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Master's Dissertation
DOI
10.11606/D.11.2008.tde-16092008-161549
Document
Author
Full name
Carolina Schultz Lopes
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Piracicaba, 2008
Supervisor
Committee
Cônsoli, Fernando Luis (President)
Parra, José Roberto Postali
Wilcken, Carlos Frederico
Title in Portuguese
Regulação do desenvolvimento e resposta imune de lagartas de Diatraea saccharalis (Fabricius) (Lepidoptera: Crambidae) por Cotesia flavipes (Cameron) (Hymenoptera: Braconidae)
Keywords in Portuguese
Brocas (insetos nocivos)
Imunobiologia
Parasitimo
Vespas.
Abstract in Portuguese
Cotesia flavipes (Cameron) (Hym.: Braconidae), como outros cenobiontes, é capaz de regular seu hospedeiro, criando um ambiente que sustenta e promove o desenvolvimento de suas larvas, comumente em detrimento do hospedeiro. Substâncias derivadas do trato reprodutivo das fêmeas (proteínas ovarianas, veneno e polidnavírus) são injetadas no hospedeiro, afetando a resposta imune e outros processos fisiológicos com o propósito de regular os níveis hormonais, nutrição e comportamento. O presente trabalho teve por objetivo avaliar o papel dessas substâncias no crescimento e desenvolvimento de Diatraea saccharalis (Fabricius) (Lepidoptera: Crambidae), e avaliar como o parasitismo afeta a resposta imune do hospedeiro. Todas as substâncias derivadas da fêmea foram obtidas após a dissecação do parasitóide, através da coleta do reservatório de veneno ou dos ovários (proteínas ovarianas e polidnavírus) em tampão resfriado. As secreções foram processadas adequadamente e injetadas logo após a coleta. O veneno e as proteínas ovarianas + polidnavírus (PDV) foram injetados juntos ou separadamente em lagartas entre 0-12h do 6º instar. O efeito de cada um dos componentes isolados do parasitóide no desenvolvimento e crescimento do hospedeiro foi avaliado através de observações no ganho de peso, duração e viabilidade da fase larval e pupal. Os efeitos do parasitismo na resposta imune do hospedeiro foram avaliados tanto ao nível celular, através da contagem do número total de hemócitos e capacidade de encapsulação, como ao nível bioquímico, medindo-se a ativação da profenoloxidase e produção de óxido nítrico na hemolinfa das lagartas de D. saccharalis em diferentes estágios de desenvolvimento do parasitóide (0, 1, 3, 5, 7 e 9 dias após o parasitismo). As proteínas ovarianas do parasitóide e o PDV sozinho, ou co-injetado com o veneno, suspenderam o desenvolvimento larval do hospedeiro, enquanto que o veneno, sozinho, afetou o processo de metamorfose. A resposta imune do hospedeiro também foi afetada por C. flavipes, de maneira dependente do tempo. Lagartas parasitadas apresentaram declínio no número total de hemócitos a partir do 3º dia e a capacidade de encapsulação foi afetada ao longo do desenvolvimento do parasitóide. A atividade da fenoloxidase do hospedeiro foi alterada apenas no final do desenvolvimento imaturo do parasitóide, enquanto que o óxido nítrico foi afetado nas 24 h iniciais após parasitismo.
Title in English
Diatraea saccharalis (Fabricius) (Lepidoptera: Crambidae) larval development and immune response regulation by Cotesia flavipes (Cameron) (Hymenoptera: Braconidae)
Keywords in English
Host immune response
Host regulation
Host-parasitoid interactions
polydnavirus.
Abstract in English
Cotesia flavipes (Cameron) (Hym., Braconidae), as other koinobionts, is capable of regulating the host development to produce an suitable host environment to sustain and promote its own larval development at the host expenses. Female-derived substances from the reproductive tract (ovarian proteins, venom, polydnavirus) are injected into the host, affecting the host immune response and other physiological processes aiming to regulate the host hormone levels, nutrition and behavior. Our goal was to evaluate the role of these substances on Diatraea saccharalis (F.) (Lepidoptera: Crambidae) growth and development, and how the parasitism affects the host immune response. All female-derived substances were collected after parasitoid dissection by collecting the venom reservoir or the ovaries (ovarian proteins and polydnavirus). Dissections were carried out in ice-cold buffer, collected tissues were processed accordingly and the desired substances injected immediately after collection. Venom and ovarian proteins+polydnavirus (PDV) were injected jointly and separated in 0-12 hold 6th instars of D. saccharalis. The effect of these substances on host development and growth was evaluated by measuring the host weight gain, larval and pupal survivorship and developmental time. The effects of the parasitism on the host immune response was evaluated either at the cellular level, by measuring the total hemocyte count and the encapsulation capacity, and at the biochemical level, by measuring the prophenoloxidase activity and nitric oxide levels at different stages of parasitoid development (0, 1, 3, 5, 7 and 9 days after parasitism). Parasitoid ovarian proteins and PDV alone or co-injected with the venom arrested the host larval development, while the venom by itself only affected the host metamorphosis process. The host immune response was also affected by C. flavipes at a time-dependent manner. The total hemocyte count dropped at day 3 of parasitism, while the host encapsulation capacity was reduced during parasitoid development. The host prophenoloxidase activity was also affected mainly towards the end of parasitoid larval development, while the nitric oxide at the first 24 h after parasitism.
 
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Publishing Date
2008-09-17
 
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