AvaliaÃÃo de nematÃides entomopatogÃnicos visando o controle da cigarra-do-cafeeiro / Evaluation of entomopathogenic nematodes aiming the control of coffee plant cicadas

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

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/cm2. 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).

ASSUNTO(S)

microbial control agronomia controle microbiano hemiptera cicadidae hemiptera cicadidae

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