Relevant bibliographies by topics / Insect impact dynamics

Academic literature on the topic 'Insect impact dynamics'

Author: Grafiati
Published: 10 December 2022
Last updated: 28 January 2023

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Journal articles on the topic "Insect impact dynamics"

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Martinez, Lili, Pushpa Soti, Jasleen Kaur, Alexis Racelis, and Rupesh R. Kariyat. "Impact of Cover Crops on Insect Community Dynamics in Organic Farming." Agriculture 10, no. 6 (June 8, 2020): 209. http://dx.doi.org/10.3390/agriculture10060209.

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Manipulating cover crops as an integrated pest management strategy has recently gained popularity in both traditional and organic agroecosystems. However, little information is available for producers to make informed decisions about cover crop selection, management, and their potential use as a pest management tool. To address this, we conducted a two-year, four-season field experiment on the potential of various cover crops during the summer seasons of both years, followed by monocultures of cash crops during winters. We hypothesized that the cover crop treatments would attract beneficial insects and repel damaging herbivores in a species-specific manner, and the insect community dynamics would be bridged to the cash crops in the subsequent season. In addition, we hypothesized that cash crops would suffer lower herbivory damage following specific cover crop treatments. Our design comprised of three cover crops. Our results indicate that cover crops support beneficial insects during the early summer season, while the time of growing season doesnot affect herbivore abundance. Crop-specific effects were found for herbivore abundance with possible cascading effects on insect community as well as damage levels on the subsequent cash crop, but without any impact on the growth traits of the cash crop. Together, our data suggest that cover crops, when carefully selected, can be an integral part of a pest management strategy for sustainable agriculture.
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Nasrin, M., MR Amin, MRU Miah, AM Akanda, and MG Miah. "Impact of Foraging Insect Pollinators on Chili Production." Bangladesh Journal of Agricultural Research 46, no. 3 (January 26, 2023): 297–306. http://dx.doi.org/10.3329/bjar.v46i3.64130.

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The abundance, foraging behavior, and diurnal and seasonal dynamics of the pollinator insects in chili ecosystem, and the impact of the pollinator insects on chili production was studied at the Bangabandhu Sheikh Mujibur Rahman Agricultural University, (BSMRAU) Gazipur, Bangladesh using the chili variety BARI Morich 2. The crop was cultivated in natural, supplemented insect and selfpollination conditions. The lime butterfly, honey bee, carpenter bee and sweat bee were found in the chili ecosystem. Honey bee depicted significantly the highest abundance and visitation frequency and carpenter bee was found as the most rapid forager. The diurnal and seasonal abundance of the pollinator insects was fluctuated and the peak abundance was found at 11.00 hour of the day. Abundance of lime butterfly, honey bee and carpenter bee revealed negative relationship with maximum and minimum temperatures, and positive relationship with relative humidity and rainfall. Abundance of sweat bee was positively correlated with maximum and minimum temperatures and rainfall, and negatively correlated with relative humidity. The chili plants exerted vulnerable response to insect pollination producing significantly the higher number of fruits per plant, fruit length, diameter and weight, number of seed per fruit, seed weight and yield. Bangladesh J. Agril. Res. 46(3): 297-306, September 2021
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Ben Dhahbi, Anis, Yassine Chargui, Salah Mahmoud Boulaaras, Sana Ben Khalifa, Waleed Koko, and Faisal Alresheedi. "Mathematical Modelling of the Sterile Insect Technique Using Different Release Strategies." Mathematical Problems in Engineering 2020 (November 6, 2020): 1–9. http://dx.doi.org/10.1155/2020/8896566.

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We study simple mathematical models for the dynamics of interactive wild and sterile insect populations. As well as being mathematically tractable, these models can be used as first approximations to real situations occurring with the Sterile Insect Technique (SIT) in which sterile males are released to reduce or eradicate a pest population. This is a method of biological control which can effectively help contain the spread of many pest insects such as the Red Palm Weevil (RPW). Models formulated in this paper are continuous-time, include a strong Allee effect that captures extinction events, and incorporate different strategies of releasing sterile insects. We perform basic studies of dynamical features of these models, with an emphasis on the condition of excitation, and the impact of the different release methods is investigated. Our findings are also demonstrated with some numerical examples.
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Ngouajio, Mathieu, and Milton E. McGiffen. "Going Organic Changes Weed Population Dynamics." HortTechnology 12, no. 4 (January 2002): 590–96. http://dx.doi.org/10.21273/horttech.12.4.590.

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Organic agriculture is growing in importance worldwide. In the United States, the rate of increase of organic growers was estimated at 12% in 2000. However, many producers are reluctant to undertake the organic transition because of uncertainty of how organic production will affect weed population dynamics and management. The organic transition has a profound impact on the agroecosystem. Changes in soil physical and chemical properties during the transition often impact indirectly insect, disease, and weed dynamics. Greater weed species richness is usually found in organic farms but total weed density and biomass are often smaller under the organic system compared with the conventional system. The improved weed suppression of organic agriculture is probably the result of combined effects of several factors including weed seed predation by soil microorganisms, seedling predation by phytophagus insects, and the physical and allelopathic effects of cover crops.
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Bonsall, Michael B. "The impact of diseases and pathogens on insect population dynamics." Physiological Entomology 29, no. 3 (August 2004): 223–36. http://dx.doi.org/10.1111/j.0307-6962.2004.00389.x.

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Lähteenmäki-Uutela, A., L. Hénault-Ethier, S. B. Marimuthu, S. Talibov, R. N. Allen, V. Nemane, G. W. Vandenberg, and D. Józefiak. "The impact of the insect regulatory system on the insect marketing system." Journal of Insects as Food and Feed 4, no. 3 (August 30, 2018): 187–98. http://dx.doi.org/10.3920/jiff2017.0073.

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Taking the macromarketing approach to insect food and feed, we study how the global insect marketing system is impacted by the global insect regulatory system. As an illustration, we study how the regulations of the European Union, USA, Canada and Australia impact marketing strategies of individual companies, and how company-level behaviour combines into the dynamics of the whole insect marketing system. The output of the global insect marketing system is the global assortment of insect products. The regulatory system has its topics, content, and tools with differences between countries. Topics are the elements of the insect business that regulators care about. Content determines what insect products can be launched. Tools are the regulatory instruments and sanctions. Regulatory differences between countries are an important determinant in the geography of launch patterns and in the resulting global assortment of insect products available.
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Wu, Yangxue, Junjie Li, Huanhuan Liu, Gexia Qiao, and Xiaolei Huang. "Investigating the Impact of Climate Warming on Phenology of Aphid Pests in China Using Long-Term Historical Data." Insects 11, no. 3 (March 5, 2020): 167. http://dx.doi.org/10.3390/insects11030167.

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Global climate warming has significant influence on individual development, population dynamics, and geographical distribution of many organisms, which has drawn much attention in recent years. As a large group of poikilotherms, insects whose life activities are closely linked with ambient temperature are supposed to be influenced by global warming. In order to test the consistency or difference of the effects of long-term climate warming on phytophagous insect pests in different geographical environments, this study collected historical data on the occurrence and population dynamics of three aphid pests (Myzus persicae, Aphis gossypii, and Sitobion avenae) in China, and systematically explored their phenological responses. We found that, during a period of about 60 years, in general, the first occurrence dates and the first migration dates of the three aphids almost moved earlier, while the end of the occurrence and the last migration dates were slightly delayed. However, these responses also represented geographical variation at a local scale. Basically, our results showed that the occurrence and migration seasons of these three aphid pests have been prolonged along with climate warming. This study based on historical literature data provides empirical evidence and valuable implications for understanding the impact of climate warming on insect pests and future management strategies.
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Guo, Jianglong, Xiaowei Fu, Shengyuan Zhao, Xiujing Shen, Kris A. G. Wyckhuys, and Kongming Wu. "Long-term shifts in abundance of (migratory) crop-feeding and beneficial insect species in northeastern Asia." Journal of Pest Science 93, no. 2 (January 3, 2020): 583–94. http://dx.doi.org/10.1007/s10340-019-01191-9.

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AbstractVast numbers of insects annually engage in trans-latitudinal migration and thereby impact structure and functioning of natural and man-made ecosystems. In eastern Asia, long-distance migration has historically been studied for single insect species rather than diverse species complexes. Here, we assessed migration dynamics of multiple economically important migratory species on an island in the Bohai Strait, China. Drawing upon 15-year trapping records of > 2.5 million specimens, we unveil inter- and intra-annual shifts in the species composition and abundance of migrant individuals. Migrants belonged to 9 orders and 36 families, primarily consisting of Lepidoptera (79% individuals), Odonata (8%), and Coleoptera (4%). Seven crop-feeding noctuids, e.g., Helicoverpa armigera (Hübner), Mythimna separata (Walker), represented 54% of the total trapping records. Trap catches exhibited marked seasonal variation, with the highest capture rate during early fall. Yearly abundance of migratory noctuids was coupled with that of their associated natural enemies. Although overall trap catches did not decrease over the monitoring period, the entire order of Odonata experienced a 14.1% annual rate of decline. Furthermore, 19 out of 108 species exhibited a progressively declining abundance over time, including the cosmopolitan cutworm Agrotis ipsilon (Hufnagel) and the insectivorous dragonfly Pantala flavescens Fabricius. Our work provides unprecedented insights into insect migration dynamics in eastern Asia, helps fine-tune forecasting and early-warning systems of crop pests, and thereby guides integrated pest management within local agro-landscapes. Also, a long-term tracking of migrant insect populations can shine light on the fate of (insect-mediated) ecosystem services and trophic dynamic processes at a macroscale.
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Korell, Lotte, Martin Schädler, Roland Brandl, Susanne Schreiter, and Harald Auge. "Release from Above- and Belowground Insect Herbivory Mediates Invasion Dynamics and Impact of an Exotic Plant." Plants 8, no. 12 (November 26, 2019): 544. http://dx.doi.org/10.3390/plants8120544.

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The enemy-release hypothesis is one of the most popular but also most discussed hypotheses to explain invasion success. However, there is a lack of explicit, experimental tests of predictions of the enemy-release hypothesis (ERH), particularly regarding the effects of above- and belowground herbivory. Long-term studies investigating the relative effect of herbivores on invasive vs. native plant species within a community are still lacking. Here, we report on a long-term field experiment in an old-field community, invaded by Solidago canadensis s. l., with exclusion of above- and belowground insect herbivores. We monitored population dynamics of the invader and changes in the diversity and functioning of the plant community across eight years. Above- and belowground insects favoured the establishment of the invasive plant species and thereby increased biomass and decreased diversity of the plant community. Effects of invertebrate herbivores on population dynamics of S. canadensis appeared after six years and increased over time, suggesting that long-term studies are needed to understand invasion dynamics and consequences for plant community structure. We suggest that the release from co-evolved trophic linkages is of importance not only for the effect of invasive species on ecosystems, but also for the functioning of novel species assemblages arising from climate change.
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Skendžić, Sandra, Monika Zovko, Ivana Pajač Živković, Vinko Lešić, and Darija Lemić. "The Impact of Climate Change on Agricultural Insect Pests." Insects 12, no. 5 (May 12, 2021): 440. http://dx.doi.org/10.3390/insects12050440.

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Climate change and global warming are of great concern to agriculture worldwide and are among the most discussed issues in today’s society. Climate parameters such as increased temperatures, rising atmospheric CO2 levels, and changing precipitation patterns have significant impacts on agricultural production and on agricultural insect pests. Changes in climate can affect insect pests in several ways. They can result in an expansion of their geographic distribution, increased survival during overwintering, increased number of generations, altered synchrony between plants and pests, altered interspecific interaction, increased risk of invasion by migratory pests, increased incidence of insect-transmitted plant diseases, and reduced effectiveness of biological control, especially natural enemies. As a result, there is a serious risk of crop economic losses, as well as a challenge to human food security. As a major driver of pest population dynamics, climate change will require adaptive management strategies to deal with the changing status of pests. Several priorities can be identified for future research on the effects of climatic changes on agricultural insect pests. These include modified integrated pest management tactics, monitoring climate and pest populations, and the use of modelling prediction tools.
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Dissertations / Theses on the topic "Insect impact dynamics"

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Gryspeirt, Aiko. "Impact des plantes Bt sur la biologie de Plodia interpunctella: évaluation de l'efficacité de la stratégie agricole "Haute dose - refuge" pour la gestion de la résistance des insectes ravageurs aux plantes Bt." Doctoral thesis, Universite Libre de Bruxelles, 2008. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210542.

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Commercialisées depuis 1996, les plantes génétiquement modifiées produisant une toxine insecticide (toxine Cry) dérivée de Bacillus thuringiensis et appelées plantes Bt ciblent certains Lépidoptères ou Coléoptères ravageurs. Au fil des ans, les surfaces cultivées en plantes Bt sont de plus en plus importantes et contrôlent de larges populations d'insectes. Pour limiter le risque de développement de populations résistantes, une stratégie agricole appelée 'Haute Dose / Zone Refuge' est actuellement recommandée aux Etats-Unis par l'Environmental Protection Agency. Cette stratégie préventive nécessite la plantation d'une 'zone refuge' composée de plantes non-Bt utilisables par le ravageur ciblé et plantée à proximité de la 'zone Bt' qui synthétise une haute dose de toxine Cry.

Mon projet de recherche s’inscrit dans le cadre de l’évaluation de l'efficacité de cette stratégie et s’articule en deux phases :une phase expérimentale et une phase théorique. La première se concentre sur la caractérisation en laboratoire de l'impact des toxines Cry sur la biologie d'un ravageur. Cette phase constitue un support au volet théorique :la mise au point d’un modèle mathématique évaluant l'efficacité de la stratégie HD/R. L'originalité de ce projet repose entre autre sur l'interactivité entre ces deux volets.

Volet expérimental. Impact des toxines Cry sur la biologie de Plodia interpunctella. Nous évaluons séparément l'impact d'une gamme de concentrations de deux toxines Cry (CryXX et CryYY) sur une série de paramètres comportementaux et biologiques d'un insecte commun des denrées stockées: Plodia interpunctella (Hübner) (Lepidoptera :Pyralidae). Ces paramètres sont sélectionnés car leur variation pourrait avoir un impact sur l'efficacité de la stratégie HD/R dans le contrôle de la résistance. Il est donc pertinent de les quantifier pour intégrer dans le modèle des ordres de grandeur réalistes et générer des résultats qui ne sont pas uniquement basés sur des spéculations théoriques.

Volet théorique A. Efficacité de la stratégie HD/R pour des plantes Bt synthétisant une ou deux toxines simultanément. La stratégie 'HD/R' a été développée pour prévenir la résistance envers les plantes Bt synthétisant une seule toxine. Or, depuis 2003, de nouvelles variétés de coton Bt synthétisant simultanément deux toxines Cry sont commercialisées (BollgardII® et WidestrikeTM). Nous évaluons, grâce au modèle que nous avons développé, l'efficacité de cette stratégie lors d'une utilisation exclusive de plantes Bt synthétisant une ou deux toxines.

Volet théorique B. Impact du ralentissement du développement des insectes sur les plantes Bt sur l'efficacité de la stratégie HD/R. Le volet expérimental met en évidence un allongement de la durée du développement des larves se nourrissant sur une diète contaminée en toxine Cry. Ce ralentissement induit une séparation temporelle entre l'émergence des adultes de la zone Bt et de la zone refuge et perturbe une hypothèse principale de la stratégie HD/R: le croisement aléatoire entre adultes, indépendamment du génotype et de la zone d'origine. Dans ce troisième chapitre, nous étudions l'impact de la perturbation du croisement aléatoire sur l'efficacité de la stratégie HD/R. Nous testons également deux options pour optimiser la stratégie en cas d'asynchronie: l'utilisation de plantes Bt synthétisant une faible concentration en toxine (atténuant le décalage entre l'émergence des adultes) ou l'augmentation de la taille de la zone refuge (favorisant la survie des individus porteurs d'allèle de sensibilité et donc optimisant la dilution de la résistance à la génération suivante).

Ce travail s'intègre dans une problématique actuelle et utilise des outils de biologie théorique (théories de la dynamique et de la génétique des populations) ainsi que le développement d'un modèle mathématique. Il apporte des éléments de réponse et de réflexion sur l'optimisation de la gestion de la résistance des insectes mais c'est aussi une illustration de la complémentarité entre la biologie expérimentale et théorique.

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On the market since 1996, genetically modified plants synthesizing an insecticidal toxin (Cry toxin) stemmed from Bacillus thuringiensis, called Bt plants, target several insect pests (Lepidoptera or Coleoptera). Bt crops cover increasingly larger areas and control important pest populations The Insect Resistance Management Strategy (IRM) strategy currently recommended in the U.S.A. to limit the development of resistant populations is the High Dose / Refuge zone (HD/R) strategy. This pre-emptive strategy requires a refuge zone composed by non-Bt plants, usable by the target insect and in close proximity of the Bt zone synthesizing a high toxin concentration.

My research project contributes to the effectiveness assessment of this HD/R strategy. It is structured on two main parts: an experimental, and a theoretical section. The first part characterizes the impact of Cry toxins on the biology of an insect pest. It is the basis of the theoretical part: the implementation of a mathematical model, which evaluates the effectiveness of the HD/R strategy.

The originality of this project is based on the interactivity of these two components.

Experimental section. Impact of the Cry toxins on the biology of Plodia interpunctella. We assess the impact of a range of concentrations of two Cry toxins (CryXX et CryYY) on several behavioural and biological parameters of a common pest of stored products: Plodia interpunctella (Hübner) (Lepidoptera :Pyralidae). These parameters are selected because their variation could influence the effectiveness of a HD/R strategy. So, it is important to quantify these parameters so that realistic values can be integrated in our model. The results of the model are thus not based on theoretical assumptions alone.

Theoretical section A. Effectiveness of a HD/R strategy with Bt plants synthesizing one or two toxins. Initially, the HD/R strategy has been developed to limit the resistance towards Bt plants synthesizing one toxin. However, since 2003, new Bt cotton varieties synthesize two toxins simultaneously (BollgardII® et WidestrikeTM). We assess, with our model, the effectiveness of this strategy for Bt plants synthesizing one or two toxins.

Theoretical section B. Impact of the slowing down of the insect development reared on Bt plants on the effectiveness of the HD/R strategy. The experimental part demonstrates that larvae reared on a Bt diet have a protracted development duration. The consequence of this is a temporal separation between adult emergence in the two zones (Bt zone and refuge zone). This could affect the main assumption of the HD/R strategy, i. e. random mating independently of the genotype and of the native zone. In this third chapter, we study the impact of random mating disruption on the effectiveness of a HD/R strategy. We test two options to optimise the strategy in case of asynchrony: the use of Bt plants synthesizing a lower toxin concentration (limiting emergence asynchrony) or increasing the refuge zone size (favouring the survival of insect carrying one or two susceptible allele and thus optimising the dilution of resistance at the next generation).

This work is applied to a current issue. It uses some of the tools of theoretical biology (theories of population dynamics and population genetics) and develops a mathematical model. It provides some responses and some elements of thought about insect resistance management. It is also an illustration of the complementarity between experimental and theoretical biology.


Doctorat en Sciences
info:eu-repo/semantics/nonPublished

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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 forestiers
Biotic 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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Gidoin, Cindy. "Impacts écologiques de l’invasion d’un insecte prédateur de graines (Hymenoptera Torymidae) dans un écosystème forestier méditerranéen." Thesis, Montpellier, SupAgro, 2014. http://www.theses.fr/2014NSAM0015/document.

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Les invasions biologiques produisent des assemblages d'espèces souvent inédits et sources de nouvelles interactions spécifiques. L'impact écologique d'une invasion peut être : (i) indirect si l'espèce envahissante entre en compétition avec une ou des espèces résidentes, et (ii) direct si l'espèce envahissante consomme ou parasite une ou des espèces résidentes. Ces deux types d'impacts sont susceptibles de s'appliquer aux insectes envahissants du genre Megastigmus (Hymenoptera: Torymidae), qui exploitent généralement une niche étroite partagée avec d'autres espèces résidentes, et contribuent à d'importantes mortalités dans les populations d'hôtes du fait de leur spécialisation sur les graines. L'objectif de cette thèse est de tester ces prédictions à travers l'étude de l'impact de l'invasion en France de Megastigmus schimitscheki sur : (i) M. pinsapinis, un compétiteur résident, et (ii) les populations en expansion de son hôte obligatoire, le cèdre de l'Atlas (Cedrus atlantica).Un suivi spatio-temporel des populations françaises de Megastigmus spp. révèle que l'expansion rapide de M. schimitscheki est associée à un déclin important de M. pinsapinis. Un modèle mécaniste et statistique a été développé afin de déterminer la contribution relative de la variabilité temporelle de la disponibilité en graines et des divergences de traits d'histoire de vie dans la dynamique de coexistence-exclusion de M. schimitscheki et M. pinsapinis. Nos résultats montrent que la phénologie plus précoce de M. schimitscheki est le principal facteur déterminant le succès de l'invasion de M. schimitscheki et l'exclusion compétitive de M. pinsapinis dans les zones de sympatrie des deux espèces.Nous avons développé une approche théorique de l'impact indirect de M. schimitscheki sur C. atlantica basée sur les modèles de réaction-diffusion. Nos résultats montrent qu'un effet Allee résultant de la prédation des graines sur un front d'expansion peut accroître la contribution des hôtes situés à l'arrière de ce front au pool génétique de la population. Ce phénomène a pour conséquence de freiner l'érosion de la diversité génétique au cours du processus de colonisation.Les approches expérimentales et théoriques développées au cours de cette thèse montrent que l'invasion de M. schimitscheki a un impact indirect négatif sur la démographie d'une espèce résidente occupant la même niche écologique, alors qu'elle pourrait favoriser directement le maintien de la diversité génétique des populations d'hôtes en pleine dynamique de régénération naturelle
Biological invasions produce novel species assemblages in communities that likely result in novel interspecific interactions. Ecological impacts of invasions may be: (i) indirect, if the invader enters competition with resident species, and (ii) indirect if the invader is a predator or a parasite of resident species. Both indirect and direct ecological invasion impacts are likely to apply to invasive wasps of the Megastigmus genus (Hymenoptera: Torymidae), which exploit narrow ecological niches that overlap with those of resident insect species, and contribute to high mortality levels in host plant populations due to their high specialization on seeds. This thesis aimed at testing such predictions by studying the impacts of the invasion of M. schimitscheki on: (i) its resident competitor for the seed resource M. pinsapinis, and (ii) the expanding populations of its obligatory host the Atlas cedar (Cedrus atlantica) in southeastern France.An extensive spatio-temporal survey of Megastigmus spp. populations indicated that the rapid expansion of M. schimitscheki was associated with a strong decline of M. pinsapinis. A mechanistic-statistical modelling approach allowed us to show that an earlier phenology of M. schimitscheki had a stronger explanatory power of both invasion success and the competitive exclusion of the resident than temporal variation in resource supply.A theoretical approach of the indirect impact of M. schimitscheki on C. atlantica expansion dynamics was based on reaction-diffusion models. We showed that an Allee effect resulting from seed predation at the expansion front of a host population may increase the genetic contribution of host individuals situated in the bulk of the expansion front. Interestingly, this phenomenon results in a limited erosion of genetic diversity during the expansion phase of the host population.The empirical and theoretical approaches developed showed that the invasion of M. schimitscheki in French cedar forests had a strong and negative indirect impact on the demography of a resident species, but, parallely, such invasion may directly favour the maintenance of genetic diversity in expanding host plant populations
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Poher, Yoann. "Dynamique de la biodiversité et changements environnementaux en Corse depuis 7000 ans : éclairages paléoentomologiques et paléobotaniques." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0435/document.

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Cette thèse a pour objectif d’identifier les trajectoires plurimillénaires des écosystèmes de Corse à basse et moyenne altitude sous la triple influence des forçages climatiques, eustatiques et anthropiques à travers l’étude des assemblages d’insectes fossiles et des données paléobotaniques disponibles ou nouvellement acquises. Cette approche multidisciplinaire a été appliquée sur trois séquences sédimentaires prélevées à l’étang du Greco sur l’île Cavallo, au marais de Cannuta et à la tourbière de Bagliettu.Les résultats obtenus révèlent des changements majeurs dans la structuration du couvert végétal. Des signes d’ouverture du paysage apparaissent sur Cavallo et à Cannuta dès 5500-5000 cal. BP. Ils coïncident avec des indices d’activités des sociétés insulaires, lesquelles s’intensifient après 3000 cal. BP et plus particulièrement depuis 1000 ans à Bagliettu. Notre étude suggère que la sensibilité et la réponse des zones humides littorales face à la remontée relative du niveau marin dépend du contexte géomorphologique. Sur l’île Cavallo où le relief est faible, la transgression marine induit une augmentation de la salinité dans l’étang du Greco vers 3700 cal. BP, qui provoque une chute irréversible de la diversité des coléoptères aquatiques et hygrophiles. Au marais de Cannuta, où l’érosion des versants a favorisé la progradation de la plaine alluviale, notre étude montre une diminution de l’influence marine après 5000 cal. BP et une diversification de cette même entomofaune à partir de 1200 cal. BP. À Bagliettu, nous avons démontré l’importance des changements hydro-morphologiques des rivières dans la dynamique des écosystèmes tourbeux attenants et de leur entomofaune
This thesis aims to define the multi-millennial trajectories of Corsican ecosystems under the climatic, eustatic and anthropic factors via the study of fossil insect assemblages and previous or new palaeobotanical data. This multidisciplinary approach was carried out at low and middle elevation on three sedimentary archives from the Greco pond on Cavallo Island, the Cannuta marsh and the Bagliettu peat-bog. The results reveal major changes in the structure of the vegetation cover over the last 7000 years. Signs of more open landscapes occurred on Cavallo and in Cannuta from 5500-5000 cal. BP. They coincide with bio-markers of insular societies activities, which increased from 3000 cal. BP onward and more particularly during the last 1000 years at Bagliettu.This study also suggests that the sensitivity and the response of coastal wetlands to the relative sea-level rise depend on the geomorphological context. On the low-lying Cavallo Island, marine transgression induced an increase of salt conditions in the Greco pond from 3700 cal. BP, which in turn, caused an irreversible loss of aquatic and hygrophilous beetle diversity. In Cannuta marsh, erosion on catchment slopes favoured the progradation of the coastal floodplain and the results reveal a progressive decrease of the marine influence from 5000 cal. BP as well as a diversification of this entomofauna over the last 1200 years. In Bagliettu, the results show how hydro-morphological changes of the rivers impact the dynamics of adjacent peaty ecosystems and beetle diversity
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Books on the topic "Insect impact dynamics"

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L, McManus Michael, Liebhold Andrew M, United States. Forest Service. Northeastern Research Station, Northeastern Forest Experiment Station (Radnor, Pa.), and United States. Forest Health Technology Enterprise Team, eds. Proceedings, population dynamics, impacts, and integrated management of forest defoliating insects: Banská Štiavnica, Slovak Republic, August 18-23, 1996. Radnor, PA: USDA Forest Service, Northeastern Research Station, 1998.

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L, McManus Michael, Liebhold Andrew M, United States. Forest Service. Northeastern Research Station., International Union of Forest Research Organizations. Working Party S7.03-06, "Integrated Management of Forest Defoliating Insects", International Union of Forest Research Organizations. Working Party S7.03.07, "Population Dynamics of Forest Insects", and United States. Forest Health Technology Enterprise Team., eds. Proceedings: Population dynamics, impacts, and integrated management of forest defoliating insects : Banská Štiavnica, Slovak Republic, August 18-23, 1996. Radnor, PA: USDA Forest Service, Northeastern Research Station, 1998.

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Beerling, David. The Emerald Planet. Oxford University Press, 2007. http://dx.doi.org/10.1093/oso/9780192806024.001.0001.

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Global warming is contentious and difficult to measure, even among the majority of scientists who agree that it is taking place. Will temperatures rise by 2ºC or 8ºC over the next hundred years? Will sea levels rise by 2 or 30 feet? The only way that we can accurately answer questions like these is by looking into the distant past, for a comparison with the world long before the rise of mankind. We may currently believe that atmospheric shifts, like global warming, result from our impact on the planet, but the earth's atmosphere has been dramatically shifting since its creation. This book reveals the crucial role that plants have played in determining atmospheric change - and hence the conditions on the planet we know today. Along the way a number of fascinating puzzles arise: Why did plants evolve leaves? When and how did forests once grow on Antarctica? How did prehistoric insects manage to grow so large? The answers show the extraordinary amount plants can tell us about the history of the planet -- something that has often been overlooked amongst the preoccuputations with dinosaur bones and animal fossils. David Beerling's surprising conclusions are teased out from various lines of scientific enquiry, with evidence being brought to bear from fossil plants and animals, computer models of the atmosphere, and experimental studies. Intimately bound up with the narrative describing the dynamic evolution of climate and life through Earth's history, we find Victorian fossil hunters, intrepid polar explorers and pioneering chemists, alongside wallowing hippos, belching volcanoes, and restless landmasses.
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Book chapters on the topic "Insect impact dynamics"

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Satpathy, S., B. S. Gotyal, and V. Ramesh Babu. "Impact of Climate Change on Insect Pest Dynamics and Its Mitigation." In Conservation Agriculture and Climate Change Impacts and Adaptations, 107–18. London: CRC Press, 2022. http://dx.doi.org/10.1201/9781003364665-8.

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Russell, D. A., and S. M. Radwan. "Modelling the impact of cotton fruiting phenology on pink bollworm population dynamics in Egypt." In Proceedings of the 8th International Symposium on Insect-Plant Relationships, 323–24. Dordrecht: Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-1654-1_105.

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Li, Ming. "Teacher Learning: A Multifaceted, Situated and Dynamic Process." In Understanding the Impact of INSET on Teacher Change in China, 89–103. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-3311-8_6.

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Karthik, Somala, M. S. Sai Reddy, and Gummudala Yashaswini. "Climate Change and Its Potential Impacts on Insect-Plant Interactions." In Global Warming and Climate Change [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.98203.

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The most dynamic and global environmental issue to date is climate change. The consequences of greenhouse effect and climate change from rising temperatures, frequent droughts, irregular rainfall, etc. are already evident. Insects and plants are affected by climate change and extreme weather events and the direct impact of anthropogenic climate change has been reported on every continent, in every ocean and in most major taxonomic groups. In the modern period, as a result of natural cycles and anthropogenic activities and their effects on the global climate, plants are typically susceptible to new environmental factors, i.e. higher levels solar radiation, rise in temperatures, greenhouse effect and changes in rainfall patterns over the seasons. Increased temperatures, CO2 and rapid changes in rainfall patterns can dramatically alter the biochemistry of plants and thus plant defence responses. This can have important implications in insect fertility, feeding rates, survival, population size, and dispersal. The relationships between plants and insects are thus changed with significant consequences for food security and natural ecosystems. Similarly, mismatches between plants and insect pollinators are caused by the acceleration of plant phenology by warming. Human nutrition which depends on insect pollination can be affected with reduction in plant reproduction and fitness. Thus, understanding abiotic stress reactions in plants and insects is relevant and challenging in agriculture. In the preparation and implementation of effective strategies for future insect pest management programmes, the impact of climate change on crop production, mediated by changes in the populations of extreme insect pests should be carefully considered.
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Bonsall, Michael B., and Michael P. Hassell. "Predator–prey interactions." In Theoretical Ecology. Oxford University Press, 2007. http://dx.doi.org/10.1093/oso/9780199209989.003.0008.

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Predation is a widespread population process that has evolved many times within the metazoa. It can affect the distribution, abundance, and dynamics of species in ecosystems. For instance, the distribution of western tussock moth is known to be affected by a parasitic wasp (Maron and Harrison, 1997; Hastings et al., 1998), the abundance of different competitors can be shaped by the presence or absence of predators (e.g. Paine, 1966), and natural enemies (such as many parasitoids) can shape the dynamics of a number of ecological interactions (Hassell, 1978, 2000). The broad aim of this chapter is to explore the dynamical effects of predators (including the large groupings of insect parasitoids) and show how our understanding of predator–prey interactions scales from knowledge of the behaviour and local patch dynamics to the population and regional (metapopulation) levels. We draw on a number of approaches including behavioural studies, population dynamics, and time-series analysis, and use models to describe the data and dynamics of the interaction between predators and prey. Predator–prey interactions have an inherent tendency to fluctuate and show oscillatory behaviour. If predators are initially rare, then the size of the prey population can increase. As prey population size increases, the predator populations also begins to increase, which in turn has a detrimental effect on the prey population leading to a decline in prey numbers. As prey become scarce then the predator population size declines and the cycle starts again. These intuitive dynamics can be captured by one of the simplest mathematical descriptions of a predator–prey interaction: the Lotka–Volterra model (Lotka, 1925; Volterra, 1926). Specifically, the Lotka–Volterra model for an interaction between a predator (P) and its prey (N) is a continuous-time model and has the form : where r is the prey-population growth rate in the absence of predators, α is the predator attack rate, c is the (positive) impact of prey on predators, and d is the death rate of predators in the absence of their prey resource.
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Van Rijn, Paul C. J., and Maurice W. Sabelis. "Impact of plant-provided food on herbivore–carnivore dynamics." In Plant-Provided Food for Carnivorous Insects, 223–66. Cambridge University Press, 2005. http://dx.doi.org/10.1017/cbo9780511542220.009.

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Wellenreuther, Maren, Rachael Y. Dudaniec, and Lesley T. Lancaster. "Genomic insights into micro- and macro-evolutionary processes in Odonata." In Dragonflies and Damselflies, 7–20. 2nd ed. Oxford University PressOxford, 2022. http://dx.doi.org/10.1093/oso/9780192898623.003.0002.

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Abstract Odonata (dragonflies and damselflies) present an unparalleled insect system for investigating biodiversity impacts of environmental change because of their ease of sampling, occupation of environmental gradients, and rapid movement dynamics. In addition, due to their ancient phylogenetic position, research into this order provides fundamental insights into key evolutionary processes such as the evolution of flight, vision, and sexual behavior. The chapter investigates how emerging genomics-based studies have provided novel insights into micro-and macro-evolutionary processes, namely: 1) movement dynamics; 2) local adaptation; and 3) species boundaries. It covers how genomic studies are starting to reveal the micro- and macro-evolutionary processes that underpin form and function in this order. It concludes that future work needs to taxonomically and geographically broaden the species investigated to capture the full extent of diversity in this order, and to enable comparative work.
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Nabi, Zahid, Mudasir Youssouf, and Javid Manzoor. "Impact of Pesticides on Aquatic Life." In Advances in Environmental Engineering and Green Technologies, 170–81. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-6111-8.ch010.

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Humans made use of pesticides to kill pests infesting crops. This was done to increase agricultural yields and improve public health. Pesticides however turn out to be damaging for the environment, causing many harmful impacts. Certain pesticides after being applied to the environment show long-term residual effects while others show acute fatal effects particularly to aquatic life. For example, organochlorine pesticides are persistent in the environment; as a result of this, these pesticides find their way to contaminate ground water, surface water, food products, air, soil, and may also affect human beings through direct contact. Pesticide exposure to humans has been found to be an important cause of some diseases such as cancer, respiratory diseases, skin diseases, endocrine disruption, and reproduction disorders. It is this aspect of pesticides in the environment that has raised concern among environmental scientists to study their behavior in the environment and then come out with a sound alternative so as to rescue the human population from their adverse effects. Fifty years (half a century) after Rachel Carson's warning to the world about the devastating effect pesticides have on birds and beneficial insects, pesticides continue to be in use. Continued usage of pesticides can be described as a massive chemical assault on our environment which threatens the survival of many birds, fish, insects, and small aquatic organisms that form the basis of the food web. More generally, pesticides reduce species diversity in the animal kingdom and contribute to population decline in animals and plants by destroying habitats, reducing food supplies, and impairing reproduction. Organisms in ecosystems exist in complex interdependent associations such that losses of one keystone species as a result of pesticides (or other causes) can have far reaching and unpredictable effects. A keystone species is a species that is disproportionately connected to more species in the food-web. The many connections that a keystone species holds mean that it maintains the organization and structure of entire communities. The loss of a keystone species results in a range of dramatic effects that alters trophic structure, other food-web connections, and can cause the extinction of other species in the community. A pesticide may eliminate a species essential to the functioning of the entire community, or it may promote the dominance of undesired species or it may simply decrease the number and variety of species present in the community. This may disrupt the dynamics of the food webs in the community by breaking the existing dietary linkages between species.
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Rossiter, MaryCarol. "The Impact of Resource Variation on Population Quality in Herbivorous Insects: A Critical Aspect of Population Dynamics." In Effects of Resource Distribution on Animal–Plant Interactions, 13–42. Elsevier, 1992. http://dx.doi.org/10.1016/b978-0-08-091881-5.50005-0.

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Golfarelli, Matteo, and Stefano Rizzi. "What-if Simulation Modeling in Business Intelligence." In Business Information Systems, 2229–47. IGI Global, 2010. http://dx.doi.org/10.4018/978-1-61520-969-9.ch135.

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Optimizing decisions has become a vital factor for companies. In order to be able to evaluate beforehand the impact of a decision, managers need reliable provisional systems. Though data warehouses enable analysis of past data, they are not capable of giving anticipations of future trends. What-if analysis fills this gap by enabling users to simulate and inspect the behavior of a complex system under some given hypotheses. A crucial issue in the design of what-if applications is to find an adequate formalism to conceptually express the underlying simulation model. In this paper the authors report on how, within the framework of a comprehensive design methodology, this can be accomplished by extending UML 2 with a set of stereotypes. Their proposal is centered on the use of activity diagrams enriched with object flows, aimed at expressing functional, dynamic, and static aspects in an integrated fashion. The paper is completed by examples taken from a real case study in the commercial area.
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Conference papers on the topic "Insect impact dynamics"

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Jankauski, Mark, Ryan Schwab, Cailin Casey, and Andrew Mountcastle. "Insect Wing Buckling Influences Stress and Stability During Collisions." In ASME 2021 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/detc2021-70551.

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Abstract Flapping insect wings frequently collide with vegetation and other obstacles during flight. Repeated collisions may irreversibly damage the insect wing, thereby compromising the insect’s ability to fly. Further, reaction torques caused by the collision may destabilize the insect and hinder its ability to maneuver. To mitigate the adverse effects of impact, some insect wings are equipped with a flexible joint called a “costal break.” The costal break buckles once it exceeds a critical angle, which is believed to improve flight stability and prevent irreversible wing damage. However, to our knowledge, there are no models to predict the dynamics of the costal break. Through this research, we develop a simple model of an insect wing with a costal break. The wing was modeled as two beams interconnected by a torsional spring, where the stiffness of the torsional spring instantaneously decreases once it has exceeded a critical angle. We conducted a series of static tests to approximate model parameters. Then, we used numerical simulation to estimate the peak stresses and reaction moments experienced by the wing during a collision. We found that costal break increased the wing’s natural frequency by about 50% compared to a homogeneous wing and thus reduced the stress associated with normal flapping. Buckling did not significantly affect peak stresses during collision. Joint buckling reduced the peak reaction moment by about 32%, suggesting that the costal break enhances flight stability.
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Cheng, B., and X. Deng. "Mathematical Modelling of Near-Hover Insect Flight Dynamics." In ASME 2010 Dynamic Systems and Control Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/dscc2010-4234.

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Using a dynamically scaled robotic wing, we studied the aerodynamic torque generation of flapping wings during roll, pitch, and yaw rotations of the stroke plane. The total torque generated by a wing pair with symmetrical motions was previously known as flapping counter-torques (FCTs). For all three types of rotation, stroke-averaged FCTs act opposite to the directions of rotation and are collinear with the rotational axes. Experimental results indicate that the magnitude of FCTs is linearly dependent on both the flapping frequency and the angular velocity. We also compared the results with predictions by a mathematical model based on quasi-steady analyses, where we show that FCTs can be described through consideration of the asymmetries of wing velocity and the effective angle of attack caused by each type of rotation. For roll and yaw rotations, our model provided close estimations of the measured values. However, for pitch rotation the model tends to underestimate the magnitude of FCT, which might result from the effect of the neglected aerodynamics, especially the wake capture. Similar to the FCT, which is induced by body rotation, we further provide a mathematical model for the counter force induced by body translation, which is termed as flapping counter-force (FCF). Based on the FCT and FCF models, we are able to provide analytical estimations of stability derivatives and to study the flight dynamics at hovering. Using fruit fly (Drosophila) morphological data, we calculated the system matrix of the linearized flight dynamics. Similar to previous studies, the longitudinal dynamics consist of two stable subsidence modes with fast and slow time constants, as well as an unstable oscillatory mode. The longitudinal instability is mainly caused by the FCF induced by an initial forward/backward velocity, which imparts a pitch torque to the same direction of initial pitch velocity. Similarly, the lateral dynamics also consist of two stable subsidence modes and an unstable oscillatory mode. The lateral instability is mainly caused by the FCF induced by an initial lateral velocity, which imparts a roll torque to the same direction of initial roll velocity. In summary, our models provide the first analytical approximation of the six-degree-of-freedom flight dynamics, which is important in both studying the control strategies of the flying insects and designing the controller of the future flapping-wing micro air vehicles (MAVs).
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Tanbour, Emad Y., and Ramin K. Rahmani. "Enhancement of Natural Convection Heat Transfer Rate in Internal Compressible Flows by Inserting Stationary Inserts." In ASME 2008 Heat Transfer Summer Conference collocated with the Fluids Engineering, Energy Sustainability, and 3rd Energy Nanotechnology Conferences. ASMEDC, 2008. http://dx.doi.org/10.1115/ht2008-56078.

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Enhancement of the natural and forced convection heat transfer has been the subject of numerous academic and industrial studies. Air blenders, mechanical agitators, and static mixers have been developed to increase the forced convection heat transfer rate in compressible and incompressible flows. Stationary inserts can be efficiently employed as heat transfer enhancement device in the natural convection systems with compressible flow. Generally, a stationary heat transfer enhancement insert consists of a number of equal motionless units, placed on the inside of a pipe or channel in order to control flowing fluid streams. These devices have low maintenance and operating costs, low space requirements and no moving parts. A range of designs exists for a wide range of specific applications. The shape of the elements determines the character of the fluid motion and thus determines thermal effectiveness of the insert. There are several key parameters that may be considered in the design procedure of a heat transfer enhancement insert, which lead to significant differences in the performance of various designs. An ideal insert for natural conventional heat transfer of compressible flow applications provides a higher rate of heat transfer and a thermally homogenous fluid with minimized pressure drop and required space. To choose an insert for a given application or in order to design a new insert, besides experimentation, it is possible to use computational fluid dynamics (CFD) tools to study insert performance. This paper presents the outcomes of the numerical studies by the authors on an industrial stationary heat transfer enhancement insert and illustrates how a heat transfer enhancement insert can improve the heat transfer in a buoyancy driven compressible flow. The numerical predictions were validated using experimental data. Using different measuring tools, the global performance of the insert and the impact of the geometrical parameters are studied in order to choose the most effective design for a given application.
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Erlich, I., and F. Shewarega. "Insert Impact of Large-Scale Wind Power Generation on the Dynamic Behaviour of Interconnected Systems." In 2007 iREP Symposium - Bulk Power System Dynamics and Control - VII. Revitalizing Operational Reliability. IEEE, 2007. http://dx.doi.org/10.1109/irep.2007.4410525.

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Hiner, Stephen D. "The Use of 3D CFD Analysis in the Design of Air Intake Systems as a Visualisation Tool to Optimise Performance in Gas Turbine Applications." In ASME Turbo Expo 2005: Power for Land, Sea, and Air. ASMEDC, 2005. http://dx.doi.org/10.1115/gt2005-68758.

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An optimised inlet air system design is an important factor in the gas turbine (GT) industry. Optimising the design of the air intake system is an increasingly challenging process as both the layout complexity and range of features that can be included in the intake system expands. These may include a combination of insect or trash screens, weather protection and filtration systems, silencers, anti-icing systems, ventilation system off takes and inlet heating or cooling systems for power augmentation. Poor designs can result in inefficient use of these components as well as losses in engine performance due to excessive pressure losses or distortion in the flow entering the gas turbine. High flow distortion, velocity, pressure or temperature, can induce compressor surge and high acromechanical stresses in compressor blades and vanes. In extreme cases this may result in blade or vane failures. Computational Fluid Dynamics (CFD) analysis is a powerful tool for visualisation of the predicted flow through a hypothetical air inlet system prior to manufacture. The CFD output plots include flow streamlines and contours, of pressure, velocity or temperature, at any plane in the model. These enable pressure losses, flow distortion issues, potential recirculation areas and high local velocities within the system to be reviewed. This allows optimisation of the installation design to minimise system pressure loss and flow distortion, both through the components and at the engine interface. This paper, with reference to case studies of gas turbine applications, highlights the impact that CFD analysis can have on the design of intake systems to ensure that the best overall performance is obtained. The process of developing the CFD geometry and how significant features of an installation are modeled is outlined. Environmental and operational conditions, such as cross winds can impact the flow through an intake system; therefore, incorporation of such factors into the model boundary conditions are covered. Typical output metrics from the CFD analysis are shown from selected case studies; total pressure drop and flow distortion at the interface plane between the intake system and gas turbine. The importance of experienced interpretation of the CFD output to define potential intake design modifications to improve system performance is highlighted. In specific cases model testing has been carried out to validate CFD results. Case study examples are used to show the improvements made in air intake performance that contribute to increased operational efficiency of the gas turbine application.
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Venanzi, T., M. Selig, A. Pashkin, S. Winnerl, M. Katzer, H. Arora, A. Erbe, et al. "Carrier dynamics in InSe and the impact of terahertz pulses." In 2022 47th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz). IEEE, 2022. http://dx.doi.org/10.1109/irmmw-thz50927.2022.9895949.

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Li, Chengyu, Junshi Wang, Geng Liu, Xiaolong Deng, and Haibo Dong. "Passive Pitching Mechanism of Three-Dimensional Flapping Wings in Hovering Flight." In ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/ajkfluids2019-4639.

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Abstract Flapping wings of insects can passively maintain a high angle of attack due to the torsional flexibility of wing basal region without the aid of the active pitching motion. However, the lift force generated by such passive pitching motion has not been well explored in the literature. Consequently, there is no clear understanding of how torsional wing flexibility should be designed for optimal performance. In this work, a computational study was conducted to investigate the passive pitching mechanism of flapping wings in hovering flight using a torsional spring model. The torsional wing flexibility was characterized by Cauchy number. The impacts of the inertial effect of wings were evaluated using the mass ratio. The aerodynamic forces and associated unsteady flow structures were simulated by an in-house immersed-boundary-method based computational fluid dynamic solver. A parametric study on the Cauchy number was performed with a Reynolds number of 300 at a mass ratio of 1.0, which covers a wide range of species of insect wings. According to the analysis of the aerodynamic performance, we found that the optimal lift can be achieved at a Cauchy number around 0.16, while the optimal efficiency in terms of lift-to-power ratio was reached at a Cauchy number around 0.3. All the corresponding wing pitching kinematics had a pitching magnitude around 60 degrees with slightly advanced rotation. In addition, 3D wake structures generated by the passive flapping wings were analyzed in detail. The findings of this work could provide important implications for designing more efficient flapping-wing micro air vehicles.
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Aguilera, Jesse, Constantine Tarawneh, Harry Siegel, Robert Jones, and Santana Gutierrez. "Conductive Polymer Pad for Use in Freight Railcar Bearing Adapters." In 2022 Joint Rail Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/jrc2022-78217.

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Abstract Many freight railcars rest on polymer adapter pads made of injection-molded Thermoplastic Polyurethane (TPU) polymers which feature two copper studs to provide electrical conductivity through the pad. This design feature allows signal transmission from the track to the onboard systems, including cargo gates and pneumatic actuators. While in service, the polymer pads experience impact and cyclic loading that produce shear, resulting in the abrasive wear and plastic compression of the copper studs which leads to signal interruptions and loss of function requiring the periodic replacement of these polymer pads. This causes increased downtime due to maintenance and reduced reliability in the automated systems since pad failure is unpredictable. This limitation in current designs is the driving concern behind the effort to create an electrically conductive polymer adapter pad that would provide a durable conductive path between the rail and freight car side-frame. To that end, the University Transportation Center for Railway Safety (UTCRS) has been working on developing a conductive composite blend of TPU and Carbon Nano Fibers (CNF) to create injection-molded polymer composite inserts that can provide the necessary conductivity without the need for the copper studs that are susceptible to wear. Previous work done on this project was successful in creating a TPU-CNF composite insert that provided the required electrical conductivity at full railcar loads but was inconsistent at empty railcar loads. Thus, current work presented here focused on studying the fiber orientation that would produce consistent conductivity at all railcar loads. Based on these findings, a new mold was fabricated to create injection-molded polymer composite inserts with the effective fiber orientation. Laboratory test results show that the newly created composite inserts provide approximately double the needed conductivity required for a 24-Volt railcar valve to actuate when tested under the minimum load conditions an adapter would experience in field service. This paper summarizes the work done on fiber alignment and the results of the testing performed on the UTCRS dynamic bearing test rigs.
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Jacobsen, Karina, and Michael Carolan. "Results of a Diesel Multiple Unit Fuel Tank Blunt Impact Test." In 2017 Joint Rail Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/jrc2017-2248.

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The Federal Railroad Administration’s Office of Research and Development is conducting research into passenger locomotive fuel tank crashworthiness. A series of impact tests is being conducted to measure fuel tank deformation under two types of dynamic loading conditions — blunt and raking impacts. The results of this research program assist in development of appropriate standards for puncture resistance requirements to be applied to alternatively-designed fuel tanks, such as on diesel multiple unit (DMU) passenger rail equipment. This paper describes the results of the first blunt impact test performed on a DMU fuel tank. On June 28, 2016, FRA performed a dynamic impact test of a fuel tank from a DMU rail vehicle. The test was performed at the Transportation Technology Center (TTC) in Pueblo, Colorado. An impact vehicle weighing approximately 14,000 pounds and equipped with a 12-inch by 12-inch impactor head struck the bottom surface of a DMU fuel tank mounted vertically on an impact wall. The impact occurred on the bottom of the fuel tank at a location centered on two baffles within the fuel tank. The target impact speed was 11.5 mph, and the measured impact speed 11.1 mph. The test resulted in a maximum indentation of approximately 8 inches, the bottom of the tank bending away from the wall, and buckling of several internal baffles. Following the test, the tank was cut open to inspect the damage to the internal structure. This revealed that the buckling behavior of the baffles was isolated to the baffles immediately adjacent the impact location, each one buckling as the tank deformed inward. Prior to the test, finite element analysis (FEA) was used to predict the behavior of the tank during the test. The FE model of the tank required material properties to be defined in order to capture plastic deformation. The combination of metal plasticity, ductile failure, and element removal would permit the model to simulate puncture for this tank at sufficiently-high impact speeds. The pre-test FE model results compared very favorably with the test measurements, and both the pre-test model and the test resulted in similar modes of deformation to the DMU fuel tank. Following the test, material coupons were cut from undamaged areas of the fuel tank and subjected to tensile testing. The post-test FE model was updated with the material behaviors from the post-test material testing. This test is part of a research program investigating puncture resistance of passenger locomotive fuel tanks. The objective of this research program is to establish the baseline puncture resistance of current locomotive fuel tanks under dynamic impact conditions and to develop performance requirements for an appropriate level of puncture resistance in alternative fuel tank designs, such as DMU fuel tanks. Future tests are planned within this research program. The lessons learned during the series of tests support finite element (FE) modeling of impact conditions beyond what was tested. Additional tests investigating the puncture resistance of fuel tanks during sideswipe or raking collisions are also planned.
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Lin, Yuan, and Nicole Abaid. "Bats Versus Bugs: Collective Behavior of Prey Decreases Predation in a Biologically-Inspired Multi-Agent System." In ASME 2013 Dynamic Systems and Control Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/dscc2013-3816.

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In this paper, we establish an agent-based model to study the impact of collective behavior of a prey species on the hunting success of predators inspired by insectivorous bats and swarming insects, called “bugs”. In the model, we consider bats preying on bugs in a three-dimensional space with periodic boundaries. The bugs follow one of the two regimes: either they swarm randomly without interacting with peers, or they seek to align their velocity directions, which results in collective behavior. Simultaneously, the bats sense their environment with a sensing space inspired by big brown bats (Eptesicus fuscus) and independently prey on bugs. We define order parameters to measure the alignment and cohesion of the bugs and relate these quantities to the cohesion and the hunting success of the bats. Comparing the results when the bugs swarm randomly or collectively, we find that collectively behaving bugs tend to align, which results in relatively more cohesive groups. In addition, cohesion among bats is induced since bats may be attracted to the same localized bug group. Due to the fact that bats need to hunt more widely for groups of bugs, collectively behaving bugs suffer less predation compared to their randomly swarming counterparts. These findings are supported by the biological literature which cites protection from predation as a primary motivator for social behavior.
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Reports on the topic "Insect impact dynamics"

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McManus, M. L., and A. M. ,. eds Liebhold. Proceedings: population dynamics, impacts, and integrated management of forest defoliating insects. Radnor, PA: U.S. Department of Agriculture, Forest Service, Northeastern Research Station, 1998. http://dx.doi.org/10.2737/ne-gtr-247.

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McManus, M. L., and A. M. ,. eds Liebhold. Proceedings: population dynamics, impacts, and integrated management of forest defoliating insects. Radnor, PA: U.S. Department of Agriculture, Forest Service, Northeastern Research Station, 1998. http://dx.doi.org/10.2737/ne-gtr-247.

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Asenath-Smith, Emily, Emily Jeng, Emma Ambrogi, Garrett Hoch, and Jason Olivier. Investigations into the ice crystallization and freezing properties of the antifreeze protein ApAFP752. Engineer Research and Development Center (U.S.), September 2022. http://dx.doi.org/10.21079/11681/45620.

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Antifreeze proteins (AFPs) allow biological organisms, including insects, fish, and plants, to survive in freezing temperatures. While in solution, AFPs impart cryoprotection by creating a thermal hysteresis (TH), imparting ice recrystallization inhibition (IRI), and providing dynamic ice shaping (DIS). To leverage these ice-modulating effects of AFPs in other scenarios, a range of icing assays were performed with AFPs to investigate how AFPs interact with ice formation when tethered to a surface. In this work, we studied ApAFP752, an AFP from the beetle Anatolica polita, and first investigated whether removing the fusion protein attached during protein expression would result in a difference in freezing behavior. We performed optical microscopy to examine ice-crystal shape, micro-structure, and the recrystallization behavior of frozen droplets of AFP solutions. We developed a surface chemistry approach to tether these proteins to glass surfaces and conducted droplet-freezing experiments to probe the interactions of these proteins with ice formed on those surfaces. In solution, ApAFP752 did not show any DIS or TH, but it did show IRI capabilities. In surface studies, the freezing of AFP droplets on clean glass surfaces showed no dependence on concentration, and the results from freezing water droplets on AFP-decorated surfaces were inconclusive.
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Barg, Rivka, Kendal D. Hirschi, Avner Silber, Gozal Ben-Hayyim, Yechiam Salts, and Marla Binzel. Combining Elevated Levels of Membrane Fatty Acid Desaturation and Vacuolar H+ -pyrophosphatase Activity for Improved Drought Tolerance. United States Department of Agriculture, December 2012. http://dx.doi.org/10.32747/2012.7613877.bard.

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Background to the topic: In previous works we have shown that Arabidopsis and tomato over-expressing H+-pyrophosphatase show increased tolerance to drought imposed by withholding irrigation of young plants in pots (Park et al. 2005). In addition, young tobacco plants over-expressing fatty acid desaturase 3 (OEX-FAD3) also showed increasing tolerance to drought stress (Zhang et al 2005), and similarly OEX-FAD3 young tomato plants (unpublished data from ARO), hence raising the possibility that pyramiding the two could further improve drought tolerance in tomato. Based on these findings the specific objects originally set were: 1. To analyze the impact of pyramiding transgenes for enhanced fatty acid desaturation and for elevated H+-PPase activity on tomato yielding under water deficit stress conditions. 2. To elucidate the biochemical relationship between elevated desaturation of the membrane lipids and the activities of selected vacuolar transporters in the context of drought responses. 3. To explore the S. pennellii introgression lines as alternative genetic sources for drought tolerance related to enhanced fatty acid desaturation and/or H+-PPase activity. 4. Since OEX-FAD3 increases the levels of linolenic acid which is the precursor of various oxylipins including the stress hormone Jasmonate. (JA), study of the effect of this transgene on tolerance to herbivore pests was added as additional goal. The Major conclusions, solutions, and achievements are: (1) The facts that ectopic over-expression of vacuolarH+-PPases (in line OEX-AVP1) does not change the fatty acid profile compared to the parental MoneyMaker (MM) line and that elevated level of FA desaturation (by OEX-FAD3) does not change the activity of either H+-PPase, H+-ATPaseor Ca2+ /H+ antiport, indicate that the observed increased drought tolerance reported before for increase FA desaturation in tobacco plants and increased H+PPase in tomato plants involves different mechanisms. (2) After generating hybrid lines bringing to a common genetic background (i.e. F1 hybrids between line MP-1 and MM) each of the two transgenes separately and the two transgenes together the effect of various drought stress regimes including recovery from a short and longer duration of complete water withhold as well as performance under chronic stresses imposed by reducing water supply to 75-25% of the control irrigation regime could be studied. Under all the tested conditions in Israel, for well established plants grown in 3L pots or larger, none of the transgenic lines exhibited a reproducible significantly better drought tolerance compare to the parental lines. Still, examining the performance of these hybrids under the growth practices followed in the USA is called for. (3) Young seedlings of none of the identified introgression lines including the S. pennellii homologs of two of the H+-PPase genes and one of the FAD7 genes performed better than line M82 upon irrigation withhold. However, differences in the general canopy structures between the IL lines and M82 might mask such differences if existing. (4). Over-expression of FAD3 in the background of line MP-1 was found to confer significant tolerance to three important pest insects in tomato: Bordered Straw (Heliothis peltigera), Egyptian cotton leafworm (Spodoptera littoralis) and Western Flower Thrips (Frankliniella occidentalis). Implications: Although the original hypothesis that pyramiding these two trasgenes could improve drought tolerance was not supported, the unexpected positive impact on herbivore deterring, as well as the changes in dynamics of JA biosynthesis in response to wounding and the profound changes in expression of wound response genes calls for deciphering the exact linolenic acid derived signaling molecule mediating this response. This will further facilitate breeding for herbivore pest and mechanical stress tolerance based on this pathway.
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