Xem 1-20 trên 41 kết quả Insect species
  • This short book is about conserving insects, the most diverse and abundant animals that share our world. In particular, it is about the common focus of conserving individual species of insects. This so-called ‘fine filter’ (or ‘fine grain’) level of conservation parallels much conservation effort for better-understood groups of animals such as mammals and birds, for which species-focused conservation exercises are commonplace.

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  • Insect development is driven by the action of ecdysteroids on morphogenetic processes. The classic ecdysteroid receptor is a protein heterodimer com-posed of two nuclear receptors, the ecdysone receptor (EcR) and Ultraspira-cle (USP), the insect ortholog of retinoid X receptor. The functional properties of EcR and USP vary among insect species, and provide a basis for identifying novel and species-specific insecticidal candidates that disrupt this receptor’s normal activity.

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  • Chapter 15 MEDICAL AND VETERINARY ENTOMOLOGY Aside from their impact on agricultural and horticultural crops, insects impinge on us mainly through the diseases they can transmit to humans and our domestic animals. The number of insect species involved is not large, but those that transmit disease, cause wounds, inject venom.

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  • Some say that ‘the cockroach’ will be the last species on Earth to survive. Then it has been calculated that one gravid aphid, left to reproduce with zero mortality, will, after one year, cover the globe with an aphid layer over 140 km thick. Not forgetting too, that flies and fleas vector disease. So, why should we even consider conserving insects? Quite simply, without insects, the likelihood is that the world as we know it would be radically changed in a matter of days. Besides, it is only a tiny minority of insects that harm our lives.

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  • Despite occupying only three percent of the earth’s surface, the ASEAN region hosts 20 percent of all known species that live deep in the region’s mountains, jungles, rivers, lakes and seas. The region includes three mega-diverse states (Indonesia, Malaysia, and the Philippines); several bio-geographical units (e.g., Malesia, Wallacea, Sundaland, Indo-Burma and the Central Indo-Pacific); and numerous centers of concentration of restricted-range bird, plant and insect species.

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  • Olfaction is primarily mediated by the large family of olfactory receptors. Although all insect olfactory receptors share the same structure with seven transmembrane domains, they present poor sequence homologies within and between species. As the only exception, Drosophila melanogaster OR83b and its orthologues define a receptor subtype singularly conserved between insect species.

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  • This book is part of the Green Chemistry series published by the Royal Society of Chemistry, and is designed to provide a modern overview of the current status of insecticides. We present the current approaches for insect pest control as green alternatives to classical agrochemicals, which should be of interest to a vast group of researchers: agrochemists, biochemists, chemists, toxicologists, etc. Throughout the book, the different approaches to pest control which involve ‘‘greener chemicals’’ in particular are emphasized.

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  • SECTION II POPULATION ECOLOGY A POPULATION IS A GROUP OF INTERBREEDING MEMBERS of a species. A number of more or less discrete subpopulations may be distributed over the geographic range of a species population.

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  • 6 Population Dynamics POPULATIONS OF INSECTS CAN CHANGE DRAMATICALLY IN SIZE OVER relatively short periods of time as a result of changes in natality, mortality, immigration, and emigration. Under favorable environmental conditions, some species have the capacity to increase population size by orders of magnitude in a few years.

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  • 7 Biogeography GEOGRAPHIC RANGES OF SPECIES OCCURRENCE GENERALLY REFLECT THE tolerances of individual organisms to geographic gradients in physical conditions (see Chapter 2). However, most species do not occupy the entire area of potentially suitable environmental conditions.

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  • SECTION III COMMUNITY ECOLOGY SPECIES CO-OCCURRING AT A SITE INTERACT TO VARIOUS degrees, both directly and indirectly, in ways that have intrigued ecologists since earliest times. These interactions represent mechanisms that control population dynamics, hence community structure, and also control rates of energy and matter fluxes.

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  • 9 Community Structure A COMMUNITY IS COMPOSED OF ALL THE ORGANISMS OCCUPYING A SITE. The extent to which these organisms are co-evolved to form a consistent and recurring integrated community or represent ad hoc assemblages of loosely interacting species remains a topic of much discussion.

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  • 10 Community Dynamics COMMUNITY STRUCTURE CHANGES THROUGH TIME AS SPECIES abundances change, altering the network of interactions. Short-term (e.g., seasonal or annual) changes in community structure represent responses to environmental changes that favor some species or affect interaction strength.

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  • SECTION IV ECOSYSTEM LEVEL THE ECOSYSTEM LEVEL OF ORGANIZATION INTEGRATES species interactions and community structure with their responses to, and effects on, the abiotic environment. Interactions among organisms are the mechanisms governing energy and nutrient fluxes through ecosystems.

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  • The defensive function of the glucosinolate–myrosinase system in plants of the order Capparales results from the formation of isothiocyanates when glucosinolates are hydrolysed by myrosinases upon tissue damage. In some glucosinolate-containing plant species, as well as in the insect herbivore Pieris rapae, protein factors alter the outcome of myrosinase-catalysed glu-cosinolate hydrolysis, leading to the formation of products other than isothiocyanates.

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  • Several species of flies are found commonly in houses. Some of them so closely resemble the true house fly that it requires very careful observation to distinguish them from it. One of these is the biting stable fly[2] (fig. 1). It occurs frequently in houses and differs from the house fly in the important particular that its mouth parts are formed for piercing the skin. This fly is so often mistaken for the house fly that most people think that the house fly can bite.

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  • Over a million different kinds of insects have so far been described and named, and many more certainly remain t o be d i s c o v e r e d . T h i s i s more t h a n a l l t h e other known animal species put together. They occupy almost every known habitat outside the polar regions and the deep sea. They are represented by immense populations - perhaps 10 m i l l i o n i n d i v i d u a l s i n a s i n g...

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  • The innate immune response of insects includes induced expression of genes encoding a variety of antimicrobial peptides. The signaling pathways that stimulate this gene expression have been well characterized by genetic analy-sis in Drosophila melanogaster, but are not well understood in most other insect species.

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  • A number of biologists have probed the history of insects to determine what factors account for their huge diversity. Peter Mayhew, a biologist at the Univer- sity of York, has tested the leading hypotheses. Insects don’t seem to have a par- ticularly high rate of speciation, he has found, but they do seem good at with- standing extinctions. Fifty percent of all families of insect species alive today existed 250 million years ago. None of the families of tetrapod species alive 250 million years ago exists today; all have been replaced by newer groups.

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  • Human kynurenine aminotransferase I/glutamine trans-aminase K (hKAT-I) is an important multifunctional enzyme. This study systematically studies the substrates of hKAT-I and reassesses the effects of pH, Tris, amino acids anda-keto acids on the activity of the enzyme. The experi-ments were comprised of functional expression of the hKAT-I in an insect cell/baculovirus expression system, purification of its recombinant protein, and functional characterization of the purified enzyme.

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