Inibição do crescimento de Spodoptera frugiperda e fitopatógenos causados por isolados bacterianos obtidos de lagartas infectadas com microrganismos do solo
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Data
2021-02-23
Autores
Sales, Cinara Ramos
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Universidade Estadual Paulista (Unesp)
Resumo
As perdas de produtividade causadas por pragas e doenças em culturas de importância agrícola acarretam grandes prejuízos econômicos em todo o mundo. Apesar da eficiência do controle químico no manejo de pragas e doenças, estes podem apresentar riscos ao meio ambiente e a saúde humana, além de seu recorrente uso favorecer a evolução da resistência. Com isso, alternativas de controle de origem biológica tem se destacado no mercado de proteção de plantas, no entanto, com um número ainda limitado de opções, em especial para os bioinseticidas de origem bacteriana, que atualmente no Brasil tem sido realizado por meio de uma única espécie, o Bacillus thunrigiensis. Assim, se objetivou prospectar a atividade inseticida e/ou fungicida de isolados bacterianos obtidos por meio de inseto-armadilha. Neste sentido, foram isoladas bactérias de lagartas mortas por meio do método de inseto armadilha, e posteriormente, realizada a avaliação da atividade inseticida e fungicida dos isolados, identificação dos isolados ativos por meio do sequenciamento do gene rRNA 16S e caracterização da curva de crescimento da bactéria acompanhada de sua atividade ao longo de sete dias. Na prospecção foram obtidos 70 isolados bacterianos, dos quais 10 causaram inibição do crescimento de S. frugiperda, por meio do sequenciamento foi possível identificar que estes se tratavam das espécies Enterococcus mundtii, Enterococcus gallinarum, Enterococcus casseliflavus e Serratia nematodiphila, outros sete isolados foram antagonistas de fungos fitopatogênicos, identificados como Serratia marcescens, Bacillus cereus, Enterobacter tabaci. Dos isolados ativos contra S. frugiperda, cinco apresentaram inibição do crescimento de lagartas superior a 90%, sendo estes E. mundtii, E. gallinarum e E. casseliflavus. Dos ativos contra fungos fitopatogênicos se destacaram S. marcescens e E. tabaci que inibiram três dos quatro fungos avaliados. Para a continuidade dos estudos, entre os isolados que se apresentaram ativos contra S. frugiperda, foi selecionada E. mundtii (isolado 60) devido a sua elevada atividade e por estar classificada no nível 1 de biossegurança. Na curva de crescimento e atividade inseticida deste isolado, obteve se taxa de inibição do crescimento superior a 90 % e U.F.C. e D.O. máxima após 12 iv e 6 horas de cultivo, respectivamente. Assim, a partir do estudo desenvolvido, uma serie de isolados bacterianos ativos contra S. frugiperda ou fungos fitopatogênicos foram obtidos. Entre estes isolados se destacou E. mundtii, que causou drástica inibição do crescimento de lagartas e apresenta escassos relatos na literatura sobre este efeito, com isso, futuros estudos serão necessários para desvendar os mecanismos envolvidos.
Productivity losses caused by pests and diseases in crops of agricultural importance cause great economic losses all over the world. Despite the efficiency of chemical control in the management of pests and diseases, they can pose risks to the environment and human health, in addition to their recurrent use favoring the evolution of resistance. With this, biological origin control alternatives have stood out in the plant protection market, however, with a still limited number of options, especially for bacterial bioinsecticides, which currently in Brazil have been carried out through a single species, Bacillus thunrigiensis. Thus, the objective was to prospect the insecticidal and/or fungicidal activity of bacterial isolates obtained through insect-trap. In this sense, bacteria were isolated from dead caterpillars using the insect-trap method, and subsequently, the evaluation of the insecticidal and fungicidal activity of the isolates was carried out, identification of active isolates through sequencing of the 16S rRNA gene and characterization of the growth curve of the bacterium followed by its activity over seven days. In the prospection, 70 bacterial isolates were obtained, 10 of which caused inhibition of the growth of S. frugiperda, through sequencing it was possible to identify that these were the species Enterococcus mundtii, Enterococcus gallinarum, Enterococcus casseliflavus and Serratia nematodiphila, another seven isolates were antagonists of phytopathogenic fungi identified as Serratia marcescens, Bacillus cereus, Enterobacter tabaci. Of the active isolates against S. frugiperda, five showed inhibition of caterpillar growth greater than 90%, these being E. mundtii, E. gallinarum and E. casseliflavus. Of the actives against phytopathogenic fungi, S. marcescens and E. tabaci stood out, which inhibited three of the four evaluated fungi. For the continuity of the studies, among the isolates that were active against S. frugiperda, E. mundtii (isolate 60) was selected due to its high activity and for being classified in level 1 of biosafety. In the growth curve and insecticidal activity of this isolate, a growth inhibition rate higher than 90% and U.F.C. It's from. maximum after 12 and 6 hours of cultivation, respectively. Thus, from the study developed, a series of vi bacterial isolates active against S. frugiperda or phytopathogenic fungi were obtained. Among these isolates, E. mundtii stood out, which caused a drastic inhibition of the growth of caterpillars and has few reports in the literature on this effect, therefore, further studies will be needed to unravel the mechanisms involved.
Productivity losses caused by pests and diseases in crops of agricultural importance cause great economic losses all over the world. Despite the efficiency of chemical control in the management of pests and diseases, they can pose risks to the environment and human health, in addition to their recurrent use favoring the evolution of resistance. With this, biological origin control alternatives have stood out in the plant protection market, however, with a still limited number of options, especially for bacterial bioinsecticides, which currently in Brazil have been carried out through a single species, Bacillus thunrigiensis. Thus, the objective was to prospect the insecticidal and/or fungicidal activity of bacterial isolates obtained through insect-trap. In this sense, bacteria were isolated from dead caterpillars using the insect-trap method, and subsequently, the evaluation of the insecticidal and fungicidal activity of the isolates was carried out, identification of active isolates through sequencing of the 16S rRNA gene and characterization of the growth curve of the bacterium followed by its activity over seven days. In the prospection, 70 bacterial isolates were obtained, 10 of which caused inhibition of the growth of S. frugiperda, through sequencing it was possible to identify that these were the species Enterococcus mundtii, Enterococcus gallinarum, Enterococcus casseliflavus and Serratia nematodiphila, another seven isolates were antagonists of phytopathogenic fungi identified as Serratia marcescens, Bacillus cereus, Enterobacter tabaci. Of the active isolates against S. frugiperda, five showed inhibition of caterpillar growth greater than 90%, these being E. mundtii, E. gallinarum and E. casseliflavus. Of the actives against phytopathogenic fungi, S. marcescens and E. tabaci stood out, which inhibited three of the four evaluated fungi. For the continuity of the studies, among the isolates that were active against S. frugiperda, E. mundtii (isolate 60) was selected due to its high activity and for being classified in level 1 of biosafety. In the growth curve and insecticidal activity of this isolate, a growth inhibition rate higher than 90% and U.F.C. It's from. maximum after 12 and 6 hours of cultivation, respectively. Thus, from the study developed, a series of vi bacterial isolates active against S. frugiperda or phytopathogenic fungi were obtained. Among these isolates, E. mundtii stood out, which caused a drastic inhibition of the growth of caterpillars and has few reports in the literature on this effect, therefore, further studies will be needed to unravel the mechanisms involved.
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Palavras-chave
Microbiologia agrícola, Fitopatologia, Microorganismos