Relevant bibliographies by topics / Chemical defence

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  2. Dissertations / Theses
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  4. Book chapters
  5. Conference papers
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Academic literature on the topic 'Chemical defence'

Author: Grafiati
Published: 28 June 2021
Last updated: 20 February 2023

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Journal articles on the topic "Chemical defence"

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Skelhorn, John, and Candy Rowe. "Frequency-dependent taste-rejection by avian predation may select for defence chemical polymorphisms in aposematic prey." Biology Letters 1, no. 4 (August 31, 2005): 500–503. http://dx.doi.org/10.1098/rsbl.2005.0359.

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Chemically defended insects advertise their unpalatability to avian predators using conspicuous aposematic coloration that predators learn to avoid. Insects utilize a wide variety of different compounds in their defences, and intraspecific variation in defence chemistry is common. We propose that polymorphisms in insect defence chemicals may be beneficial to insects by increasing survival from avian predators. Birds learn to avoid a colour signal faster when individual prey possesses one of two unpalatable chemicals rather than all prey having the same defence chemical. However, for chemical polymorphisms to evolve within a species, there must be benefits that allow rare chemical morphs to increase in frequency. Using domestic chicks as predators and coloured crumbs for prey, we provide evidence that birds taste and reject proportionally more of the individuals with rare defence chemicals than those with common defence chemicals. This indicates that the way in which birds attack and reject prey could enhance the survival of rare chemical morphs and select for chemical polymorphism in aposematic species. This is the first experiment to demonstrate that predators can directly influence the form taken by prey's chemical defences.
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Hantak, Maggie M., Daniel J. Paluh, and Ralph A. Saporito. "Bufadienolide and alkaloid-based chemical defences in two different species of neotropical anurans are equally effective against the same arthropod predators." Journal of Tropical Ecology 32, no. 2 (March 2016): 165–69. http://dx.doi.org/10.1017/s0266467416000055.

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Abstract:Defensive chemicals in anuran skin secretions function in protection against potential predators. Although studies have demonstrated that particular chemicals are effective against certain predators, very little is known about how different chemicals from different species function against the same predators. Understanding how different chemicals function as a defence against similar predators is fundamental to the ecology and evolution of chemical defences in frogs. In the present study, the defensive function of bufadienolide-based defences in adult Rhaebo haematiticus (Bufonidae) were compared with alkaloid-based defences in adult and juvenile Dendrobates auratus (Dendrobatidae) against the same predators. Most bufonids contain synthesized bufadienolides, whereas dendrobatids contain dietary-derived alkaloids. Predation trials were performed with two potential invertebrate predators, Paraponera clavata (bullet ant) and Cupiennius coccineus (ctenid spider), to determine how these predators respond to two different types of frog chemical defence. The non-chemically defended frog Craugastor fitzingeri served as a control in all predation trials. Our results suggest that bufadienolide defences of R. haematiticus and alkaloid defences of D. auratus are equally effective towards bullet ant and ctenid spider predators. The similar avoidance and cleaning behaviours exhibited by these ants and spiders after contact with bufadienolides and alkaloids suggest that both types of defence are unpalatable to these arthropod predators.
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Arbuckle, Kevin. "Chemical antipredator defence is linked to higher extinction risk." Royal Society Open Science 3, no. 11 (November 2016): 160681. http://dx.doi.org/10.1098/rsos.160681.

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Many attributes of species may be linked to contemporary extinction risk, though some such traits remain untested despite suggestions that they may be important. Here, I test whether a trait associated with higher background extinction rates, chemical antipredator defence, is also associated with current extinction risk, using amphibians as a model system—a group facing global population declines. I find that chemically defended species are approximately 60% more likely to be threatened than species without chemical defence, although the severity of the contemporary extinction risk may not relate to chemical defence. The results confirm that background and contemporary extinction rates can be predicted from the same traits, at least in certain cases. This suggests that associations between extinction risk and phenotypic traits can be temporally stable over long periods. The results also provide novel insights into the relevance of antipredator defences for species subject to conservation concerns.
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Skelhorn, John, and Candy Rowe. "Avian predators taste–reject aposematic prey on the basis of their chemical defence." Biology Letters 2, no. 3 (April 25, 2006): 348–50. http://dx.doi.org/10.1098/rsbl.2006.0483.

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Avian predators learn to avoid defended insects on the basis of their conspicuous warning coloration. In many aposematic species, the level of chemical defence varies, with some individuals being more defended than others. Sequestration and production of defence chemicals is often costly and therefore less defended individuals enjoy the benefits of the warning signal without paying the full costs of chemical production. This is a fundamental theoretical problem for the evolutionary stability of aposematism, since less defended individuals appear to be at a selective advantage. However, if predators sample aposematic prey and selectively reject individuals on the basis of their chemical investment, aposematism could become evolutionarily stable. Previous research aimed at testing whether birds can use taste to discriminate between palatable and unpalatable prey has been confounded by other experimental factors. Here, we show that birds can taste and reject prey entirely on the basis of an individual's level of chemical defence and more importantly, they can make decisions on whether or not to consume a defended individual based upon their level of chemical investment. We discuss these results in relation to the evolution of aposematism, mimicry and defence chemistry.
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Guan, Chi, Mahasweta Saha, and Florian Weinberger. "Chemical Defence of a Seagrass against Microfoulers and Its Seasonal Dynamics." Applied Sciences 9, no. 6 (March 26, 2019): 1258. http://dx.doi.org/10.3390/app9061258.

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In marine environments bacterial microfoulers are an important determinant for the settlement of algal and animal macrofoulers. At the same time fouling is usually subject to seasonal fluctuation. Additionally, the seagrass Zostera marina is prone to microfouling, although this marine spermatophyte is known to be chemically defended against bacterial settlers. Spermatophytes are often capable of induced or activated defences against biological enemies such as pathogens or herbivores, but it is still unknown whether they can fine-tune their antifouling-defence according to settlement pressure. We therefore assessed the seasonality of bacterial settlement pressure, defence against microsettlers and concentrations of a previously identified defence compound, rosmarinic acid, on surfaces of Z. marina. All examined variables peaked in summer, while they tended to be lower in spring and autumn. The seasonality of defence activity and rosmarinic acid surface concentration was positively correlated with the seasonal fluctuation of fouling pressure, which suggests that Z. marina can adjust its defence level to the relatively high bacterial fouling pressure in summer. Besides of biotic factors the seasonal change of environmental factors, such as nitrogen supply, and in particular temperature, also affected the defence level, either directly or through indirect effects on the microbial settlers.
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Rasher, Douglas B., and Mark E. Hay. "Competition induces allelopathy but suppresses growth and anti-herbivore defence in a chemically rich seaweed." Proceedings of the Royal Society B: Biological Sciences 281, no. 1777 (February 22, 2014): 20132615. http://dx.doi.org/10.1098/rspb.2013.2615.

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Many seaweeds and terrestrial plants induce chemical defences in response to herbivory, but whether they induce chemical defences against competitors (allelopathy) remains poorly understood. We evaluated whether two tropical seaweeds induce allelopathy in response to competition with a reef-building coral. We also assessed the effects of competition on seaweed growth and seaweed chemical defence against herbivores. Following 8 days of competition with the coral Porites cylindrica , the chemically rich seaweed Galaxaura filamentosa induced increased allelochemicals and became nearly twice as damaging to the coral. However, it also experienced significantly reduced growth and increased palatability to herbivores (because of reduced chemical defences). Under the same conditions, the seaweed Sargassum polycystum did not induce allelopathy and did not experience a change in growth or palatability. This is the first demonstration of induced allelopathy in a seaweed, or of competitors reducing seaweed chemical defences against herbivores. Our results suggest that the chemical ecology of coral–seaweed–herbivore interactions can be complex and nuanced, highlighting the need to incorporate greater ecological complexity into the study of chemical defence.
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Curley, Edward A. M., Hannah E. Rowley, and Michael P. Speed. "A field demonstration of the costs and benefits of group living to edible and defended prey." Biology Letters 11, no. 6 (June 2015): 20150152. http://dx.doi.org/10.1098/rsbl.2015.0152.

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Both theoretical and laboratory research suggests that many prey animals should live in a solitary, dispersed distribution unless they lack repellent defences such as toxins, venoms and stings. Chemically defended prey may, by contrast, benefit substantially from aggregation because spatial localization may cause rapid predator satiation on prey toxins, protecting many individuals from attack. If repellent defences promote aggregation of prey, they also provide opportunities for new social interactions; hence the consequences of defence may be far reaching for the behavioural biology of the animal species. There is an absence of field data to support predictions about the relative costs and benefits of aggregation. We show here for the first time using wild predators that edible, undefended artificial prey do indeed suffer heightened death rates if they are aggregated; whereas chemically defended prey may benefit substantially by grouping. We argue that since many chemical defences are costly to prey, aggregation may be favoured because it makes expensive defences much more effective, and perhaps allows grouped individuals to invest less in chemical defences.
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Braekman, J. C., and D. Daloze. "Chemical defence in sponges." Pure and Applied Chemistry 58, no. 3 (January 1, 1986): 357–64. http://dx.doi.org/10.1351/pac198658030357.

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Read, Jennifer, Emma Gras, Gordon D. Sanson, Fiona Clissold, and Charlotte Brunt. "Does chemical defence decline more in developing leaves that become strong and tough at maturity?" Australian Journal of Botany 51, no. 5 (2003): 489. http://dx.doi.org/10.1071/bt03044.

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Leaves that are expanding cannot be very tough or strong because of the constraints of cell expansion, and therefore are particularly vulnerable to being eaten. We predicted that expanding leaves would be better defended chemically than mature leaves, and that this difference would be most pronounced in species whose leaves are tougher and stronger at maturity, i.e. that chemical defence declines as the leaf increases its mechanical defences. We tested this hypothesis by comparing leaf mechanical properties and total phenolics in three species with relatively tough and strong mature leaves (Doryphora sassafras Endl., Acmena smithii (Poir.) Merr. & Perry and Nothofagus moorei (F.Muell.) Krasser) and two species with soft mature leaves (Eucryphia moorei F.Muell. and Toona ciliata M.Roem.).A significantly higher concentration of total phenolics per leaf dry weight was recorded in expanding leaves than in mature leaves in D. sassafras, N. moorei and A. smithii, but not in the two soft-leaved species. However, the decline in total phenolics in mature leaves of D. sassafras, N. moorei and A. smithii was entirely explained by dilution caused by increased concentration of cell wall. The absence of any difference in 'protoplasmic' concentrations of phenolics is consistent with the view of polyphenols as 'immobile' defences. High protoplasmic concentrations of polyphenols in expanding leaves may be less likely in species whose leaves become toughened and strengthened at maturity if they cannot quickly reclaim the chemical defence as its defence value declines. Instead, these species may be predicted to exhibit higher levels of mobile defences in expanding leaves. Despite the higher concentrations of phenolics in expanding leaves of D. sassafras and N. moorei they were eaten more by a generalist herbivore, Epiphyas postvittana, than were mature leaves, consistent with the higher nitrogen concentration in leaves that required less force and energy to chew.
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Nakano, Saya, Michio Oguro, Tomoyuki Itagaki, and Satoki Sakai. "Florivory defence: are phenolic compounds distributed non-randomly within perianths?" Biological Journal of the Linnean Society 131, no. 1 (July 29, 2020): 12–25. http://dx.doi.org/10.1093/biolinnean/blaa099.

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Abstract Plants might allocate chemical defences unequally within attractive units of flowers including petals, sepals, and bracts because of variations in the probability of florivory. Based on optimal defence theory, which predicts that plants allocate higher chemical defences to tissues with higher probabilities of herbivore attack, we predicted that distal parts and sepals would have higher chemical defence allocations than proximal parts and petals. To test this prediction, we compared total phenolics and condensed tannins concentrations as well as presence of florivory within attractive units of ten angiosperm species. In agreement with the prediction, the overall results showed that the distal parts had higher total phenolics and condensed tannins than the proximal parts. On the other hand, contrary to the prediction, petals and sepals showed no tissue-specific variations. Florivory was more severe on the distal parts than the proximal parts, although statistical support for the variation was slightly weak, while the variations in presence of florivory between petals and sepals differed between the distal and proximal parts. These results may support the prediction of the optimal defence theory because distal parts of attractive units had higher presence of florivory and concentration of chemical defences.
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Dissertations / Theses on the topic "Chemical defence"

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Danielsson, Marie. "Chemical defence in Norway spruce." Doctoral thesis, KTH, Organisk kemi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-31133.

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Norway spruce (Picea abies) responds to stress by biosynthesis of chemical substances, which can deter invading insects or pathogens. Some of these substances are volatile and can be emitted to the surroundings while others are accumulated within the tree. Information about the susceptibility of individual plants to infestation, their volatile emissions and chemical defence is of interest, for example, in selecting plants for tree breeding programs. The first part of this research focused on volatiles emitted by Norway spruce plants. Collection of headspace volatiles by SPME and subsequent separation and identification with GC-MS was used to investigate Norway spruce plants of different ages and stress conditions as well as trapping semiochemicals like nepetalactone emitted by the spruce shoot aphids. It was even possible to analyse the emission of single needles in vivo and obtain spatial localisation of the stress reaction to methyl jasmonate or spruce spinning mites. Seedlings of different ages showed differences in chemical composition of emitted volatiles, with the pine weevil repellent, (4S)-(-)-limonene, one of the main compounds. Wounded phloem of conventional plants emitted high amounts of monoterpenes while the phloem of mini plants emitted (3Z)-hexenal and (3Z)-hexen-1-ol. In addition, a method to separate and identify the four diastereomers of nepetalactone by GC-MS and characteristic m/z-fragments was accomplished. The second part of the research deals with the chemical response of Norway spruce roots to inoculation with Heterobasidion annosum. Terpene concentrations increased after inoculation or wounding but the composition was mainly associated with clone identity and not to susceptibility or treatment. In contrast, inoculation with H. annosum induced a treatment-specific alteration of phenol composition. The constitutive phenol composition differed between more and less susceptible clones. The phenols astringin and astringin dimers (piceasides) as well as the terpene α-longipinene may be suitable markers of low susceptibility for P. abies to Heterobasidion.
QC 20110314
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Hsieh, Ji-Fan (Sarah). "Molecular and Chemical Mechanisms of Defence against Myrtle Rust in Australian Myrtaceae." Phd thesis, Canberra, ACT : The Australian National University, 2018. http://hdl.handle.net/1885/143530.

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Increased human disturbance to forest ecosystems has exacerbated the spread of fungal pathogens to non-native environments. Rust pathogens (Pucciniales) can spread long distances by human activity and wind dispersal, and can cause severe disease outbreaks in cereal crops and in forest trees. The exotic fungus Austropuccinia psidii (myrtle rust) arrived in Australia in 2010 and most species of native Myrtaceae including Eucalyptus and Melaleuca are susceptible to infection to various degrees. Plants infected by A. psidii can suffer from crown loss and eventual mortality, which can be detrimental to ecosystems as well as to many rural industries that produce essential oils and flavourings from species of Myrtaceae. Within-species variation in resistance to A. psidii has been discovered in many native species. However, the molecular and chemical mechanisms of resistance to A. psidii infection in these species are largely unknown. Finding the molecular and chemical basis of resistance against A. psidii is therefore an essential part of ensuring that future plantations and re-afforestation programs are resistant to this pathogen. This thesis therefore aims to elucidate the molecular and chemical mechanisms of resistance to A. psidii in Myrtaceae in Australia, with the goal of obtaining a comprehensive view of potential mechanisms involved in defence to identify candidate genes that may be implemented into resistance breeding. After first screening multiple species of Myrtaceae, I selected Melaleuca alternifolia (tea tree) and M. quinquenervia (broadleaf paperbark) for detailed molecular study because they showed varying disease symptoms from resistance to susceptibility among individuals, and were economically and ecologically important and amenable to molecular studies. I used a variety of experimental approaches, including RNA-Seq, qRT-PCR, GC-MS, and functional characterisation through heterologous gene expression in E. coli to apply an integrated analysis that examined both molecular and chemical aspects of plant defence. I constructed the transcriptomes of M. alternifolia and M. quinquenervia de novo and investigated differential gene expressions between resistant and susceptible plants. I showed that resistant M. alternifolia and M. quinquenervia over-express genes which may be contribute to defence against to A. psidii infection, and have found and functionally characterised new terpene synthase genes that showed induction in response to infection by A. psidii in M. quinquenervia.
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Knapp, Jennifer J. "Chemical aspects of communication and defence in leaf-cutting ants." Thesis, University of Southampton, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295675.

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Law-Brown, Janette. "Chemical defence in the red-billed wood hoopoe : phoeniculus purpureus." Master's thesis, University of Cape Town, 2001. http://hdl.handle.net/11427/6119.

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Red-billed Woodhoopoes, Phoeniculus purpureus, produce a pungent smelling secretion from their uropygial gland. Previous researchers have noted this odour and there has been much speculation on its function. This encouraged me to undertake this study to determine the origin of the odour and the role that the secretion plays. The chemical analysis of this secretion shows that it consists of 17 compounds including acids, aldehydes, lactones and other miscellaneous compounds. Cultures of the secretion showed the presence of a symbiotic bacterium resident within the gland. Antibiotic treatment of the gland suggested that this bacterium was instrumental in the synthesis of the secretion of P. purpureus. This bacterium has not previously been identified and has been proposed as 'Enterococcus phoeniculicola' (GenBank accession number: AYO28437). The secretion was synthesized and the responses of a range of 13 pathogenic and one parasitic bacteria were tested against it and its individual constituent compounds. The synthetic secretion and seven of its constituent compounds inhibited the growth of these bacteria. However, exposing feather mites resident upon the birds to the synthetic secretion did not illicit any significant response from these mites. Wanless (1998) showed that the synthetic secretion causes an averse reaction in cats. In this study I was able to identify indole, phenol and propionaldehyde as being responsible for eliciting this reaction in cats. A similar averse reaction is shown by Rock Monitor Lizards, Varanus albigularis, upon encountering mice tainted with the synthetic secretion. This is the first demonstration of a symbiotic relationship between birds and bacteria in which the modification of the birds' uropygial oils affords the birds some protection against pathogens and preators.
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Thornton, Robert. "The effect of the aircrew chemical defence assembly on thermal strain." Thesis, University of Edinburgh, 1988. http://hdl.handle.net/1842/27005.

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Paul, Nicholas Andrew School of Biological Earth &amp Environmental Sciences UNSW. "The ecology of chemical defence in a filamentous marine red alga." Awarded by:University of New South Wales. School of Biological, Earth and Environmental Sciences, 2006. http://handle.unsw.edu.au/1959.4/24304.

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I investigated the ecological functions of halogenated secondary metabolites from the red alga Asparagopsis armata, their localisation in specialised cells and also their cost of production. A. armata produces large amounts of halogenated metabolites ( < 20 ??g / mg dry weight) that are sequestered in gland cells, as was demonstrated with light, epifluorescence and transmission electron microscopy. Cellular structures were identified that likely assist the release of metabolites from the gland cells to the algal surface. The halogenated metabolites of A. armata have multiple ecological roles, functioning as both inhibitors of bacterial fouling and as herbivore deterrents. Their activity against bacteria and herbivores was measured by a novel test in which the metabolites were manipulated in A. armata by omitting bromide ions from the culture media. This technique prevented the production of halogenated metabolites, but did not impact on other aspects of algal biology. Algae lacking halogenated metabolites (bromide [-] algae) had higher densities of epiphytic bacteria than those that continued to produce metabolites (bromide [+] algae). Bioassays with pure compounds against individual bacterial isolates further supported an inhibitory role for the halogenated metabolites against epiphytic bacteria, and also indicated an affect on bacterial community structure as well as abundance. Bromide (+) A. armata produced halogenated metabolites that also deterred feeding by two herbivores (an amphipod and an abalone), but not a third (an opisthobranch mollusc). A novel outcome from these feeding assays was the demonstration of a relationship between herbivore size and consumption of the chemically defended A. armata by the abalone Haliotis rubra. In addition to the fitness benefits gained from chemical defence, there were also costs for allocating resources to secondary metabolites. These costs were only detected under limiting light resources, consistent with predictions of the plant defence models. The integration of chemical analyses and cellular measures of chemical defence proved essential in elucidating resource allocation to chemical defence in the filamentous stage of A. armata. This thesis highlights that the simple relationships between growth and defence in filamentous algae can provide an excellent model for studies of the ecology and evolution of chemical defences in marine algae.
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Ohlsson, Åse. "Do plants change their defence strategy from a structural defence to a chemical one as a response to heavier herbivory?" Thesis, Södertörn University College, School of Life Sciences, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-310.

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To the main part, this paper is the result of a literature survey and to the minor part of a field survey. The study is found on the question of, if and why unpalatable plant species invade heavily grassed rangelands and if plants change their defence strategy from a mechanical defence to a chemical defence if the herbivory pressure increase. I conclude that defended plants do invade heavily grassed rangelands if the rangelands lose essential recourses (often nutrients) and/or the defended plants are strongly avoided by mammalian herbivores. I also conclude that plants do go from a mechanical defence strategy to a chemical strategy if their environment loses essential recourses under a threshold. This firstly depends on that mechanical defended plants can not develop a complete defence if they suffer from a shortage in the nutrient supply, and secondly of that plants in resources rich environments often have lager possibilities of responding to herbivory with regrowth. They do not therefore have to defend them self as hard as plants in environments with low supply of recourses.

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Foster, Rosie. "Plants signalling to herbivores : is there a link between chemical defence and visual cues?" Thesis, University of Sussex, 2013. http://sro.sussex.ac.uk/id/eprint/45168/.

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The use of visual cues by insect herbivores is likely to be an important component of plant-herbivore interactions in the wild, yet has until recently received little attention from researchers. In the last decade, however, interest in this topic has intensified following Hamilton & Brown's (2001) autumn colouration hypothesis, which proposes that the intensity of colouration of trees at autumn time is a signal of their defensive commitment to potential herbivores. This idea remains controversial and to date robust empirical data linking colouration with chemical defence and herbivory have been lacking. This thesis begins with a meta-analysis, in which I synthesize and analyse previously published data to determine the evidence for the use of host plant colouration by herbivores. I then move to explore the relationship between chemical defences and colouration in a classic plant-herbivore system: the wild cabbage (Brassica oleracea) and its herbivores the cabbage white butterfly (Pieris rapae) and the cabbage aphid (Brevicoryne brassicae). Both species have colour vision, and I use spectral sensitivity data to model the colour of the host ‘through the eyes' of the herbivores. First, I present data from a field study of wild cabbage populations showing significant relationships between herbivory, plant colouration and levels of glucosinolates defensive compounds. These results suggest that plant colouration could be used by herbivores to gain information about plant chemical defence. I then show colouration has a fixed genetic component in a common garden experiment; a necessary requirement for evolution of a colour signal. I explore the use of colouration in host choice by herbivores in more detail in a series of behavioural experiments. I show that cabbage aphids do not use leaf brightness as a cue when selecting among plants, but they do respond to different leaf colours. I also show that cabbage white butterflies do not choose hosts based on particular colour cues, even though this colouration potentially provides important information about host defence levels, which are shown to impact upon offspring fitness. Together, these results provide a clear demonstration of a link between plant chemistry and colouration in the wild cabbage system. However, the data presented in this thesis indicate that the use of colouration as a guide to host defence is limited, and I conclude by discussing possible reasons why this might be the case.
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Hedner, Erik. "Bioactive Compounds in the Chemical Defence of Marine Sponges : Structure-Activity Relationships and Pharmacological Targets." Doctoral thesis, Uppsala University, Division of Pharmacognosy, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8218.

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Marine invertebrates, in particular sponges, represent a source of a wide range of secondary metabolites, many of which have been attributed various defensive capabilities against environmental stress factors. In this thesis sponge-derived low-molecular peptide-like compounds and associated analogs are investigated for bioactivity and pharmacological targets.

The compound bromobenzisoxazolone barettin (cyclo[(6-bromo-8-(6-bromo-benzioxazol -3(1H)-one)-8-hydroxy)tryptophan)]arginine) was isolated from the sponge Geodia barretti and its ability to inhibit larval settlement of the barnacle Balanus improvisus was determined. With an EC50 value of 15 nM, this compound’s antifouling effect was higher than those of the previously reported brominated dipeptides from Geodia barretti, i.e., barettin and 8,9-dihydrobarettin; moreover, this antifouling effect was demonstrated to be reversible. However, the compound lacked affinity for 5-HT1-7 receptors, whereas barettin possessed specific affinity to 5-HT2A, 5-HT2C and 5-HT4, while 8,9-dihydrobarettin interacted with 5-HT4. In an attempt to evaluate structure-activity relationships synthesized analogs with barettin and dipodazine scaffolds were investigated for antifouling activity. The analog benso[g]dipodazine, with an EC50 value of 34 nM, displayed the highest settlement inhibition.

The studies of the structure-activity relationships of sponge-derived compounds were extended to cover analogs of agelasines and agelasimines originally isolated from sponges of the genus Agelas. Synthesized (+)-agelasine D and two structurally close analogs were investigated for cytotoxic and antibacterial activity. The profound cytotoxicity and broad spectrum antibacterial activity found prompted a further investigation of structure-activity relationships in 42 agelasine and agelasimine analogs and several characteristics that increased bioactivity were identified.

In conclusion this work has produced new results regarding the potent bioactivity of compounds derived from the sponges Geodia barretti and Agelas spp. and increased SAR knowledge of the fouling inhibition, cytotoxicity and antimicrobial activity of these compounds.

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Pöykkö, H. (Heikki). "Host range of lichenivorous moths with special reference to nutritional quality and chemical defence in lichens." Doctoral thesis, University of Oulu, 2005. http://urn.fi/urn:isbn:951427959X.

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Abstract Host use and range of herbivorous insects are determined by several factors, of which nutritional quality and secondary chemistry have been shown to play very important roles. For herbivores feeding on lichens these traits are assumed to be more critical than for species feeding on higher plants, since lichens are nutritionally poor and often contain high concentrations of secondary metabolites. I examined the role of lichens' nutritional quality and secondary chemicals on the performance of lichen-feeding Lepidopteran larvae. I also tested whether females of lichenivorous species preferably oviposit on host species of the highest nutritional quality for the growth of larvae. Larvae of Eilema depressum performed best on Melanelia exasperata, which is of the highest nutritional quality, as indicated by the high N concentration and the absence of lichen secondary metabolites compared to the other lichens studied. Host nutritional quality did not promote the production of an additional generation. Larvae of E. depressum needed fewer instars and grew bigger on a high-quality diet than larvae reared on a diet of poorer quality. However, the main factor contributing to the wide variation in the number of larval instars was the question of whether or not larvae overwintered. Growth of Cleorodes lichenaria at the beginning of the larval period matched equally the nutritional quality of the hosts. However, the final larval period was shortest on Ramalina species, which was preferred by both females ovipositing their eggs and larvae searching for a host. In the field, larvae were found almost exclusively on Ramalina species. Larvae of E. depressum were not able to survive on intact thalli of Vulpicida pinastri and Hypogymnia physodes, but after removal of lichen's secondary metabolites, larval survival remained equally high as on other lichens. Larvae also showed a clear preference towards thalli with lowered concentrations of secondary metabolites in Parmelia sulcata, V. pinastri and H. physodes. Parietin in Xanthoria parietina was the only secondary metabolite that had no impact on the survival or host selection of E. depressum larvae. The present results show that the nutritional quality and some lichen secondary chemicals are important factors for the growth, survival and host selection of lichen-feeding Lepidopteran larvae. The preference-performance hypothesis is at least partly able to explain the host range of C. lichenaria, although it seems that there are also other factors, such as larval dispersal and host selection or top-down forces, that might contribute to host range of lichenivorous Lepidopteran larvae. Moreover, lichenivorous larvae seem to be partly responsible for their own host selection.
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Books on the topic "Chemical defence"

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Sen, A. K. Defence against chemical and biological agents. New Delhi: Defence Research and Development Organisation, Ministry of Defence, 2009.

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K, Sen A. Defence against chemical and biological agents. New Delhi: Defence Research and Development Organisation, Ministry of Defence, 2009.

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Defence Research & Development Organisation (India), ed. Defence against chemical and biological agents. New Delhi: Defence Research and Development Organisation, Ministry of Defence, 2009.

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Great Britain. Ministry of Defence. Medical manual of defence against chemical agents: By command of the Defence Council. 6th ed. London: H.M.S.O., 1987.

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B, Carter G., ed. Chemical and biological defence at Porton Down, 1916-2000. London: H.M.S.O., 2000.

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Canada. Department of National Defence. Research, development and training in chemical and biological defence within the Department of National Defence and the Canadian Forces: A review. S.l: s.n, 1989.

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Collins, Charles J., and John C. Carrano. Optically based biological and chemical detection for defence V: 1 September 2009, Berlin, Germany. Bellingham, Wash: SPIE, 2009.

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The killing factory: The top secret world of germ and chemical warfare. London: Smith Gryphon, c1996., 1996.

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1955-, Grote James Gerard, Kajzar F, Lindgren Mikael, SPIE Europe, Defence IQ (Organization), and Society of Photo-optical Instrumentation Engineers., eds. Optical materials in defence systems technology III: 13-14 September 2006, Stockholm, Sweden. Bellingham, Wash: SPIE, 2006.

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Hol, Wilhelmina Hermina Geertruida. The role of pyrrolizidine alkaloids from Senecio jacobaea in the defence against fungi. [Leiden: Universiteit Leiden, 2003.

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Book chapters on the topic "Chemical defence"

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Putz, Annika, and Peter Proksch. "Chemical Defence in Marine Ecosystems." In Functions and Biotechnology of Plant Secondary Metabolites, 162–213. Oxford, UK: Wiley-Blackwell, 2010. http://dx.doi.org/10.1002/9781444318876.ch3.

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Lindsay, Christopher D., James R. Riches, Neil Roughley, and Christopher M. Timperley. "CHAPTER 8. Chemical Defence Against Fentanyls." In Chemical Warfare Toxicology, 259–313. Cambridge: Royal Society of Chemistry, 2016. http://dx.doi.org/10.1039/9781782628071-00259.

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van Dam, Nicole M., and Sheila K. Bhairo-Marhé. "Induced chemical defence in Cynoglossum officinale." In Proceedings of the 8th International Symposium on Insect-Plant Relationships, 79–82. Dordrecht: Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-1654-1_24.

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Kumar, Narendra, and Ambesh Dixit. "Nanotechnology-Enabled Management of Chemical, Biological, Radiological, and Nuclear Threats." In Nanotechnology for Defence Applications, 117–53. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-29880-7_4.

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Pasteels, Jacques M., Martine Rowell-Rahier, Jean-Claude Braekman, and Désiré Daloze. "Chemical defence of adult leaf beetles updated." In Novel aspects of the biology of Chrysomelidae, 289–301. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-011-1781-4_22.

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Moreira, Xoaquín, Rafael Zas, and Luis Sampedro. "Methyl Jasmonate as Chemical Elicitor of Induced Responses and Anti-Herbivory Resistance in Young Conifer Trees." In Plant Defence: Biological Control, 345–62. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-94-007-1933-0_15.

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Tiku, Anupama Razdan. "Direct and Indirect Defence Against Insects." In Plant-Pest Interactions: From Molecular Mechanisms to Chemical Ecology, 157–92. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-15-2467-7_8.

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Davis, Bradley S. "Transitional Perspectives on Conventional, Chemical and Biological Weapons Production." In United States Post-Cold War Defence Interests, 131–48. London: Palgrave Macmillan UK, 2004. http://dx.doi.org/10.1057/9780230000834_8.

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Bologna, Mauro. "Immunological Defence Mechanisms Against Biological Agents." In Detection of Chemical, Biological, Radiological and Nuclear Agents for the Prevention of Terrorism, 11–16. Dordrecht: Springer Netherlands, 2014. http://dx.doi.org/10.1007/978-94-017-9238-7_2.

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Harborne, J. B. "Role of Secondary Metabolites in Chemical Defence Mechanisms in Plants." In Ciba Foundation Symposium 154 - Bioactive Compounds from Plants, 126–39. Chichester, UK: John Wiley & Sons, Ltd., 2007. http://dx.doi.org/10.1002/9780470514009.ch10.

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Conference papers on the topic "Chemical defence"

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Sivalingam, Yuvaraj, Gabriele Magna, Roberto Paolesse, and Corrado di Natale. "Photo-assisted chemical sensors." In SPIE Security + Defence, edited by Douglas Burgess, Gari Owen, Harbinder Rana, Roberto Zamboni, François Kajzar, and Attila A. Szep. SPIE, 2014. http://dx.doi.org/10.1117/12.2071187.

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Ruxton, K., G. Robertson, W. Miller, G. P. A. Malcolm, G. T. Maker, and C. R. Howle. "Infrared hyperspectral imaging for chemical vapour detection." In SPIE Security + Defence, edited by Colin Lewis and Douglas Burgess. SPIE, 2012. http://dx.doi.org/10.1117/12.975057.

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Brett, Cory J. C., Robert S. DiPietro, Dimitris G. Manolakis, and Vinay K. Ingle. "Efficient implementations of hyperspectral chemical-detection algorithms." In SPIE Security + Defence, edited by Gary W. Kamerman, Ove K. Steinvall, Gary J. Bishop, and John D. Gonglewski. SPIE, 2013. http://dx.doi.org/10.1117/12.2028562.

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Takehisa, K. "New concepts of realizing a chemical oxygen laser." In SPIE Security + Defence, edited by David H. Titterton, Mark A. Richardson, Robert J. Grasso, Willy L. Bohn, and Harro Ackermann. SPIE, 2014. http://dx.doi.org/10.1117/12.2069708.

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Park, Yoon S., P. Pasupathy, and Dean P. Neikirk. "Resonant chemical surveillance tags." In Optics/Photonics in Security and Defence, edited by Gary W. Kamerman, Ove K. Steinvall, Keith L. Lewis, Keith A. Krapels, John C. Carrano, and Arturas Zukauskas. SPIE, 2007. http://dx.doi.org/10.1117/12.736975.

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Lavoie, Hugo, Jean-Marc Thériault, François Bouffard, Eldon Puckrin, and Denis Dubé. "LWIR hyperspectral imaging application and detection of chemical precursors." In SPIE Security + Defence, edited by Colin Lewis and Douglas Burgess. SPIE, 2012. http://dx.doi.org/10.1117/12.974605.

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Clewes, Rhea J., Chris R. Howle, David J. M. Stothard, Malcolm H. Dunn, Gordon Robertson, William Miller, Graeme Malcolm, et al. "Stand-off spectroscopy for the detection of chemical warfare agents." In SPIE Security + Defence, edited by Colin Lewis and Douglas Burgess. SPIE, 2012. http://dx.doi.org/10.1117/12.974574.

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Munk, Jens K., Ole T. Buus, Jan Larsen, Eleftheria Dossi, Sol Tatlow, Lina Lässig, Lars Sandström, and Mogens H. Jakobsen. "CRIM-TRACK: sensor system for detection of criminal chemical substances." In SPIE Security + Defence, edited by Douglas Burgess, Gari Owen, Harbinder Rana, Roberto Zamboni, François Kajzar, and Attila A. Szep. SPIE, 2015. http://dx.doi.org/10.1117/12.2194915.

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Webber, Michael E., Michael B. Pushkarsky, and C. Kumar N. Patel. "Optical detection of chemical warfare agents and toxic industrial chemicals." In European Symposium on Optics and Photonics for Defence and Security, edited by John C. Carrano and Arturas Zukauskas. SPIE, 2004. http://dx.doi.org/10.1117/12.579109.

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Bellecci, C., P. Gaudio, M. Gelfusa, S. Martellucci, M. Richetta, P. Ventura, A. Antonucci, F. Pasquino, V. Ricci, and A. Sassolini. "Database for chemical weapons detection: first results." In SPIE Europe Security and Defence, edited by John C. Carrano and Arturas Zukauskas. SPIE, 2008. http://dx.doi.org/10.1117/12.800193.

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Reports on the topic "Chemical defence"

1

Nayfack, Nicholas, and Robert W. MacDougall. Chemical Biological Defense (CBD) Simulations. Fort Belvoir, VA: Defense Technical Information Center, July 1996. http://dx.doi.org/10.21236/ada396828.

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Shuely, Wendel J. Chemical-Material Data Bases: Chemical Defense Material Data Base. Fort Belvoir, VA: Defense Technical Information Center, April 1997. http://dx.doi.org/10.21236/ada327593.

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Morris, Mariana. Low Level Chemical Toxicity: Relevance to Chemical Agent Defense. Fort Belvoir, VA: Defense Technical Information Center, July 2003. http://dx.doi.org/10.21236/ada422716.

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Larsen, James P. Chemical Warfare, Terrorism, and National Defense. Fort Belvoir, VA: Defense Technical Information Center, April 2001. http://dx.doi.org/10.21236/ada394318.

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Ross, Jo, and Cay Ervin. Chemical Defense Flight Glove Ensemble Evaluation. Fort Belvoir, VA: Defense Technical Information Center, June 1987. http://dx.doi.org/10.21236/ada188401.

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Johnson-Winegar, Anna. DoD Chemical/Biological Defense Program Overview. Fort Belvoir, VA: Defense Technical Information Center, April 2002. http://dx.doi.org/10.21236/ada422847.

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Thedford, Debra. Department of Defense Chemical, Biological, Radiological and Nuclear Defense Program Overview. Fort Belvoir, VA: Defense Technical Information Center, April 2004. http://dx.doi.org/10.21236/ada423645.

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Bonin, Benjamin J., Nataly Lyn Beck, Patricia Marie Hernandez, Trisha Hoette Miller, and Janson Wu. DHS Chemical and Biological Defense Architecture Development. Office of Scientific and Technical Information (OSTI), March 2019. http://dx.doi.org/10.2172/1592857.

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DEPARTMENT OF DEFENSE WASHINGTON DC. Department of Defense Nuclear/Biological/Chemical (NBC) Defense, Annual Report to Congress. Fort Belvoir, VA: Defense Technical Information Center, February 1998. http://dx.doi.org/10.21236/ada339415.

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Robinette, Kathleen M., and James F. Annis. A Nine-Size System for Chemical Defense Gloves. Fort Belvoir, VA: Defense Technical Information Center, July 1986. http://dx.doi.org/10.21236/ada173193.

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