Avaliação de nematóides entomopatogênicos visando o controle da cigarra-do- cafeeiro
Data
2007-02-27
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Federal de Lavras
Resumo
A cafeicultura no Brasil é bastante expressiva, sendo responsável pela maior produção, consumo e exportação de café do mundo. As espécies Coffea arabica e C. canephora são predominantes e são hospedeiras de alguns insetos- praga de importância econômica como as cigarras. A espécie Quesada gigas (Olivier, 1790) é considerada a principal por apresentar maior tamanho e causar danos mais sérios às plantas. Assim, este trabalho teve como objetivos, desenvolver uma metodologia que permitisse a manutenção das ninfas de cigarras em condições de laboratório, avaliar a eficiência de diferentes isolados de nematóides entomopatogênicos contra ninfas de cigarras, bem como avaliar a virulência destes entomopatógenos e o deslocamento dos mesmos em coluna de solo. Foi realizado um teste para a escolha da concentração utilizada na seleção, que foi de 300 juvenis infectantes (JI) /inseto. Para os bioensaios, as ninfas foram coletadas e inseridas em mudas de cafeeiro e, no dia seguinte, instalado o experimento. Foi avaliada a patogenicidade de diferentes isolados de Heterorhabditis e Steinernema sobre ninfas de cigarras. Cada tratamento constou de quatro repetições e em cada repetição cinco mudas, ou seja, 20 insetos/tratamento, aplicados em 1 mL de suspensão. As avaliações foram realizadas após três e seis dias de inoculação e a confirmação feita cinco dias depois. Os isolados mais virulentos foram selecionados e avaliados nas concentrações que variaram entre 0 e 500 JI/inseto. Foi avaliada também a eficiência de Heterorhabditis sp. JPM 4 e S. riobrave, aplicados em coluna de solo, para observação do comportamento de busca destes nematóides. Este bioensaio foi realizado em cilindros de cano PVC (5 x 15, altura e diâmetro, respectivamente), contendo três ninfas de cigarra cada um, sendo aplicados 4,4 JI/cm 2 . A avaliação foi realizada após cinco dias, sendo realizada a confirmação após este mesmo período. Verificou-se que todos os isolados testados foram patogênicos ao inseto, exceto S. feltiae. Os isolados Heterorhabditis sp. (JPM 4) e S. riobrave foram os mais virulentos, causando mortalidade 50 e 30%, respectivamente, após seis dias de inoculação. Na avaliação de deslocamento vertical, o isolado Heterorhabditis sp. (JPM 4) causou mortalidade total e confirmada até a última profundidade testada (30 cm).
Coffee plantation in Brazil is very important, once it is responsible for the greatest production, consumption and exportation of coffee in the world. The species Coffea arabica and C. canephora are predominant and also host some insect-pests of economical importance such as the cicadas. The species Quesada gigas is considered the principal because it presents bigger size and cause more serious damages to the plants. Therefore, this work aimed developing a methodology which allowed maintaining the nymphs of cicada in laboratory conditions, evaluating the efficiency of different strains of entomopathogenic nematodes against nymphs of cicadas, as well as to assessing the virulence of those entomopathogens and the dislocation of them in ground column. A test was carried out to choose the concentration used in the selection, which was of 300 juvenile infectives (IJ) /insect. For the bioassays, the nymphs were collected and inserted into the seedlings of coffee plant (one nymph/plant) and on the following day the experiment was installed. It was evaluated the pathogenicity of different strains of Heterorhabditis and Steinernema on the cicada nymphs. Each treatment consisted in four replications and in each replication five seedlings; it means 20 insects/treatments, being applied in 1 mL of nematode suspension. The evaluations were carried out after three and six days of inoculation and the confirmation of mortality due five days later. The isolated most virulent were selected and evaluated at the concentrations which varied between 0 and 500 IJ/insect. It was also assessed the efficiency of Heterorhabditis sp. (JPM 4) and S. riobrave, applied in the ground column, for the behavior of searching observation of these nematodes. This bioassay was carried out in cylinders of pipe PVC (5 x 15, height and diameter, respectively), containing three nymphs of cicada each one, being applied 4,4 IJ/cm 2 . The evaluation was carried out five days later, with the confirmation being done after this same period. It was concluded that all the strain tested were pathogenic to the insect, except S. feltiae. The strain Heterorhabditis sp. (JPM 4) and S. riobrave were the most virulent, causing mortality rate around 50% and 30 %, respectively, after six days inoculation. In the evaluation of vertical dislocation, the isolate Heterorhabditis sp. (JPM 4) caused total confirmed mortality up to the last depth tested (30 cm).
Coffee plantation in Brazil is very important, once it is responsible for the greatest production, consumption and exportation of coffee in the world. The species Coffea arabica and C. canephora are predominant and also host some insect-pests of economical importance such as the cicadas. The species Quesada gigas is considered the principal because it presents bigger size and cause more serious damages to the plants. Therefore, this work aimed developing a methodology which allowed maintaining the nymphs of cicada in laboratory conditions, evaluating the efficiency of different strains of entomopathogenic nematodes against nymphs of cicadas, as well as to assessing the virulence of those entomopathogens and the dislocation of them in ground column. A test was carried out to choose the concentration used in the selection, which was of 300 juvenile infectives (IJ) /insect. For the bioassays, the nymphs were collected and inserted into the seedlings of coffee plant (one nymph/plant) and on the following day the experiment was installed. It was evaluated the pathogenicity of different strains of Heterorhabditis and Steinernema on the cicada nymphs. Each treatment consisted in four replications and in each replication five seedlings; it means 20 insects/treatments, being applied in 1 mL of nematode suspension. The evaluations were carried out after three and six days of inoculation and the confirmation of mortality due five days later. The isolated most virulent were selected and evaluated at the concentrations which varied between 0 and 500 IJ/insect. It was also assessed the efficiency of Heterorhabditis sp. (JPM 4) and S. riobrave, applied in the ground column, for the behavior of searching observation of these nematodes. This bioassay was carried out in cylinders of pipe PVC (5 x 15, height and diameter, respectively), containing three nymphs of cicada each one, being applied 4,4 IJ/cm 2 . The evaluation was carried out five days later, with the confirmation being done after this same period. It was concluded that all the strain tested were pathogenic to the insect, except S. feltiae. The strain Heterorhabditis sp. (JPM 4) and S. riobrave were the most virulent, causing mortality rate around 50% and 30 %, respectively, after six days inoculation. In the evaluation of vertical dislocation, the isolate Heterorhabditis sp. (JPM 4) caused total confirmed mortality up to the last depth tested (30 cm).
Descrição
Dissertação de Mestrado defendida na Universidade Federal de Lavras
Palavras-chave
Controle microbiano, Hemiptera, Cicadidae
Citação
SILVA, M. A. T. Avaliação de nematóides entomopatogênicos visando o controle da cigarra-do- cafeeiro. 2007. 49 f. Dissertação (Mestrado em Agronomia/Entomologia) - Universidade Federal de Lavras, Lavras. 2007.