Influence of Plant Induced Defenses on Cannibalistic Behavior of Spodoptera Frugiperda Caterpillars PDF Download
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Author: Rajeev Roy
Publisher:
ISBN:
Category :
Languages : en
Pages : 98
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Author: Rajeev Roy
Publisher:
ISBN:
Category :
Languages : en
Pages : 98
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Author: Flor Acevedo
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Feeding by insect herbivores induces defense responses in plants. Numerous studies have shown that plants recognize the mechanical damage as well as a variety of herbivore-derived cues present in insect oral secretions, saliva and frass to activate the production of specific defenses responses. Plant defenses negatively affect herbivore fitness; therefore to be able to feed on plants, insects need to develop specific adaptations to overcome defenses of their hosts. This can be challenging for herbivores that feed on a wide range of plants with diverse structural and biochemical defenses. In this dissertation, I studied defense responses induced by a polyphagous herbivore in some of its host plants as well as some of its adaptation mechanisms to counter the effect of these defenses. I used the lepidopteran fall armyworm (FAW) Spodoptera frugiperda, and its host plants maize, Bermuda grass, rice and tomato as a model system. The FAW comprises two host strains that are associated with different host plants in field conditions; the corn strain is mainly associated with maize, while the rice strain is mostly associated with forage grasses and rice. I specifically tested the presence of intraspecific differences in plant defense induction by the FAW strains and the composition of their caterpillar saliva. I also investigated the effect of caterpillar-associated gut bacteria on the modulation of defense responses in different hosts. In addition, I documented morphological and developmental adaptations of the FAW larvae to cope with their host structural defenses. The results of this study show that feeding by the FAW strains induced different defense responses in maize and Bermuda grass; this plant defense induction was associated with differences in the caterpillar saliva. The saliva of the FAW strains also has divergent protein profiles and differing expression of several salivary proteins. In addition, the saliva of the FAW contains non-protein compounds that actively regulate defenses in different hosts; these include several phytohormones and other presumptive small molecules. During feeding, the FAW larvae also secrete small amounts of regurgitant, I identified two bacteria isolates in the caterpillar oral secretions that modulated defense responses in tomato and maize plants. In addition, feeding by this insect induced the production of glandular trichomes in tomato and the deposition of silica in maize and rice plants. As adaptive strategies to feed on Bermuda grass and rice, the FAW larvae increased their head size to house larger mandibular muscles and potentially increase the biting force needed to feed on tough leaves. I conclude that FAW feeding modulates the induction of plant biochemical and physical defenses, which in turn induced plastic physiological and morphological changes in this insect species. The results of this dissertation highlight the importance of insect physiological and morphological plastic adaptations as means to feed on different host plants.
Author: Ching Wen Tan
Publisher:
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Category :
Languages : en
Pages :
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Almost all plant species are attacked by multiple herbivore species and have evolved various strategies to defend themselves. These plant defense strategies include inducible physical and chemical traits; for example, induced defensive proteins and secondary metabolites can impair herbivore growth and survival. These induced defenses rely on the recognition of herbivore presence. The oral secretions (regurgitant and saliva) of insect herbivores play a crucial role in providing cues that are recognized by plants, which then trigger plant defense responses. However, the interactions between plants and insects are considerably more complex in nature where other trophic levels are involved and can influence these interactions. Microorganisms are abundant in the environment and can impact interactions in many ways including altering the perception of herbivores by plants. Braconid parasitoids are small wasps which lay their eggs inside host caterpillars. These parasitoids possess obligate mutualistic viruses called polydnaviruses (PDVs). PDVs are injected by parasitoids with their eggs into host caterpillars. PDVs suppress caterpillar immune responses and metabolism, thus allowing parasitoid eggs to hatch and develop. In nature, 35-80% of caterpillars are parasitized, depending on locations and host plant species. However, it is not clear how parasitoid/PDVs influence plant and herbivore interactions. The main objective of this study were to: 1. Reveal the mechanism and impacts of the parasitoid and its PDV (Microplitis croceipes) on tomato plant defenses through its host caterpillar (Helicoverpa zea); 2. Evaluate the consequences of parasitoid suppression of induced plant defenses on plant fitness; and 3. Determine if the parasitoid effect on plant defenses are commonly present in other plant and insect systems. These objectives were approached by a series of biochemical, physiological and molecular experiments and results provide solid evidence to support the hypothesis that plants can distinguish between feeding by parasitized and non-parasitized caterpillars, thus altering their defense responses accordingly. Microplitis croceipes parasitized Helicoverpa zea larvae produced lower elicitor activity in their saliva (i.e., glucose oxidase) compared with non-parasitized caterpillars, and significantly downregulated tomato defense-related gene expression and defense protein activities during feeding. The ultimate cause of downregulation of plant defense responses was due to the obligate mutualist PDVs of the parasitoid. PDVs suppressed GOX gene expression and activity in parasitized caterpillar salivary glands thereby downregulating plant defense responses. The lower induced plant defenses benefit the parasitoid by promoting parasitized caterpillar growth performance, producing heavier cocoon mass and overall higher parasitoid survival rate. Besides, tomato plants treated by parasitized caterpillar saliva had significantly higher fitness (increased flower number and fruit weight) compared to those treated by non-parasitized caterpillars. These results support the hypothesis that plants benefit from parasitoids indirectly. This is a previously unidentified benefit of parasitoids on plant productivity/fitness. Two other plant and insect systems were also tested and confirmed that parasitoids can indirectly influence plants perception of insect herbivores. These findings have revealed a novel aspect of microbe-mediated interactions between plants and insects. The symbiotic PDV virus not only alters the phenotype of its primary host (i.e., parasitoid) and secondary host (i.e., caterpillar), but also the host plant of the caterpillar. This is the most extreme example of the extended phenotype known: a virus phenotype that extends across three trophic levels. This work has important implications for the evolutionary ecology of plant-herbivore-parasitoid interactions and points out a new perspective of mutualism between plants and parasitoids.
Author: Corné M. J. Pieterse
Publisher: Frontiers E-books
ISBN: 2889191907
Category :
Languages : en
Pages : 358
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Plants are members of complex communities and interact both with antagonists and beneficial organisms. An important question in plant defense-signaling research is how plants integrate signals induced by pathogens, insect herbivores and beneficial microbes into the most appropriate adaptive response. Molecular and genomic tools are now being used to uncover the complexity of the induced defense signaling networks that have evolved during the arms races between plants and the other organisms with which they intimately interact. To understand the functioning of the complex defense signaling network in nature, molecular biologists and ecologists have joined forces to place molecular mechanisms of induced plant defenses in an ecological perspective. In this Research Topic, we aim to provide an on-line, open-access snapshot of the current state of the art of the field of induced plant responses to microbes and insects, with a special focus on the translation of molecular mechanisms to ecology and vice versa.
Author: H. Martin Schaefer
Publisher: OUP Oxford
ISBN: 0191620971
Category : Science
Languages : en
Pages : 298
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Communication is an essential factor underpinning the interactions between species and the structure of their communities. Plant-animal interactions are particularly diverse due to the complex nature of their mutualistic and antagonistic relationships. However the evolution of communication and the underlying mechanisms responsible remain poorly understood. Plant-Animal Communication is a timely summary of the latest research and ideas on the ecological and evolutionary foundations of communication between plants and animals, including discussions of fundamental concepts such as deception, reliability, and camouflage. It introduces how the sensory world of animals shapes the various modes of communication employed, laying out the basics of vision, scent, acoustic, and gustatory communication. Subsequent chapters discuss how plants communicate in these sensory modes to attract animals to facilitate seed dispersal, pollination, and carnivory, and how they communicate to defend themselves against herbivores. Potential avenues for productive theoretical and empirical research are clearly identified, and suggestions for novel empirical approaches to the study of communication in general are outlined.
Author: Kenneth Wilson
Publisher: Cambridge University Press
ISBN: 1107136563
Category : Mathematics
Languages : en
Pages : 693
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Introduces readers to key case studies that illustrate how theory and data can be integrated to understand wildlife disease ecology.
Author:
Publisher:
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Category : Agriculture
Languages : en
Pages : 2568
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Author:
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ISBN:
Category : Agriculture
Languages : en
Pages : 1238
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Author: M. D. Pathak
Publisher: Int. Rice Res. Inst.
ISBN: 9712200280
Category : Technology & Engineering
Languages : en
Pages : 88
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Author: Omkar
Publisher: Springer Nature
ISBN: 9811580758
Category : Science
Languages : en
Pages : 539
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Book Description
Polyphagous pests are primarily agricultural pests that feed on economically important agricultural and horticultural crops of wide taxonomic diversity across the globe. They cause immense damage across different crop varieties owing to their generalist and voracious food habits. The advent of mono-crop culture in a huge area and the massive use of pesticides post green revolution have massively increased pest outbreaks all over the world. The Middle Eastern countries, African continent and even the Indian subcontinent is increasingly facing resurgences of polyphagus pests. This book compiles an inclusive account of polyphagous pests. It covers locusts, termites, aphids, whiteflies, mealybugs, scale insects, gram pod borer, fall armyworm, thrips, mites and rodents. The book discusses mode of spread, enormity of losses caused, mechanism of action, and also means to reduce the crop losses. It brings together a unique perspective for researchers to learn effective pest management practices across all crops. This book is a reference guide to researchers and also useful for academicians and students of entomology.
