Efeitos da ecdisona e de um an?logo de horm?nio juvenil sobre o desenvolvimento de ninfas de Rhodnius prolixus STAL, 1859 (Hemiptera, Reduviidae) tratadas com precoceno II

Autor: Montera, Patricia de Azambuja
Přispěvatelé: Garcia, Eloi de Souza
Jazyk: portugalština
Rok vydání: 1981
Předmět:
Zdroj: Biblioteca Digital de Teses e Dissertações da UFRRJ
Universidade Federal Rural do Rio de Janeiro (UFRRJ)
instacron:UFRRJ
Popis: Submitted by Celso Magalhaes (celsomagalhaes@ufrrj.br) on 2020-10-14T13:46:00Z No. of bitstreams: 1 1981 - Patricia de Azambuja Montera.pdf: 577502 bytes, checksum: d234250e7c751ff5ba74c222c4e60f04 (MD5) Made available in DSpace on 2020-10-14T13:46:00Z (GMT). No. of bitstreams: 1 1981 - Patricia de Azambuja Montera.pdf: 577502 bytes, checksum: d234250e7c751ff5ba74c222c4e60f04 (MD5) Previous issue date: 1981-01-02 Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPq The effects of precocene II, given orally, on the development of third- and fourth-instar larvae of R. prolixus were studied. Precocene, at 10 to 100 ?g/ml of blood meal, progressively reduced the amount of blood ingested (antifeedant action) and caused a high mortality in doses higher than 30 ?g/ml of blood. Moulting was dependent on the doses of precocene, and in several cases the bugs had the ecdysis prevented despite the ingestion of enough blood. Large number of insects underwent premature metamorphosis. A high correlation between the duration of the moulting cycle and the morphogenetic adultoid was ebtained. Precocious adults with slight imaginal characters were able to feed and initiate the next ecdysis. Adultiforms with distinct imaginal characteristics were short-lived and did not feed despite repeated opportunities. The ecdysis prevention activity of precocene (20 ?g /ml) could be counteracted by ecdysone given orally (5 ?g /ml) although this hormone did not interfer in the adultiform production. On the other hand, a juvenile hormone analogue applied topically a day after feeding (50 ?g/bug) precluded the premature metamorphosis and reduced the intermoulting period in these insects. Microscopic examination of the prothoracic glands (PG), corpus allatum (CA) and neurosecretory cells (NSC), ten days after treatment, revealed: a- the PG, contrarily to 67 the control bugs, were atrophied; the glands cells were elongated and presented a scarce cytoplasm; b- the CA were absent or very much atrophied; c- the NSC of type A did not show any apparent difference with the control group; d- the NSC of type A' accumulated paraldehyde-fuchsin positive material whereas in the control bugs they were empty. The results suggested that precocene II treatment may affect the development of R. prolixus larvae by interfering with the production and/or release of ecdysone and juvenile hormone. Our findings are consistent with the hypothesis that the precocene affect the growth by acting in the brain-CA-PG interactions. Foram estudados os efeitos do precoceno II, administrado por via digestiva, sobre o desenvolvimento de ninfas do 3? e 4? est?dio de R. prolixus. O precoceno, nas concentra??es de 10 a 100 ?g/ml de sangue, reduziu progressivamente o volume de sangue ingerido (a??o "antifeedant") e provocou uma alta mortalidade nas concentra??es acima de 30 ?g/ml de sangue. O retardamento da ecdise foi dose-dependente e em v?rios casos os insetos tiveram a muda inibida apesar de ingerirem grande volume de sangue. Grande n?mero de insetos sofreu metamorfose prematura. As caracter?sticas morfol?gicas destes insetos foram correlacionadas com a dura??o do ciclo da muda. Os adultos precoces com caracter?sticas "ninfais" se alimentaram e iniciaram a ecdise seguinte. Os insetos com caracter?sticas predominantemente imaginais tiveram uma vida curta e n?o se alimentaram, apesar de lhes serem oferecidas v?- rias oportunidades de alimenta??o. O retardamento da ecdise provocado pelo precoceno II foi revertido pela ecdisona; este horm?nio n?o interferiu na produ??o de metamorfose precoce. Por outro lado, a aplica- ??o t?pica de um an?logo de horm?nio juvenil um dia ap?s a alimenta??o inibiu a produ??o de metamorfose precoce e reduziu o per?odo de intermuda nestes insetos. O exame microsc?pico das gl?ndulas protor?cicas (GP), corpus allatum (CA) e das c?lulas neurossecretoras (CNS) cerebrais, no 10? dia ap?s a alimenta??o, revelou: a) que as GP 65 estavam atrofiadas) contrariamente ao que ocorria no grupo controle; as c?lulas das GP estavam alongadas e apresentavam citoplasma escasso; b) os CA estavam ausentes ou muito atrofiada; c) a CNS do tipo A n?o apresentavam nenhuma diferen?a com as c?lulas do grupo controle; d) a CNS do tipo A' estavam repletas de material paralde?do-fucc?nico enquanto que as do grupo controle estavam vazias. Os resultados sugerem que o precoceno II pode afetar o desenvolvimento de ninfas de R. prolixus, interferindo na produ??o e/ou libera??o de ecdisona e horm?nio juvenil. Estes dados s?o coerentes com a hip?tese de que o precoceno II afeta o crescimento de R. prolixus por agir na intera??o c?rebro-CA-GP.
Databáze: OpenAIRE
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