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Composição química e atividades biológicas dos metabolitos secundários de Cryptomeria japonica (L.f.) D.Don sobre a lagarta da pastagem Pseudaletia unipuncta Haworth (Lepidoptera: Noctuidae)
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Abstract(s)
Na presente tese foram avaliadas, pela primeira vez, as atividades biológicas (ovicida, larvicida, efeitos subletais, efeito antialimentar, efeito de inibição de crescimento e repelência) dos óleos essenciais (OEs) e de extratos orgânicos de Cryptomeria japónica (espécie florestal mais relevante dos Açores) sobre a lagarta das pastagens Pseudaletia unipuncta, uma das principais pragas agrícolas da Região com consequências graves para a economia local.
Os extratos vegetais a testar (OEs e extratos orgânicos) foram obtidos da ramada de C. japonica oriunda da ilha de São Miguel (Açores). O OE foi obtido por hidrodestilação (OE-HD) e por arraste de vapor (OE-AV). Os extratos orgânicos foram obtidos por maceração a frio com acetona e por extração com Soxhlet usando, sequencialmente, solventes orgânicos de polaridade crescente (hexano, diclorometano e metanol). Tendo-se observado a formação de duas fases heterogéneas nos 4 extratos orgânicos obtidos, procedeu-se à sua separação antes da concentração total, resultando assim oito amostras de extratos orgânicos.
No ensaio ovicida, à concentração de 10 mg ml-1, o ACE-Sol (parte sólida do extrato de acetona) e o HEX-FrSol (fração solúvel do extrato de hexano) foram os que apresentaram uma maior atividade inibitória seguido do MET-Res (parte resinosa do extrato de metanol), com valores de 78,6, 66,8 e 55,2%, respetivamente. Em relação à dose letal (DL50 e DL90) de inibição de eclosão de ovos, os valores (em mg ml-1) mais baixos foram observados em ACE-Sol (6,58 e 28,16), DIC-Res (parte resinosa do extrato de diclorometano) (9,55 e 24,41) e HEX-FrSol (8,94 e 28,84), respetivamente.
No ensaio larvicida (por contacto, fumigação e ingestão) só foi detetada toxicidade por ingestão, sendo o OE-HD o tratamento mais ativo, originando 12% de mortalidade, seguido pelos OE-AV, HEX-FrIns (fração insolúvel do extrato de hexano) e HEX-FrSol com 6% de mortalidade.
Os efeitos subletais em larvas eclodidas no ensaio da atividade ovicida foram monitorizados. Verificou-se uma diminuição significativa na duração do ovo provocada pelo OE-HD de menos 0,3 dias comparando com o controlo e foi também o responsável pelo aumento da mortalidade das pupas juntamente com o MET-Res. O OE-AV teve influência na percentagem de larvas mortas e de adultos deformados. A duração larvar e longevidade dos adultos, bem com número de ovos postos pelas fêmeas obtidas dos ovos anteriormente tratados, não foram afetadas pelo efeito dos tratamentos. Os extratos HEX-FrIns, MET-Res, HEX-FrSol e DIC-Res apresentaram influência na duração das pupas. O ACE-Sol foi o que reduziu mais o peso das pupas. Os extratos ACE-Ole (parte oleosa do extrato de acetona), MET-Res e DIC-Res originaram uma redução significativa no número de fêmeas o que levou a uma redução no valor do sex ratio da população.
Relativamente ao efeito na nutrição e metabolismo das larvas de P. unipuncta no 4º estado larvar, todos os OEs e extratos testados reduziram significativamente, tanto o alimento consumido como o peso ganho, com o DIC-Res, o ACE-Sol e o OE-HD a provocarem o decrescimento mais pronunciado no comportamento alimentar. Os parâmetros nutricionais feeding deterence index e a inibição de crescimento foram influenciados principalmente pelos DIC-Res e ACE-Sol. Estes extratos também apresentaram um efeito negativo no processo de assimilação e conversão do alimento em massa corporal, influenciando significativamente os índices eficiência de conversão do alimento digerido, eficiência de conversão do alimento ingerido e a taxa metabólica relativa causando um elevado custo metabólico.
No que diz respeito à repelência através de teste com hipótese de escolha, à 1h e 2h de ensaio, o OE-AV foi o que se mostrou mais ativo, seguido pelo OE-HD.
A partir dos resultados obtidos neste trabalho podemos concluir que existe potencial inseticida dos OEs e extratos orgânicos de C. japonica sobre P. unipuncta e que podem vir a ser usados no controlo desta praga. Os OEs apresentaram atividade de toxicidade por ingestão (OE-HD), diferentes efeitos subletais, antialimentares (OE-HD) e acentuada atividade repelente (OE-AV). Em relação aos extratos orgânicos verificamos, de uma forma geral, que ACE-Sol, HEX-FrSol e MET-Res mostraram atividade ovicida, efeitos subletais e antialimentares, para além do efeito repelente de DIC-Res e ACESol. Mais estudos terão de ser realizados de modo a otimizar a sua utilização.
ABSTRACT: In the present thesis, the biological activities (ovicide, larvicide, sublethal effects, antifeedant effect, growth inhibition and repellency) of essential oils (EOs) and organic extracts of Cryptomeria japonica (the most relevant forest species from the Azores) were evaluated for the first time against Pseudaletia unipuncta, one of the main agricultural pests in the Region with serious consequences for the local economy. The plant based extracts to be tested (EOs and organic extracts) were obtained from C. japonica leafs and stems from the island of São Miguel (Azores). EO was obtained by hydrodistillation (EO-HD) and by steam-distillation (EO-SD). The organic extracts were obtained by cold maceration with acetone and extraction with Soxhlet using sequentially organic solvents of increasing polarity (hexane, dichloromethane and methanol). The formation of two heterogeneous phases in the 4 organic extracts obtained were observed, reason why they were fractionated before the total concentration, resulting in eight samples of organic extracts. In the ovicidal assay, at 10 mg ml-1 concentration, ACE-Sol (solid part of the acetone extract) and HEX-FrSol (soluble fraction of hexane extract) showed the highest inhibitory activity followed by MET- Res (resinous part of the methanol extract), with values of 78.6, 66.8 and 55.2%, respectively. Regarding the lethal dose (LD50 and LD90) of egg hatching inhibition, the lowest values (in mg ml-1) were observed in ACE-Sol (6.58 and 28.16), DIC-Res (resinous part of the dichloromethane extract) (9.55 and 24.41) and HEX-FrSol (8.94 and 28.84), respectively. In the larvicidal test (contact, fumigation and ingestion) only toxicity by ingestion was detected, with EO-HD being the most active treatment, causing 12% mortality, followed by EO-SD, HEX-FrIns (insoluble fraction of hexane extract) and HEX-FrSol with 6% mortality. The sublethal effects in larvae emerged in the ovicidal assay were monitored. There was a significant decrease on egg duration of 0.3 days, caused by EO-HD, compared to control and was also responsible for the increase of pupal mortality along with METRes. EO-SD had an influence on the percentage of dead and adult deformed larvae. The larval duration and the longevity of the adults, as well as the number of eggs laid by the females obtained from the eggs previously treated, were not affected by the treatments. The extracts HEX-FrIns, MET-Res, HEX-FrSol and DIC-Res had influence on pupae’s duration. ACE-Sol showed more influence on the pupae’s weight. ACE-Ole extracts (oily part of the acetone extract), MET-Res and DIC-Res resulted in a significant reduction in the number of females, which led to a reduction in the sex ratio of the population. Regarding the nutritional and metabolic effects on P. unipuncta larvae in the 4th larval stage, all EOs and extracts tested reduced significantly both consumed diet and gained weight with DIC-Res, ACE-Sol and EO-HD causing the most pronounced decrease in food behavior. The nutritional feeding deterrence index (FDI) and growth inhibition parameters were mainly influenced by DIC-Res and ACE-Sol. These extracts also had a negative effect on the process of assimilation and conversion of food into body mass, significantly influencing the digestible food conversion efficiency, conversion efficiency of the ingested food and the relative metabolic rate causing a high metabolic cost. The repellency assay, at 1h and 2h showed that EO-SD was most active, followed by the EO-HD. From the results obtained in this work we can conclude that there is an insecticidal potential of the EOs and extracts of C. japonica on P. unipuncta and that can be used in the control of this pest. The EOs presented toxicity through ingestion (EO-HD), different sublethal effects, antifeedant (EO-HD) and high repellent activity (EO-SD). In general, ACE-Sol, HEX-FrSol and MET-Res showed ovicidal effects, sublethal and antifeedant effects, in addition to the repellent effect of DIC-Res and ACE-Sol. More studies will have to be carried out in order to optimize its use.
ABSTRACT: In the present thesis, the biological activities (ovicide, larvicide, sublethal effects, antifeedant effect, growth inhibition and repellency) of essential oils (EOs) and organic extracts of Cryptomeria japonica (the most relevant forest species from the Azores) were evaluated for the first time against Pseudaletia unipuncta, one of the main agricultural pests in the Region with serious consequences for the local economy. The plant based extracts to be tested (EOs and organic extracts) were obtained from C. japonica leafs and stems from the island of São Miguel (Azores). EO was obtained by hydrodistillation (EO-HD) and by steam-distillation (EO-SD). The organic extracts were obtained by cold maceration with acetone and extraction with Soxhlet using sequentially organic solvents of increasing polarity (hexane, dichloromethane and methanol). The formation of two heterogeneous phases in the 4 organic extracts obtained were observed, reason why they were fractionated before the total concentration, resulting in eight samples of organic extracts. In the ovicidal assay, at 10 mg ml-1 concentration, ACE-Sol (solid part of the acetone extract) and HEX-FrSol (soluble fraction of hexane extract) showed the highest inhibitory activity followed by MET- Res (resinous part of the methanol extract), with values of 78.6, 66.8 and 55.2%, respectively. Regarding the lethal dose (LD50 and LD90) of egg hatching inhibition, the lowest values (in mg ml-1) were observed in ACE-Sol (6.58 and 28.16), DIC-Res (resinous part of the dichloromethane extract) (9.55 and 24.41) and HEX-FrSol (8.94 and 28.84), respectively. In the larvicidal test (contact, fumigation and ingestion) only toxicity by ingestion was detected, with EO-HD being the most active treatment, causing 12% mortality, followed by EO-SD, HEX-FrIns (insoluble fraction of hexane extract) and HEX-FrSol with 6% mortality. The sublethal effects in larvae emerged in the ovicidal assay were monitored. There was a significant decrease on egg duration of 0.3 days, caused by EO-HD, compared to control and was also responsible for the increase of pupal mortality along with METRes. EO-SD had an influence on the percentage of dead and adult deformed larvae. The larval duration and the longevity of the adults, as well as the number of eggs laid by the females obtained from the eggs previously treated, were not affected by the treatments. The extracts HEX-FrIns, MET-Res, HEX-FrSol and DIC-Res had influence on pupae’s duration. ACE-Sol showed more influence on the pupae’s weight. ACE-Ole extracts (oily part of the acetone extract), MET-Res and DIC-Res resulted in a significant reduction in the number of females, which led to a reduction in the sex ratio of the population. Regarding the nutritional and metabolic effects on P. unipuncta larvae in the 4th larval stage, all EOs and extracts tested reduced significantly both consumed diet and gained weight with DIC-Res, ACE-Sol and EO-HD causing the most pronounced decrease in food behavior. The nutritional feeding deterrence index (FDI) and growth inhibition parameters were mainly influenced by DIC-Res and ACE-Sol. These extracts also had a negative effect on the process of assimilation and conversion of food into body mass, significantly influencing the digestible food conversion efficiency, conversion efficiency of the ingested food and the relative metabolic rate causing a high metabolic cost. The repellency assay, at 1h and 2h showed that EO-SD was most active, followed by the EO-HD. From the results obtained in this work we can conclude that there is an insecticidal potential of the EOs and extracts of C. japonica on P. unipuncta and that can be used in the control of this pest. The EOs presented toxicity through ingestion (EO-HD), different sublethal effects, antifeedant (EO-HD) and high repellent activity (EO-SD). In general, ACE-Sol, HEX-FrSol and MET-Res showed ovicidal effects, sublethal and antifeedant effects, in addition to the repellent effect of DIC-Res and ACE-Sol. More studies will have to be carried out in order to optimize its use.
Description
Dissertação de Mestrado, Biodiversidade e Biotecnologia, 19 setembro de 2019, Universidade dos Açores.
Keywords
Cryptomeria japonica Pseudaletia unipuncta Lagarta da Pastagem Metabolitos Secundários Botanical Insecticide Essential Oil Organic Extracts Repellency, Antifeedant
Citation
Rodrigues, Ana Carolina Serpa. "Composição química e atividades biológicas dos metabolitos secundários de Cryptomeria japonica (L.f.) D.Don sobre a lagarta da pastagem Pseudaletia unipuncta Haworth (Lepidoptera: Noctuidae)". 2019. 70 p.. (Dissertação de Mestrado em Biodiversidade e Biotecnologia). Ponta Delgada: Universidade dos Açores, 2019. [Consult. Dia Mês Ano]. Disponível em www:<http://hdl.handle.net/10400.3/5227>.