insecticide, acephate (Orthene®), and the pyrethroid, bifenthrin (Capture®). Overall, lygus from throughout the state were very susceptible to bifenthrin. However, some populations were significantly less susceptible to bifenthrin than were others. Lygus populations with greater than 20% survivorship of 100 μg/ml vial bioassays with bifenthrin should be monitored to provide early warning of future problems with pyrethroid resistance. Resistance of lygus to acephate appeared to be widespread but not uniform in Arizona. While some populations had individuals surviving exposure to vial treatments of as high as 10,000 pg/ml acephate, other populations had no survivors of 1,000 pg/ml treatments. Lygus populations with survivors of 10,000 pg/ml vial bioassays should be considered highly resistant to acephate. Our findings illustrate that resistance levels are often unique from farm to farm, even within the same region. To preserve the long-term usefulness of acephate, where possible, cotton growers should consider using it no more than once or twice per season, on any given field.
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Henneberry, T. J., L. A. Bariola, J. E. Leggett, T. Meng, D. Akey, and B. Deeter. "Report on the Effect of PREP on Cotton Fruiting, Boll Opening, and Boll Weevil Populations." College of Agriculture, University of Arizona (Tucson, AZ), 1986. http://hdl.handle.net/10150/219768.
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Butler, G. D., B. A. Kimball, and J. R. Mauney. "Populations of the Sweetpotato Whitefly on Cotton Grown in Open-Top Field Carbon Dioxide-Enrichment Chambers." College of Agriculture, University of Arizona (Tucson, AZ), 1985. http://hdl.handle.net/10150/204054.
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Young, Belinda. "Selective Harvesting in Headwater Streams: Investigating the Effects of Habitat Discontinuity on Adult Aquatic Insect Populations." Thesis, Griffith University, 2012. http://hdl.handle.net/10072/367775.
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Connectivity in aquatic ecosystems is a broad concept that refers to the transfer of both abiotic (i.e. matter and energy) and biotic (organisms) elements through the landscape across a range of spatial and temporal scales. The present study focuses on the patterns of connectivity between populations of aquatic insects in headwater streams. Dispersal, emigration and immigration are the demographic forms of population connectivity, which are largely thought to be by the winged adult stages that spend much of their lives in the riparian zone. These flying adults may disperse laterally and longitudinally to circumvent terrestrial barriers between headwater streams and catchments, thus allowing gene flow between populations in different streams.
Riparian vegetation has a potentially strong influence on the survival and success of adult stages through the alteration of the microclimate, habitat structure and potential food sources. Habitat fragmentation caused by forest harvesting can reduce population connectivity by increasing the area of open forest and altering microclimatic conditions, particularly air temperature and humidity. Degradation of adjacent terrestrial habitat through forest harvesting may egatively affect adult dispersal because altered microclimatic conditions may create a barrier to dispersal. For example, the extreme conditions caused by harvesting may exceed tolerance limits of adult aquatic insects. In addition, aquatic insect life history traits may influence the degree to which forest harvesting affects their populations. For example, if a species with a short emergence period emerges during peak summer temperatures, temperatures could be higher in cleared areas compared to forested, thus exceeding the tolerance limit of the species. However, little direct evidence exists on the effects of selective harvesting and the associated changes to the microclimate on adult
dispersal and genetic population connectedness.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
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Terry, L. I., J. C. Silvertooth, and C. Summers. "Effect of Date of Planting and Irrigation Termination on Pink Bollworm Populations in Pima and Upland Cotton." College of Agriculture, University of Arizona (Tucson, AZ), 1990. http://hdl.handle.net/10150/208314.
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Field experiments conducted in 1989 comparing effects of planting date and irrigation termination date on pink bollworm in both in- season and overwintering infestations indicated different responses depending upon the location and type of cotton. Tests were located at: Yuma Agricultural Center; Marana Agricultural Center; and Maricopa Agricultural Center. Infestations at Yuma ranged from 0% at early flowering to 80% infested bolls prior to harvest. Marana had equally high infestations at the end of the season, while Maricopa had the lowest infestations ranging from 2% to 5% for Pima and 3 %-17% for Upland. Planting date or species of cotton did not affect early infestation. Data comparing plots for overwintering infestations are still being evaluated. Continuous insecticide treatments were made at all locations after squaring began.
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Chu, Chang-chi, Thomas J. Henneberry, Louis A. Bariola, and Brian Deeter. "Effect of Plant Growth Regulators Under Short-Season Conditions on Pink Bollworm Populations, Cotton Yields and Defoliation." College of Agriculture, University of Arizona (Tucson, AZ), 1991. http://hdl.handle.net/10150/208370.
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Plant growth regulators (PGR's) [thidiazuron (Dropp®) N-phenyl-N' -1,2,3-thiadiazol -5 ylurea, 50% wettable powder, Nor-Am Agricultural Products, Inc., Naperville, IL, and ethephon (Prep®) a- chloroethyl phosphonic acid Rhone - Poulenc Ag Co., Research Triangle Park NC] were applied to reduce late- season fruiting forms as a source of host material for developing overwintering PBW populations. Combinations of ethephon and thidiazuron or thidiazuron alone were more effective than ethephon alone for reducing late -season immature green bolls. None of the PGR's alone or in combination affected yields. Highest rates of defoliation occurred after applications of thidiazuron. The data suggest that temperature thresholds for highest plant growth regulator activity occur.
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Anderson, Robert Derek. "Reducing orthophosphates in retention ponds and its impact on larval mosquito abundance." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 98 p, 2007. http://proquest.umi.com/pqdweb?did=1397903371&sid=5&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Bronzato, Aline Ribeiro [UNESP]. "Análise da estrutura populacional de Aedes aegytpi (Linnaeus, 1762) em algumas regiões do Brasil." Universidade Estadual Paulista (UNESP), 2015. http://hdl.handle.net/11449/144079.
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000869614.pdf: 7034100 bytes, checksum: 68b8ee31f062952cc1cfe255a55cc99e (MD5)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Aedes aegypti é considerado o principal vetor de arboviroses que acomentem os seres humanos. Até o momento a única medida disponível para erradicação da dengue, é o controle do vetor, Ae. aegypti. O conhecimento aprofundado sobre a estruturação genética e dinâmica populacional dessa espécie em diferentes ambientes é crucial, uma vez que populações geneticamente diferentes podem apresentar diferenças quanto à capacidade e competência vetorial. O Brasil possui regiões com diferentes características climáticas e geográficas, assim o conhecimento detalhado sobre populações de mosquitos que colonizam diferentes habitats, é pertinente. Este trabalho avaliou a estrutura populacional de mosquitos Ae. aegypti provenientes de cinco cidades do Brasil (i.e., Belo Horizonte, Botucatu, Campo Grande, Maringá e Rondonópolis) utilizando marcadores microssatélites. Ainda, empregouse esses marcadores para investigar a dinâmica de oviposição e consequente dispersão de mosquitos Ae. aegypti em Botucatu. Em macro-análises populacionais, utilizando DAPC, observamos agrupamento entre indivíduos de mesma localidade e estruturação populacional para mosquitos de Belo Horizonte. Análises de micro-estruturação populacional identificaram seis sub-populações de mosquitos Ae. aegypti entre as seis sub-regiões de Belo Horizonte, ainda foram sugeridas estruturação populacional intermediária para mosquitos das sub-regiões de Campo Grande e falta de estruturação genética entre mosquitos das subregiões de Botucatu. Com esses resultados acreditamos que estruturação genética ocorra em correlação com o tamanho da cidade - localidades maiores parecem proporcionar estruturação genética para populações de mosquitos Ae. aegypti. Análises de PCA em ovitrampas da cidade de Botucatu apontaram organização populacional de Ae. aegypti em famílias. Análises de Pedigree e coeficiente de inbreeding, indicaram que de 30 mosquitos...
Aedes aegypti is considered the main vector of arboviruses affecting humans. Nowadays, the only feasible measure to eradicate the dengue fever depends exclusively of vector control. The deep knowledge about the structure and dynamics of Ae. aegypti population in distinct environments is critical, since genetically different populations may present differences related to vector competence and capacity. Brazil has regions with different climatic and geographic characteristics, therefore, detailed knowledge about mosquito population that colonizes different habitats is extremely important. The present study evaluated the population structure of Ae. aegypti mosquitoes in five different Brazilian cities (i.e., Belo Horizonte, Botucatu, Campo Grande, Maringá and Rondonópolis) using a microsatellite markers. Those markers were also used to evaluate the oviposition dynamic and the consequences of Ae. aegypti mosquitoes dispersion, of the city of Botucatu. Population macro-analysis, using DAPC evidenced, genetic clusters among individuals of the same locality, and population structure in mosquitoes of Belo Horizonte. Population microstructure analysis identified six sub-populations of Ae. aegypti mosquitoes among six sub-regions of Belo Horizonte. In addition, the microstructure analysis suggested intermediate population structure in the sub-regions of Campo Grande, and lack of genetic structure among mosquitoes from the sub-regions of Botucatu. Therefore, these results indicate that genetic organization occurs in correlation with city size - where large towns seem to provide genetic structure to the populations of Ae. aegypti. PCA analysis of ovitraps obtained in Botucatu indicated population organization of Ae. aegypti mosquitoes in families. Pedigree analysis and inbreeding coefficient indicated that only for out of 30 mosquitoes analyzed in the same ovitrap, keep restricted familial relationships. These results suggest that Ae. aegypti...
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Bronzato, Aline Ribeiro. "Análise da estrutura populacional de Aedes aegytpi (Linnaeus, 1762) em algumas regiões do Brasil." Botucatu, 2015. http://hdl.handle.net/11449/144079.
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Orientador: Paulo Eduardo Martins RibollaBanca: Fernando Araújo Monteiro
Banca: Jayme Augsto de Souza Neto
Banca: Mara Anice Mured Allum
Banca: Renata Schama
Resumo: Aedes aegypti é considerado o principal vetor de arboviroses que acomentem os seres humanos. Até o momento a única medida disponível para erradicação da dengue, é o controle do vetor, Ae. aegypti. O conhecimento aprofundado sobre a estruturação genética e dinâmica populacional dessa espécie em diferentes ambientes é crucial, uma vez que populações geneticamente diferentes podem apresentar diferenças quanto à capacidade e competência vetorial. O Brasil possui regiões com diferentes características climáticas e geográficas, assim o conhecimento detalhado sobre populações de mosquitos que colonizam diferentes habitats, é pertinente. Este trabalho avaliou a estrutura populacional de mosquitos Ae. aegypti provenientes de cinco cidades do Brasil (i.e., Belo Horizonte, Botucatu, Campo Grande, Maringá e Rondonópolis) utilizando marcadores microssatélites. Ainda, empregouse esses marcadores para investigar a dinâmica de oviposição e consequente dispersão de mosquitos Ae. aegypti em Botucatu. Em macro-análises populacionais, utilizando DAPC, observamos agrupamento entre indivíduos de mesma localidade e estruturação populacional para mosquitos de Belo Horizonte. Análises de micro-estruturação populacional identificaram seis sub-populações de mosquitos Ae. aegypti entre as seis sub-regiões de Belo Horizonte, ainda foram sugeridas estruturação populacional intermediária para mosquitos das sub-regiões de Campo Grande e falta de estruturação genética entre mosquitos das subregiões de Botucatu. Com esses resultados acreditamos que estruturação genética ocorra em correlação com o tamanho da cidade - localidades maiores parecem proporcionar estruturação genética para populações de mosquitos Ae. aegypti. Análises de PCA em ovitrampas da cidade de Botucatu apontaram organização populacional de Ae. aegypti em famílias. Análises de Pedigree e coeficiente de inbreeding, indicaram que de 30 mosquitos...
Abstract: Aedes aegypti is considered the main vector of arboviruses affecting humans. Nowadays, the only feasible measure to eradicate the dengue fever depends exclusively of vector control. The deep knowledge about the structure and dynamics of Ae. aegypti population in distinct environments is critical, since genetically different populations may present differences related to vector competence and capacity. Brazil has regions with different climatic and geographic characteristics, therefore, detailed knowledge about mosquito population that colonizes different habitats is extremely important. The present study evaluated the population structure of Ae. aegypti mosquitoes in five different Brazilian cities (i.e., Belo Horizonte, Botucatu, Campo Grande, Maringá and Rondonópolis) using a microsatellite markers. Those markers were also used to evaluate the oviposition dynamic and the consequences of Ae. aegypti mosquitoes dispersion, of the city of Botucatu. Population macro-analysis, using DAPC evidenced, genetic clusters among individuals of the same locality, and population structure in mosquitoes of Belo Horizonte. Population microstructure analysis identified six sub-populations of Ae. aegypti mosquitoes among six sub-regions of Belo Horizonte. In addition, the microstructure analysis suggested intermediate population structure in the sub-regions of Campo Grande, and lack of genetic structure among mosquitoes from the sub-regions of Botucatu. Therefore, these results indicate that genetic organization occurs in correlation with city size - where large towns seem to provide genetic structure to the populations of Ae. aegypti. PCA analysis of ovitraps obtained in Botucatu indicated population organization of Ae. aegypti mosquitoes in families. Pedigree analysis and inbreeding coefficient indicated that only for out of 30 mosquitoes analyzed in the same ovitrap, keep restricted familial relationships. These results suggest that Ae. aegypti...
Doutor
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Palumbo, John, Clayton Jr Mullis, Francisco Reyes, and Andreas Amaya. "Timing and Frequency of Provado® Applications for Management of Aphid Populations in Head Lettuce." College of Agriculture, University of Arizona (Tucson, AZ), 1996. http://hdl.handle.net/10150/214752.
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Provado insecticide (imidacloprid) was compared to Admire and other standard insecticides for management of aphids in head lettuce in Yuma 1995 and 1996. Foliar applications of Provado appear to provide an alternative method of controlling aphids on lettuce comparable to prophylactic applications of Admire. The prevention of aphid colonization in lettuce heads with Provado may depend greatly on the timing and frequency of applications before harvest occurs. These studies and other studies on spinach suggest that more than one application of Provado will be necessary to adequately suppress aphid contamination in heads. The label suggests that applications be timed 5-7 apart. Our data tends to support this recommendation. Furthermore, timing applications should be based on days to harvest, level of aphid colonization and duration of aphid migration.
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Dennehy, T. J., and T. J. Russell. "Susceptibility of Lygus Bug Populations in Arizona to Acephate (Orthene®) and Bifenthrin (Capture®), with Related Contrasts of Other Insecticides." College of Agriculture, University of Arizona (Tucson, AZ), 1996. http://hdl.handle.net/10150/210912.
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Adult lygus bugs, Lygus hesperus (Knight), were collected from alfalfa fields in 11 different cotton producing areas of Arizona. A standardized glass vial method was used to estimate susceptibility of the collected populations to the organophosphate insecticide, acephate (Orthene®), and the pyrethroid bifenthrin (Capture®). Overall, lygus from throughout the state were significantly less susceptible to acephate and bifenthrin in 1995, than in 1994. Resistance of lygus to acephate continues to be widespread and intense, but not uniform in Arizona. In 1995, all populations possessed individuals capable of surviving exposure to vial treatments of 10,000 μg/ml acephate. Lygus bugs from Safford and Maricopa represented the most and least susceptible populations, respectively, to both acephate and bifenthrin. These two populations were tested for susceptibility to nine other insecticides: aldiaarb (Temik®), dimethoate (Gowan Dimethoate E267®), endosulfan (Gowan Endosulfan 3EC®), imidacloprid (Admire 2F®), malathion (Gowan Malathion 8®), methamidophos (Monitor 4®®), methomyl (Lannate LV®), oxamyl (Vydate 3.77L®), apt oxydemeton- methyl (Metasystox-R SC®). The Maricopa population was significantly less susceptible to six of these insecticides. Our findings support the hypothesis that the intensive use of pyrethroid and organophosphate insecticides for whitefly control in cotton has selected for resistance in lygus. This result portends increased problems with lygus control in the future, points to the need for developing new tools for controlling lygus bugs in Arizona cotton, and underscores the urgent need to find alternatives to the current heavy reliance on insecticides for managing whiteflies in cotton.
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Bedet, Charlotte. "Soil fertility, crop nutrients, weed biomass and insect populations in organic and conventional field corn (Zea mays L.) agroecosystems /." The Ohio State University, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488196781734832.
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Narita, Nobuyoshi 1961. "Epidemiologia do "Cowpea aphid borne mosaic virus" (CABMV) em maracujazeiros na região produtora da Alta Paulista, SP /." Botucatu : [s.n.], 2007. http://hdl.handle.net/11449/103210.
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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.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 doesnt 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.
Orientador: Marcelo Agenor Pavan
Coorientador: Valdir Atsushi Yuki
Banca: Renate Krause Sakate
Banca: Aloisio Costa Sampaio
Banca: Alexandre Levi R. Chaves
Banca: Hugo Kuniyuki
Doutor
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Schultheis, Alicia Slater. "Gene Flow and Dispersal Among Populations of the Stonefly Peltoperla tarteri (Plecoptera: Peltoperlidae) in the Southern Appalachians." Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/29750.
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Despite a number of recent studies focused on the issue, patterns of stream insect dispersal in temperate streams of North America remain poorly understood. Movement of benthic invertebrates is notoriously difficult to measure directly using traditional means; however, genetic markers provide an ideal method for estimating stream insect dispersal. In this study, the control region of mitochondrial DNA was used to study gene flow and dispersal among populations of the stonefly Peltoperla tarteri in the Southern Appalachians. The control region of P. tarteri is approximately 1270 base pairs (bp) in length, 81% AT-rich, and contains variable numbers of a 74 bp tandem repeat containing the sequence motif "5'-GGGGGC-3".
Many stream insects have long life cycles that result in the simultaneous existence of multiple cohorts throughout the larval development period. If larval development is fixed, genetic isolation among cohorts may confound genetic estimates of dispersal. Although larval head width data indicated that P. tarteri is semivoltine in southwestern Virginia, low levels of genetic differentiation among cohorts suggested that larval development of P. tarteri is not fixed and that some individuals complete development in one or three years rather than two. This 'cohort splitting' would result in individuals from distinct cohorts maturing at the same time and mating with one another. Such developmental plasticity may allow some individuals to avoid adverse environmental conditions.
The extent and likely mechanism of dispersal was determined by comparing levels of population genetic differentiation within drainages to that among drainages. While there was no consistent relationship between genetic and geographic distance, genetic differentiation was generally high within and among drainages. Nested clade analysis indicates that historical fragmentation and range expansion coupled with contemporary gene flow explain the present day pattern of genetic variation in P. tarteri. In order for these historical patterns to have such a strong influence on present day genetic structure, both larval and adult dispersal must be restricted. However, the genetic data suggest that larval dispersal is more frequent than adult dispersal.Ph. D.
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Modelski, Kimberly A. "Comparison of climatic conditions and mosquito abundances in New Castle County, Delaware." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 3.25 Mb., 229 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:1435830.
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Doublet, Violette. "Interactions biotiques et dynamiques des populations : approches empiriques et théoriques de la prédation pré-dispersion des graines par les insectes." Thesis, Montpellier, 2020. http://www.theses.fr/2020MONTG007.
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Les interactions biotiques figurent parmi les processus clés de la dynamique des populations et constituent un enjeu fort pour le renouvellement et la persistance des espèces au sein des écosystèmes. En particulier, l’herbivorie par les insectes prédateurs des graines avant dispersion est un processus écologique majeur de la dynamique forestière par son impact sur le succès reproducteur des arbres et leur régénération naturelle. Cependant, les conséquences de cette herbivorie sur la dynamique et l’évolution des populations d’arbres demeurent des fronts de science, qui ont été abordés dans cette thèse de façon intégrative en combinant des approches empirique et théorique. L’approche empirique a visé la caractérisation des déterminants de la dynamique spatio-temporelle du taux de prédation des graines en forêt naturelle. Le système modèle d’interactions arbres-insectes analysé implique des Hyménoptères séminiphages (Megastigmus spp., Torymidae) et leur hôte obligatoire, le Cèdre de l’Atlas (Cedrus atlantica, Pinaceae), localisé dans le sud-est de la France. À l’échelle de la population d’hôtes, les résultats ont révélé le caractère transitoire de la distribution spatiale des insectes qui est fortement déterminée par les variations spatio-temporelles de la densité des graines. En outre, la dynamique de fructification de type ‘masting’ du Cèdre est un moteur majeur de la dynamique spatio-temporelle des insectes. De plus, on a pu montrer l’existence d’une variation inter-individuelle de la sensibilité des arbres à la prédation des graines. Une analyse préliminaire a suggéré que cette variation est en partie d’origine génétique, et les travaux complémentaires à mener en ce sens ont pu être précisés. L’approche théorique a permis d’analyser les effets conjoints du masting et de la distribution spatiale des prédateurs des graines sur les processus démographiques et la diversité génétique dans une population d’arbres en expansion naturelle. La modélisation analytique de ces interactions a révélé d’une part que la prédation des graines avant dispersion génère des effets Allee influençant la mise en place de la diversité génétique de la population d’arbres au cours d’une expansion, et que le masting est susceptible de tempérer cet impact de la prédation des graines. Ces travaux ont apporté un éclairage nouveau sur les implications possibles des insectes prédateurs des graines avant dispersion dans la dynamique et l’évolution des peuplements forestiersBiotic interactions are among key processes in population dynamics and critical issues for the renewal and persistence of species within ecosystems. In particular, herbivory by pre-dispersal seed insect predators is a major ecological process in forest dynamics due to its impact on tree reproductive success and on natural regeneration. However, its consequence on tree population dynamics and evolution remain poorly documented. This thesis contributed to fill this gap as an integrative combination of empirical and theoretical approaches. The empirical approach aimed to characterize the drivers of the spatio-temporal dynamics of seed predation rates in natural forest. We used a system of tree-insect interactions involving seed predators (Megastigmus spp., Hymenoptera: Torymidae) and their obligate host, the Atlas Cedar (Cedrus atlantica, Pinaceae), located in south-eastern France. At the host population scale, our results revealed that the transient pattern of the spatial distribution of insects was primarily explained by spatiotemporal variations in seed density. Thus, Cedar masting appeared to be a major driving force of the insects’ spatial and temporal dynamics. We have also highlighted the existence of an inter-individual variation in the sensitivity of trees to seed predation. A preliminary analysis has suggested that such variation is partly under genetic control and we propose further analyses to be carried out in such perspective. The theoretical approach aimed to analyse the joint effects of masting and the spatial distribution of pre-dispersal seed predation by insects on demographic processes and genetic diversity in an expanding tree population. The analytical modelling of these interactions revealed on the one hand that pre-dispersal seed predation induce Allee effects that may affect the spatial structure of genetic diversity in the expanding tree population, and on the other hand, that masting was likely to buffer such demogenetic impact of seed predation. This work has shed new light on the possible implications of pre-dispersal predation by insects in the dynamics and evolution of forests
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Santos, Luan Alberto Odorizzi dos [UNESP]. "Contribution of marginal non-crop vegetation and semi-natural habitats to the regulation of insect pest populations by their natural enemies." Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/150943.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
L'expansion des zones agricoles a conduit à la perte de biodiversité due à la réduction des habitats naturels et semi-naturels dans les paysages agricoles. Avec l'augmentation de la production agricole dans le monde, des techniques écologiquement rationnelles sont de plus en plus discutées qui permettent une gestion durable des habitats environnants. Les effets de ces habitats sur la population des insectes nuisibles et de leurs ennemis naturels sont encore mal connus. L'objectif de cette thèse était de comprendre les effets des environnements naturels et semi-naturels sur la population des insectes nuisibles et des ennemis naturels dans les régions tropicales (Brésil) et tempérées (France). Au Brésil (chapitre II), on a évalué l'effet de la distance des fragments sur la population de fourmis prédatrices et omnivores dans la canne à sucre. Les résultats montrent que la richesse en espèces diminue avec la distance des fragments forestiers et que la prédominance des espèces Dorymyrmex bruneus et Pheidole oxyops augmente. Des espèces de fourmis colonisant les champs de canne à sucre ont également été trouvées dans des fragments forestiers, ce qui suggère que ces derniers habitats sont des refuges pour les espèces de fourmis prédatrices pendant les périodes de perturbation comme la récolte de la canne à sucre ou le travail du sol. Cela a été confirmé par des différences plus fortes dans les communautés de fourmis après la récolte de la canne à sucre (saison sèche) que quatre mois plus tard / (saison des pluies) quand l'absence de perturbation a permis la re-lonosiation par les fourmis. Il y avait aussi une différence dans la richesse des espèces de fourmis entre les différents types de fragments (vallées fluviales et plaines). En France, on a évalué l'effet des bandes de fleurs sauvages, de la végétation spontanée et des bandes d'herbe sur la communauté des ennemis naturels et la régulation du puceron de la pomme rosâtre Dysaphis plantaginaea (chapitre III). En ce qui concerne les principaux ennemis naturels, nos résultats ont montré une densité plus élevée de hoverflies par rapport à d'autres types de bande, mais aucune différence pour les coccinelles (coccinelidae). Cependant, aucune différence de densité naturelle de l'ennemi n'a été observée à l'intérieur des vergers. Le nombre de pucerons était plus élevé près des marges, ce qui suggère que la colonisation à partir des bandes marginales peut contrecarrer les effets régulateurs positifs des ennemis naturels. Les effets positifs de la végétation de la marge de bande sur la régulation des ravageurs de la pomme nécessitent un mouvement d'ennemis naturels dans le verger. Nous avons testé les mouvements des prédateurs généralistes en étiquetant les bandes de marge avec des protéines d'oeufs et nous avons vérifié si elles se nourrissaient d'insectes nuisibles en utilisant l'analyse de marqueurs génétiques des gènes de papillon (Cydia pomonella) à l'intérieur des prédateurs (chapitre IV). Les résultats ont montré que peu de personnes se déplaçaient des marges de champ dans le verger. Cependant, 25% des prédateurs capturés se nourrissaient de C. pomonella indiquant encore un haut niveau de régulation naturelle. En conclusion, le mouvement limité des prédateurs à partir des bandes de marges dans les vergers peut expliquer l'absence de différences entre les traitements de bandes dans la régulation des ravageurs du verger (pucerons). Les habitats naturels et semi-naturels peuvent contribuer à la lutte contre les ravageurs en marge des cultures, mais dans les vergers de pommiers cet effet a fortement diminué avec la distance.
A expansão das áreas agrícolas levou à perda de biodiversidade devido à redução dos habitats naturais e semi-naturais nas paisagens agrícolas. Com o aumento da produção agrícola no mundo, são cada vez mais discutidas técnicas ambientais que permitem uma gestão sustentável dos habitats do entorno. Os efeitos desses habitats sobre a população de insetos-pragas e seus inimigos naturais ainda são mal compreendidos. O objetivo desta tese foi compreender os efeitos dos ambientes naturais e semi-naturais na população de insetos-pragas e inimigos naturais nas regiões tropicais (Brasil) e temperadas (França). No Brasil (Capítulo II) foi avaliado o efeito da distância de fragmentos sobre a população de formigas predadoras e omnívoras em cana-de-açúcar. Os resultados mostraram que a riqueza de espécies diminui com a distância dos fragmentos florestais e que a dominância das espécies Dorymyrmex bruneus e Pheidole oxyops aumenta. As espécies de formigas que colonizam áreas de cana-de-açúcar também foram encontradas em fragmentos de florestas, sugerindo que estes últimos são abrigos para espécies de formigas predatórias durante períodos de perturbação como colheita de cana-de-açúcar ou preparo do solo. Isto foi confirmado por diferenças mais fortes nas comunidades de formigas após a colheita da cana (estação seca) do que quatro meses depois (estação chuvosa) quando a ausência de perturbação permitiu recolonização por formigas. Houve também uma diferença na riqueza de espécies de formigas entre diferentes tipos de fragmentos (vales de rios e planícies). Na França, foi avaliado o efeito de faixas de flores silvestres, vegetação espontânea e gramíneas na comunidade de inimigos naturais e a regulação do pulgão cinza Dysaphis plantaginaea (Capítulo III). No que diz respeito aos principais inimigos naturais, os nossos resultados mostraram uma maior densidade de sirfideos nas faixas de flores em comparação com outros tipos de faixas, mas nenhuma diferença para joaninha (Coccinelidae). Não foram observadas diferenças nas densidades de inimigos naturais dentro dos pomares. O número de afídeos foi maior perto das margens, sugerindo que a colonização das faixas nas margens pode neutralizar os efeitos reguladores positivos dos inimigos naturais. Os efeitos positivos da vegetação nas faixas da margem na regulação de pragas da maçã requerem um movimento de inimigos naturais no pomar. Nós testamos os movimentos de predadores generalistas marcando as faixas das margens com proteína de ovo e verificamos se eles se alimentavam de insetos pragas usando a análise de marcadores moleculares de genes de mariposas (Cydia pomonella) nos predadores (capítulo IV). Os resultados mostraram que poucos indivíduos se movimentaram das margens do campo para o pomar. No entanto, 25% dos predadores capturados alimentados com C. pomonella ainda indicam um alto nível de regulação natural. Em conclusão, o movimento limitado de predadores das faixas de plantas nas margens em pomares pode explicar a ausência de diferenças entre os tratamentos na regulação de pragas do pomar (pulgões). Habitats naturais e semi-naturais podem contribuir para o controle de pragas nas margens das culturas, mas em pomares de maçã este efeito diminuiu fortemente com a distância.
The expansion of agricultural areas has led to the loss of biodiversity due to the reduction of natural and semi-natural habitats in agricultural landscapes. With the increase of agricultural production in the world, environmentally sound techniques are increasingly discussed that allow a sustainable management of surrounding habitats. The effects of these habitats on the population of insect pests and their natural enemies are still poorly understood. The objective of this thesis was to understand the effects of natural and semi-natural environments on the population of insect pests and natural enemies in tropical (Brazil) and temperate (France) regions. In Brazil (Chapter II) the effect of the distance of fragments on the population of predatory and omnivorous ants in sugarcane was evaluated. The results showed that the species richness decrease with distance from forest fragments and that the dominance of the species Dorymyrmex bruneus and Pheidole oxyops increase. Ant species colonizing sugarcane fields were also found in forest fragments suggesting that the latter habitats are refuges for predatory ant species during periods of disturbance such as sugarcane harvest or soil tillage. This was confirmed by stronger differences in ant communities after sugarcane harvest (dry season) than four months later (rainy season) when absence of disturbance allowed re-colonosiation by ants. There was also a difference in the richness of ant species between different fragment types (river valleys and plateaus). In France, the effect of wildflower strips, spontaneous vegetation and grass strips on the community of natural enemies and the regulation of the rosy apple aphid Dysaphis plantaginaea (Chapter III) were evaluated. Concerning major natural enemies, our results showed a higher density of hoverflies in wild flower strips compared with other strip types but no differences for ladybirds (coccinelidae). However, no differences in natural enemy densities were observed inside orchards. Aphid number was higher close to the margins suggesting that colonization from margin strips may counteract positive regulatory effects of natural enemies. Positive effects of strip margin vegetation on regulation of apple pests require a movement of natural enemies into the orchard. We tested the movements of generalist predators by labelling margin strips with egg protein and we checked whether they fed on pest insects using specific genetic marker of the codling moth (Cydia pomonella) (chapter IV). The results showed that few individuals were moving from the field margins into the orchard. However, 25% of the captured predators fed on C. pomonella still indicating a high level of natural regulation. In conclusion, the limited movement of predators from margin strips into orchards may explain the absence of differences between strip treatments in orchard pest regulation (aphids). Natural and semi-natural habitats can contribute to pest control at the margins of crops, but in apple orchards this effect strongly decreased with distance.
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Rethwisch, Michael D., and Michael Kruse. "Effect of Late Winter 1998 Furadan4F Alfalfa Stubble Treatment on Alfalfa Growth and Alfalfa Weevil, Aphid, and Threecornered Alfalfa Hopper Populations." College of Agriculture, University of Arizona (Tucson, AZ), 1999. http://hdl.handle.net/10150/205153.
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Furadan 4F was applied to alfalfa regrowth stubble following the first harvest of 1998 to examine treatment effects of alfalfa weevils, aphids, resultant plant growth, and threecornered alfalfa hoppers. Furadan 4F reduced larval numbers throughout the period that larvae were present (25 days after treatment). Little effect was noted for adult weevil numbers in field. Aphid numbers were also reduced by the treatment, and alfalfa stems in Furadan 4F plots were significantly taller at 21 days post treatment. Little, if any, effect from the Furadan 4F treatment was noted for adult threecornered alfalfa hopper populations during the five months following application.
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Vatka, E. (Emma). "Boreal populations facing climatic and habitat changes." Doctoral thesis, Oulun yliopisto, 2014. http://urn.fi/urn:isbn:9789526203607.
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Abstract Anthropogenic climate change and habitat loss and deterioration affect populations worldwide. Climate warming has changed phenologies of many species across trophic levels. Some predator populations now experience temporal mismatches with their prey, as timings of peak prey abundance and of the predator’s highest food demands no longer meet. The temporal mismatch hypothesis suggests that the population’s recruitment rate is related to its degree of synchrony with the food resources needed to feed offspring. However, species’ and populations’ responses to climate warming differ. Human land use alters and destroys habitats of countless species. For example, many boreal forest bird populations have declined, presumably due to intensive forestry. It has decreased the amount of dead wood, causing a threat to saproxylic species. Identification of the key characteristics of high-quality habitats is essential for conservation planning and for developing sustainable forestry. As individuals are suspected to settle in habitats that maximize their fitness, analysis of nest site selection can be used to identify the key habitats. My dissertation concerns the impacts of climate change and habitat deterioration on boreal populations. I use hole-nesting passerines as model species. By utilizing long-term data I show that breeding phenologies of Parus major and Poecile montanus, but not of Cyanistes caeruleus, have shifted earlier. Also, the timing of the food peak has advanced, improving the synchrony between P. montanus and caterpillars. In P. major and C. caeruleus, synchrony has remained good. However, the positive effect of good synchrony on breeding success seems to be conditional, arising only in certain circumstances, such as in years of high caterpillar abundance. I suggest that in boreal populations temperature affects timing of breeding mostly as a proximate factor. The availability of standing decaying trees used for nesting sites was the most important habitat characteristic determining the nest site selection of P. montanus. Remote sensing data alone was insufficient to produce reliable models, as the ecologically important small-scale factor can only be determined by direct field surveys. Omission of forest thinning in selected forest sites would ensure the continuous availability of decaying wood with positive influence on biodiversity in managed forestsTiivistelmä Ihmisen aiheuttama habitaattien katoaminen ja huononeminen sekä ilmastonmuutos vaikuttavat populaatioihin kaikkialla maailmassa. Ilmaston lämpeneminen on muuttanut monien lajien fenologioita eri trofiatasoilla. Osalla saalistajalajien populaatioista suurin ravinnontarve ei enää ajoitu samaan aikaan saaliin runsaushuipun kanssa. Ajoituksen eriaikaisuus -hypoteesin mukaan todennäköisyys populaatioon rekrytoitumiselle riippuu synkronian asteesta saaliin kanssa. Ilmaston lämpenemisen vaikutuksissa lajeihin ja populaatioihin on kuitenkin vaihtelua. Ihmisen maankäyttö muuttaa ja tuhoaa lukuisien lajien elinympäristöjä. Esimerkiksi useiden boreaalisten metsien lintupopulaatioiden pienentymistä on selitetty intensiivisellä metsätaloudella. Lahopuun määrä metsissä on vähentynyt, mikä on uhka lahopuusta riippuvaisille lajeille. Korkealaatuisten habitaattien keskeisten piirteiden tunnistaminen on tärkeää luonnonsuojelun ja kestävän metsätalouden suunnittelulle. Koska yksilöiden oletetaan valitsevan niiden kelpoisuutta maksimoivia elinympäristöjä, pesäpaikanvalinta-analyysiä voidaan käyttää tärkeiden habitaattipiirteiden tunnistamiseen. Tarkastelen väitöskirjassani ilmastonmuutoksen ja habitaattien laadun vaikutuksia boreaalisiin populaatioihin. Mallilajeina käytän koloissa pesiviä varpuslintuja. Hyödyntämällä pitkäaikaisaineistoja osoitan, että lisääntymisen ajoittuminen on aikaistunut tali- ja hömötiaisella, mutta ei sinitiaisella. Myös ravintohuippu on aikaistunut, mikä on parantanut synkroniaa hömötiaisen ja sen pääasiallisen ravinnon eli toukkien välillä. Tali- ja sinitiaisella synkronia on pysynyt hyvänä. Hyvän synkronian myönteinen vaikutus lisääntymismenestykseen vaikuttaa kuitenkin ehdolliselta: se tulee esiin vain tietyissä olosuhteissa, kuten vuosina jolloin toukkia on runsaasti. Kevään lämpötilat näyttävät vaikuttavan pesinnän ajoittumiseen erityisesti proksimaattisena tekijänä. Pesäpaikkoina toimivien seisovien lahopuiden määrä on tärkein hömötiaisen pesäpaikanvalintaa määräävä tekijä. Kaukokartoitusaineisto yksinään ei riitä luotettavien mallien tuottamiseen, sillä ekologisesti tärkeät pienen skaalan tekijät voidaan kartoittaa vain suorin maastomittauksin. Metsien harventamatta jättäminen valituilla laikuilla turvaisi lahopuun jatkuvan saatavuuden, mikä vaikuttaisi myönteisesti talousmetsien biodiversiteettiin
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Costa, Suzana Regina Silveira [UNESP]. "Caracterização molecular de populações do inseto praga psilídeo de concha (Glycaspis brimblecombei) por meio de marcadores do tipo ITS 1 (Internal Tanscribed Spacer 1)." Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/92450.
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O gênero Eucalyptus é originário da Austrália e está estabelecido no Brasil há mais de um século. Atualmente, o Brasil tem a segunda maior área plantada, formando monoculturas, que favorecem o estabelecimento de insetos praga. No ano de 2003 foi verificada pela primeira vez no país a ocorrência de Glycaspis brimblecombei, espécie descrita por Moore (Hemiptera, Psyllidae). Tal espécie também é conhecida por psilídeo de concha, em plantios de Eucalyptus sp. no estado de São Paulo. Devido sua alta capacidade adaptativa, atualmente se encontra amplamente distribuído por todo território nacional. Os danos causados por sua infestação são inúmeros, resultando em perdas consideráveis para o setor florestal e consequentemente para a economia brasileira. As populações do psilídeo de concha apresentam baixa variação morfológica, dificultando sua identificação; assim, análises moleculares, tais quais o uso de marcadores, podem auxiliar a responder essas questões. Um marcador amplamente utilizado, por sua alta variabilidade, é o espaçador interno transcrito do DNA ribossomal (ITS). Deste modo, o marcador ITS foi utilizado neste trabalho para averiguar a dinâmica populacional do psilídeo de concha de quatro regiões do estado de São Paulo. A sequência do ITS1 apresentou um intervalo de 291 pb em 88,73% das amostras. Os sítios polimórficos foram identificados no intervalo de 80 a 200 pb, sendo que na população de Pedra Bela foi observada a maior distribuição destes. Além disso, observou-se a ocorrência de seis haplótipos distribuídos nas quatro populações. O haplótipo 1 esteve presente em todas as populações, enquanto que o haplótipo 6 foi somente identificado na população de Criação de Laboratório. A diversidade nucleotídica (Pi) das populações foi de 0,00445, sendo que a de Criação de Laboratório...
Eucalyptus genus is derived from Australia and is settled in Brazil for more than a century now. Currently, Brazil has the second largest planted area, forming monocultures that smooth infestation with pest-insects. In 2003, the occurrence of Glycaspis brimblecombei, species described by Moore (Hemiptera, Psyllidae), was detected in Brazil for the first time. The said species is also known as red gum lerp, in Eucalyptus sp plantations in the State of São Paulo. Because of their high capacity of adaptation, nowadays they are found widely distributed all over the domestic territory. Damages caused by their infestation are numerous, resulting in considerable losses for the forestry sector and, consequently, for the Brazilian economy. Red gum lerp populations present a low rate of morphological variation, which makes their identifiction more difficult. Accordingly, molecular tests, such as the use of markers, may help answering such questions. A widely used marker, due to its high variability, is the internal transcribed spacer of ribosomal DNA (ITS). Thus, the ITS marker was used in this paper to investigate the population dynamics of red gum lerps from four regions in the State of São Paulo. ITS1 sequence showed a range of 291 bp in 88.73% of the samples. Polymorphic sites were identified in the range of 80-200 bp, with the population from Pedra Bela showing the highest distribution. Moreover, the occurrence of six haplotypes distributed in the four populations was found. Haplotype 1 was present in all populations, while haplotype 6 was identified in lab-developed population only. The nucleotide diversity (Pi) of populations was 0.00445, while the lab-developed population showed the highest Pi value as between the four populations. In Botucatu, no diversity was found. Specific oligonucleotides flanking the polymorphic regions of the... (Complete abstract click electronic access below)