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‣ Efeito de borda e de distúrbio antrópico sobre a fauna de insetos galhadores em transições floresta-campo

Toma, Tiago Shizen Pacheco
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Dissertação Formato: application/pdf
Português
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O efeito de borda em florestas é bastante estudado, porém pouco se sabe sobre as respostas das interações entre espécies a este efeito. O mesmo acontece quando se trata de distúrbios antrópicos, muitas vezes presentes após o processo de fragmentação. Apesar de não terem sido originadas por tal processo, as transições floresta-campo existentes nas florestas com Araucaria do sul do Brasil são submetidas aos distúrbios causados pelo pastejo e manejo por fogo, possuindo características semelhantes às bordas florestais mantidas no seu ponto de criação. No Capítulo 1, o efeito de borda e de distúrbios antrópicos sobre a fauna de insetos galhadores foi testado em transições floresta-campo, em termos de riqueza e composição destes organismos, comparando-se tanto bordas e interiores florestais quanto graus de distúrbio (com distúrbio e em regeneração), e adicionalmente foram feitas comparações entre manchas florestais naturais e a floresta contínua. Considerando as hipóteses propostas para os padrões de distribuição dos insetos galhadores, espera-se que existam mais espécies nas bordas de florestas comparadas ao interior, e que os distúrbios afetem estas respostas. Apesar das bordas em geral não terem apresentado maior riqueza de espécies que o interior...

‣ Estratégias de controle de insetos-pragas nas culturas do tomateiro (Lycopersicum esculentum Mill) e pimentão (Capsicum annum L.)

Macedo, Marcos Aurélio Anequini de
Fonte: Universidade Estadual Paulista (UNESP) Publicador: Universidade Estadual Paulista (UNESP)
Tipo: Tese de Doutorado Formato: xxi, 125 f. : gráfs., tabs.
Português
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Pós-graduação em Agronomia (Proteção de Plantas) - FCA; O objetivo do presente trabalho foi estudar diferentes estratégias de controle de insetospragas nas culturas do tomateiro e do pimentão, procurando associar amostragens, níveis de controle, resistência de plantas a insetos, controle químico, produtos naturais, irradiação e controle cultural. Foram amostrados o número de B. tabaci, F. schultzei, M. persicae, a porcentagem de plantas com virose, a produção de frutos e a porcentagem do custo dos produtos aplicados em relação a produção. Os dados obtidos foram submetidos à análise de variância pelo teste de Fisher, e quando significativo às médias foram comparadas pelo teste de Tukey, a 5% de probabilidade. Pelos resultados obtidos conclui-se que: a) cultura do tomateiro: os cultivares menos infestados por T. absoluta foram AP 529 e AP 533 na fase de frutificação; a estratégia convencional foi a mais eficiente no controle dos insetos vetores, porcentagem de plantas com virose e da traça, e, promoveu maior produção de frutos; as estratégias MIP, doses de 75,100 e 125 Gy + MIP-nim a 0,5% e MIP-nim a 0,5% e MIP-nim a 0,5% com barreiras de plantas de milho...

‣ Efficient, low-cost protein factories: expression of human adenosine deaminase in baculovirus-infected insect larvae.

Medin, J A; Hunt, L; Gathy, K; Evans, R K; Coleman, M S
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/1990 Português
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Human adenosine deaminase (EC 3.5.4.4), a key purine salvage enzyme essential for immune competence, has been overproduced in Spodoptera frugiperda cells and in Trichoplusia ni (cabbage looper) larvae infected with recombinant baculovirus. The coding sequence of human adenosine deaminase was recombined into a baculovirus immediately downstream from the strong polyhedrin gene promoter. Approximately 60 hr after infection of insect cells with the recombinant virus, maximal levels of intracellular adenosine deaminase mRNA, protein, and enzymatic activity were detected. The recombinant human adenosine deaminase represented 10% of the total cellular protein and exhibited a specific activity of 70 units/mg of protein in crude homogenate. This specific activity is 70-350 times greater than that exhibited by the enzyme in homogenates of the two most abundant natural sources of human adenosine deaminase, thymus and leukemic cells. When the recombinant virus was injected into insect larvae, the maximum recombinant enzyme was produced 4 days postinfection and represented about 2% of the total insect protein with a specific activity of 10-25 units/mg of protein. The recombinant human adenosine deaminase was purified to homogeneity from both insect cells and larvae and demonstrated to be identical to native adenosine deaminase purified from human cells with respect to molecular weight...

‣ Two Distinct Hemolytic Activities in Xenorhabdus nematophila Are Active against Immunocompetent Insect Cells

Brillard, Julien; Ribeiro, Carlos; Boemare, Noël; Brehélin, Michel; Givaudan, Alain
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /06/2001 Português
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Xenorhabdus spp. and Photorhabdus spp. are major insect bacterial pathogens symbiotically associated with nematodes. These bacteria are transported by their nematode hosts into the hemocoel of the insect prey, where they proliferate within hemolymph. In this work we report that wild strains belonging to different species of both genera are able to produce hemolysin activity on blood agar plates. Using a hemocyte monolayer bioassay, cytolytic activity against immunocompetent cells from the hemolymph of Spodoptera littoralis (Lepidoptera: Noctuidae) was found only in supernatants of Xenorhabdus; none was detected in supernatants of various strains of Photorhabdus. During in vitro bacterial growth of Xenorhabdus nematophila F1, two successive bursts of cytolytic activity were detected. The first extracellular cytolytic activity occurred when bacterial cells reached the stationary phase. It also displayed a hemolytic activity on sheep red blood cells, and it was heat labile. Among insect hemocyte types, granulocytes were the preferred target. Lysis of hemocytes by necrosis was preceded by a dramatic vacuolization of the cells. In contrast the second burst of cytolytic activity occurred late during stationary phase and caused hemolysis of rabbit red blood cells...

‣ Comparative analysis of secondary structure of insect mitochondrial small subunit ribosomal RNA using maximum weighted matching

Page, Roderic D. M.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
Publicado em 15/10/2000 Português
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Comparative analysis is the preferred method of inferring RNA secondary structure, but its use requires considerable expertise and manual effort. As the importance of secondary structure for accurate sequence alignment and phylogenetic analysis becomes increasingly realised, the need for secondary structure models for diverse taxonomic groups becomes more pressing. The number of available structures bears little relation to the relative diversity or importance of the different taxonomic groups. Insects, for example, comprise the largest group of animals and yet are very poorly represented in secondary structure databases. This paper explores the utility of maximum weighted matching (MWM) to help automate the process of comparative analysis by inferring secondary structure for insect mitochondrial small subunit (12S) rRNA sequences. By combining information on correlated changes in substitutions and helix dot plots, MWM can rapidly generate plausible models of secondary structure. These models can be further refined using standard comparative techniques. This paper presents a secondary structure model for insect 12S rRNA based on an alignment of 225 insect sequences and an alignment for 16 exemplar insect sequences. This alignment is used as a template for a web server that automatically generates secondary structures for insect sequences.

‣ Molecular identification of the insect adipokinetic hormone receptors

Staubli, Frank; Jørgensen, Thomas J. D.; Cazzamali, Giuseppe; Williamson, Michael; Lenz, Camilla; Søndergaard, Leif; Roepstorff, Peter; Grimmelikhuijzen, Cornelis J. P.
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
Publicado em 19/03/2002 Português
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The insect adipokinetic hormones (AKHs) are a large family of peptide hormones that are involved in the mobilization of sugar and lipids from the insect fat body during energy-requiring activities such as flight and locomotion, but that also contribute to hemolymph sugar homeostasis. Here, we have identified the first insect AKH receptors, namely those from the fruitfly Drosophila melanogaster and the silkworm Bombyx mori. These results represent a breakthrough for insect molecular endocrinology, because it will lead to the cloning of all AKH receptors from all model insects used in AKH research, and, therefore, to a better understanding of AKH heterogeneity and actions. Interestingly, the insect AKH receptors are structurally and evolutionarily related to the gonadotropin-releasing hormone receptors from vertebrates.

‣ Specific targeting of insect and vertebrate telomeres with pyrrole and imidazole polyamides

Maeshima, Kazuhiro; Janssen, Samuel; Laemmli, Ulrich K.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
Publicado em 15/06/2001 Português
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DNA minor groove-binding compounds (polyamides) that target insect and vertebrate telomeric repeats with high specificity were synthesized. Base pair recognition of these polyamides is based on the presence of the heterocyclic amino acids pyrrole and imidazole. One compound (TH52B) interacts uniquely and with excellent specificity (Kd = 0.12 nM) with two consecutive insect-type telomeric repeats (TTAGG). A related compound, TH59, displays high specificity (Kd = 0.5 nM) for tandem vertebrate (TTAGGG) and insect telomeric repeats. The high affinity and specificity of these compounds were achieved by bidentate binding of two flexibly linked DNA-binding moieties. Epifluorescence microscopy studies show that fluorescent derivatives of TH52B and TH59 stain insect or vertebrate telomeres of chromosomes and nuclei sharply. Importantly, the telomere-specific polyamide signals of HeLa chromosomes co-localize with the immunofluorescence signals of the telomere-binding protein TRF1. Our results demonstrate that telomere-specific compounds allow rapid estimation of relative telomere length. The insect-specific compound TH52 was shown to be incorporated rapidly into growing Sf9 cells, underlining the potential of these compounds for telomere biology and possibly human medicine.

‣ For the Insect Pathogen Photorhabdus luminescens, Which End of a Nematode Is Out?

Ciche, Todd A.; Ensign, Jerald C.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /04/2003 Português
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The nematode Heterorhabditis bacteriophora is the vector for transmitting the entomopathogenic bacterium Photorhabdus luminescens between insect larvae. The dauer juvenile (DJ) stage nematode selectively retains P. luminescens in its intestine until it releases the bacteria into the hemocoel of an insect host. We report the results of studying the transmission of the bacteria by its nematode vector. Cells of P. luminescens labeled with green fluorescent protein preferentially colonized a region of the DJ intestine immediately behind the basal bulb, extending for various distances toward the anus. Incubation of DJ nematodes in vitro in insect hemolymph induced regurgitation of the bacteria. Following a 30-min lag, the bacteria migrated in a gradual and staggered movement toward and ultimately exited the mouth. This regurgitation reaction was induced by a low-molecular-weight, heat- and protease-stable, anionic component present in arthropod hemolymph and in supernatants from insect cell cultures. Nematodes anesthetized with levamisole or treated with the antihelmenthic agent ivermectin did not release their bacteria into hemolymph. The ability to visualize P. luminescens in the DJ nematode intestine provides the first clues to the mechanism of release of the bacteria during infection of insect larvae. This and the partial characterization of a component of hemolymph triggering release of the bacteria render this fascinating example of both a mutualistic symbiosis and disease transmission amenable to future genetic and molecular study.

‣ Stability and Activities of Antibiotics Produced during Infection of the Insect Galleria mellonella by Two Isolates of Xenorhabdus nematophilus

Maxwell, Philip W.; Chen, Genhui; Webster, John M.; Dunphy, Gary B.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /02/1994 Português
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Xenorhabdus nematophilus subsp. dutki, an entomopathogenic bacterium, is vectored by steinernematid nematodes into insects, where it produces broad-spectrum antibiotics. The use of the nematode-bacterium complex against soil-dwelling pest insects could introduce antibiotics into the soil via the dead insect fragments during the emergence phase of the nematodes. Studies on the stability and activities of these antibiotics produced in the insect Galleria mellonella may contribute to assessing the possible impact of antibiotics on soil bacteria. Two isolates of X. nematophilus subsp. dutki (isolates GI and SFU) produced xenocoumacins 1 and 2 in cadavers of G. mellonella larvae in a 1:1 ratio. Total xenocoumacin 1 and 2 production was 800 ng/200 mg (wet weight) of insect tissue for the GI isolate. Antibiotic activity of water extracts from insects that had been infected with X. nematophilus was stable at 60°C for 1 h and after repeated freeze-thaw cycles. The antibiotic titer of extracts held at 27°C declined by day 10. The spectrum of bacterial species killed by antibiotics produced in insect cadavers varied with the isolate of X. nematophilus. Levels of antibiotic activity were greater in vivo than in tryptic soy broth, which may represent a nutrient effect. The bacterial isolate...

‣ Insect immunity: isolation from immune blood of the dipteran Phormia terranovae of two insect antibacterial peptides with sequence homology to rabbit lung macrophage bactericidal peptides.

Lambert, J; Keppi, E; Dimarcq, J L; Wicker, C; Reichhart, J M; Dunbar, B; Lepage, P; Van Dorsselaer, A; Hoffmann, J; Fothergill, J
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /01/1989 Português
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We have isolated from the hemolymph of immunized larvae of the dipteran insect Phormia terranovae two peptides that are selectively active against Gram-positive bacteria. They are positively charged peptides of 40 residues containing three intramolecular disulfide bridges and differ from one another by only a single amino acid. These peptides are neither functionally nor structurally related to any known insect immune response peptides but show significant homology to microbicidal cationic peptides from mammalian granulocytes (defensins). We propose the name "insect defensins" for these insect antibiotic peptides.

‣ PARP promoter-mediated activation of a VSG expression site promoter in insect form Trypanosoma brucei.

Urményi, T P; Van der Ploeg, L H
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 25/03/1995 Português
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In trypanosomes the rRNA, PARP and VSG gene promoters mediate alpha-amanitin-resistant transcription of protein coding genes, presumably by RNA polymerase (pol) I. We compared the activity of PARP and VSG promoters integrated at one of the alleles of the largest subunit of pol II genes in insect form trypanosomes. Even though both promoters are roughly equally active in transient transformation assays in insect form trypanosomes, only the PARP promoter functioned effectively when integrated at the pol II largest subunit or other loci. Promoter activity in transient transformation assays is therefore not necessarily predictive of transcriptional activity once integrated into the trypanosome genome. The integrated fully active PARP promoter could upregulate in cis an otherwise poorly active integrated VSG promoter. The PARP promoter nucleotide sequence elements responsible for VSG promoter activation coincided with most of the important PARP promoter elements mapped previously by linker scanning mutagenesis, indicating that it is not a single unique promoter element that was responsible for VSG promoter activation. The data suggest that PARP promoter-mediated activation of the VSG promoter does not result from complementation of the VSG promoter with a single insect form-specific transcription factor whose binding site is missing from the VSG promoter and present in the PARP promoter. We favor a model in which chromatin structure at the locus is altered by the PARP promoter...

‣ The contractile and regulatory proteins of insect flight muscle

Bullard, Belinda; Dabrowska, Renata; Winkelman, Lowell
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /10/1973 Português
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1. Myosin, actin and the regulatory proteins were prepared from insect flight muscle. 2. The light subunit composition of the myosin differed from that of vertebrate muscle myosin. The ionic strength and pH dependence of the myosin adenosine triphosphatase (ATPase) were measured. 3. Actin was associated with a protein of subunit molecular weight 55000 and was purified by gel filtration. Impure actin had protein bound at a periodicity of about 40nm. 4. Regulatory protein extracts had tropomyosin and troponin components of subunit molecular weight 18000, 27000 and 30000. Crude extracts of regulatory proteins inhibited the ATPase activity of desensitized or synthetic actomyosin; this inhibition was relatively insensitive to high Ca2+ concentrations. Purified insect regulatory protein produced as much sensitivity to Ca2+ as did the rabbit troponin–tropomyosin complex. 5. Synthetic actomyosins were made from rabbit and insect proteins. Actomyosins containing insect myosin had a low ATPase activity that was activated by tropomyosin. The Ca2+ sensitivity of actomyosins containing insect myosin or actin, with added troponin–tropomyosin complex from rabbit, was comparable with that of rabbit actomyosin.

‣ Identification of a novel class of insect glutathione S-transferases involved in resistance to DDT in the malaria vector Anopheles gambiae.

Ranson, H; Rossiter, L; Ortelli, F; Jensen, B; Wang, X; Roth, C W; Collins, F H; Hemingway, J
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 15/10/2001 Português
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The sequence and cytological location of five Anopheles gambiae glutathione S-transferase (GST) genes are described. Three of these genes, aggst1-8, aggst1-9 and aggst1-10, belong to the insect class I family and are located on chromosome 2R, in close proximity to previously described members of this gene family. The remaining two genes, aggst3-1 and aggst3-2, have a low sequence similarity to either of the two previously recognized classes of insect GSTs and this prompted a re-evaluation of the classification of insect GST enzymes. We provide evidence for seven possible classes of insect protein with GST-like subunits. Four of these contain sequences with significant similarities to mammalian GSTs. The largest novel insect GST class, class III, contains functional GST enzymes including two of the A. gambiae GSTs described in this report and GSTs from Drosophila melanogaster, Musca domestica, Manduca sexta and Plutella xylostella. The genes encoding the class III GST of A. gambiae map to a region of the genome on chromosome 3R that contains a major DDT [1,1,1-trichloro-2,2-bis-(p-chlorophenyl)ethane] resistance gene, suggesting that this gene family is involved in GST-based resistance in this important malaria vector. In further support of their role in resistance...

‣ Retrospective study of clinical observations on insect hypersensitivity and response to immunotherapy in allergic dogs.

Rothstein, E; Miller, W H; Scott, D W; Mohammed, H O
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/2001 Português
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A retrospective study was conducted to evaluate the importance of insect hypersensitivity in atopic dogs in the northeastern United States. Fifty (63%) of 79 dogs tested with 7 insect allergens, other than flea, had positive reactions to one or more insects. No dog had positive reactions to insects only. Forty-four dogs underwent immunotherapy. Thirty-one had insect antigens in their prescription mixture and 13 had only conventional environmental allergens. There was no statistical difference in the response rate between the 2 groups. Thus, testing with insect allergens did not decrease the number of dogs with negative skin tests, and including insect allergens in immunotherapy mixtures did not improve the response rate.

‣ Heterologous expression of rat epitope-tagged histamine H2 receptors in insect Sf9 cells

Beukers, M W; Klaassen, C H W; De Grip, W J; Verzijl, D; Timmerman, H; Leurs, R
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /11/1997 Português
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Rat histamine H2 receptors were epitope-tagged with six histidine residues at the C-terminus to allow immunological detection of the receptor. Recombinant baculoviruses containing the epitope-tagged H2 receptor were prepared and were used to infect insect Sf9 cells.The His-tagged H2 receptors expressed in insect Sf9 cells showed typical H2 receptor characteristics as determined with [125I]-aminopotentidine (APT) binding studies.In Sf9 cells expressing the His-tagged H2 receptor histamine was able to stimulate cyclic AMP production 9 fold (EC50=2.1±0.1 μM) by use of the endogenous signalling pathway. The classical antagonists cimetidine, ranitidine and tiotidine inhibited histamine induced cyclic AMP production with Ki values of 0.60±0.43 μM, 0.25±0.15 μM and 28±7 nM, respectively (mean±s.e.mean, n=3).The expression of the His-tagged H2 receptors in infected Sf9 cells reached functional levels of 6.6±0.6 pmol mg−1 protein (mean±s.e.mean, n=3) after 3 days of infection. This represents about 2×106 copies of receptor/cell. Preincubation of the cells with 0.03 mM cholesterol-β-cyclodextrin complex resulted in an increase of [125I]-APT binding up to 169±5% (mean±s.e.mean, n=3).The addition of 0.03 mM cholesterol-β-cyclodextrin complex did not affect histamine-induced cyclic AMP production. The EC50 value of histamine was 3.1±1.7 μM in the absence of cholesterol-β-cyclodextrin complex and 11.1±5.5 μM in the presence of cholesterol-β-cyclodextrin complex (mean±s.e.mean...

‣ Insect-like flapping wing mechanism based on a double spherical Scotch yoke

Galiński, Cezary; Żbikowski, Rafał
Fonte: The Royal Society Publicador: The Royal Society
Tipo: Artigo de Revista Científica
Português
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We describe the rationale, concept, design and implementation of a fixed-motion (non-adjustable) mechanism for insect-like flapping wing micro air vehicles in hover, inspired by two-winged flies (Diptera). This spatial (as opposed to planar) mechanism is based on the novel idea of a double spherical Scotch yoke. The mechanism was constructed for two main purposes: (i) as a test bed for aeromechanical research on hover in flapping flight, and (ii) as a precursor design for a future flapping wing micro air vehicle. Insects fly by oscillating (plunging) and rotating (pitching) their wings through large angles, while sweeping them forwards and backwards. During this motion the wing tip approximately traces a ‘figure-of-eight’ or a ‘banana’ and the wing changes the angle of attack (pitching) significantly. The kinematic and aerodynamic data from free-flying insects are sparse and uncertain, and it is not clear what aerodynamic consequences different wing motions have. Since acquiring the necessary kinematic and dynamic data from biological experiments remains a challenge, a synthetic, controlled study of insect-like flapping is not only of engineering value, but also of biological relevance. Micro air vehicles are defined as flying vehicles approximately 150 mm in size (hand-held)...

‣ Antioxidant defense response in a galling insect

Mittapalli, Omprakash; Neal, Jonathan J.; Shukle, Richard H.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
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Herbivorous insect species are constantly challenged with reactive oxygen species (ROS) generated from endogenous and exogenous sources. ROS produced within insects because of stress and prooxidant allelochemicals produced by host plants in response to herbivory require a complex mode of antioxidant defense during insect/plant interactions. Some insect herbivores have a midgut-based defense against the suite of ROS encountered. Because the Hessian fly (Mayetiola destructor) is the major insect pest of wheat worldwide, and an emerging model for all gall midges, we investigated its antioxidant responses during interaction with its host plant. Quantitative data for two phospholipid glutathione peroxidases (MdesPHGPX-1 and MdesPHGPX-2), two catalases (MdesCAT-1 and MdesCAT-2), and two superoxide dismutases (MdesSOD-1 and MdesSOD-2) revealed high levels of all of the mRNAs in the midgut of larvae on susceptible wheat (compatible interaction). During development of the Hessian fly on susceptible wheat, a differential expression pattern was observed for all six genes. Analysis of larvae on resistant wheat (incompatible interaction) compared with larvae on susceptible wheat showed increased levels of mRNAs in larvae on resistant wheat for all of the antioxidant genes except MdesSOD-1 and MdesSOD-2. We postulate that the increased mRNA levels of MdesPHGPX-1...

‣ Increased Insect Virulence in Beauveria bassiana Strains Overexpressing an Engineered Chitinase▿

Fan, Yanhua; Fang, Weiguo; Guo, Shujuan; Pei, Xiaoqiong; Zhang, Yongjun; Xiao, Yuehua; Li, Demou; Jin, Kai; Bidochka, Michael J.; Pei, Yan
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Português
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Entomopathogenic fungi are currently being used for the control of several insect pests as alternatives or supplements to chemical insecticides. Improvements in virulence and speed of kill can be achieved by understanding the mechanisms of fungal pathogenesis and genetically modifying targeted genes, thus improving the commercial efficacy of these biocontrol agents. Entomopathogenic fungi, such as Beauveria bassiana, penetrate the insect cuticle utilizing a plethora of hydrolytic enzymes, including chitinases, which are important virulence factors. Two chitinases (Bbchit1 and Bbchit2) have previously been characterized in B. bassiana, neither of which possesses chitin-binding domains. Here we report the construction and characterization of several B. bassiana hybrid chitinases where the chitinase Bbchit1 was fused to chitin-binding domains derived from plant, bacterial, or insect sources. A hybrid chitinase containing the chitin-binding domain (BmChBD) from the silkworm Bombyx mori chitinase fused to Bbchit1 showed the greatest ability to bind to chitin compared to other hybrid chitinases. This hybrid chitinase gene (Bbchit1-BmChBD) was then placed under the control of a fungal constitutive promoter (gpd-Bbchit1-BmChBD) and transformed into B. bassiana. Insect bioassays showed a 23% reduction in time to death in the transformant compared to the wild-type fungus. This transformant also showed greater virulence than another construct (gpd-Bbchit1) with the same constitutive promoter but lacking the chitin-binding domain. We utilized a strategy where genetic components of the host insect can be incorporated into the fungal pathogen in order to increase host cuticle penetration ability.

‣ Valuing Insect Pollination Services with Cost of Replacement

Allsopp, Mike H.; de Lange, Willem J.; Veldtman, Ruan
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 10/09/2008 Português
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Value estimates of ecosystem goods and services are useful to justify the allocation of resources towards conservation, but inconclusive estimates risk unsustainable resource allocations. Here we present replacement costs as a more accurate value estimate of insect pollination as an ecosystem service, although this method could also be applied to other services. The importance of insect pollination to agriculture is unequivocal. However, whether this service is largely provided by wild pollinators (genuine ecosystem service) or managed pollinators (commercial service), and which of these requires immediate action amidst reports of pollinator decline, remains contested. If crop pollination is used to argue for biodiversity conservation, clear distinction should be made between values of managed- and wild pollination services. Current methods either under-estimate or over-estimate the pollination service value, and make use of criticised general insect and managed pollinator dependence factors. We apply the theoretical concept of ascribing a value to a service by calculating the cost to replace it, as a novel way of valuing wild and managed pollination services. Adjusted insect and managed pollinator dependence factors were used to estimate the cost of replacing insect- and managed pollination services for the Western Cape deciduous fruit industry of South Africa. Using pollen dusting and hand pollination as suitable replacements...

‣ Arabidopsis-thrips system for analysis of plant response to insect feeding

Abe, Hiroshi; Onnishi, Jun; Narusaka, Mari; Seo, Shigemi; Narusaka, Yoshihiro; Tsuda, Shinya; Kobayashi, Masatomo
Fonte: Landes Bioscience Publicador: Landes Bioscience
Tipo: Artigo de Revista Científica
Publicado em /07/2008 Português
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Insect feeding retards plant growth and decreases crop productivity. Plants respond to insect feeding at the molecular, cellular and physiological levels. The roles of the plant hormones jasmonic acid (JA), ethylene (ET) and salicylic acid (SA) in plant responses to insect feeding have been studied. However, these studies are focused on the plant responses to feeding by well-studied caterpillar type insects or aphid pests. In contrast, we have focused on a minute insect pest, the western flower thrips (Frankliniella occidentalis). Analyses of the responses of hormone-related mutants of Arabidopsis (i.e., JA-insensitive mutant coi1-1, ET-insensitive mutants ein2-1 and ein3-1, and SA-deficient mutant eds16-1) and transcriptome-based comparative analyses indicate the central role of JA in plant responses to thrips feeding. Our work clearly shows that JA signaling, but not JA/ET signaling, is involved in plant tolerance to thrips feeding. We intend to examine the utility and suitability of the Arabidopsis-thrips system in studies of plant responses to insect feeding.